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Friday, 25 January 2019

Plesiosaurs on the rocks: the terrestrial capabilities of four-flippered marine reptiles

Maurice Wilson's charming c. 1958 painting of plesiosaurs coming ashore, from the Daily Mail Boys Annual (note "boys": girls aren't allowed to be interested in prehistory. Get out of our tree house!). Such depictions were commonplace until a few decades ago, but are all but extinct now. So what's happened to the idea that plesiosaurs could venture onto land?
Until comparatively recently it was not uncommon to see depictions of plesiosaurians* on rocks and beaches as if they had hauled themselves from the sea like breeding sea turtles or basking pinnipeds. Such restorations have a long history. Some of the earliest marine reptile palaeoart shows plesiosaurians on beaches or very shallow water, and we've even seen land-based plesiosaurians in feature films and documentaries, including notable sequences in When Dinosaurs Roamed the Earth (1969) and Walking with Dinosaurs (1999, below).

*Why 'plesiosaurians' rather than 'plesiosaurs'? Though a common vernacular, the term 'plesiosaurs' is potentially confusing as it could either refer to a number of marine reptile clades (e.g. plesiosauroids, plesiosaurids) or body plans (plesiosauromorphs). 'Plesiosauria' has a less ambiguous meaning as it specifically refers to the clade encompassing rhomaleosaurids, pliosauroids and plesiosauroids, so it might be a preferable catch-all term this marine reptile clade.

Today, it's much rarer to see plesiosaurians depicted outside of the aquatic realm. For... reasons, I'm restoring a number of marine reptiles at the moment, so I've been wondering if it would be acceptable to revive artwork of these creatures on rocky shores, beaches and other coastlines, if only to bring some variation to my marine scenes. As usual, this inquiry began with a literature crawl. Because 19th century palaeoart suggests palaeontologists once imagined these animals as routinely emerging from the waves, I expected marine reptile papers to be full of discussion about the terrestrial prospects of plesiosaurians, perhaps with an in-depth analysis of the concept bringing an end to the artistic tradition of depicting them on land. The transition from imagining plesiosaurians as semi-aquatic to fully aquatic seems to have happened organically, however: if there's a watershed paper or significant debate behind this, I've missed it. Richard Ellis' 2003 book Sea Dragons - perhaps the closest thing we have to an all-encompassing introductory review of marine reptiles - seems to confirm my independent findings, portraying plesiosaur terrestrial abilities as highly doubtful, but also a question without a firm answer in scientific literature.

Jurassic plesiosaur Cryptocleidus sits around the coasts of the Oxford Clay Sea in 1999's Walking with Dinosaurs. Uploaded to Youtube by user MARTINEZZZ365.

The idea of plesiosaurians leaving water has been strongly tied to historic uncertainty about their reproductive habits. It stands to reason that, if plesiosaurians laid eggs, they must have somehow dragged their way out of the sea to construct their nests (Taylor 1981, 1986). The notion that plesiosaurians could have given birth to live young is pretty old (e.g. Seeley 1896) but scant evidence of their reproductive strategies prevented dismissal of land-based nesting habits until relatively recently. We now have evidence of live birth in plesiosaurian relatives (nothosauroids, Sander 1988; Renesto et al. 2003; Cheng et al. 2004) as well as a true plesiosaurian (a polycotylid, O'Keefe and Chiappe 2011), and so we needn't imagine plesiosaurians hauling out onto beaches to lay eggs, turtle-style.

But I'm going to keep pulling at this thread. While their capacity to give birth to live offspring eliminates the behavioural necessity for leaving water, it does not, in itself, demonstrate that plesiosaurian anatomy was functionally incapable of land-based locomotion, or that they did not leave the sea to find refuge or seize prey - orca style - from shorelines. After all, viviparity does not mean that seals, sea otters or even manatees have committed to a fully aquatic life (a voluntarily beached manatee deserves a citation - see Motani et al. 2015). Is there a cogent functional argument for why plesiosaurians might struggle out of water that will let me (and others) escape painting nothing but blue and green pictures?

How plesiosaurians might have moved on land

Our discussion will be aided by first outlining what we might realistically expect of a walking or crawling plesiosaurian. No one, for instance, predicts that plesiosaurians could stride around like sea lions or the plesiosaur in When Dinosaurs Roamed the Earth. Their flipper skeletons were essentially inflexible so they were incapable of being articulated into a walking limb. This precludes walking on their hands and feet in the way that eared seals can. They were also likely incapable of bouncing along in the manner of true seals, where the flexibility of the spine is used to 'hump' their way forward while powerful, gripping claws pull and steer them around. Plesiosaurian bodies were pretty rigid - their robust gastralia and ribs are sometimes superficially compared to turtle shells - and likely incapable of the twisting and bending necessary to bounce their way over shorelines. And in lacking claws, the only contribution their flippers could make to crawling would be crude pushing and lifting actions.

True seals, such as the grey seal (Halichoerus grypus), are far less terrestrially proficient than the eared seals (sea lions, fur seals etc.) and have to bounce or drag themselves around when ashore. Large claws on their flippers help in this activity (and are also useful for scratching). Grey seal cow photo by Georgia Witton-Maclean.
If plesiosaurians could leave the water at all, we have to imagine something more akin to turtle locomotion: using their flippers to push and pull themselves along while lying on their bellies. Their weight and a likely inability to clear their bodies entirely from the ground predicts that much of their energy would go into overcoming drag incurred by their wide bodies and tails. Terrestrial plesiosaurians would need to make full use of their powerful flipper downstroke muscles (soundly evidenced by the enormous muscles of their chest and the underside of their hips; see Carpenter et al. 2010; Araújo and Correia 2015) to lift their bodies and propel themselves forward. The exact motion of their flippers remains controversial, but is likely to have been a wingbeat-like action (Taylor 1986; Carpenter et al. 2010; Liu et al. 2015; Muscutt et al. 2017) that may have been enough to shove plesiosaurians over shorelines. The picture we're building here is of a slow and laborious means of locomotion. If plesiosaurians did intentionally leave water, they almost certainly visited locations inaccessible to terrestrial predators.

Polycotylid Dolichorhynchops bonneri demonstrating a fairly typical plesiosaurian torso and flipper construction. At face value, the retention of four limbs and stout limb girdles looks like terrestrial locomotion shouldn't be too hard for these guys - they certainly look more terrestrially capable than many other marine tetrapods. From Carpenter et al. (2010). Scale bar is 1 m.
I also think we should rule out raw body size as a compelling reason to doubt land-based locomotion in plesiosaurians. There's no reason to regard plesiosaurians as atypically heavy compared to other marine animals (Everhart 2000, Henderson 2006) and, indeed, their general lack of pachyostosic skeletons might make them lightweight compared to some other aquatic tetrapods (e.g. Street and O'Keefe 2010). Many species were probably within the mass ranges of living species known to transition between land and sea. The known maximum limit for this lifestyle is set by bull elephant seals which, according to Wikipedia, reach 3,000 - 4,000 kg. We don't have many plesiosaurian mass estimates to compare this figure to, but a few noteworthy values are Everhart's (2000) predicted mass of 2.8 tonnes for a 9 m long plesiosauroid, and Henderson's (2006) 217 kg 3 m Cryptocleidus. Truly giant plesiosaurians - 10 and 11 m long individuals - are beyond the masses of big elephant seals (Henderson 2006), but this still leaves plenty of small and mid-sized species at or below the mass threshold of marine species that we know can venture onto land, assuming they have the right adaptations. For me, our question is most appropriately addressed through assessment of anatomy and functional morphology, not a priori judgements about size.

Scrutinising the model

The bar we've set for plesiosaurian terrestrial locomotion is thus pretty low: even if they can only shamble up a beach we could consider our conditions met. But how feasible is even this laborious means of getting around on land? To cut to the chase: not very. There are multiple aspects of plesiosaurian anatomy that probably precluded even very basic terrestrial capabilities.

Plesiosaurian flippers, for instance, seem poorly suited for use on coastal substrates. Semi-aquatic species such as turtles, seals and terrestrially-roaming fish have a degree of jointing or articulation in their forelimbs which transforms them from flippers or paddles into walking limbs (Mazouchova et al. 2013, also see this post on the potentially amphibious ichthyosaur Cartorhynchus). A jointed limb performs considerably better on loose substrates (such as those common on beaches, mudflats and other shoreline locations) because it enables greater control of force distribution as animals move. Immobile flippers tend to skim over or dig into sand or mud, while jointed limbs can respond to yielding substrates to maximise lift and propulsive forces. Where substrates have already been disturbed, fixed-shape flippers can struggle to get any purchase at all (Mazouchova et al. 2013).

The evolution of the plesiosaurian flipper - represented here with early sauropterygians (A - B) and true plesiosaurians (C - D) involves the development of tightly fitting bones and removal of joint mobility. This makes for a superior flipper for an underwater flier, but compromises their terrestrial capacity. Image and caption from Storrs (1993).
Assuming these findings apply to plesiosaurians - and there's no reason they shouldn't - their effectively immobile flippers present a major barrier to terrestrial activity. Plesiosaurian flippers lack both obvious bony joints or significant cartilaginous regions that would allow them to flex, so they best fit those modelled flippers which skid around or dig into the substrates they're meant to traverse. We must consider that their flippers are married to animals that are already encumbered by large size and weight, as well as the additional difficulty of drag forces operating on their bodies as they moved forward. The it hard not to imagine a beached plesiosaurian like a heavy vehicle stuck in sand, spinning its wheels as it tries to move forward.

The issues with plesiosaurian limbs do not stop there as their limb girdles are also ill-equipped for supporting their weight on land. While augmented ventrally to accommodate big downstroke muscles, the upper regions of plesiosaurian shoulder and pelvic girdles are only weakly developed. This isn't unusual for aquatic species as a major role of expanded upper limb girdles - specifically the scapulae of the shoulder, and ilium in the hips - is stabilisation of the limb girdles during terrestrial locomotion (some readers may recall us discussing this recently in context of another marine reptile, Helveticosaurus). But while adequate for life at sea, on land these small girdle elements provide only weak girdle support and thus impede locomotion, and this was probably true for plesiosaurians. Though retaining a connection between the ilia and sacral vertebrae, the articulation is weak and ligamentous, and thus unsuited to weight-bearing (O'Keefe and Chiappe 2011). Similarly, their small scapulae leave little space for muscles associated with stabilising the shoulder against the body, and the shoulder is poorly braced for terrestrial locomotion (see Rieppel 1989 for discussion, also Araújo and Correia 2015). We thus have flippers ill-suited to land-based locomotion attached to limb girdles which are maladapted to weight-bearing. These are not the features of animals that are regularly hauling themselves onto shorelines.

Pelvis of Brancasaurus brancai in lateral (A) and medial (B) view, from Carpenter et al. (2010). Note the extremely narrow ilium: this structure articulates with the vertebrae overlying the hip to act as an important brace for the pelvic girdle during terrestrial locomotion, so its small size does not bode well for the prospects of plesiosaurs leaving water.
And there are further impacts from the reduction of the scapula to be explored. The muscles that elevate our heads and necks are anchored to our scapulae as well as our vertebrae, so the size of bones making up our shoulders dictates how large muscles important to neck elevation and control (e.g. the trapezius, levator scapulae) can be. Plesiosaurians famously have large necks and/or heads, but lack the weight-saving adaptations of similarly proportioned land animals such as pneumatic tissues and reduction or displacement of neck musculature towards the body (e.g. Taylor and Wedel 2013, also see this discussion of the lifestyle of Tanystropheus). Their necks and heads must have thus been heavy compared to those of large necked or big headed terrestrial reptiles**, so we might expect substantial shoulder bones to anchor massive neck elevators if they were routinely leaving water. This casts their tiny scapulae as the exact opposite of what we might expect if these animals were routinely crawling around on land.

**To put some numbers on this, Henderson (2006), modelled plesiosaurian heads and necks with tissue densities of 1.05 g/l, about 1.5 times heavier than a value we assume for a bird or bird-like dinosaur.

The pectoral region and musculature of Rhomaleosaurus, modified from Araújo and Correia (2015). While the humerus is well muscled, the scapula is proportionally tiny compared to the chest, which has implications for shoulder stability and carriage of the head and neck.
Plesiosaurians could have developed an alternative approach to supporting the weight of their heads and necks out of water, such as bulking up the muscles surrounding their neck vertebrae. If so, we could predict structures equivalent to withers (elevated vertebral spines over the shoulders related to expanded neck musculature) in species with particularly large heads and necks. Such structures are not to be found plesiosaurians however, so I don't think this idea is compelling. This being so, it looks like neither the shoulders or anterior trunk vertebrae provide sufficient space for the powerful neck muscles needed to elevate their necks and heads on land for sustained periods. The impact of struggling to lift their heads for long intervals could include further impedance to their locomotion (additional drag, difficulty overcoming obstacles) as well as exposing their facial tissues to abrasion and other damage.

Ventral view of rhomaelosaurid Meyerasaurus victor, as figured by Smith and Vincent (2010). Note that the extensive bones of the chest, hips and gastric regions are entirely unfused: like many secondarily marine animals, plesiosaurian skeletons were likely far more cartilaginous than their terrestrial ancestors. Scale bar is 1 m.
A final, but no less significant, consideration for our inquiry is the high volume of cartilage associated with the plesiosaurian skeleton. A glut of unfused bones and loosely fitting contours between closely associated elements betrays a skeletal system held together primarily through extensive amounts of cartilage tissue. This includes areas of relevance to land-based locomotion, such as the shoulder and hip joints, the limb girdles and the region between the gastralia and ribs. In water, these softer connections wouldn't cause any issue, but on land the flexibility and softness of cartilage might weakens skeletal support and strength. The hypothesis outlined above posits that land-based plesiosaurians are essentially moving around with brute force, shoving their large masses around with motions of their flippers against large drag forces. Under this scenario, a relatively rigid and uncompromising skeletal frame would be ideal, whereas one with large volumes of cartilage would make movement less efficient.

What about small-bodied plesiosaurians?

With ,any aspects of plesiosaurian anatomy looking incompatible with terrestrial activity, we might need to play a biomechanical get-out-of-jail-free card to prevent abandonment of this concept altogether: small body size. Inescapable rules of scaling mean that a given bauplan, expressed at smaller size, can perform biomechanical feats impossible for bigger individuals. Might small plesiosaurian species or juveniles exploit greater relative tissue strength ratios, lower body masses and improved muscle power:weight ratios to haul themselves onto land, leaving only larger plesiosaurians confined to water?

The pliosaurid Thalassiodracon hawkinsi is one of the smallest plesiosaurians known at c. 2 m long, and yet it bears all the same hallmarks of incompetent terrestrial abilities as its larger relatives. Are the virtues of small size enough to justify thinking animals of this size could leave the water? Photo from Wikipedia, by the paleobear, CC BY 2.0.
I must admit that I'm skeptical even here. Anatomically speaking, small plesiosaurians have the same terrestrially-inhibited anatomy as their larger relatives: inflexible flippers, high cartilage volumes, and low weight bearing capabilities for the body, head and neck. Smaller size could make all the difference, but size alone is of ambiguous significance to predictions of extinct animal behaviour. It's clearly a factor in what fossil species could and couldn't do, but it should not overshadow better established relationships between form and function when considering extinct animal lifestyles (see also: flight in giant pterosaurs). So while small size theoretically makes terrestrial locomotion more achievable for an aquatic animal, it's ultimately circumstantial evidence for this behaviour and not an especially compelling counterargument.

And as a final, closing thought on this, it's also worth considering that plesiosaurians were generally large bodied creatures. Genuinely small species (such as the c. 2 m long Thalassiodracon hawkinsi) are rare and even their offspring were large (e.g. 1.5 m calf lengths in 4.7 m long mothers - O'Keefe and Chiappe 2011). Mesozoic shorelines were probably not swarming with small plesiosaurians even if they did have superior terrestrial capabilities, because by and large plesiosaurians weren't small creatures.

Bring on the blue paints

So, should palaeoartists get back to painting plesiosaurs out of water? Sadly, no. Any notion that plesiosaurians were capable of hauling themselves onto land is not only unnecessary in light of what we know of their reproductive biology, but also contradicts much of what we understand about the functional morphology of semi-aquatic animals. Their four-flipped construction looks a little more terrestrially-apt than the bodies of a whale or ichthyosaur, but I suspect an accidentally beached plesiosaurian would be in just as much trouble as these more classically-shaped marine forms. History shows that we can make beached plesiosaurians look half convincing in art, but it's a hollow victory: the science is not on our side.

I still find it odd that there isn't a more detailed discussion of plesiosaurian - or maybe broader sauropterygian - terrestrial capability in marine reptile literature. After all, many clades generally regarded as relatives or even ancestral to plesiosaurians are regarded as semi-aquatic (e.g. nothosaurs, Helveticosaurus) and there has to be an interesting story there regarding the progressive abandonment of land. Hopefully studies along these lines will be performed before we're much older. But for the time being, I'll be restoring all my plesiosaurians in water, where they almost certainly belonged. I'll leave you with this painting of Pliosaurus kevani in their rightful habitat.

Pliosaurus kevani large and small, at home in the sea. Junior is particularly happy that it doesn't have to venture out onto land, probably because it's always freezing cold getting out of the water, and pliosaurids were surprisingly wimpy about that sort of thing. #palaeofact

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References

  • Carpenter, K., Sanders, F., Reed, B., Reed, J., & Larson, P. (2010). Plesiosaur swimming as interpreted from skeletal analysis and experimental results. Transactions of the Kansas Academy of Science, 1-34.
  • Cheng, Y. N., Wu, X. C., & Ji, Q. (2004). Triassic marine reptiles gave birth to live young. Nature, 432(7015), 383.
  • Ellis, R. (2003). Sea dragons: predators of the prehistoric oceans. University Press of Kansas.
  • Everhart, M. J. (2000). Gastroliths associated with plesiosaur remains in the Sharon Springs Member of the Pierre Shale (Late Cretaceous), western Kansas. Transactions of the Kansas Academy of Science (1903), 64-75.
  • Henderson, D. M. (2006). Floating point: a computational study of buoyancy, equilibrium, and gastroliths in plesiosaurs. Lethaia, 39(3), 227-244.
  • Liu, S., Smith, A. S., Gu, Y., Tan, J., Liu, C. K., & Turk, G. (2015). Computer simulations imply forelimb-dominated underwater flight in plesiosaurs. PLoS computational biology, 11(12), e1004605.
  • Mazouchova, N., Umbanhowar, P. B., & Goldman, D. I. (2013). Flipper-driven terrestrial locomotion of a sea turtle-inspired robot. Bioinspiration & biomimetics, 8(2), 026007.
  • Motani, R., Jiang, D. Y., Chen, G. B., Tintori, A., Rieppel, O., Ji, C., & Huang, J. D. (2015). A basal ichthyosauriform with a short snout from the Lower Triassic of China. Nature, 517(7535), 485.
  • Muscutt, L. E., Dyke, G., Weymouth, G. D., Naish, D., Palmer, C., & Ganapathisubramani, B. (2017). The four-flipper swimming method of plesiosaurs enabled efficient and effective locomotion. Proc. R. Soc. B, 284(1861), 20170951.
  • O’Keefe, F. R., & Chiappe, L. M. (2011). Viviparity and K-selected life history in a Mesozoic marine plesiosaur (Reptilia, Sauropterygia). Science, 333(6044), 870-873.
  • Renesto, S., Lombardo, C., Tintori, A., & Danini, G. (2003). Nothosaurid embryos from the Middle Triassic of northern Italy: an insight into the viviparity of nothosaurs? Journal of Vertebrate Paleontology, 23(4), 957-960.
  • Rieppel, O. (1989). Helveticosaurus zollingeri Peyer (Reptilia, Diapsida) skeletal paedomorphosis, functional anatomy and systematic affinities. Palaeontographica Abteilung A, 123-152.
  • Sander, P. M. (1988). A fossil reptile embryo from the Middle Triassic of the Alps. Science, 239(4841), 780-783.
  • Seeley, H.G. (1896) On a pyritous concretion from the Lias of Whitby. Annual Report of the Yorkshire Philosophical Society, 1895, 20–9.
  • Storrs, G. W. (1993). Function and phylogeny in sauropterygian (Diapsida) evolution. American Journal of Science, 293(A), 63.
  • Street, H. P., & O'Keefe, F. R. (2010). Evidence of pachyostosis in the cryptocleidoid plesiosaur Tatenectes laramiensis from the Sundance Formation of Wyoming. Journal of Vertebrate Paleontology, 30(4), 1279-1282.
  • Taylor, M. A. (1981). Plesiosaurs-rigging and ballasting. Nature, 290, 628-629.
  • Taylor, M. A. (1986). Marine reptiles: Lifestyle of plesiosaurs. Nature, 319(6050), 179-179.
  • Taylor, M. P., & Wedel, M. J. (2013). Why sauropods had long necks; and why giraffes have short necks. PeerJ, 1, e36.

Sunday, 23 December 2018

No, Cretaceous sharks did not leap from water to eat flying pterosaurs

How the heavy hitters covered Hone et al. 2018: a short, open-access and easy-to-read paper about a shark tooth preserved with Pteranodon. The Sun gets bonus stupid points for making their own graphic. 
Sigh.

Major news outlets have been reporting this week that a new study evidences prehistoric sharks predating pterosaurs by leaping from the water to snatch them in mid-air. It would be an awesome discovery, if it were true. In reality, these headlines are nothing but a construct by journalists based on a misread palaeoart image, ignorance of some basic facts of animal biology, and lazy science reporting. I'm particularly angry because the study being misreported, and the art being misread, stems from a paper that I recently published with with my friends and colleagues Dave Hone and Mike Habib (Hone et al. 2018). The paper is in PeerJ, and is thus open-access. Anyone - including our dear media - can fact check what we have to say without hitting a paywall.

The nature of modern news is that stories can spread like wildfire, and it's effectively impossible to correct major gaffes once a story gains momentum. With that in mind, the best I can do is outline here what our new paper actually says, what our artwork actually shows, and hope that readers link to this post wherever they see this ridiculous press story being shared. It must be said that a number our outlets are reporting the story more accurately, but enough have mangled our findings that I feel I need to do something. I genuinely care about the accurate conveyance of science, and I've found this distortion of our work and my painting very distressing.

What our paper actually says

OK, first up: a summary of our paper. Mike, Dave and I have documented a series of neck vertebrae from the famous Late Cretaceous pterosaur Pteranodon associated with the tooth of a lamniform shark, Cretoxyrhina mantelli. The vertebrae and their teeth were found in 1965 but our records about their discovery are confused and we don't know whether they were part of a larger discovery of bones, or just a few isolated remains. There are hints that they may have been part of a more impressive skeleton, but it's pretty hard to tell. In any case, today this string of vertebrae is on display at the Los Angeles County Museum as part of a composite skeleton.

Vertebrae are not diagnostic for different Pteranodon species so we refrain from identifying the pterosaur beyond Pteranodon sp. The specimen was found in Niobrara Formation rocks that traditionally yield P. longiceps however, and this is probably the likely species identity- we just can't verify it*. The identification of the shark is better constrained as the tooth is a perfect match for C. mantelli. Indeed, we can even tell which part of the mouth it came from thanks to Cretoxyrhina mantelli being exceptionally well known: even complete skulls and skeletons have been found. This allows us to roughly gauge the size of the Cretoxyrhina as c. 2.5 m long, which makes it a small individual compared to the 6-7 m specimens known from other remains. Our Pteranodon was on the small size as well at c. 5 m across the wings. This is within the upper size range of Pteranodon fossils, but still 1-2 m off the full wingspread of this species.

*If anyone's wondering, yes, we follow the traditional Bennettian concept of Pteranodon taxonomy. It was actually writing the manuscript for this paper that prompted my blog post on Pteranodon taxonomy.

Pteranodon sp. specimen LACM 50926 as mounted as part of a composite skeleton in the Los Angeles County Museum, and in more detail with their hitchhiking Cretoxyrhina mantelli tooth (arrowed). Scale bar is 50 mm. From Hone et al. 2018.
The Cretoxyrhina tooth does not actually penetrate the pterosaur bone, but is wedged beneath a vertebral process in a complex, intimate manner. We assume this evidences the shark biting into the pterosaur neck and shedding a tooth into its soft-tissues. An alternative - that the specimens became associated through actions of currents or storms - is less plausible given the strange position of the tooth, its tightness to the specimen, as well as the gentle, low-energy marine conditions of the Niobrara Formation.

But what sort of circumstances brought these animals together? It's here that our questions go beyond what the fossils can tell us. There's only so much a single tooth and string of vertebrae can objectively reveal about an ancient animal interaction, and we conclude that either a predatory and scavenging act could have produced the association - there's just no way to tell. While a scavenging story explains itself (short version: pterosaur dies over water; shark gets a meal), we explored how a predatory scenario may have played out given the known fish-eating habits of Pteranodon and hypotheses that this pterosaur regularly dived or swam to catch its prey (e.g. Bennett 2001; Hone and Henderson 2014; Witton 2013, 2018). Swimming pterosaurs are a new idea to many but substantiated by several lines of evidence, including swimming tracks, modelling of their aquatic launch strategy, and studies of their floating capability (Lockley et al. 2003; Habib and Cunningham 2010; Hone and Henderson 2014). We propose that if Pteranodon was a regular swimmer it would be vulnerable to sharks and other large predators, and its flight muscles would surely be a decent meal for many carnivores. Pterosaurs were probably pretty sinewy across their limbs, but there'd be some sizeable steaks to carve from their shoulders and chests. As big, powerful predators, it seems entirely plausible that even a half-size Cretoxyrhina would be capable of subduing a large Pteranodon, assuming they could catch one.

And that is as far as we go in our paper - it's pretty conservative stuff. You can read another summary of the paper at Dave Hone's Archosaur Musings.

The illustration

Rocket shark eats flying pterosaur? No. Artwork of a small Cretoxyrhina mantelli attacking a group of floating Pteranondon longiceps, erupting from the sea with one in its jaws. Note the other swimming pterosaurs in this picture - it's almost like pterosaurs weren't always flying, or something. From Hone et al. 2018.
Mike, Dave and I are palaeoart fans and we all - perhaps myself especially - enjoy well-illustrated papers, so we decided to include a reconstruction of Cretoxyrhina vs. Pteranodon in our paper (above). Having recently drawn an image of Pteranodon being hounded by another Cretaceous shark, Squalicorax, at the water surface, I wanted to do something different with this illustration and decided on a more exciting breaching scene: a shark leaping from the water with a Pteranodon in its mouth. Anyone who's watched even a few wildlife documentaries will know this behaviour is far from speculative: it's a widely-filmed, photographed and documented behaviour of South African white sharks (see Planet Earth excerpt from BBC Earth, below). These sharks strike floating prey with such speed that they leap entirely from the water. It's very dramatic, very awesome and seemed like great inspiration for a palaeoartwork. And sure, we have no idea that Cretoxyrhina did this, but a breaching attack is no more or less speculative than any other means of depicting a shark tooth lodging in a Pteranodon neck. I won't bore you with some additional practical factors that influenced the composition (in short, this image is being featured in an upcoming book where I have some firm ideas about visual narrative, and this strongly influenced choices of posture and colour).

In my mind, shark breaching is a widely known, instantly recognisable behaviour that shouldn't be foreign to folks writing science articles. It's routinely covered in major documentary programmes like Planet Earth, as shown here in this YouTube clip from BBC Earth. It's weird to me that folks are assuming my artwork has to be something more awesome than this, just because a pterosaur is involved.

A number of swimming and water-launching pterosaurs were added in the background of the image to make it clear that the Pteranodon was caught from a floating position. In my mind, the image shows a flock of pterosaurs busying themselves in the sea before Cretoxyrhina crashes their party - you can invent your own reasons for all the Pteranodon milling about. Maybe they're foraging, maybe they're congregating for another reason - it doesn't matter too much, what matters is that the sea has six or so Pteranodon either floating or launching from the water. Also note that water is shedding from the main pterosaur's wings, as if it's just left the water along with the shark. I carefully referenced how much water should be flying about using footage and photos of breaching sharks around the peak of their arcs: we often overdo water dynamics in palaeoart, and I was keen to make this image grounded in spite of its spectacular action.

So what's gone wrong?

What we've ended up with, then, is a pretty simple, conservative paper with an illustration that is pretty bleeding edge in terms of pterosaur science (flying reptiles as swimmers) and radical in terms of shark behaviour (breaching). But the two are entirely compatible with one another and the image is appropriately grounded in zoology and palaeontology. It looks extreme, but it's not ridiculous compared to what happens in modern natural history.

Unfortunately, this broader face of our project has been neglected in the media. Instead, our artwork - or rather a knee-jerk, lunkhead interpretation of it - has become the media story and we now have 'science-endorsed' headlines stating that sharks shot out of the water to grab pterosaurs (or even 'flying dinosaurs' in several articles) when they soared overhead. As I've outlined here, this is entirely false, and not representative of our ideas at all. Any hope that our paper could be used to broadly communicate some cool ideas about pterosaur ecology, the role of sharks as important predators throughout the Mesozoic, or even the simple fact that pterosaurs could likely swim has been lost behind ridiculous headlines based on erroneous readings of my picture.

So that's basically that - this is essentially a tale of how quickly false information can spread when it's attached to a pretty image, and why we shouldn't believe everything we read. Perhaps there's a lesson here in the power of imagery, and I am certainly now wondering if I erred in my reconstruction being too complex (to my defence, I did not contribute to the PR campaign for this and did not get the opportunity to sign off on an appropriate description for the picture). Perhaps we're looking at the reality of naive audiences assuming that anything to do with sharks or prehistoric creatures must automatically be the most awesome, badass thing. Maybe I erred in my assumption that people would be familiar with the basics of breaching shark behaviour.

But what this hits home hardest for me is the reality of science reporting in our digital, content-fuelled age. Anyone who led with the stupid shark vs. flying pterosaur headline went nowhere near our actual paper to check what we said, even though it was literally just a link click away. They simply parroted one another to make sure their outlets have the same stories as everyone else. Only a few thought to double check what our conclusions were, and I find that distressing. Remember folks, these are the same guys who're reporting news about far more important things than pterosaurs: vaccinations, climate change, health and environmental issues, and so on: these pterosaur-devouring rocket sharks are stark reminders of how they work. If you've seen accurately reported examples of this story (and they do exist) then add those news services to your bookmarks: they are rare examples of media outlets that aren't jumping our shark.

If understanding pterosaur ecology through fossil associations is of interest, be sure to check out this series of three blog posts: part 1, part 2, and part 3.

Enjoy monthly insights into palaeoart, fossil animal biology and occasional reviews of palaeo media? Support this blog for $1 a month and get free stuff!

This blog is sponsored through Patreon, the site where you can help online content creators make a living. If you enjoy my content, please consider donating $1 a month to help fund my work. $1 might seem a meaningless amount, but if every reader pitched that amount I could work on these articles and their artwork full time. In return, you'll get access to my exclusive Patreon content: regular updates on research papers, books and paintings, including numerous advance previews of two palaeoart-heavy books (one of which is the first ever comprehensive guide to palaeoart processes). Plus, you get free stuff - prints, high quality images for printing, books, competitions - as my way of thanking you for your support. As always, huge thanks to everyone who already sponsors my work!

References

  • Bennett, S. C. (2001). The Osteology and Functional Morphology of the Late Cretaceous Pterosaur Pteranodon Part II. Size and Functional Morphology. Palaeontographica Abteilung A, 113-153.
  • Habib, M. B., & Cunningham, J. (2010). Capacity for water launch in Anhanguera and Quetzalcoatlus. Acta Geoscientica Sinica, 31, 24-25.
  • Hone, D. W., & Henderson, D. M. (2014). The posture of floating pterosaurs: ecological implications for inhabiting marine and freshwater habitats. Palaeogeography, Palaeoclimatology, Palaeoecology, 394, 89-98.
  • Hone, D. W., Witton, M. P., & Habib, M. B. (2018). Evidence for the Cretaceous shark Cretoxyrhina mantelli feeding on the pterosaur Pteranodon from the Niobrara Formation. PeerJ, 6, e6031.
  • Lockley, M. G., & Wright, J. L. (2003). Pterosaur swim tracks and other ichnological evidence of behaviour and ecology. Geological Society, London, Special Publications, 217(1), 297-313.
  • Witton, M. P. (2013). Pterosaurs: natural history, evolution, anatomy. Princeton University Press.
  • Witton, M. P. (2018). Pterosaurs in Mesozoic food webs: a review of fossil evidence. Geological Society, London, Special Publications, 455(1), 7-23.

Friday, 30 November 2018

Helveticosaurus: the small-headed, long-armed Triassic marine reptile that just wants to be your friend :(

Helveticosaurus zollingeri, one of those strange Triassic marine reptiles that no-one ever talks about, wrestling in a coastal swamp. Not everything about being a marine tetrapod takes place in the sea.
The fossil record is full of fascinating, relatively well-represented species that, on paper, seem like they should be widely known and featured in all sorts of palaeontological media, and yet in reality are almost entirely overlooked in popular literature, documentaries and games. Triassic marine reptiles are definitely among these animals. Many are distinctive, unusual and well-researched species that are just as interesting (if not more so) than many more familiar Triassic animals, and yet their popular coverage is frequently dire: even their Wikipedia pages are little more than footnotes.

In interests of trying to correct this injustice even a little, it's time to talk about a Triassic marine reptile with a criminally poor popular coverage/deserved interest ratio: Helveticosaurus zollingeri. Discovered in Middle Triassic rocks of Switzerland in 1933 and described some years later (Peyer 1955), this small-headed, long-armed marine reptile represents a unique anatomical experiment among aquatic tetrapods: a sort of lizard-seal thing with a skull from an '80s supernatural horror film. Its basic bauplan is well demonstrated thanks to a mostly complete and reasonably preserved holotype, missing only the end of the tail and some parts of the limbs. Alas, some especially informative aspects of its anatomy are poorly represented, including the skull, distal limbs and pelvis. Though all are present, they are disarticulated and difficult to interpret. Additional Helveticosaurus specimens are known (Kuhn-Schnyder 1974), but are not as well preserved or complete as the holotype and don't add much to our knowledge of this species (Rieppel 1989). Though attracting reasonable scientific interest in the last half century, much about its lifestyle and evolutionary relationships remain unexplored or contentious.

The Helveticosaurus zollingeri holotype, as illustrated by Kuhn-Schnyder (1974). Although a little jumbled, a good portion of the skeleton is preserved. It's unfortunate the skull is such a mess. Check out Wikipedia for a photo of the actual specimen.
Much of our modern take on this animal has been informed by Olivier Rieppel's 1989 paper on its anatomy and function, and the following overview is largely based on this assessment. Helveticosaurus was a small-headed creature with a short neck, long body and a tail of unknown length. The preserved portion of the tail comprises large, well developed vertebrae and it doesn't seem unreasonable to assume it was much longer when complete. If we had a more secure idea of the phylogenetic position of Helveticosaurus we might take a stab at estimating the tail length, but this doesn't seem possible at the moment.

Tail proportions are not the only issue confusing predictions of the overall body length of this animal. When preparing this post I found that the total length estimates of Helveticosaurus provided in modern papers are at odds with measurements of skeletal elements within the holotype, to the effect that we might be significantly underestimating its overall size. Recent papers give a total predicted length of c. 2 m for the holotype animal (e.g. Rieppel 1989; Cheng et al. 2014), while also reporting that the lower jaw of the same specimen is 250 mm long, and the humerus as 205 mm (Rieppel 1989; Cheng et al. 2014). Even just eyeballing images of the holotype suggests some sort of miscalculation here: there's no way the entire animal - including the missing tail - is just 10 times the length of these bones. Using a line drawing of the holotype from Khun-Schnyder (1974) and the reported mandible and humerus measurements, I found that 2.1 - 2.8 m better describes the length of the preserved skeleton (see calculations in the image below, note that the reported 45 mm difference between the humerus and mandible length is not obvious in the drawing I used, resulting in two different body length estimates. Scaling from photos or illustrations is not a substitute for measuring actual specimens). This is back-of-the-envelope stuff, but it's enough to convince me that Helveticosaurus wasn't a 2 m long animal. I wonder if the figures reported by Khun-Schnyder (1974) are more plausible: he reported a 2.5 m length for the preserved holotype skeleton, and an estimated total length of 3.6 m. That would add another metre onto the holotype, which seems quite plausible - maybe even conservative - to me.

Just how big was Helveticosaurus? It's hard to say without a complete specimen, but the individual represented by the holotype skeleton clearly exceeded the oft-cited 2 m body length. Perhaps other published estimates of 3.6 m are more reasonable?
One of the most interesting features of Helveticosaurus is its short, c. 25 cm long skull. Alas, the best Helveticosaurus skull remains we have look as if they were hit by a truck before fossilisation: scattered, broken, and with many unidentifiable parts (Rieppel 1989). Enough is known to allow for a tentative reconstruction but a confident picture of the face of Helveticosaurus awaits better preserved material. The front of the upper jaw was abbreviated, blunt and tall, creating a skull profile that might have been somewhat box-like in lateral aspect. The orbital and temporal regions are poorly known, but they seem to hint at the presence of an upper and lower temporal fenestrae and a large eye socket. A number of oversize conical teeth line each jaw. The exact number of teeth is unknown, but a notable feature is the large 'canine' in the upper jaw. Neither the size of the temporal region or the lower jaw (the latter being one of the best preserved cranial elements) imply an especially large set of jaw muscles, though the mandible has an expanded retroarticular process - a prong of bone at the back of the jaw associated with opening the mouth. This likely has implications for the feeding style of Helveticosaurus, although I'm unaware of any studies into its function. The aberrant size of the Helveticosaurus skull is peculiar for a marine reptile lacking a long neck, and perhaps only challenged in proportion by the Triassic marine vacuum cleaner Atopodentatus (Cheng et al. 2014). Distinct anatomy make it clear that these animals were very different ecologically however, and it's possible that their diminutive skulls reflect very different adaptive regimes.

Tentative Helveticosaurus skull reconstruction, from Rieppel (1989). The jaws remain the best known elements, and some question exists over the arrangement of the rest of the skull. Scale bar represents 50 mm.
The body of Helveticosaurus is similar, at least superficially, to many other Triassic marine reptiles, especially early sauropterygians. It's torso was long, with well-developed and high-spined vertebrae, stout ribs and an extensive set of gastralia (belly ribs). Differentiation between the vertebral spines at the front and back of the body hint at some functional distinction, perhaps related to larger muscles associated with the shoulder region (Rieppel 1989). As is assumed for plesiosaurs, the combination of stout ribs and gastralia likely reduced the flexibility of the torso and may have improved swimming efficiency. The tail, so much as it is known, bears the same high neural spines as the trunk vertebrae, as well as caudal ribs. These features indicate it was likely well-muscled for use in sculling propulsion, although the chevrons are not particularly large. Assuming these anchored the caudofemoralis muscle, as they do in most reptiles, I wonder if this indicates diminished musculature associated with hindlimb retraction.

After the peculiar head, the forelimbs of Helveticosaurus are perhaps its most unusual feature. They anchored to an atypically well-developed pectoral girdle which - unlike most marine reptiles - has a long, robust scapula. Marine reptile shoulder blades are often extremely reduced, little more than bony nubbins that create a shoulder joint. But here, the scapulae are long enough to create a deep, U-shaped shoulder girdle that would not look out of place on a terrestrial animal (Rieppel 1989). The forelimb itself is proportionally elongate, both with respect to the body and in comparison to the hindlimb. It's exact length remains uncertain because the bones of the hand are scattered, but the major limb bones are each 10% longer than their counterparts in the hindlimb. The humerus in particular is very long for a marine reptile, and maintains hallmarks of functionality beyond just being the top of an stiffened flipper (Rieppel 1989). The fingers are hyperphalangic (i.e. they have an enhanced number of finger bones) in a fashion typical of marine tetrapods, and - in contrast to several Helveticosaurus palaeoartistic reconstructions (all five of them that exist) - they lack claws. The arrangement of the fingers requires some reconstruction but their slender bones and arrangement in the holotype implies more of a broad, rounded paddle than a narrow ichthyosaur or plesiosaur-like flipper.

Helveticosaurus forelimb, as illustrated by Rieppel (1989). Some ribs and gastralia have been removed for clarity. Note the elongate scapulae and long forelimb elements - this is not a typical marine reptile arm. Scale bar represents 100 mm.
The hindlimb shares some general characteristics with the forelimb - relatively elongate limb bones for a marine form, hyperphalangy, spreading, unclawed digits - but is shorter, noticeably more gracile and probably more cartilaginous than the forelimb. The pelvis is poorly known, but it also appears to have been at least partly cartilaginous, the joints of the pelvic bones being insufficient to contact one another around the hip joint without some additional skeletal material (Rieppel 1989). These features imply that the hindlimb was structurally weaker than the forelimb.

How might this mix of anatomies have functioned? A qualified assessment by Rieppel (1989) makes some sensible interpretations of Helveticosaurus locomotion. On the whole, the animal is mostly adapted for life in water, with aquatic adaptations being especially obvious on the limbs, pelvis and tail. Although the tail is missing, its robust, high-spined and complex vertebrae are consistent with features of sculling animals and we might envisage Helveticosaurus propelling itself with powerful motions of its tail when swimming, akin to marine iguanas or crocodylians. The weak pelvis and hindlimb indicate the rear limbs contributed less to propulsion. Rieppel proposes that, like swimming lizards, they may have been pulled against the body when swimming save for the occasional action to help with steering or thrust. The forelimbs were evidently strong and likely useful in swimming, though the configuration of the shoulder girdle does not imply any rigid kinematics for underwater flight in the manner of a penguin or turtle. They might have functioned more like the foreflippers of otariid seals (the eared seal group: sealions, fur seals etc.) in providing some thrust, but also playing important roles in steering and breaking (Rieppel 1989). While the shoulder girdle does not seem optimised for powerful downstrokes, the large size of the arm, and implied articulation of at least some parts of the limb (see below), suggest it was a dynamic steering aid. Helveticosaurus may have been quite an agile swimmer.

But where Helvetiosaurus becomes especially interesting is out of the water. Even in the Middle Triassic many marine reptiles had wholly committed themselves to aquatic lifestyles, but Helveticosaurus appears to have remained some terrestrial capabilities. Why it did this remains uncertain: did it still lay eggs? Did it have a complex life history involving both land and sea phases? Did it live in settings where periodic escapes from the sea were advantageous? We don't have insights into any of this yet, but we can predict how Helveticosaurus might have moved around on land. Supporting limbs during terrestrial gaits is not simply a matter of having strong limb bones, it's also necessary to have a robust and stable limb girdle. For shoulders, this requires support and control exerted by muscles attached to the torso and neck, as well as having a big enough scapula for these to act on. The robust shoulder girdle of Helveticosaurus seems to meet these criteria. It not only provides space for the necessary muscle to support and move the forelimb on land but also - with particular reference to the relatively big scapula - is sufficiently developed to brace the shoulder against the body skeleton (Rieppel 1989). The length and robustness of the forelimb is also notable, as are the retention of humeral features associated with flexing the lower limb. Marine reptile limbs are often immobile south of the shoulder or hip, and readers with good memories might recall that this makes terrestrial locomotion difficult. The articulations of the Helveticosaurus limb are not well preserved - they seem to have been highly cartilaginous - so we don't know the full extent of its forelimb mobility, but muscle attachment scars hint at abilities to flex the wrist and fingers (Rieppel 1989). Any flexible jointing would enhance its terrestrial potential, so this is another tick in the box for relatively proficient land locomotion. The hindlimb, in being less developed and more cartilaginous, probably contributed little to terrestrial locomotion. Helveticosaurus may have therefore crawled and flopped around more like a seal than a lizard, using its arms to drag and push itself around, maybe occassionally assisted by its legs and thrashing motions of the tail to propel itself faster. It must have been pretty neat to see a reptile move like this: a sort of creeping, lolopping reptile-mermaid topped off with the face of the Engineer from Hellraiser.

When Helveticosaurus collide. In the image illustrating this article, I've assumed that the terrestrial capabilities of Helveticosaurus were sufficient to bring them into terrestrial coastal habitats, perhaps for mating, nesting or some other reason. We have no evidence of this happening, but analogous behaviours are seen today in turtles and seals, some of which travel kilometres inland despite their limited terrestrial abilities. Maybe some Mesozoic marine reptiles did the same.
We can't go this far into discussion of Helveticosaurus without questioning its ecology. I'm not aware of any analyses that address this issue, so this paragraph is shot from the hip based on what others have said about its functional morphology and a basic form-function reading of Helveticosaurus anatomy - take it with an appropriate pinch of salt. As already noted, the skull of Helveticosaurus is too poorly preserved to say much about specifics of foraging, but its long, slender teeth clearly betray a predatory lifestyle. Worn tooth tips indicate that it did not eat entirely soft, fleshy prey, but the teeth are not robust enough to suggest a tough diet. I'm aware that a similar suite of dental features occur in pterosaurs that are assumed to small fish, squid and other diminutive swimming creatures (Ősi 2010), and I wonder if a similar diet might apply here. The skull of Helveticosaurus is also too small to suggest it routinely ate large prey, though I guess scavenging carcasses is difficult to rule out. The enlarged retroarticular process is of interest because such features are often seen in suction feeders - aquatic animals which rapidly open their mouths to suck up prey within a pressure gradient. Short faces often characterise suction feeders too, but we need knowledge of other anatomies - such as the bones of the throat - to reliably infer such foraging strategies (Motani et al. 2014). We also have to acknowledge that a short jaw and specifics of the posterior mandible can be related to other functions. A small head capable of fitting between rocks and other obstacles would be useful if Helveticosaurus sought benthic or demersal prey, for instance. The combination of a swimming tail and large limbs may have made Helveticosaurus relatively agile, a useful trait when chasing small prey. In all, I wonder if the seal analogy applied to some aspects of Helveticosaurus anatomy and locomotion might extend to its lifestyle. It would be great to see this looked into with a dedicated study.

Bringing this post back to firmer scientific ground, it's finally time to ask: just what the heck is Helveticosaurus? Initially interpreted as a placodont (Peyer 1955), Helveticosaurus has since jumped all over the reptile tree as different teams use different approaches to resolve its placement. There are probably several reasons for our inability to pin down the evolutionary home of Helveticosaurus. Firstly, the anatomy of Helveticosaurus confuses character distribution in phylogenetic trees, it having features of enough groups to scramble easy reading of homologies and convergences (Ezcurra et al. 2014). This makes Helveticosaurus very sensitive to taxon and character choices used in our evolutionary calculations, and prone to shifting in position dramatically from one cladogram to the next (e.g. Chen et al. 2014). Helveticosaurus is far from the only marine reptile to present such a problem, and there are debates among researchers about how to deal with what some regard as a problematic amount of convergence between aquatic Mesozoic reptiles (see, for recent takes, Chen et al. 2014 vs. Scheyer et al. 2017). A third issue concerns the ongoing controversy over the origins of marine reptiles generally. The relationships of even well-supported groups like ichthyosauromorphs, turtles and sauropterygians to other reptiles remain contested, and these clades have major 'pull' in phylogenies when they move about, hauling possible relatives like Helveticosaurus around as tree topologies change.

We don't know of any species quite like Helveticosaurus, but the Triassic diapsid Eusaurosphargis dalsassoi - here represented by an excellent fossil of a juvenile skeleton - has been recovered as a near relative in several recent analyses. Intriguingly, it also seems well adapted for terrestrial locomotion, implying that such abilities may have been common to their branch of marine reptile evolution. Image from Scheyer et al. (2017).
Perhaps for this reason, it's not uncommon to see many authors sidestepping classifying Helveticosaurus altogether, instead simply labelling it an 'enigmatic diapsid' and moving on. But others have tackled the issue more head on and, while it would be premature to say we know what Helveticosaurus is, some clarity is emerging about which branch of reptile evolution it belongs to (even if the position of that branch is a more open question). The placodont affinity for Helveticosaurus has been questioned on grounds of very limited shared anatomies (Sues 1987; Rieppel 1989) and this identification has not been supported in recent analyses. Other ideas - a tentative interpretation as some sort of archosauromorph (Rieppel 1989; Naish 2004) or a near relative of lepidosaurs (Chen et al. 2014) - have also not found much traction. But a large number of authors have recovered Helveticosaurus as a close relative of Sauropterygia (Müller 2004; Bickelmann et al. 2009; Li et al. 2011, 2014; Neenan et al. 2013; Chen et al. 2014; Scheyer et al. 2017), and it's looking like this is the best horse to back concerning the phylogenetic position of this historically enigmatic animal.

Alas, this is not the neat end of the story we might think it is, as the origins of Sauropterygia itself remain poorly understood. In at least some analyses Helveticosaurus and Sauropterygia is part of a marine reptile 'superclade', a huge, unnamed group containing ichthyosaurs, sauropterygians and a number of Triassic lineages that have long struggled to find homes. Another Swiss Triassic reptile, the possibly mostly terrestrial Eusaurosphargis dalsassoi (above), has been postulated as a close relative of Helveticosaurus several times (e.g. Scheyer et al. 2017). Sauropterygians are deeply nested in this 'superclade' and the position of the terrestrially-enabled Helveticosaurus and Eusaurosphargis is interesting with respect to the evolution of aquatic lifestyles in Triassic marine reptiles. Given that more rootward lineages in the 'superclade' are entirely aquatic forms, might genera like Helveticosaurus and Eusaurosphargis represent animals that returned to land from swimming ancestors, or are they representatives of a more basic semiaquatic ancestral bauplan that remains underrepresented in other lineages? At the risk of ending on an old palaeontological cliche, we need more specimens, more data and more investigations to answer these questions.

It turns out that marine reptiles are a pretty fun group, I think you'll be seeing more art and reading more about them here in the coming months. If all goes to plan, we'll be walking (or not) with plesiosaurs and meeting some giant ichthyosaurs before too long.

Enjoy monthly insights into palaeoart, fossil animal biology and occasional reviews of palaeo media? Support this blog for $1 a month and get free stuff!

This blog is sponsored through Patreon, the site where you can help online content creators make a living. If you enjoy my content, please consider donating $1 a month to help fund my work. $1 might seem a meaningless amount, but if every reader pitched that amount I could work on these articles and their artwork full time. In return, you'll get access to my exclusive Patreon content: regular updates on research papers, books and paintings, including numerous advance previews of two palaeoart-heavy books (one of which is the first ever comprehensive guide to palaeoart processes). Plus, you get free stuff - prints, high quality images for printing, books, competitions - as my way of thanking you for your support. As always, huge thanks to everyone who already sponsors my work!

References


  • Bickelmann, C., Müller, J., & Reisz, R. R. (2009). The enigmatic diapsid Acerosodontosaurus piveteaui (Reptilia: Neodiapsida) from the Upper Permian of Madagascar and the paraphyly of “younginiform” reptiles. Canadian Journal of Earth Sciences, 46(9), 651-661.
  • Chen, X. H., Motani, R., Cheng, L., Jiang, D. Y., & Rieppel, O. (2014). The enigmatic marine reptile Nanchangosaurus from the Lower Triassic of Hubei, China and the phylogenetic affinities of Hupehsuchia. PLoS One, 9(7), e102361.
  • Cheng, L., Chen, X. H., Shang, Q. H., & Wu, X. C. (2014). A new marine reptile from the Triassic of China, with a highly specialized feeding adaptation. Naturwissenschaften, 101(3), 251-259.
  • Ezcurra, M. D., Scheyer, T. M., & Butler, R. J. (2014). The origin and early evolution of Sauria: reassessing the Permian saurian fossil record and the timing of the crocodile-lizard divergence. PLoS One, 9(2), e89165.
  • Kuhn-Schnyder, E. (1974). Die Triasfauna der Tessiner Kalkalpen. Neues Jahrbuch der Naturforschenden Gesellschaft in Zürich, 176, 1–119
  • Li, C., Rieppel, O., Wu, X. C., Zhao, L. J., & Wang, L. T. (2011). A new Triassic marine reptile from southwestern China. Journal of Vertebrate Paleontology, 31(2), 303-312.
  • Li, C., Jiang, D. Y., Cheng, L., Wu, X. C., & Rieppel, O. (2014). A new species of Largocephalosaurus (Diapsida: Saurosphargidae), with implications for the morphological diversity and phylogeny of the group. Geological Magazine, 151(1), 100-120.
  • Motani, R., Ji, C., Tomita, T., Kelley, N., Maxwell, E., Jiang, D. Y., & Sander, P. M. (2013). Absence of suction feeding ichthyosaurs and its implications for Triassic mesopelagic paleoecology. PLoS One, 8(12), e66075.
  • Müller, J. (2004). The relationships among diapsid reptiles and the influence of taxon selection. In G. Arratia, M. V. H. Wilson & R. Cloutier (eds.): Recent advances in the origin and early radiation of vertebrates, 379-408.
  • Naish, D. (2004). Fossils explained 48: Placodonts. Geology Today, 20(4), 153-158.
  • Neenan, J. M., Klein, N., & Scheyer, T. M. (2013). European origin of placodont marine reptiles and the evolution of crushing dentition in Placodontia. Nature Communications, 4, 1621.
  • Ősi, A. (2011). Feeding‐related characters in basal pterosaurs: implications for jaw mechanism, dental function and diet. Lethaia, 44(2), 136-152.
  • Peyer, R. (1955). Die Triasfauna der Tessiner Kalkalpen. XVIII. Helveticosaurus zollingeri, n. g. n. sp. Schweizerische Palaeontologische Abhandlungen, 72, 1–50.
  • Rieppel, O. (1989). Helveticosaurus zollingeri Peyer (Reptilia, Diapsida) skeletal paedomorphosis, functional anatomy and systematic affinities. Palaeontographica Abteilung A, 123-152.
  • Scheyer, T. M., Neenan, J. M., Bodogan, T., Furrer, H., Obrist, C., & Plamondon, M. (2017). A new, exceptionally preserved juvenile specimen of Eusaurosphargis dalsassoi (Diapsida) and implications for Mesozoic marine diapsid phylogeny. Scientific reports, 7(1), 4406.
  • Sues, H. D. (1987). On the skull of Placodus gigas and the relationships of the Placodontia. Journal of Vertebrate Paleontology, 7(2), 138-144.

Tuesday, 23 October 2018

An interview with Katrina van Grouw, author and artist of The Unfeathered Bird and Unnatural Selection

If you're the sort of person who's interested in cool stuff like anatomy, evolution and functional morphology, you can't have missed two incredible books published in recent years by author and artist Katrina van Grouw: The Unfeathered Bird (2013) and Unnatural Selection (2018). Although tackling different topics, they are united by their exceptional illustrations of animals in various states of dissection (though mostly skeletonised), lavish design, great production quality and highly detailed yet accessible text. The Unfeathered Bird, which focuses on bird skeletal anatomy and functional morphology, caused ripples in the palaeontological community upon release for being a book which looks at modern birds the way we look at fossil animals. As a monumental book - huge, comprehensive, scholarly and aesthetically spectacular - I'm sure we would all have been happy with more of the same for Katrina's follow up project (The Unfuzzy Mammal, The Unscaled Reptile, The Un... er... skinned Amphibian?) but her latest book, Unnatural Selection, is even more ambitious in scope, detailing how human-controlled animal breeding - the titular 'unnatural selection' - offers a window into the mechanics of biological evolution.

Katrina's new book, Unnatural Selection, available now from Princeton University Press, all the usual online retailers and good book shops.
To celebrate the release of Unnatural Selection a few months ago, I invited Katrina to give an interview about her new book, her art, and her future projects. I do this as a certified van Grouw fan: the Disacknowledgement and I have three van Grouw artworks on our wall in addition to her books on our shelves. Katrina has always skirted the line between author, scientist and artist and, before The Unfeathered Bird, she already had a background in fine art, museum curation (bird skin curation at the Natural History Museum) and book writing. I will fully confess to finding her skills and knowledge intimidating, and was a little frightened of meeting her at the 2015 TetZooCon. After all, if anyone was ever going to expose my work for the hack job it is, it would be this Baroness van Grouw, dual master of detailed anatomy and artistry (lightning flashes, thunder rumbles)*. It turns out that it's actually impossible to be scared of Katrina once you talk to her however, and we remain close friends today.

*Note that Katrina's status as a Baroness is a product of my over-active imagination, not reality. 

There's lots to like about Katrina's books, and I mean no disrespect when saying that they're some of my favourite books simply to look at. Katrina's illustrations - drawn in pencil and then tinted to sepia tones digitally - are truly world class, and her subjects are frequently drawn in lively, life-appropriate poses so that, even when skeletonised or half-dissected, they look very much alive. But it's not only the drawings which make her books exceptional to behold: their size, ivory-coloured pages, font hues and text layouts recall a romanticised age of 19th century museums and scholarship. It's impossible not to think of exhibition halls filled with wooden cabinets, animal bones, taxidermy specimens, curiosities in jars and stuffy formalwear when reading these books. They evoke the atmosphere of a classic age of learning and exploration on every page. It must be stressed how, for their size and quality, both The Unfeathered Bird and Unnatural Selection are exceptionally good value for money ($45-50 cover price, but being sold at £20-25 at Amazon UK, and equivalent in the US). I can only wonder what Mephistophelian deal Princeton University Press has made to to sell these fantastic books at such low costs and, to the poor production editors suffering in the afterlife for making such a deal, know that it was really worth it: I can't think of many books published in recent years that are anywhere near as splendid to look at in this price bracket. For next-level book quality I can only think of tomes like the considerably more expensive (but ultimately disappointingPaleoart: Visions of the Prehistoric Past (Lescaze 2017), with a cover price twice that of Katrina's books.

Fans of The Unfeathered Bird will be intimately familiar with Katrina's skeletonised birds. Unnatural Selection offers a greater proportion of art devoted to living individuals, including this jungle fowl, the ancestral species of chickens. © Katrina van Grouw.
But to only look at The Unfeathered Bird or Unnatural Selection would be a huge disservice to their scholarly content. The academic merits of The Unfeathered Bird are widely known and I won't rehash them here - suffice to say that, if you're a regular reader of this blog, you'll want a copy. Although much newer, the amazingness of Unnatural Selection has already been sung in several reviews and previews (hereherehere, here and here) and I want to quickly add my own endorsement of Katrina's latest book before we delve into the interview.

Unnatural Selection is genuinely a fascinating and thought provoking insight into a side of evolutionary mechanics that we often ignore or stigmatise. Like many people - including other scientists - I've often thought that human-bred animals have little to tell us about evolution because they're somehow 'artificial', and that the genetic interplay that underlies their development somehow doesn't compare to what happens in 'real' natural selection. But Unnatural Selection shows the folly of this view, exploring how animal breeding reveals much about the ease and frequency of trait development, how our breeding choices are analogous to splitting and extintinguishing evolutionary lineages, the mechanisms behind expressing certain phenotypes, and evolutionary rates. Human-led breeding might be shaping animals towards a pre-ordained goal of our choosing, but it's still evolution. Ignoring it severs a wealth of insight and knowledge pertaining to evolutionary processes of any sort, human-led or otherwise. 

The strangely deformed skull of a King Charles spaniel. We view this sort of anatomical modification as extreme, and certainly there are welfare issues to consider with many domestic breeds (and not just dogs, as is most widely reported). But many of the extreme (and healthy) breeds we've created are no more bizarre than what we see in nature. In response to questions about pushing animal anatomy too far, Unnatural Selection responds "...look at what nature has done to the sword-billed hummingbird!". However we feel about the ethics of breeding bizarrely proportioned animals, we're not the only evolutionary force behind their creation. From Unnatural Selection, © Katrina van Grouw.
It's worth stressing that this is not a book about the ethics of purebreds or pedigree lineages: Unnatural Selection is book about evolutionary science viewed through the lens of domesticated species, and it leaves the politics and ethics of animal welfare at the door. Some may find the lack of ethical discussion a little peculiar given that any mention of animal fancy is so often presented hand-in-hand with animal welfare, but I can understand why this was left out: a good scientist presents their work objectively for society to implement as it sees fit, they don't present science to support their own opinions on a subject, no matter how strongly they personally feel about it. As an animal owner herself, Katrina is on record as being just as concerned with the health of animal breeds as anyone, but she didn't feel her book was the place to share her opinions - I can respect this.

So yes, Unnatural Selection is a fascinating, unique and spectacular book that I heartily endorse. But that's enough preamble, over to its author and artist. I've included, with Katrina's help, a selection of artwork from The Unfeathered Bird, Unnatural Selection and some rarely-seen earlier works. All artwork in this post is Katrina's, and used with her permission.

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MW. Much of Unnatural Selection discusses the prolonged challenge of having artificial selection viewed as having useful insights on 'natural' evolution. As you argue, this seems peculiar - a bit like a physicist arguing that experiments done on atomic particles in the lab have no bearing on 'naturally occurring' particles. Why do you think this issue has persisted for as long as it has?

KvG. I honestly have no idea. I too used to be what I call a ‘wild animal snob’ i.e. I considered domesticated animals as something man-made and irrelevant, though I’ve come to revise my opinions significantly!

It’s always said that Darwin drew up his analogy between natural and artificial selection specifically in order to introduce to the Victorian public the frightening concept that all the diversity of life could have come about without the need for a divine creator. Like the spoon full of sugar that makes the medicine go down. I suspect, as Darwin later maintained in his revised autobiography, that artificial selection was indeed highly influential in the formulation of his theory.

However, even Darwin had problems accepting that certain radical traits (like achondroplasia, or disproportionate dwarfism, discussed in the next question) could be successful in the evolution of wild animals, so he drew a line between them.

Richard Goldschmidt in the 1940s also made macro mutations appear ridiculous as a result of his ‘hopeful monster’ theory, which may have caused scientists to dismiss selective breeding as useless in comparison with evolution in nature. As you’ll be able to see from the next question, and especially in the book itself, there is actually very strong evidence that the same traits not only occur in wild animals, but may be favoured by natural selection.

Four-winged dinosaurs have evolved a number of times, including at the hands of pigeon breeders (pigeon hindwing, or 'muff' foot, shown at the base of the image). Understanding the genetic changes behind the development of such traits may help us understand the mechanisms through which these evolved in nature, something of obvious interest to palaeontologists interested in development of stem birds and avian flight. From Unnatural Selection, © Katrina van Grouw.
Every so often geneticists make a so-called breakthrough revealing some trend in domesticated animals that sheds light on evolutionary biology, and invariably these ‘discoveries’ have been known already to generations of animal fanciers who breed them. Feathered feet in pigeons are a good example. Every pigeon fancier knows that the wing-like ‘muff’ feet (palaeo-people will know these as ‘hind wings’) are produced by combining two very different foot feather types. Geneticists would do well to pay attention to the knowledge of animal fanciers instead of constantly re-inventing the wheel.

Whereas in past centuries scientists had eclectic interests and would happily turn to the products of horticulture as to botany, or to animal breeding as to wild animals, it seems that the more knowledge that’s available the more blinkered and over-specialised scientists become. I even know molecular geneticists who don’t fully understand Mendelian principles.

Sadly for too many of us, even though the subject of domestication is currently very popular in scientific circles, selective breeding is viewed either with derision or contempt. Fit only for children or eccentric losers, or an emotive subject to stir up the wrath of animal welfare crusaders.

I hope that my book will do something to redress the balance.

Unnatural Selection draws attention to the rapidity of evolutionary modification, specifically how animal form can be dramatically modified in a generation thanks to single genetic changes. You somewhat playfully speculate that this may have had a role in the evolution of some groups - such as the short limbs of mustelids: would you care to suggest - speculatively or otherwise - if any other groups may have benefited from these rapid changes?

That’s right. Though it’s important to stress that the most significant evolutionary change is the result of an accumulation of tiny steps – ‘natura non facit saltus’, as Darwin was fond of saying: ‘nature does not make leaps’. But there are plenty of traits that are single step, all or nothing, changes. Think of the spiralling direction of shells, or horns, for example. Colour aberrations too can result in major phenotypic changes just by the addition or subtraction of a pigment. (Colour ‘aberrations’ are only aberrant when they’re in low numbers in a population, but if they prove to be advantageous, or if they’re isolated in a small gene pool, these aberrations of today can be the colour morphs, races, or even species of tomorrow.)

Vertebral counts are considered a big deal in vertebrate palaeontology, often being used to distinguish different species. It turns out that gaining additional vertebrae is not particularly difficult and is not just the remit of weirdos with extreme numbers of axial elements, like snakes. We've emphasised this trait among species that we harvest for meat, such as landrace pigs, which have several more vertebrae than other breeds. From Unnatural Selection, © Katrina van Grouw.
However, I’m deviating in my preamble. There are lots, and lots, of other examples, besides the short limbs of mustelids, where you can suggest, speculatively, that the evolution of wild animal groups may have been given a ‘leg up’ (no pun intended!) by a single major mutation. The naked neck trait in chickens is a good one - the heat-reducing naked necks of marabou storks, ostriches, and vultures is comparable and is probably caused by the same genetic process. Henny feathering in chickens (where the male has the same plumage as the female with no loss of virility) possibly has a connection with the seasonal eclipse plumage in waterfowl. Mutations that cause winglessness in chickens may sound pretty gross, but moas were totally wingless too, and there’s no fossil evidence to suggest that they ever went through a gradual evolution towards winglessness. Rex fur in rabbits may seem like just a fancy coat type for the show bench, but a similar coat (without directional guards hairs) allows moles to move freely backwards and forwards in their burrows.

The exact same mutations are equally likely to occur in wild as domesticated animals and their success is all down to whether or not they find themselves in an environment that’s favourable. The ‘right’ environment can come in many forms, and it can change, but traits that might not be successful in the wild for whatever reason might just appeal to the whims of fanciers. There are only a finite number of possible traits that will ever be viable, and the same things tend to occur across a wide range of animal groups, albeit expressed differently. Meaning that speculative zoologists would do well to pay more attention to domesticated animals and the traits they exhibit. This is variation in its most likely forms and a very accurate suggestion of the possible directions evolution might take in the future. Again, the initial mutation only needs to be a start. After that, natural selection can refine it further and fine tune it over millions of years to each particular environment.

Both The Unfeathered Bird and Unnatural Selection are simply stunning to look at, but not all your readers will know how instrumental you were to their design, not only creating the text and illustrations, but also having tight control over the page layouts and overall aesthetics. I gather this level of control is not typical in publishing, and it very much makes these your books. Can you tell us a little about your design decisions? 

I’m glad you asked that; indeed, most people assume that the publisher designed the books, which is the more normal arrangement. I’m exceedingly lucky to have a publisher that has so much faith in me.

After nearly two decades of trying to find a publisher for The Unfeathered Bird, I was painfully aware that many people associate anatomy with greyscale diagrams in academic textbooks. I wanted it to be as much a work of art as of science, so changing the colour of the finished pencil drawings to a sepia brown colour, and printing onto ivory-coloured paper was a deliberate attempt to make the book softer and more accessible and to be suggestive of the beautiful historical natural history illustrations of past centuries. This particularly suited the historical theme of both books: The Unfeathered Bird references Linnaeus (this was a clever way to discuss adaptations through convergence rather than adhering to actual phylogenetic relationships) and Unnatural Selection is all about Darwin and Mendel.

The many faces of exhibition homing pigeons, an example of one of the full page spreads from Unnatural Selection. I can't be the only one thinking the Exhibition Homer resembles a certain piece of Therizinosaurus artwork. © Katrina van Grouw.
Personally designing the books sort of happened by accident – I preferred to prepare the digital image files because I was reluctant to allow the original drawings out of my care. Also, I knew exactly how the different images on the page should be arranged in relation to one another. The drawings are all done on separate pieces of paper, so putting them together digitally myself seemed to make more sense than trying to explain where they should go. After that I discovered that my publishers were also happy to let me choose the fonts, guide the positioning of text, and even design the entire jacket, all of which I loved doing.

I had a lot of fun designing the page layouts, especially the chapter opening pages in Unnatural Selection where I’ve shown historical museum specimens against antiquated-looking background paper. And the three coloured images in the book where I discuss pigment changes. The ‘let’s colour a Gouldian finch!’ page was based on Andy Warhol’s Marilyn Monroe prints, with more than a passing nod towards Edward Lear’s coloured birds. This pleased me immensely as John Gould treated Edward Lear very badly in life, so it seemed like justice for Lear!

I'm curious about the poses of many of your subjects. Where you have control over this aspect of their illustration, what helped you decide to pose them a certain way, other than the simple practicalities of "I want to show this feature"?

Many of my decisions were indeed guided by ‘I want to show this feature’. The Unfeathered Bird is all about adaptations, so it was important to show the features that I describe in the text as being particularly adapted to specific behaviour. So it made sense from a scientific and aesthetic point of view to show skeletons actually engaged in that behaviour. Husband put together the majority of the skeletons so it seemed fair to give him an input into the choice of positions. We had endless pleasure discussing the behaviour of birds and arguing (in a friendly way) about which position to choose.

Of course it’s not just the position of the actual skeleton, but the viewpoint I select to draw it from. The diver in the surface swimming position may be fairly straightforward, but I decided on a fish’s-eye view, looking up at it from below, as this was the viewpoint that most clearly showed the boat-like sternum, sideways-angled hind-limbs, and razor-thin legs.

A budgie skeleton passes the mirror test, from The Unfeathered Bird. © Katrina van Grouw.
Some of the poses, although superficially just for fun, are for practical as well as aesthetic reasons. The budgie skeleton looking at itself in a mirror in The Unfeathered Bird was a way of showing both sides of the skull in the same drawing (while making it crystal clear that it’s a budgie!). I did the same thing with the reflection in the water under the porpoising penguin.

I enjoyed playing around with visual references, for example I deliberately showed the avocet in the same position as the RSPB logo; the red grouse was modelled on the whisky label, and the robin on the spade handle was modelled on 90% of the Christmas cards ever printed!

For all the major bird groups I included a page showing the feather tracts, musculature and skeleton of a species all together and for these it made sense to show them like an actual group of birds interacting. So I made up little tableaus: three rooks rushing to get a worm that’s just disappearing underground, or a pigeon’s frantic pouting courtship ritual being completely ignored by the other pigeons only intent on eating.

The skeleton of the mighty auroch, one of my favourite pieces from Unnatural Selection. Katrina didn't pose this individual (it's based on a museum mount) but has really captured its implied energy and mass. We might be looking at a skeleton, but you can almost see the muscles rippling as the animal moves. From Unnatural Selection, © Katrina van Grouw.

I can't look at your anatomical work without wondering how you could translate your skill into palaeoart, and I must not be the only person imagining that a van Grouw restoration of a fossil bird or (based on some of the amazing work in Unnatural Selection) a fossil mammal would be spectacular. Will we ever see a life restoration of a Gastornis, entelodont or Microraptor emerge from your pencils? And can I have a copy if it happens? I'll be your best friend.

Proof, as if it were needed, that Katrina knows her way around skeletons and musculature as well as the best palaeoartists: a parade of cow bottoms. Note the 'double muscle' individual at the end of the row. From Unnatural Selection, © Katrina van Grouw.
Haha, if it happens I promise you you’ll be the first to know! Probably because I’ll need your help to get it right and won’t be brave enough to show it to anyone until you’ve given it your seal of approval! I’m not adverse to the idea, but at the present moment I can’t envisage how it would fit into the planned book projects which, for the foreseeable future, will be purely anatomical.

It’s not entirely impossible though. With the right incentive (for example, producing commissioned illustrations for someone else’s book) I could probably be persuaded.

Katrina's take on Pomarine skuas. I can't be the only person wanting to see this anatomical expertise and style applied to fossil animals. © Katrina van Grouw.

Before your recent books you were best known for your work illustrating fantastic cliffs and seabird colonies. These are amazing images and I understand a number of folks were sad to hear you declare that this part of your artistic life is behind you. Is the door completely closed to this sort of wildlife art, or will it reinvent itself in some form? And if not, what lies ahead? 

When I finished The Unfeathered Bird I was fully intending to return to those sorts of pictures and to being a fine artist again, but I found that I’d moved on. It’s not that I refuse to do the same work; it’s because my heart is somewhere else now. You can’t force it – it has to come from genuine passion. Ever had a persistent ex who tries to convince you that you can fall in love with them again, while you know damned well it ain’t ever gonna happen? It’s a bit like that.

One of Katrina's pre-Unfeathered Bird cliffscapes, St. Abbs Head, Scotland. © Katrina van Grouw.
To be brutally honest I have nothing but contempt people who find it sad that I no longer do the same old work. It shows a lack of respect for my artistic integrity. It wouldn’t be so bad if these were faithful collectors and patrons from my past, but they’re not. Most, in fact, are creative people too so they should understand that creative development is a one-way process and not a matter of personal choice.

Before the rocks/seabird colony drawings I did images of big dramatic birds doing exciting things: fighting and chasing each other and stuff. Then I had a… I guess you’d call it an epiphany, on the cliffs of Hermaness in Shetland, and my work changed to the rocks overnight. And yep, you’ve guessed it, loads of people expressed regret that I wasn’t still doing the same bird pictures…

The important thing to remember is that the illustrations in my books are just that – illustrations. The book’s aren’t art books showcasing my anatomical art; they’re science books – albeit very beautiful ones. Each illustration is just a means to an end and a very small part of the whole. To me the creation of the book – the entire book, from conception to design - is the creative process. What can possibly be finer than bringing into existence an entirely original and very beautiful book?! It ticks all the boxes for me at every creative and intellectual level.

The important thing is to bring all this stuff – pictures or books or whatever - into the world, and the fact that it can’t be relied upon to be repeated forever is what makes it precious. I don’t know what lies ahead, of course, but I think it highly unlikely that I’ll ever return to being a fine artist. But if I do develop in an unexpected direction, promise me you won’t say it’s sad that I no longer produce books!

Katrina's terrifically moody albatross piece, a big dramatic bird doing an exciting thing. A skeletonised version of this image graces the opening of The Unfeathered Bird. © Katrina van Grouw.

In some respects we have arrived at a similar career path from opposing directions: I became an author/illustrator through training as a scientist, while you trained as an artist before authoring science books. You mention in Unnatural Selection that this professional path was not without its struggles, and I can entirely empathise with this. You have to become equally skilled in two, sometimes very different fields and practical issues mean it's not easy to be highly trained in both. Despite these challenges, you've produced two spectacular and very well received books. How have you dealt with the challenge of transitioning from artist to author who does art?

To be fair to myself, although I was deprived of the opportunity of a formal science education, my world before The Unfeathered Bird wasn’t entirely devoid of science, though it was practical rather than theoretical. I was a passionate birder from childhood, and my interests led me to train as a bird ringer in my early 20’s. I took part in long term ringing expeditions to Senegal and Ecuador and was particularly interested in moult and other physiological indicators that ringers use to age and sex birds. Around this time I taught myself taxidermy and began to assemble my own bird skin collection, and also prepared bird skins for museums. The personal project that let to me to make an in-depth study of bird anatomy (beginning with a dead duck I christened Amy) has been told many times already. Ironically, many of these elements are not things that science undergraduates are taught. I know plenty of lettered biologists who have never even touched a scalpel. That was all back in the late 1980’s so the transition into science hasn’t been a sudden recent change.

Anyone can educate themselves. The difficulties lie in the lack of opportunity for discussion with peers and tutors, and the difficulty of accessing academic texts, but it’s certainly not impossible. Harder to throw off is the bias based on your actual qualifications.

A disproportionately dwarfed "ancon" sheep, an example of a single-step evolution. Such sheep are more common than we may expect, and we have to wonder how often such radical changes occur naturally. It's conceivable that major, single-step changes in animal form could be selected for under some natural circumstances, and may have even played a role in 'natural' animal evolution. From Unnatural Selection, © Katrina van Grouw.
What I find most difficult, and personally infuriating, is people’s preconceptions; the tendency to put two and two together to make five. Many people find it difficult to accept that someone with an art background can have a genuinely scientific interest in something. They’ll assume that my anatomical interests have an artistic root – as though I’m inspired by textures and shapes and all that. And of course I do enjoy drawing this sort of thing, but it’s not the reason for it. I try to explain that if I wasn’t producing books, I wouldn’t be drawing skeletons, but no-one wants to hear that. Even on my book tour this year I sometimes had to really fight to be described as an author and not an artist. One venue insisted on advertising my talk: ‘Katrina van Grouw’s evolutionary illustrations’. It was humiliating.

The most damaging element of all this, and one that I find deeply painful, is the assumption that I must rely on Husband to help me with the science in my books, because I’m an artist (‘only’ an artist is the unspoken word here). In fact neither of us have an academic science background, and both of us formerly shared a career as curator of the bird collections at the Natural History Museum. Husband is indeed useful for mounting skeletons, and for his knowledge of domesticated animals, but I’m the one with the interest in evolutionary biology.

All in all it seems to be a lot easier for a scientist to be respected as a self-taught artist than the other way around.

Being self-taught does have its plus side however. Having to learn science the hard way means that I know a lot of the pitfalls and barriers to grasping each subject, so I’m in a good place to explain difficult concepts to others in a clear way. It’s made me a really good science communicator.

Given that this is primarily a palaeontology-led blog, I feel we should end with the news that The Unfeathered Bird will be making a return at some point in future, and will have a significant palaeo-themed component this time. Can you give any hints as to what to expect?

Yep, that’s right. I actually signed the contract to do a second edition of The Unfeathered Bird last spring, but I haven’t quite gotten into gear with it yet due to all the work of production and publicity for Unnatural Selection.

It’ll have an extra 96 pages, making a total of 400. You’ll remember that the first edition is divided into two sections: ‘generic’ – talking about birds in general - and ‘specific’ – talking about particular bird groups. The new material will mostly go into the generic section, looking at the definition of what makes a bird, what birds are and aren’t, and of course a whole load of stuff about bird evolution.

Red throated diver skeleton, from The Unfeathered Bird. A new edition will be with us one day! © Katrina van Grouw.

Bird wings will be compared with bats and pterosaurs (and Yi qi?). There’ll be stuff about feather evolution (maybe I can get a palaeo reconstruction in here somewhere...), lots of stuff about the loss of digits, the rotation of the wrist, shortening of tails, lengthening of necks, and the orientation of thighs. And you can expect a few active maniraptoran skeletons doing maniraptoran things.

In addition to this I’ll be replacing some of the drawings in the ‘specific section’; adding some more and giving the existing ones a good polish. I’ll be completely re-writing all the text and replacing the short family sections with entire chapters. The total word count is estimated to be around 110,000 words, in comparison with the 46,000 of the first edition. The science will be better, though still easily accessible. There’ll probably be a new jacket design, but almost certainly still showing peacocks. And I’m guessing the original title will be followed by a subtitle (suggestions on a postcard, please).

The Unfeathered Bird NEEDS a palaeo-themed component. It’s incomplete without it, and any reviewer who wanted blood could easily and justifiably have torn the first edition into shreds. But that didn’t happen. Instead the palaeo-world received us with open arms and heaped praise upon us. It was possibly the most humbling experience of my life. This new edition is my way of expressing my gratitude.

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Thanks very much to Katrina for the interview, and please leave your suggestions for the subtitle of the next edition of The Unfeathered Bird in the comment field below. Personally, I'm thinking Unfeathered Bird II: The Birdening; UB2: Judgement Day; Unfeathered Bird: First Blood Part 2; or The Return of the Unfeathered Bird: Rave to the Grave. Alternatively, use those same seconds to grab yourself a copy of Unnatural Selection and The Unfeathered Bird, both available now from Princeton University Press and all good bookstores.

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