It could look a giraffe in the eyes

i-dbf8d11d1c2645a71c76fd49a0c4971c-Witton, giraffe, azhdarchid.jpg

The day-job, a dinner date, a committee meeting, and some work identifying Tanzanian reptiles from photos means that I don't have time to post more conference thoughts on the blog today. In, as always, an effort to keep hits coming in (remember: visit, visit, and visit again), I'll therefore default to the 'picture of the day' game...

By now, I'm guessing that everyone who's been reading the stuff on the Wellnhofer pterosaur meeting has seen the above pic: Mark Witton used it in his talk on pterosaur mass estimates - he discusses that issue here, and I'll say things about it whenever I post further thoughts on the conference (tomorrow, if things go to plan). For the few that haven't seen the image, it shows Quetzalcoatlus to scale with Giraffa camelopardalis and a 65-kg Homo sapiens. It is perhaps one of the coolest images I've yet seen in palaeontological artwork, and you won't be surprised to hear that a low murmur of surprise/amusement/approval occupied the lecture theatre when the image was shown in Mark's talk. Anyway, more later.

If you're interested in giraffes, check out the ver 1 article on giraffe taxonomy here and ver 2 article on the necks-for-sex hypothesis here: for more on azhdarchids like Quetzalcoatlus go here on ver 1.

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Wow. Impressive. I've seen a mounted skeleton cast of Big Q, but the comparison is amazing...

And then to imagine that the animal lifts off!!!

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However, does it make sense to show Quetzalcoatlus so scrubby?

And is there a way to give it eyes that are at least as big as the giraffe's, or does the skull really have such surprisingly small orbits?

By David Marjanović (not verified) on 19 Sep 2007 #permalink

David,

The orbit of Quetzalcoatlus certainly is pretty small compared to the size of the skull. The azhdarchid Zhejiangopterus also has atypically small orbits, so maybe this is something to expect from all azhdarchids. However, I must admit that the eye was an area that didn't get a disproportionate amount of attention when I was sketching it, so there may be a bit of slop in the picture as well. That being said, note that giraffes have very shady eyes - the giraffe eyeball itself is smaller than it appears.

As for the shagginess, I guess I just ran with the fact that some pterosaurs appear to have particularly dense and long fur down the dorsal surfaces of their necks. With so much neck to play with here, I've gone one step further and given it a mane. Oh, and some heron-like chest plumes, just for fun. I guess I exaggerate pterosaur fuzz for three reasons:

1) It demonstrates the presence of fur to folk who otherwise wouldn't know it's there.
2) lots of modern animals have elaborate integumentary structures, so it's not unreasonable to speculate that some pterosaurs had them too.
3) I'm a scruffy, unkempt bugger myself, and I see no reason why my Quetzalcoatlus should be dressed any smarter than I am. Unless we're out for dinner, of course, in which case I won't leave the house until it's wearing a tie.

Azhdarchid pterosaurs did have ridiculously small orbits. I like the picture a lot, Mark, but where is the big guy's enormous throat pouch? You've got the notch for it in the mandible, but there's no pouch!

That's the way I like to see biologists drawn. The well-distributed hair complement's Q's.

By Nathan Myers (not verified) on 19 Sep 2007 #permalink

Oops, that's "complements".

And I like how Q is deplicted rolling its eyes, as if to say "Oh, please".

By Nathan Myers (not verified) on 19 Sep 2007 #permalink

Wow, that is one cool picture! But I keep seeing the little crest on top as a French beret, and wonder why the quetzlcoatl is slouching around Paris. It might well have had a throat pouch to hold the crocs ? it swallowed.

"...and wonder why the quetzlcoatl is slouching around Paris"

Ah, oui oui - it's actually Eric Buffetaut's Quetzalcoatlus like azhdarchid from southern France: it's just like the north American Quetzalcoatlus, but drinks more wine and squawks with a continental accent. Tres bien!

As for the throat pouch, I keep mine (and those of the pterosaurs that I draw) tucked neatly away until they distend into action.

"That's the way I like to see biologists drawn. The well-distributed hair complement's Q's."

I took great care to map it in detail.

Ah, thanks.

I'm a scruffy, unkempt bugger myself, and I see no reason why my Quetzalcoatlus should be dressed any smarter than I am.

Aerodynamics?

By David Marjanović (not verified) on 20 Sep 2007 #permalink

Aha! A perfect example of convergent evolution!

Obviously Q. evolved into a size too large to fly and converged into a life-style like giraffes. The wings were kept for sexual attraction (you know big wings mean big ...).

Darren wrote, so long ago, "Of course, there is a new azhdarchid which was _substantially_ bigger than Quetzalcoatlus, but, err, let's not talk about that yet (ask me later)." So, it's later, now...

I wonder if it could touch its wingtips together behind/above its head, and if so, whether that would shade its eyes, or whether the tips would only reach to somewhere above the neck.

Mark: Now can we have a picture of a herd of Qs thundering across the veldt? Would their limb articulation permit galloping?

By Nathan Myers (not verified) on 20 Sep 2007 #permalink

Yikes!!!
That's...hard to believe.
That thing flew? With what kind of muscles? What did it eat, fish?
wow

By Sven DiMilo (not verified) on 20 Sep 2007 #permalink

My 1 1/2 year old is fascinated by this picture.

I think it's pretty cool too.

By Stephanie (not verified) on 20 Sep 2007 #permalink

Nathan, the gigantic pterosaur apparently quite a bit larger than Quetzalcoatlus - it was estimated to have a wingspan of about 25 m turned out to be bogus. It was based on some immense pterosaur tracks from Mexico, 80 cm long, and some wing finger fragments from Jordan (if I remember correctly). The tracks turned out to be distorted theropod tracks; the wing finger fragments turned out to be fossil wood. How embarrassing, good job none of this got out into the media. Oh, wait, it did :)

As for galloping.. you'll have to wait to see what Mike Habib publishes (though see part III, to be posted later today). In short, forelimb bone strength in azhdarchids does indeed indicate that they could run and launch quadrupedally.

> Aerodynamics?

A surface textured by hair or other integument can actually improve aerodynamics. The texture may delay separation of the boundary layer from the body. Early separation, as seen on a smooth surface, causes significant wake turbulence, the principal cause of drag. The separation delay caused by the texture therefore may reduce this wake turbulence, and hence the drag.

With what kind of muscles?

You can see its chest muscles in the pic.

What did it eat, fish?

Anything that moved and was able to pass between its jaw joints, probably. Think stork (and search the archives for the "azhdarchids were giant storks" post).

By David Marjanović (not verified) on 21 Sep 2007 #permalink

Um, when you say Giraffe, do you mean a small subspiecies like the Masai or the biggy one? (cant recall its name, -Grants?)

" With what kind of muscles?
You can see its chest muscles in the pic."

I meant not which muscles, but what kind of muscles? My understanding of bird physiology is that power output required for flight increases in direct proportion to body mass, but maximum power available from flight muscle scales differently, such that the lines cross (power required becomes greater than power available) at a body mass of only 15-20 kg or so.
This giant pterosaur (Q.) weighed an order of magnitude more, 100-250 kg depending on who one believes. The largest bird ever (afaik) was Argentavis, which might have weighed as much as 100 kg but must have soared (instead of flapped) almost all the time, and would have needed a pretty impressive headwind just to take off. If Q. was capable of powered flight, it had to have had some muscles of phenomenal strength; a type wholly unknown in extant vertebrates. What am I missing here?

By Sven DiMilo (not verified) on 24 Sep 2007 #permalink

Sven's question is very good, and applies equally well to the sauropods. In the first half of the last century their large size was taken, along with the puzzle-pieces form of the continents, by some serious geologists as evidence that the Earth must once have been much smaller. Since that hypothesis was rejected, we are left with a mystery. Could the dinosaurs have evolved a formula for much stronger muscles, now lost? If so, why did the birds lose it? Has anybody worked out what must have been the cross-sectional loading on sauropod (and Q.) muscles, or is this sort of thing not discussed?

By Nathan Myers (not verified) on 24 Sep 2007 #permalink

All I can say is that the muscles grow faster than isometrically. Q. has a humongous deltopectoral crest, for example.

It has also been calculated, as reported several times on the Dinosaur Mailing List, that Q. was able to take off in a dead calm by pushing itself off the ground with its wings, quadrupedally. The trabeculae in the (famously hollow) arm bones are aligned for these stresses, not so much for those of flight.

Concerning the sauropods, all early mass estimates were way too high because they assumed a density of or close to 1 (as in little lizards) and were often made by dunking crassly wrong commercial models in water. Whenever you see Apatosaurus estimated at 30 t, laugh.

By David Marjanović (not verified) on 25 Sep 2007 #permalink

What an incredible picture. I do wonder though, if our depictions of creatures long gone are based on sure assumptions. A creature of the size of a giraffe would need immense wing power to fly.