Gallery and print store

Thursday, 4 April 2013

Phat Air meets wide gauge

So, here's something you don't see every day: giant azhdarchid pterosaurs and sauropods, living together in peace and harmony. Well, living together, anyway. This azhdarchid looks like a bit of a jerk, what with his swooping down to buzz the local titanosaurs for no obvious reason. They don't seem to like him very much. 

We can be confident that giant azhdarchids and gigantic sauropods once coexisted. Both are known from Maastrichtian age rocks in North and South America, and two celebrity Mesozoic species, the famous titanosaur Alamosaurus sanjuanensis and giant azhdarchid Quetzalocatlus northropi are denizens of the  Javelina Formation of Texas. Newly discovered vertebrae of Alamosaurus have boosted its maximum size estimates considerably, demonstrating it attained similar proportions to the gigantic titanosaurs of South America, Argentinosaurus and Puertasaurus (Fowler and Sullivan 2011). But while we can be certain that these giant animals occupied the same landscape, there's a lot of slop in trying to reconstruct them. Accordingly, I should stress that the animals depicted here are fairly generalised because, hand on heart, we don't know much about their appearance at all. Even basic attributes like their overall size are difficult to pin down. I thought Fowler and Sullivan (2011) were sensible for not including some shonky estimates of length or mass in their recent work on the new giant Alamosaurus material. Being simply content to say it was 'as big as Argentinosaurus and Puertasaurus' and 'among the largest sauropods in the world' works for me. Mike Habib and I took the same approach for the giant pterosaur Arambourgiania in our 2010 paper on giant pterosaur flight (Witton and Habib 2010). Arambourgiania is a probably the least known giant pterosaur among laymen, and is only represented by a few scrappy bones from Maastrichtian deposits of Jordan. The most impressive and discussed of these is its incomplete, 660 mm long neck holotype vertebra. But how does that link into the rest of its anatomy? Despite the propensity and popularity of reconstructions of giant pterosaurs, the truth is that we actually have very little idea of their dimensions and scaling regimes. Even the widely reported 10 m span for Quetzalcoatlus northropi is based on (unpublished) extrapolation from an animal half its size. Accordingly, it's difficult to say for certain how large Arambourgiania was, other than that it clearly had a very long neck (2.9 m is my most recent estimate for the combined length of Arambourgiania cervicals III-VII) and was probably among the largest pterosaurs we know of. That's not as cool as saying we know it spanned 11-13 m or whatever, but it's probably more honest.

Size is, of course, only one aspect to consider. Specific proportions and anatomies are pretty much impossible to reconstruct for many giant species, so I figure there's no point pretending that we really know what they look like. In 99% of cases, we're better off not kidding ourselves by saying "I'm painting [precise giant species]", but instead just acknowledging that we're rendering fairly generalised giant variants of their probable anatomy until we can refine them with new fossil data. 

Righto, blogging time is over. Back to work.

References
  • Fowler, D. W., and Sullivan, R. M. 2011. The first giant titanosaurian sauropod from the Upper Cretaceous of North America. Acta Palaeontologica Polonica, 56, 685-690.
  • Witton, M. P., and Habib, M. B. 2010. On the size and flight diversity of giant pterosaurs, the use of birds as pterosaur analogues and comments on pterosaur flightlessness. PLoS One, 5, e13982.

15 comments:

  1. Pleased to see that you got 2.9 m for the neck of Aramboughiania. As you probably know, we estimated it 3.0 m in our recent PeerJ paper, and it pleases me that someone who actually knows something about pterosaurs came in within 3.3% of our estimate.

    BTW., Aramboughiania is, as far as we know, the longest-necked non-aquatic animal outside of Sauropoda. Congratulations are in order.

    ReplyDelete
    Replies
    1. "Aramboughiania is, as far as we know, the longest-necked non-aquatic animal outside of Sauropoda."

      I thought so. It would be cool to investigate how a flying animal managed to develop a neck that large. My gut tells me that it's the combined effects of extensive cervical pneumaticity, quadrupedality and the Awesome Power of Quad Launch. The former two factors would, of course, match observations you and Matt provided in the PeerJ paper, while the latter provides enough power to lift such a large neck - and the body attached to it - into the air.

      Delete
    2. Oddly, I'm not sure that vertebral pneumaticity would make much of a difference here. Comparing figures 1 and 9 of your and Darren's azhdarchid palaeoecology paper, I see your life reconstruction of the neck is about four times as deep as the bones. If the same applies to width, then the bone only accounts for 1/16 of the neck volume, and reducing its mass to, say 1/4 of what it was would only take out 3/4 of 1/16, that is 3/64 or about 1/21 of the volume. Even allowing for the density of compact bone being twice that of flash, you're still only knocking out less than 1/10 of the neck mass by extensive pneumatising.

      In that sense, sauropod cervicals are very different from those of pterosaurs: the pneumaticity sort of inflated the bones, as shown in our fig. 4.

      I'd be interested to see the range of results you'd get if you asked a bunch of pterosaur specialists, indepedendently and without priming, to sketch the fleshy outline onto the neck of your skeleton.

      Delete
  2. Yay, I was hoping there would be black-and-white titanosaurs! They're surprisingly cute for spiky behemoths. I like these high-contrast drawings.

    ReplyDelete
  3. hollow bones on sauropod back is for speed and to excape because of heavy giant armo thermoregulated cold blooded croc bums and spine skin. modern dinosaurs the crocodilian do not have hollow bones on there body because they are aquatic that why they swallow stone to help them balance in water the prehistoric crocodilian the dino are mostly land animal so body were design for land even the simi aquatic dinosaur like the carnotaurus group

    ReplyDelete
    Replies
    1. Good luck with that one, Mark! :-)

      Delete
    2. Coelophysis,

      Thanks for the comment, but I'm not really sure what you're trying to say either here or in your comment here. Are you saying that our taxonomic concept of Mesozoic dinosaurs is incorrect and that they can either be classified as crocodiles or birds?

      Delete
  4. yes dinosaurs has been misclassified by some scientist for years and crocodilian ancestor allso has misclassified .dinosaurs and crocodilian are the same animal crocodilian came from spinosauridae .crocodilian did not come from sphenosuchian protosuchian toes and finger and claws do not match crocodilian spinosauridae do when you add catcroc by the evidence regrow claws so they can regrow fingers too crocodilian 5 finger 3 claws 4 toe 3 claws prehistoric crocodilian 5 finger 3 claws 4 toe 4 claws.as you can see crocodilian finger are awful design handicap and is very fast animal and they are in water and muddy shore must have come from ancestor with powerful finger and arm that is spinosauridae and no animal has finger and toe design like crocodilian and crocodilian body is more lizard like and they are many simi aquatic animal and croc like animal none have that design.sphenosuchian protosuchian never learn that design dinosaurs body plan is crocodilian success on land and water. protosuchian sphenosuchian has no verticalised secondary bony palate sensory dot skin long mouth nose on top of its mouth and many more feature. crocodilian is just a extreme aquatic dinosaurs and there is no dinosaurs.dinosaurs is a prehistoric crocodilian .scientist john ruben say they are crocs. but i did not use any of his evidence to find it.bird finger and toe do not match dinosaurs the skull is different and brain tooth replacement. protoavis bird was before no fuse furcula 4 finger coelophysis bird have nothing to do with dinosaurs .all these new crocs confirm crocodilian as dinosaurs like catcroc simosuchus pristichampsus duckcroc sheildcroc but some scientist did not need those evidence

    ReplyDelete
  5. sorry sphenosuchian protosuchian I should have said only verticalised. t.rex gharial do not verticalised

    ReplyDelete
    Replies
    1. OK... I think I follow most of what you're saying. Sorry, but I have a hard time buying any of it. The separation of dinosaurs and crocodiles is well supported by hundreds of anatomical characteristics, as is the nestling of Aves within Theropoda. This is so well established by hundreds of years of comparative anatomy, phylogenetic studies and embryological analyses that I don't consider it worth debating. The contrary opinions of folks like John Ruben, Larry Martin and others like them represent the extreme minority on this issue, and their claims have been falsified by many other dinosaur workers.

      Delete
  6. science is not popularity contest no won is bigger thaN THE EVIDENCE evidence is the evidence badit is the won that falsified evidendence and the sleezy media the tabloid who try to milk every thing out of dinosaurs badit have no evidence they falsified to keep story going and wait for a ghost fossil that is not there. the science is there that show dinosaurs as crocodilian other badit falsified bad science stuff is not science its man made propoganda .come on now scientist have known for years that dinosaurs were crocs large croc bums 2 row or more gum with croc teeth nose on end of mouth and top of the mouth long false gharial mouth only animal has that feature is spinosauridae crocodilian and share these feature too secondary palate sensory dot skin triceratops head skin this is from sheildcroc unigue belly skin brain size brain architecture deversety in the crocodilian brain system paul sereno 5 odd ball crocs hepatic piston diaghragm 2 compsognathus group fossil they find that with them t.rex unigue teeth crocodilian tail dinosaurs tail hoof toe large size supercroc no mandibular fenestra mandibular fenestra armo bony eyelid croc bums on foot chewing real ziphodont teeth not the fake kind like dromaeosauridae ziphodont means crocodilian dinosaurs teeth they thought sebecus was a dinosaurs till the find complete fossil simular plant eating teeth diaghragm similar to advance crocodilian alligator the advance dinosaurs brain carnotaurus allosaurus t.rex are similar to crocodilians carnotaurus not even closely related to crocodilian fuse skull a jaw does not look like birds and snake .top candidate to turn into crocodilian protosuchian protosuchus 5 finger 5 claws 5 toes 5 claws no bony palate or secondary palate junggarsuchus 4 finger 4 claws 4 toe 4 claws only a bony palate could not do the dead roll.bird finger are 2,3,4, toe are 2,3,4,5, dinosaurs finger are 1,2,3, toe are 1,2,3,4, bird finger and toe does not match land bipedism evolution they lose finger and toe first than evolve bipedalism in the tree they have flat braincase short bony palate short secondary palate no nasal cavity separation no fuse skull no verticalised teeth and teeth replacement brain are different from dinosaurs they have no hepatic piston or diaghragm .to silly crocodilian ankle thing both sphenosuchian protosuchian and dinosaurs do not walk like crocodilian they can not sprawl return of sprawling is evolution in water for crocodilian when they become ambush hunter and not all crocodilian can do high walk or sprawling adult gharial can not do high walk or sprawl yes ankle of sphenosuchus protosuchus look similar to crocodilian and look nothing like dinosaurs but they are not same many animal similar feature look similar but are complete different animal .sphenosuchian protosuchian are convergen to look like crocodilian but clearly mouth are small nose below eyes a land feature no evidence of aquaticness. crocodilian become aquatic 150 millon years spinosauridae date 155 millon years ago unigue skull link with eoraptor coelophysis protosuchus dated 155 millon years ago junggarsuchus dated 175 millon years ago. and crocodilian have moble pelvis pubis joint not found in dinosaurs sphenosuchian protosuchian .and catcroc have flexible spine like a cat not found in dinosaurs sphenosuchus protosuchus you can see dinosaurs is no different from odd ball croc paul sereno found those croc was on evolution rampage. you think crocodilian ancestor is over that not what evidence say just because some scientist did a bad job does mean its over some these classification take 10-20-30 years to finish if do your way some crocodilian would be call mammal because chewing because they have mammal teeth.

    ReplyDelete
    Replies
    1. "science is not popularity contest no won is bigger thaN THE EVIDENCE"

      I agree. The overwhelming evidence from multiple disciplines, in this case, points the the traditional view of archosaur evolution being most likely.

      As for the rest of your comment, I'm afraid I really cannot understand the way it is written. It reads like a list of words rather than standard syntax, and I'm not really sure what you're trying to say.

      Delete
    2. Well, Mark. Just remember: http://www.theonion.com/articles/seemingly-mentally-ill-internet-commenter-presumab,33570/

      Somewhere out there coelophysis is living out his life. :(

      Delete
  7. Meanwhile, some contrarian is scheming that BANDits are not in fact primates.

    ReplyDelete
  8. Meanwhile, some contrarian is scheming that BANDits are not in fact primates.

    ReplyDelete