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Thursday, 20 December 2012

Chilly pterosaurs and rushed festive wishes

Christmas is all well and good, but it doesn't half take up a lot of time, which can be a bugger if you're already busy with what seems like 100 other things. With this in mind, I won't dawdle and will simply wish everyone best wishes for the Christmas and New Year holidays, and direct you to the hastily-created image above. Inspired by a set of starlings noted outside our kitchen window a few weeks ago, it depicts four Darwinopterus modularis huddling together for warmth, with puffed-up pycnofibres, on a snowy tree branch. Did Darwinopterus ever see snow? Perhaps: the Darwinopterus-yielding Tiaojishan Formation seems to have been in a warm temperate biome, so the odd excursion into temperatures conducive to snow may not be impossible. I have a post planned on more definitively cold-weather Mesozoic animals, and a more developed painting to go with it, but that will have to wait a bit. Happy holidays all!

Sunday, 9 December 2012

Deconstructing All Yesterdays, or How palaeoart is flawed, but everything's cool

It's time to face facts. Try as we might, we will never reconstruct long extinct animals accurately. We may be able to cobble together fairly accurate images of Pleistocene mammals through analysis of their frozen remains and heavy reliance on closely related modern species, but the appearances of species extinct for millions of years are beyond are grasp. Our problems are far greater than the most common complaint, that we simply do not know what colours they were. So much data on soft tissue distribution, muscle bulk and integumentary structures are lost through the death, taphonomic processes, fossilisation and exhumation of extinct creatures that very little can be said for certain about their actual life appearance. The remains that weather the fossilisation process - skeletons and shells - only provide the bare minimum of information about the life appearance of their owners, and it seems that osteological correlates - features of skeletons that betray the presence or development of certain soft-tissue structures - are often ambiguous or unreliable. And we haven't even mentioned the problems with trying to deduce behaviour from bones alone. (Image above: the underlying sketch to this controversial painting of a carrion-eating, bristly Styracosaurus. From 2007.)

This is one of the messages I've taken from the presentations, internet articles and new book All Yesterdays. The brainchild of John Conway, C. M. Kosemen and Darren Naish, this minor internet phenomenon needs little introduction to most of the readers here (if you're unfamiliar with it, check out the provided links for background info). This opinion contrasts with the attitudes of some palaeontologists and artists, who consider our abilities to reconstruct extinct animals fairly decent and reliable. Pains me as it does to say it, but I have to agree with the All Yesterdays chaps. There's simply too much anatomical and behavioural detail lost to time, and we're never going to get that back.

The All Yesterdays project seems to be the result of looking into this deep abyss of lost palaeontological data. But rather than staying safe at the edge, Conway et al. have dived in, exploring the virtually infinite possibilities of ancient animal reconstructions, critiquing the rationale and methodologies of palaeoart and questioning its very purpose. The results are novel, highly creative, insightful and thought provoking, and should be given serious thought by anyone interested in the palaeobiology and depiction of extinct animals. In short, All Yesterdays argues that modern palaeoart fails one of the only tests we can apply to it, that many depictions of extinct animals compare poorly against the morphological and behavioural diversity of modern species. Specifically, modern palaeoart is too conservative, frequently depicting set behavioural patterns for some species (e.g. the Tenontosaurus vs. Deinonychus meme) and 'shrink wrapping' skin over the skeletomuscular system without any consideration of other soft-tissues. All Yesterdays argues that this can be rectified, in part, through bold transference of modern animal anatomy and behaviour to extinct species, which fills the gulfs of missing data and creates more plausible concepts of life in the past than by following the current, perhaps overly conservative palaeoart methods. The word 'concept' is important here, as this is all we can hope to realistically hope to achieve in palaeoart. For all our efforts, our reconstructions will probably never depict these animals exactly as they were in life, and we just have to live with that. Science will hone and refine our concepts to more closely resemble what was once reality, but most of the details we need to exactly reconstruct ancient worlds are unlikely to ever emerge. There will always be several plausible ideas for the life appearance of extinct creatures*, and we should focus on exploring these concepts to reproduce believable renditions of animals, not ignoring because of (probably) unobtainable data or because they stray from established ideas.

*Is there more than one way to reconstruct a fossil animal? According to some, no, but others would disagree. I think the answer lies somewhere inbetween. The skeletomuscular system of extinct animals may be reconstructed more-or-less correctly from fossils of some species but, as we'll see below, this is only half of the story.

But we must be careful with this liberation of creativity in a science-based discipline. All Yesterdays calls not for recklessness in palaeoart, but confidence, allowing extinct animals to be diverse and unusual, but still constrained by what is known for their evolutionary history and anatomy. The payoff for this confidence is that the All Yesterdays project often portrays extinct animals in a more convincing and realistic manner than much of the work we're familiar with. For example, John's tripodal Therizinosaurus is just as plausible, scientifically speaking, as a more traditional version, but is 100 times more believable. John's Camarasaurus rolling in mud is just as plausible as the hundreds of illustrations of this animal standing and eating, and Memo's super-stocky Lambeosaurus is entirely consistent with fossils of this species. The results are just as valid as hypotheses of appearance and behaviour - arguably moreso - than the ultra-conservative reconstructions currently dominating palaeoart. Erring on the side of caution is still an error, and some of the entrenched, 'conservative' reconstructions of ancient life are actually harder to substantiate than the seemingly bolder ones.

Elements of what I'll call 'the All Yesterdays philosophy' have been creeping into palaeoart for years, but I think Conway et al. have burst the dam here, highlighting the need for a fresh approach in how we approach the reconstruction of extinct life. So far as I see it, there are four points to consider in the All Yesterdays philosophy that both palaeontologists and palaeoartists need to embrace: when to apply it, the composition of our images, what it means for animal appearance, and its application for extinct animal behaviour.

Application
All Yesterdays is entirely about reconstructing long extinct animals with no ecologically similar modern relatives. We don't need to extrapolate data wildly for relatively recently extinct species with lots of closely related modern relatives, and doing so will probably make our work less accurate. All Yesterdays is a philosophy that need only be applied to species for which soft-tissue data and behavioural aspects are inadequately known or entirely unknown. This includes some of the stranger Cainozoic mammals, reptiles and birds, and essentially everything that lived in the Mesozoic or before.

Composition, or aspect and attitude
What do extinct animals look like when not viewed in direct lateral view? Because the fossil skeletons of many species are laterally compressed, and because lateral views arguably show off more anatomy than other aspects, palaeoartists rarely show animals in anything other than side-on attitudes. 3D skeletal remains allow us to reconstruct animals in multiple aspects however, often with surprising and unfamiliar results. This has not percolated into palaeoart yet however, and if animals are shown in non-lateral aspects, their proportions are often 'generic'.  In my view, one of Greg Paul's crowing achievements was revealing the variation in dinosaur width, highlighting the extremely wide ribs of ankylosaurs and pachycepahlosaurs, and the narrowness of many theropods. All Yesterdays encourages us to remember that animals are three-dimensional beings, and can be accurately treated as such in art. (Below: the rarely seen anterior aspect of a famous pterosaur. But which one? Detail of a painting from my book.)

Appearance: the anti-shrink wrapping movement
Arguably the most important aspect of All Yesterdays is our reconsideration of extinct animal appearance. As a response to the inaccurate and often shapeless animals common to palaeoart in the early 20th century, most artists in the Age of Greg Paul employ the celebrated 'Rigorous Anatomical Approach' (RAA) to reconstructing fossil animals, and depict their animals with much of their detailed musculature and skeletal anatomy obvious under the skin (classic example of strict RAA in dinosaur art, Greg Paul's running Daspletosaurus, shown below. Image © Gregory S. Paul, from his website). These ultra-lean, toned animals are often devoid of any obvious extraneous tissues, including fats, loose skin or elaborate integuments. Strict RAA remains the most scientifically sound route to reconstructing an extinct animal, as it rigorously employs available data to render an extinct animal, and minimises speculation. It is also an effective way to demonstrate anatomical distinctions between extinct species and produces dynamic looking creatures, which are undeniably appealing to viewers. The rise in popularity of this technique at the time of the Dinosaur Renaissance is probably not a coincidence.

© Gregory S. Paul
However, most modern animals do not look like those produced under strict RAA. Fat, excessive skin, and integumentary structures hide much of their muscle profile and skeletal details, so they are not 'shrink wrapped' in the way that strict RAA suggests. The All Yesterdays philosophy embraces this fully, using RAA to provide the blueprint for an animal, but appreciating that not every anatomical feature will be discernible. Openings in the skull are not clearly seen on animal heads, large teeth are sheathed behind lips, limbs can be hidden beneath fur and feathers, details of muscles are obscured by wrinkly or thickened skin and so forth. Palaeoart produced with this in mind is more consistent with the appearance of modern animals, and make their subjects seem more plausible as living species. We must also not be too concerned about depicting extinct animals as looking ridiculous on occasion: there are numerous modern species which are frankly preposterous to behold, which surely must be true for some ancient species too. If our intended soft-tissue depictions can be functionally rationalised, and are consistent with fossil data and evolutionary hypotheses, then they are plausible inclusions for palaeoart. 

Behaviour
Anyone familiar with the history of palaeoart will recognise recurrent memes associated with specific animals. Ornitholestes always chases a bird. Archaeopteryx (which is always blue and green) perches on a branch with its wings outspread, its back always to the viewer. Tyrannosaurus is always roaring. Most prevalent of all is the depiction of prehistoric animals incessantly trying to murder each other. Memes often perpetuate because they reflect a certain trait specific to a certain animal (e.g. sleeping Mei, the use of the 'terrible claw' in Deinonychus), but they quickly became clichéd tropes when over used. All Yesterdays makes a case for showing animals undertaking other essential activities such as preening and bathing, socialising (without engaging in life-or-death intraspecific combat), playing, resting, sleeping, nesting and, well, all the other things that real animals do. Phylogenetic tracing of animal behaviour shows that there is no reason not to depict ancient animals undertaking these activities, but we rarely show them doing anything but fighting and eating. Moreover, All Yesterdays emphasises the behavioural plasticity of modern animals, noting that apparently strict carnivores or herbivores will supplement their diets with meat or plant matter on occasion, that animals can locomote in unexpected ways and are proficient at activities that we would not predict from their skeletons alone (this image being the chief All Yesterdays case study). As with the morphological aspects of reconstruction, this is not a call out for all unabashed craziness in palaeoart, but simply to say that we should be more broad minded about the way we depict the behaviour of extinct species, and that some initially outlandish ideas (like my carrion-eating Styracosaurus) are not as ridiculous as they first appear.

A new age in palaeoart?
Taken together, these points can be summarised in one two three sentences. Palaeoart must be both scientifically credible and realistic, but may be generally too conservative and clichéd to achieve these goals successfully. We are likely to be misjudging aspects of our reconstructions anyway, but we may be better off erring through the bold use of informed speculation about animal appearance and behaviour rather than through strict conservatism. Each produces results that cannot be refuted by current scientific data, but only the former produces art fully consistent with our understanding of real animals. 

It will be interesting to see how much of a shift All Yesterdays generates in attitudes to palaeoart. It's probably very clear by now that I'm a convert, but will others pick up on this, too? The rosy reviews of the All Yesterdays book suggest so, but what actual effect will this project have? I do not think the results will be as obvious as the popularisation of RAA in the 1970s and 80s, but I am optimistic that All Yesterdays marks a 'formalisation' of the anti-shrink wrapping movement, and need for depicting more complex compositions and behaviours. I look forward to seeing its results. Darren suggested at the All Yesterday's book launch that modern palaeoartists are currently working in the 'Age of Gregory S. Paul', with most of us following Paul's methods of strict RAA reconstruction to greater or lesser extent. Looking at the celebratory response to the All Yesterdays project across the internet, I wonder if the Age of Gregory S. Paul is about to end, and palaeoart will enter the 'Dynasty of All Yesterdays'?

Wednesday, 5 December 2012

Out with the old, in with the, er... old

There are busy, exciting times afoot. Not only did my book proofs arrive this morning, but my PR image of the oldest known dinosaur, which accompanies the hot-off-the-press paper by Sterling Nesbitt and colleagues, has been making waves on Internet press sites. There's lots of cool things to say about the paper and the image, but time is a little short today, so I'll have to keep my discussion brief.

Starring front and centre in the image Nyasasaurus parringtoni, the 2-3 m long possible dinosaur (or extremely dinosaur-like dinosauriform) from the Middle Triassic Manda Formation of Tanzania. As anyone with an ear to the ground for palaeontology news will know, Nesbitt et al. (2012) have rescued Nyasasaurus from the nomina nuda bin and made a compelling case for it to represent the oldest dinosaur remains yet known, or at least a dinosauriform species that was only a evolutionary stones throw from Dinosauria proper (see Nesbitt et al. 2012 for full details, or one of the many write ups populating the Internet). Unfortunately, Nyasasaurus is known from only a handful of scrappy bones including a few vertebrae and a partial humerus, which doesn't give much to work from for an artist. Paul Barrett and Sterling Nesbitt, the brains behind this image, suggested that another ancient dinosaur, Eoraptor, should be the primary reference, but with a some influence from early sauropodomorphs. The result is an admittedly slightly speculative animal, but one that hopefully captures the generalised anatomy that may have been common to the first dinosaurs and their immediate ancestors. The question of integument, a crucial consideration for any modern image of a Mesozoic dinosaur, was addressed fairly quickly: "...definitely no feathers!" It's funny to think that palaeontologists now have to defend the choice not to cover their dinosaurs in feathers or other fancy integuments, but I don't disagree with the decision here. Feathers are spreading down towards the base of Dinosauria at a rapid rate, but direct evidence is still some distance from the root of the tree. Of course, the occurrence of fuzz in pterosaurs, which some authors have already controversially interpreted as representing early types of feather, does create the potential for fuzzy integuments in all ornithodirans, but we're still waiting for smoking gun evidence of this. Elaborate restorations of prehistoric animals are definitely in fashion at the moment, but we do need to keep perspective on what the fossil record tells us. In the absence of fuzz, I chose the wrinkly, dappled scales of a perente monitor as the inspiration for the Nyasasaurus skin.


At least part of the rationale behind the dabbled, camouflaged tones of the centre animal came from its likely place in its Middle Triassic ecosystem. Nyasasaurus and other dinosauriforms were minor faunal components of a world dominated by other types of reptile (Nesbitt et al. 2012), so they may have done well to remain largely remain inconspicuous for much of the time. The rhynchosaur Stenaulorhynchus (see image detail above, showing the rhynchosaurs in all their inelegant glory) seems to have been a particularly common animal in the Manda Formation, with dozens of individuals being found compared to the one occurrence of Nyasasaurus. We wanted to feature this ecological relationship in the image, showing a lonely early dinosaur in a landscape controlled by other animals. Rather than simply including a bunch of Stenaulorhynchus in the distance however, we thought it would be cool to have the Nyasasaurus following a trail of destructive rhynchosaur foraging. Rhynchosaurs are noted for their adaptations for scratch digging with their hindlimbs, which may have been used to unearth roots, tubers or other food (Benton 1983, 1990) . In this image, several shallow excavations have been made by a troop of Stenaulorhynchus in their quest for food, which the Nyasasaurus is picking over to nab exhumed invertebrates and nutritious plant matter left behind. I must admit that the charisma of Stenaulorhynchus almost stole the show for me when drawing the image: I didn't realise how cool digging, buck-toothed reptopigs were, and I think the depiction of them digging is a first for palaeoart generally.

Finally, a quick word on the environment. Say 'Triassic climate' to most folks and their thoughts will travel to arid, barren landscapes, but this is only true for the latter half of the Triassic. The Early and Middle Triassic (which account for only the first 40 % of Triassic time) were rather wetter and, presumably, lusher than we usually imagine them (e.g. Benton 1983). In keeping with this trend, the Manda Formation palaeoenvironment was a fairly mesic, temperate setting that was likely a lot greener than the Triassic scenes we're used to. And that will have to do for now. So much for a 'brief' post. Again.

References

  • Benton, M. J. 1983. Dinosaur Success in the Triassic: A Noncompetitive Ecological Model. The Quarterly Review of Biology, 58, 29-55.
  • Benton, M. J. 1990. The species of Rhynchosaurus, a rhynchosaur (Reptilia, Diapsida) from the Middle Triassic of England. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 328, 213-306.
  • Nesbitt, S. J., Barrett, P. M., Werning, S., Sidor C. A. and Charig, A. J. 2012. The oldest dinosaur? A Middle Triassic dinosauriform from Tanzania. Biology Letters, 9. doi. 10.1098/rsbl.2012.0949

Sunday, 2 December 2012

The Joy of Rex

There is enough text, imagery and pop culture references to Tyrannosaurus rex that, if laid end to end, they would give the Martian rover Curiosity a bridge back home. (Image above: my painting of Tyrannosaurus, which extends that bridge far enough to give Curiosity something to wipe its feet on when it gets back). Tyrannosaurus has invaded the consciousness of palaeontologists and the public like no other extinct species. Far older than the dodo, more spectacular than mammoths and more frightening than the gigantic sauropods, Tyrannosaurus is the ultimate symbol of prehistoric life. Its rise to fame was helped by being discovered in plenty of time for dinosaur movie makers to become acquainted with its size and awesomeness, by being the largest predatory dinosaur for the best part of a century, and having a PR-perfect name. You don't have to be a scholar of ancient languages to know that something called Tyrannosaurus rex is going to be a whole heap of badassery, and unlike many Greek names, it's pronounceable on your first try. The truncated binomial, T. rex, is a piece of cake to remember and sounds cool, like the name of a sports car, a swish computer processer, or an assassinatobot from the Terminator franchise. The latter is entirely fitting for an animal of gigantic size, bone crushing bite and ability to swallow eight year old children-sized prey whole.

Like most child dinofanciers, I drew buttloads of Tyrannosaurus when I was growing up, a hobby spurned on by the 1993 release of Jurassic Park. Looking back on that movie, Tyrannosaurus was clearly its star and the creature that most effectively demonstrated the transition from the lumbering, lizard-like dinosaurs of Hollywood's Golden Age to the fast, cunning monsters we recognise them as today. The brachiosaur may have evoked awe, but it didn't behave in a dissimilar fashion to other movie sauropods. Velociraptor revealed an unfamiliar and sinister side to the dinosaur cannon, but mot people had no concept of Velociraptor or other dromaeosaurs before then. Tyrannosaurus, though, was already familiar through its out-of-shape, tail-dragging variants being featured in the 1925 The Lost World, the 1933 King Kong and 1964 Valley of Gwangi*. When the toned, fast and ferocious Jurassic Park version started overturning cars, smashing a small building to matchwood, and almost outrunning a jeep, it was clear that the perception of dinosaurs had received a complete makeover, and that their interpretation as lizard-like creatures had been banished.

*Yes, yes: I know. Gwangi wasn't a straight Tyrannosaurus, but he was half. Harryhausen made Gwangi, as he did his other prehistoric creatures, by compositing his favourite bits of different animals into one model. Gwangi was a mix of Tyrannosaurus and Allosaurus, which Harryhausen termed 'Allo-rex'.


Since 2005, I've drawn considerably fewer Tyrannosaurus, and certainly never painted one. In coming back to Tyrannosaurus after all this time, I made a wholehearted effort to do it justice. All too often, Tyrannosaurus is rendered as a generic theropod with short, two-fingered arms, a large head and massive teeth, but such portrayals miss a lot of remarkable anatomy (above, lateral view of the restored skull and mandible of FMNH PR2081, better known as the Tyrannosaurus called 'Sue', showing the characteristic shapes common to Tyrannosaurus skulls. Image by me, 2008). Tyrannosaurus is the acme of tyrant dinosaur evolution, knocking 'standard' tyrannosaurid anatomy up to 11 to become on the most 'extreme' dinosaurs known. Anatomical quirks include the very wide temporal region of the skull, the abrupt, vertical termination to the muzzle, and the cool shades over the eyes. Their necks probably heavily muscled, judging by the space for neck muscle attachment on the Tyrannosaurus skull, cervical vertebrae and anterior trunk skeleton. The torso shape is unusual too, with their gently arcing ribs forming a thoroughly barrel-chested torso, which would partially obscure the big thigh muscles when viewed from anterior aspect. As with depiction of a coelurosaur nowadays, a decision had to be made about whether to apply a covering of feathers, as is increasingly plausible for theropods of all sizes. I followed the data offered by several scrappy Tyrannosaurus skin impressions showing pebbly scales for much of the body, but also figured that a few large, thickened scales across the face, neck and back wouldn't look out of place. These were animals that habitually tried to bite each others faces off after all, so few bits of toughened hide would not have gone amiss. Oh, and a few feathers can be seen at the end of the tail, because even tough animals have their sensitive sides.

Some time was spent pondering what to have my Tyrannosaurus doing, too. Tyrannosaurus is a seriously busy animal in palaeoartistic renditions. It's always doing something, be it roaring, chasing a hadrosaur, eating a dead Triceratops, roaring, running for no obvious reason, roaring, stalking unseen animals, roaring, making or nurturing babies, roaring, battling other theropods or perhaps roaring (if our depictions of Tyrannosaurus are accurate, the Maastrichtian fauna of North America must've been deafened by the incessant screaming of the local tyrannosaurs, because they always seem to be making noise in our pictures of them!). To avoid these clichés, the Tyrannosaurus here is doing, well, not very much, really. He's just standing around, looking like he's trying to remember why he walked over to that point in the first place, or perhaps wondering where he left his car keys. Point is, it's doing nothing in particular, which seems to be a relative rarity among tyrannosaur palaeoart, but perhaps allows for a little more appreciation of its shape and form. Plus, this is clearly a Tyrannosaurus from the northern extreme of its range, where forests of conifer and deciduous trees were common. I think I may have spent more time on the plants in this image than any other I've drawn, which requires a hat tip towards palaeoart man of the moment John Conway. John's attention to vegetation in his palaeoart has shown up other palaeoartists for all too often using plants as a generic, green backdrop to their work, which I'm entirely guilty of, and need to stop. There does seem to have been a bit of a push against purely green, tropical worlds in Mesozoic palaeoart recently , which joins the 'anti-shrink wrap' palaeoart movement mentioned in the previous post in marking a new age in our depictions of ancient worlds.

Anyway, I've gone on enough for the time being. I think the above painting is one of the more successful bits of artwork I've done, which may be why I'm still going on about it. Still, so much for a word-light approach to blogging.