Tetrapod Zoology

Yay – another one from the archives. This article first appeared on Tet Zoo ver 1 in April 2006 (here). If you’ve read it before, please have the decency to pretend that you haven’t, thanks [excellent macronarian sauropods below from wikipedia].

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I’ve stated before on this blog that I do quite a bit of consultancy work for companies that produce prehistoric animal books for children. In advising and assisting artists as often as I do, I find that they consistently screw up on the same things, every time. One of the biggest problem areas seems to be the hands and feet of sauropod dinosaurs – I reckon that every single artist whose work I’ve had to check has screwed up on these. By the way, the artists I’m talking about here lack palaeontological expertise or training: I’m not talking about your Luis Reys, Todd Marshalls and Mark Halletts, but rather about wildlife artists who find themselves being asked to illustrate dinosaurs.

I also want to note that in no way is it the ‘fault’ of the artists concerned, given that (1) they’ve mostly based what they’ve done on the published work of those who have gone before them, and (2) while many of them have a history of working with palaeontologists, none of the experts they’ve been advised by before have bothered to tell them what they’ve been getting wrong. In fact I note that book-writing palaeontologists in general (you know who you are) rarely seem to bother providing their artists with any information, nor in correcting their mistakes, hence the incredible number of god-awful restorations that clutter the literature. Incidentally, this situation is getting worse as companies increasingly use CG images produced by people who seem to know nothing about animals, let alone fossil ones. But enough of that.

To save myself work in the future it occurred to me that it might be a good idea to post on sauropod hands and feet: that way, I can just direct interested parties to this web page in future, and save myself the usual to-ing and fro-ing of notes, scans, and scribbled on diagrams. Several people have already produced overviews of sauropod hand and foot morphology, but unfortunately they’re somewhat obscure and inaccessible to many. Greg Paul (1987) discussed in detail what sauropod hands and feet probably looked like, based on trackways and morphology, and provided a summarized version of the same information in his Japanese book The Complete Illustrated Guide to Dinosaur Skeletons (Paul 1996). Tracy Ford (1999) also published a guide to restoring sauropod hands and feet. Numerous technical studies describe or review sauropod hands and feet, with the most useful works being Christiansen (1997), Bonnan (2001, 2003, 2005) and Apesteguía (2005). Here, we look at hands only.

The basics

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Let’s note to begin with that sauropod hands were only very superficially like those of elephants, and in fact in several details were fundamentally different. In fact they’re unique in that the metacarpals did not spread out from the wrist as they usually do in tetrapods, but were arranged in a vertical column. My biggest peeve concerning restorations of sauropod hands is that people seem unable to resist the temptation to illustrate multiple claws sticking out all over the place, or to depict hooves on all of the digits [adjacent pic, from wikipedia, shows how NOT to do sauropod hands. Apologies to the artist]. As we’ll see, the evidence is against both details. I know that many skeletal mounts give the animals multiple claws, but that’s because the mounts are inaccurate, outdated composites.

I should note here that the following discussion applies only to members of Eusauropoda, given that it now seems that basal sauropods outside of Eusauropoda lacked the distinctive hands of the better known, fully graviportal sauropods.

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The metacarpal colonnade

As noted, the eusauropod hand is formed from a columnar arcade of five vertically arranged metacarpals [see adjacent pic showing right hand of a Portugese sauropod. The tall columns are the metacarpals; the only visible ungual ('claw bone') is the large thumb claw]. If you were to look at the animal’s hand from underneath (the plantar surface), the distal metacarpal tips would be seen to be arranged in a semi-circle, and the posterior surface of the hand would be concave. The hand was not backed by a pad (as McGowan (1991) wrongly stated), as it is in elephants. There is no doubt that this configuration was the case in life, as it’s verified by numerous horseshoe-shaped hand tracks. In a new, as-yet-unpublished sauropod from the Lower Cretaceous of the Isle of Wight, it’s been claimed that the first and fifth metacarpals virtually touch on the posterior surface of the hand, but this is unique so far as we know (this animal wouldn’t have left horseshoe-shaped tracks, but subcircular ones… if the proposed interpretation is valid, and it might not be). An even more peculiar claim – in fact it’s downright ridiculous – is that sauropods walked with their fingers curled under the distal ends of the metacarpals (Beaumont & Demathieu 1980). This is totally at odds with the morphological and trackway evidence and can be disregarded.

Not only did the metacarpals form this unique tubular structure, they and their digits seem to have been bound together to form a sort of pseudo-hoof: the digits didn’t splay outwards from the metacarpus, but were bound together with them, nor did digits II to V possess hooves, claws or nails. This is supported by both anatomy and trackways, so distinct digits were almost certainly not visible in life.

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Thumb claws, or lack of them

Claws were absent from all digits except for digit I (the thumb). This thumb claw varied in size, shape and orientation among the sauropod groups: it was particularly big in diplodocoids, where it was also laterally compressed and notably deep, and clearly separated from the rest of the metacarpus. In contrast, in brachiosaurids it was small, subtriangular in cross-section, and not separated from the rest of the metacarpus. In forms with large pollex claws (like diplodocoids), the anatomy of the penultimate phalanx and the distal end of the first metacarpal indicates that some flexion and extension of the claw was possible: in other words, these sauropods could both lift and lower their claws (albeit not by much compared to what was possible in other dinosaurs) [adjacent image, from a 1961 paper by Werner Janensch, shows the right hands of Brachiosaurus (left) and Janenschia (right), with images at top showing the metacarpus as seen proximally (viz, looking down on the articular ends of the bones). Note the small brachiosaur thumb claw].

What did sauropods do with this lone thumb claw? Pretty much every conceivable function has been proposed, including fighting, digging, ripping foliage or tree trunk gripping. The claw’s anatomy and range of motion led Upchurch (1994) to conclude that a trunk-gripping function was most likely, but if this is right then it seems odd that titanosaurs – the sauropods perhaps best suited for bipedality and rearing – were the ones that lost the claws [cladogram below, from Milàn et al. (2005), shows manus evolution in sauropodomorphs (though, confusingly, with the two most basal hands being left hands and all the others being right hands. Note reduction and loss of thumb claw].

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That’s right: even the thumb claw was not present in all eusauropods. During the evolution of titanosauriform macronarians (the group that includes brachiosaurids and titanosaurs) the thumb claw was reduced in size and eventually lost altogether. We know that brachiosaurids such as Brachiosaurus possessed a short, small thumb claw, but Lower Cretaceous trackways apparently produced by other brachiosaurids indicate that the thumb claw was absent in these forms (it’s been suggested that the thumb claw was still present in these forms, but that it was so small that it failed to leave an impression. I find this less likely than the idea that the claw really was absent). With the exception of the controversial Jurassic form Janenschia (and probably a few basal taxa from the Cretaceous), titanosaurs were all devoid of thumb claws.

Pads and spiky tubercles

But there’s more – derived titanosaurs lacked not just claws, but finger bones too, and thus fingers. Their column-shaped hands were bizarre fingerless stumps, and they walked on the distal ends of the metacarpals, which is pretty odd to say the least. As described by Apesteguía (2005), the distal ends of the metacarpals in fingerless titanosaurs were wider and more rectangular than those of other sauropods, and with unusual sculpturing. The latter feature suggests that some kind of cushioning tissue encased the metatarsal ends, and a few titanosaurs preserve what appears to be some kind of soft tissue in this area.

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Evidence for entirely different soft-tissue structures on the sauropod metacarpus might have been present in other sauropods, according to recently described trackway evidence. A manus impression from the Upper Jurassic of Lourinhã in Portugal – probably produced by a brachiosaurid – preserves vertical score marks on its sides that seem to have been produced by rough tubercles on the metacarpal surface (Milàn et al. 2005). These authors [their reconstruction of the sauropod manus is shown here, from Milàn et al. (2005)] proposed that at least some sauropods had spiky skin covering the distal end of the metacarpus, though how widespread this was we don’t know.

Banana-shaped first metacarpals: why?

While all five metacarpals in most eusauropods were more or less straight and parallel, this was not true of some titanosaurs. In these forms the first metacarpal was curved outwards at its distal end, and thus roughly banana-shaped. This is first seen in Janenschia, in which a thumb claw was present, but it’s also the case in various other taxa, including Andesaurus and Argyrosaurus [the latter shown below, note 'banana-shaped' first metacarpal visible at bottom left]. Apesteguía (2005) made the intriguing suggestion that the bowed first metacarpal may first have evolved in claw-bearing basal titanosaurs in order to help support the claw, that it was then later retained when the claw was lost, and that it was later reversed (back to the straight condition) in derived lithostrotian titanosaurs.

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This raises the question as to why a bowed first metacarpal was needed ‘to help support the claw’ however, given that other sauropods with thumb claws had straight, rather than bowed, first metacarpals. In Janenschia, a raised lip around the outer surface of the first metacarpal’s distal end is very nearly in contact with the dorsoproximal part of the claw. This creates the impression that the metacarpal’s distal end had evolved to help conduct stress along the curved ungual’s dorsal margin. If that’s true (let me emphasize that this is just an idea), it could mean that the thumb claw was used in a manner quite different from that of other sauropods. Maybe the claw tip was actually used for piercing something: presumably a substrate, or bark. Any better ideas?

So there we have it. I had planned to cover sauropod feet as well, but that’ll have to wait for a future post [UPDATE: err, whoops. I wrote this article two years ago, and here we are...].

Refs – -

Apesteguía, S. 2005. Evolution of the titanosaur metacarpus. In Tidwell, V. & Carpenter, K. (eds) Thunder-Lizards: The Sauropodomorph Dinosaurs. Indiana University Press (Bloomington & Indianapolis), pp. 321-345.

Beaumont, G. & Demathieu, G. 1980. Remarques sur les extremités antérieures des sauropodes (reptiles, saurischiens). Compte Rendu des Séances de la Société de Physique et d’Histoire Naturelle de Genève 15, 191-198.

Bonnan, M. F. 2001. The Evolution and Functional Morphology of Sauropod Dinosaur Locomotion. Unpublished phd thesis, Northern Illinois University.

- . 2003. The evolution of manus shape in sauropod dinosaurs: implications for functional morphology, forelimb orientation, and phylogeny. Journal of Vertebrate Paleontology 23, 595-613.

- . 2005. Pes anatomy in sauropod dinosaurs: implications for functional morphology, evolution, and phylogeny. In Tidwell, V. & Carpenter, K. (eds) Thunder-Lizards: The Sauropodomorph Dinosaurs. Indiana University Press (Bloomington & Indianapolis), pp. 346-380.

Christiansen, P. 1997. Locomotion in sauropod dinosaurs. Gaia 14, 45-75.

Ford, T. L. 1999. How To Draw Dinosaurs, book 1. T. L. Ford (privately published).

McGowan, C. 1991. Dinosaurs, Spitfires, & Sea Dragons. Harvard University Press (Cambridge, Mass. & London).

Milàn, J., Christiansen, P. & Mateus, O. 2005. A three-dimensionally preserved sauropod manus impression from the Upper Jurassic of Portugal: implications for sauropod manus shape and locomotor mechanics. Kaupia 14, 47-52.

Paul, G. S. 1987. The science and art of restoring the life appearance of dinosaurs and their relatives – a rigorous how-to guide. In Czerkas, S. J. & Olson, E. C. (eds) Dinosaurs Past and Present Vol. II. Natural History Museum of Los Angeles County/University of Washington Press (Seattle and London), pp. 4-49.

- . 1996. The Complete Illustrated Guide to Dinosaur Skeletons. Gakken.

Upchurch, P. 1994. Manus claw function in sauropod dinosaurs. Gaia 10, 161-171.

Comments

  1. #1 Ed
    October 29, 2008

    I had not read this before but I think it’s great. I have 3 pet peeves about dinosaur articles: inaccurate illustrations, inaccurate titles and lamarkian language.

  2. #2 Darren Naish
    October 29, 2008

    I’m guessing I failed on all three :)

    Is it right to describe a structure as having evolved ‘in order to’ perform a certain function? I was criticised for this before (the ‘why do owls have ear tufts’ article). In the end: sod it, I decided.

  3. #3 Lorena
    October 29, 2008

    Thank you for writing this. I illustrate and while I have not been asked to work on dinosaurs, this will help if I ever am.

  4. #4 Zach Miller
    October 29, 2008

    It’s never been a problem for me. I just look at the technical literature and–huzzah–I have at least five papers discussing sauropod manus morphology. It strikes me as slothful that nature artists don’t just go out and find some technical reference material before doing an illustration. I can’t imagine NOT doing that. I’m doing Epidexipteryx right now, and would there be any other way to do it?

    You can get a LOT right by just reading an animal’s description and/or looking at its close relatives. It’s not always a case of a writer not giving the artist enough feedback (although there’s that too).

  5. #5 Karl Zimmerman
    October 29, 2008

    Roughly the same forearm conditions were true of Hadrosaurs, IRRC. The otherwise great new book, Feathered Dinosaurs by John Long is marred somewhat by a totally unrealistic Hadrosaur manus in one of the “action” pictures.

    Come to think of it, reduction of digits IV and V seems to be basal to Dinosauria – perhaps the basal condition for Dinosauria also included absence of claws on these two digits as well, with a few groups later re-evolving them.

  6. #6 Rosel
    October 29, 2008

    I noted the single clawed stumps on the brachiosaur( both skeleton and animated reconstruction) at the Berlin Natural History Museum. Thought they were pretty unusual.

    I know that that the animations were made with the BBC…

  7. #7 Gray Stanback
    October 29, 2008

    Which sauropods are the ones you show in the picture at the top of this post. If I were to guess, they look like a Brachiosaurus, a Giraffatita, a Jobaria, and a Sauroposiedon.

  8. #8 Andreas Johansson
    October 29, 2008

    According to the labels on the original, it’s a Brachiosaurus (grey), a Giraffatitan (yellowish), a Camarasaurus (brown), and an Euhelopus (greenish).

  9. #9 Tim Morris
    October 30, 2008

    wow, there was asuch a thing as a knuckle walking dinosaur ;)

  10. #10 Jerzy
    October 30, 2008

    Thanks for interesting and informative post :-)

  11. #11 Steve O'C
    October 30, 2008

    Great Stuff Darren!

    Zach
    ”It strikes me as slothful that nature artists don’t just go out and find some technical reference material before doing an illustration”

    I kinda disagree; it’s very difficult sometimes when you don’t have access to 90% of technical literature. I can’t afford to subscribe to every journal I could possibly need. To be fair, the first hit on Google for ”sauropod manus” is a free Pdf. That assumes you search for the word ‘manus’ and not ‘feet’ for example. I think that academic people sometimes forget that non academic artists are not going to have a clue what to look for. They are more likely to read a book rather than the technical lit.

  12. #12 Mo Hassan
    October 30, 2008

    “Is it right to describe a structure as having evolved ‘in order to’ perform a certain function? I was criticised for this before (the ‘why do owls have ear tufts’ article). In the end: sod it, I decided.”

    I said something similar to that in an assignment about mustelid body plans (“ferrets evolved a slim body plan in order to follow their prey down burrows” or something like that) and was penalised… I now have an aversion to writing “designed for” or “evolved for”, although maybe I have no reason to.

  13. #13 John T.
    October 30, 2008

    I suppose I’ll totally expose my ignorance, but here it goes. When I see pictures of dinosaurs it strikes me that none of them seem to have protruding ears. Why wouldn’t predatory dinos have ears like lions and tigers? Why wouldn’t the lower end of the food chain have ears like a deer or a mouse? Dinos had all kinds of time to evolve compared to mammals. If a mammal can evolve into something that looks like a fish couldn’t dinosaurs evolve protruding ears? Okay, now I’m really gonig to sound stupid. Why wouldn’t some of them have a fleshy nose with whiskers like a cat or a dog?

  14. #14 Ed
    October 30, 2008

    Using lamarkian language is fairly common, it’s been done by the best. The problem I have with it is that it is misleading to laymen and creationists latch on to it and use it to refute evolution. In this day and age, where science itself is under attack, we need to be careful about saying what we really mean or it will be used against us.
    I can’t count the number of times I have had to explain that it just does not happen that way. And it’s Darwin who is blamed, not Lamark. I recently read Aaron Filler’s “Upright Ape” and he did the same thing (I sent him a note on it) but only once in the entire book. Bakker’s done it and I have heard it many times in documentaries. We just have to be more careful to avoid fanning the flames of creationism.
    ps
    Darren, I don’t think your titles or pictures are misleading or inaccurate. There is a difference when presenting a generalization and presenting what is supposedly a factual illustration. Similies don’t mislead. I refer to articles about a “dinosaur” that talks about a mammoth for instance. This only fuels the ignorant rather than educating them.

  15. #15 Ed
    October 30, 2008

    John T.
    Protuding ears are a mammilian feature. Dinosaurs are transitional between reptiles and birds, neither of which have protruding ears.

  16. #16 Dartian
    October 30, 2008

    Ed:

    lamarkian….Lamark

    It’s lamarckian and Lamarck. Sorry to nitpick, but the name of such a major figure in the history of biology should not be misspelled*.

    *Not that anyone’s name should, of course. I find it particularly annoying that so many people persistently write ‘Leaky’ when they should write Leakey.

  17. #17 Ed
    October 30, 2008

    Thanks, I get Leakey right but have trouble with Goethe Lamarck and Cuvier(?). Sometimes I can remember and sometimes I can’t. Getting old is a pain but I starting loosing memory coincidental with diabetes just before I retired. Not fun.

  18. #18 David Marjanovi?
    October 30, 2008

    Why wouldn’t some of them have a fleshy nose with whiskers like a cat or a dog?

    Because only mammals* have a fleshy nose — or a nose cartilage in the first place. This is easy to see from the fact that mammalian nostrils are not separated by bone; those of dinosaurs always are. (And fused bony nostrils still aren’t a guarantee for a fleshy nose; see turtles and crocodiles.)

    * I am, hypocritically, using the crown-group definition here. Morganucodon still had separate nostrils in its skull.

  19. #19 John T.
    October 30, 2008

    “Protuding ears are a mammilian feature”. Maybe my question is why are they only a mammilian feature? Isn’t it true that when it comes to adaptation that form follows function? If protruding ears are a favorable adaptation didn’t dinosaurs have time to adapt that way? Or are mammals less favorably adapted with ears likely to disappear through time?

  20. #20 David Marjanovi?
    October 30, 2008

    Yes, Cuvier is right, and Goethe is fairly easy if you know how the oe is pronounced (…though occasionally the good man spelled himself Göte, which would make even more sense).

  21. #21 David Marjanovi?
    October 30, 2008

    Maybe my question is why are they only a mammilian feature? Isn’t it true that when it comes to adaptation that form follows function?

    Form follows function plus phylogenetic constraints* plus random. Outer ears are the mammalian solution to a particular problem. Other animals solve it in different ways — and it’s difficult or impossible to switch between these.

    * Evolution can only work with what is there. It modifies structures present in ancestors, rather than creating completely new ones.

  22. #22 David Marjanovi?
    October 30, 2008

    That’s also why whales and otters undulate up-down rather than left-right the way all other vertebrates that use their vertebral column to swim do.

  23. #23 Felicia Gilljam
    October 30, 2008

    David Marjanovic – you meant to say “aquatic mammals” rather than “whales and otters”, right? I mean, even if we generously substitute “whales” with Cetaceans, the Sirenians and Pinnipeds are still complaining about being forgotten again! ;)

  24. #24 Felicia Gilljam
    October 30, 2008

    (Although to be fair Pinnipeds do look more like they undulate from side to side than anything else… But the way they swim is not really analogous to the way for instance fish or aquatic reptiles swim.)

  25. #25 Raymond
    October 30, 2008

    David, for shame, you forget *Potamogale* and the Desmans!

    Felicia, Phocids don’t just “look” like they perform lateral undulations, it is their primary method of locomotion when in the water.

  26. #26 David Marjanovi?
    October 31, 2008

    I deliberately didn’t mention the phocids (lateral undulation, more or less, using their feet as a tail fin) or the other pinnipeds (underwater flight — the vertebral column isn’t used). Desmans undulate the tail from side to side, right? I don’t know how Potamogale swims…

  27. #27 Dartian
    October 31, 2008

    David Marjanovic:

    Desmans undulate the tail from side to side, right? I don’t know how Potamogale swims…

    According to Frank Fish (1996), Potamogale swims by lateral undulation. (He doesn’t discuss the swimming styles of desmans or Micropotamogale, however.)

    Reference:

    Fish, F.E. 1996. Transitions from drag-based to lift-based propulsion in mammalian swimming. American Zoologist 36, 628-641.

  28. #28 Jenny Islander
    October 31, 2008

    Sauropods have gotten steadily cooler in my lifetime. My _Big Golden Book of Natural History_ depicted damp grayish tubular things crouching in a mudpit on dislocated joints. First their legs straightened, then somebody fixed their necks, then they started acquiring dorsal spines and patterned hides . . . I wonder what’s going to appear in popular depictions next?

    Anybody else who posts here tear up when Dr. Grant gets his first look at a live sauropod in _Jurassic Park?_ It still gets me right here. Right here, I tell you.

  29. #29 David Marjanovi?
    October 31, 2008

    Anybody else who posts here tear up when Dr. Grant gets his first look at a live sauropod in _Jurassic Park?_

    Most impressive scene in cinema ever.

    (cue music)

  30. #30 Michael P. Taylor
    October 31, 2008

    Anybody else who posts here tear up when Dr. Grant gets his first look at a live sauropod in _Jurassic Park?_ It still gets me right here. Right here, I tell you.

    Check out this five-year-old email:

    Date: Tue, 02 Sep 2003 15:28:01 -0700
    From: Matt Wedel <sauropod@socrates.Berkeley.EDU>
    To: Mike Taylor <mike@indexdata.com>

    (I’m not kidding about loving JP, though. The scene where they first see the Brachiosaurus moved me like no other scene in any other film I’ve ever seen.)

    You are preaching to the choir. I have yet to actually cry at the Brachiosaurus scene, but it does cause me to tear up almost every time. I don’t think you can pour a big chunk of your life into something without falling in love with it at least a little bit (or maybe I’ve just been lucky, but the operative word is ‘pour’), and I am definitely and hopelessly in love with brachiosaurids, which is a bit of a problem in that I’ll never get to see one. So to get to see one, or to get to watch other people get to see one, is pretty moving. I’ve seen just the Brachiosaurus scene about thrice as many times as I’ve seen the whole movie; for me it is the climax of the movie and the rest is only a mildly diverting romp.

  31. #31 Zach Miller
    October 31, 2008

    I’m in the same boat. There are two scenes in Jurassic Park that cause me to become incredibly emotional:

    Brachiosaur scene (tear up every time), and;

    Tyrannosaurus stepping out of its pen for the first time and roaring (makes every hair on my body stand on end).

    Only one other dinosaur movie moves me in such a way, and it’s the first ten minutes of Disney’s otherwise-awful CG “Dinosaur” movie. You know, before the lemurs start yammering. The opening sequence has everything: oviraptors, Carnotaurus, pachyrhinosaurs, ankylosaurs, parasaurs…it just doesn’t get a whole lot better. I tear up every time, although the rising score certainly adds to the emotional impact. I need to blog about this sometime…

  32. #32 Hai~Ren
    October 31, 2008

    Wow, looks like I’m not alone.

    As an 11-year old, watching that Brachiosaurus scene in the cinema brought a tear to my eye.

    And when the Tyrannosaurus broke out of its enclosure, I was genuinely gripped with fear.

    The other notable moments was that scene with the herd of Parasaurolophus and the pair of brachiosaurs, by the lake, and the Gallimimus stampede. I did love the first appearance of the “Velociraptor“, after having been held in suspense for so long as to how they would appear.

    For The Lost World, there was the scene where the herd of oversized Stegosaurus emerged, as well as the scene where the hunters were rounding up all the various dinosaurs. I had so much fun trying to identify all the species represented! Also, considering that the ceratopsids are my favourite dinosaurs of all time, seeing a Triceratops wreak so much havoc in the hunters’ camp was awesome, when the only one in the first movie was sick.

    The final scene showing the tyrannosaur family, reunited, while a herd of stegosaur ambles nearby and the Pteranodon comes in to land was pretty cool.

    JP3 was a crapfest for me, but I could still find it in me to appreciate the hadrosaur stampede, and the final scene where the Pteranodon were flying off into the clouds.

    Dammit, those were magical moments.

  33. #33 Dartian
    November 3, 2008

    Emotionally, ‘Jurassic Park’ doesn’t quite do it for me, I’m afraid. (Frankly, I think that movie is somewhat overrated.)

    For me, the saddest Mesozoic moment is episode 4 of ‘Walking with Dinosaurs’, the one with the last journey of the old Ornithocheirus. Now that was heartbreaking.

  34. #34 wazza
    November 3, 2008

    If the finger bones were replaced by soft tissue, it might indicate that the cartilage was never replaced by bone, which would explain where the pads come from…

    Oh, sorry, was everyone having an emotional moment?

  35. #35 David Marjanovi?
    November 3, 2008

    For me, the saddest Mesozoic moment is episode 4 of ‘Walking with Dinosaurs’, the one with the last journey of the old Ornithocheirus. Now that was heartbreaking.

    For me it wasn’t because it was all so stupid. :-)

    If the finger bones were replaced by soft tissue, it might indicate that the cartilage was never replaced by bone, which would explain where the pads come from…

    Could be.

  36. #36 Olga
    November 9, 2008

    woah, fingerlss foot, thats smth eally new.
    I am an animalist myself, so it was a very interesting post. I’d like to see the article about sauropod feet someday.

  37. #37 Graham King
    November 22, 2008

    Form follows function plus phylogenetic constraints* plus random. Outer ears are the mammalian solution to a particular problem. Other animals solve it in different ways — and it’s difficult or impossible to switch between these.

    * Evolution can only work with what is there. It modifies structures present in ancestors, rather than creating completely new ones.

    So where did external ears (pinnae) ever come from, then?
    (Are you handing an opening to creationists here?!)

    A blanket dismissal of the possibility (of dinosaurs having protruding ears) seems rather excessive, to me.

    The point surely is that there are so many novel and even unique features in various dinosaurs (distinctive head crests, supraorbital pointy bits, horn arrays, dorsal spines, ridges, sails, plates, massive dermal armour, feathery scales, etc); all of which (in order to exist at all!) somewhere, somehow, necessarily appeared for the first time; de novo features, neomorphologies, what you will.

    So why not external ears, which seem a relatively minor and possibly widely useful modification (to augment or directionalize hearing acuity?)

    Could no mutation that would produce external ear tissues in a reptile ever occur, in principle? Whyever not?

    One might speculate on the likely range of sound audible to, or producible by, dinosaurs, and of relevance to them (eg sounds of their predators or their prey, of running water or changing weather, etc). And then discuss whether plausible tissue modifications would actually have been effective for those frequencies/wavelengths, or not.

    And of course we see external ears in living animals also serving for display, cooling, etc, as well as sound-related uses.

    But a blanket dismissal of the possibility (of dinosaurs having outward ear structures of any sort) seems excessive.

  38. #38 David Marjanovi?
    November 22, 2008

    So where did external ears (pinnae) ever come from, then?

    I don’t know, but I bet someone will find out.

    (Are you handing an opening to creationists here?!)

    To the contrary.

    A blanket dismissal of the possibility (of dinosaurs having protruding ears) seems rather excessive, to me.

    If they are easy to evolve, why don’t more animals have them? Why is there no evidence that it happened more than a single time? Why do not even owls have external ears? (Last time I checked, their tufts don’t have a function in hearing.)

    de novo features, neomorphologies, what you will.

    None of this is really new: enhanced growth of certain body parts, bone formation in places where bone used not to form, scales growing into spikes and then splitting open…

  39. #39 Philip Kahn
    November 29, 2008

    Oh good, I was not just utterly bonkers in thinking I was seeing foot inconsistency in drawings. It actually exists …

    I did not, however, know that there were no carpals on many Eusauropoda! Now that is definitely an interesting evolutionary structure.

    @ Mike and Zach: Yeah, JP is one of my favorite movies, and those are still stirring scenes. I can’t believe it came out what, 15 years ago now? It still looks so much better than a lot of the crap CGI coming out of movies today.

    Finally, regarding the bowed metacarpal: It is possible that it is bowed to create a preferential direction for the bone to stress in without breakage. Think a longbow: it is not curved to necessarily conduct stress, but instead to be able to not break when stressed (and to make it easier to store energy, but that is probably incidental to this bit of idle speculation). A perfectly straight structure makes a poor bow, and is more likely to break than a structure with a pre-existing degree of curvature.

    However, that would imply that there should be some evidence of bone strength/stress to support this, and might have some interesting behavioural implications. But carrying the “bow” analogy to its inevitable conclusion is just bizzarre, though; so far as I know, no animals have used their skeletons for energy storage. However, using it for locomotion has engineering precedent: http://www.engadget.com/2008/01/17/prosthetic-limbed-runner-disqualified-from-olympics/

  40. #40 Nima
    June 1, 2009

    This is truly sad. Elephant hoofs and extra claws on the hands… I mean is it that hard for these guys to just look up a fossil on the internet? Plenty of museums have corrected their sauropod hands (well, the ones outside of China anyway… I keep seeing Mamenchisaurus pop up in Chinese museums with those fake hand claws which are merely recasts of the foot claws).

    As for artists making such mistakes with sauropod hands… I was thinking exactly the same thing, somebody needs to correct them and actually care about the quality of the art. I have never drawn sauropods this way, and in fact I am alarmed that the paleontologists that work with these guys didn’t bother to correct them. I have Dr. Michael Benton’s old book on dinosaurs from the 90′s, and the illustrations (by various artists) are downright horrible. What I see in newer books is often even worse.

    By the way Darren, I am very interested in illustrating dinosaur books – without the errors of course. As you do consultancy work for publishing companies, I am hoping you might know this: What is the best way to get in contact with these publishers and get started drawing dinosaurs for their books? I am equally frustrated by the amount of errors I see in sauropod illustrations (plus plenty other dinosaur groups that are often drawn the wrong way). And I am very interested in doing something to change that.

    To see samples of my work on my blog (click my name to go there) or go to:

    http://sassani-dinoart.webs.com/portfolio.htm

    I would appreciate any help in this matter. Thanks in advance.

  41. #41 Raymond Minton
    June 1, 2009

    I think of the elephant analogy when I see sauropods, but this can be taken too far, and I was surprised when I first learned that they had neither elephant-like feet or thick, wrinkled skin. I was also struck by Gregory Paul’s observation about dinosaurs in general: none of them had hind feet that looked like the front feet. I hope that in the future illustrators will make a more concerted effort to produce anatomically accurate sauropod pictures.

  42. #42 Lois
    December 29, 2010

    I know this is an older article, but I found it fascinating and just had to respond to it. As an artist and dinosaur lover, I’m always wondering how dinos should really be drawn. Glad to learn what the feet looked like. I will draw them correctly from now on!

    This is truly sad. Elephant hoofs and extra claws on the hands… I mean is it that hard for these guys to just look up a fossil on the internet?

    I think a lot of the problem is that artists do not generally have the ability to interpret what they are seeing when they look at fossils, as a scientist does. They then make assumptions based on what they know of living animals, because that is all they have as a reference point. Elephants have big, thick, stumpy legs; so do sauropods; therefore they must have similar feet. If nobody corrects them and they don’t bother researching thoroughly, we wind up with brachiosaurus sporting elephant toes.

    Someone wondered why dinosaurs are never shown with an external ear, like a horse or cow. I am not sure, but I think if one were to examine the skull (or fossilized skull) of a horse,cow, dog, etc., one would find evidence of attachment points for the ear muscles and cartilage. I assume that dinosaurs lack such attachment points, so there is no reason to believe they ever had external ears. Of course, it could be that nobody has bothered looking for them, or the evidence has been misinterpreted. Remember, it was once thought that all the sauropods lived in swamps because they couldn’t support their own weight on land!

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