Monthly Archives: October 2015

My cat’s neck skeleton (first five cervicals)

When I separated my cat’s head from its body, the first five cervical vertebrae came with it. Never one to waste perfectly good cervicals, I prepped them as well as the skull. Here they are, nicely articulated. (Click through for high resolution.) Dorsal view at the top, then right lateral (actually, slightly dorsolateral) and ventral view at the bottom.

cat-first-five-cervicals-white

Or you may prefer the same image on a black background:

cat-first-five-cervicals

For those of us used to sauropod necks, where the atlas (C1) is a tiny, fragile ring, mammal atlases look bizarre, with their grotesque over-engineering and gigantic wings.

Fighting apatosaur art #7: the world speaks!

I’d hoped that we’d see a flood of BRONTOSMASH-themed artwork, but that’s not quite happened. We’ve seen a trickle, though, and that’s still exciting. Here are the ones I know about. If anyone knows of more, please let me know and I will update this post.

First, in a comment on the post with my own awful attempts, Darius posted this sketch of a BROTOSMASH-themed intimidation display:

apatosaurinae_sp_scene

And in close-up:

apatosaurinae_sp_scene-closeup

Very elegant, and it’s nice to see an extension of our original hypothesis into other behaviours.

The next thing I saw was Mark Witton’s beautiful piece, described on his own site (in a post which coined the term BRONTOSMASH):

BRONTOSMASH Witton low res

And in close-up:

BRONTOSMASH Witton low res-closeup

I love the sense of bulk here — something of the elephant-seal extant analogue comes through — and the subdued colour scheme. Also, the Knight-style inclusion in the background of the individual in the swamp. (No, sauropods were not swamp-bound; but no doubt, like elephants, they spent at least some time in water.)

And finally (for now, at least) we have Matthew Inabinett’s piece, simply titled BRONTOSMASH:

brontosmash_by_cmipalaeo-d9dy1kg

I love the use of traditional materials here — yes, it still happens! — and I like the addition of the dorsal midline spike row to give us a full on TOBLERONE OF DOOM. (Also: the heads just look right. I wish I could do that. Maybe one day.)

Update (Monday 26 October)

Here is Oliver Demuth’s sketch, as pointed out by him in a comment.

uqske

Thanks, Oliver! Nice to see the ventral-on-dorsal combat style getting some love.

So that’s where we are, folks. Did I miss any? Is anyone working on new pieces on this theme? Post ’em in the comments!

 

Which was the biggest dinosaur? (Answer: it’s complicated)

I just gave an answer to this question on Quora, and it occurred to me that I ought to also give it a permanent home here. So here it is.

This is a great example of a question that you’d think would have a simple, clear answer, but doesn’t. In fact, as a palaeontologist specialising in dinosaur gigantism, I have an abiding fear of being asked this question in a pub quiz, and not being able to produce the name that’s written on the quizmaster’s answer sheet.

First, what do we mean by “biggest”? Diplodocus was longer than Apatosaurus, but Apatosaurus was heavier. Giraffatitan was taller than either. Let’s simplify and assume we want to know the heaviest dinosaur.

Second, estimating the masses of extinct animals is incredibly hard even when we have a pretty complete skeleton. For example, the gigantic mounted brachiosaur skeleton in Berlin (which used to be called “Brachiosaurus” brancai but is now recognised as the separate genus Giraffatitan) has been subject to at least 14 estimates in the published scientific literature, as summarised here. They vary from 13,618 kg to 78,258 kg — a factor of 5.75 for the same individual. That’s like looking at a human skeleton and not knowing whether its from Kate Moss or Arnold Schwazenegger. (There are reasons for this and I urge you to read the linked article.)

Third, the big dinosaurs tend to be very poorly represented. Giraffatitan is probably the heaviest dinosaur known from a more or less complete skeleton (though even that is put together from several different individuals) so I could give that as the answer to the hypothetical pub-quiz — though the answer sheet would probably be out of date and call it Brachiosaurus.

Fourth, which individual of a given species do we mean? I said Giraffatitan is known from a more or less complete skeleton. And my best guess is that that individual massed, say, 30,000 kg. But an isolated fibula of the same species is known that’s 12.6% longer than the one in the skeletal mount. That suggest an animal that masses 1.126^3 = 1.43 times as massive as the mounted skeleton — say 43,000 kg. There might be yet bigger Giraffatitan individuals. On the other hand, there is some evidence that Apatosaurus, which is usually thought of as not being so big, might have got even bigger.

Fifth, the very biggest specimens tend to be known from only a handful of bones. A good example here is the titanosaur Argentinosaurus, which is known from several vertebrae and a few limb bones, but not all from the same individual. It’s a good bet that it massed 60-70 tonnes — so maybe about twice as much as Giraffatitan, but much less than the often-cited 100 tonnes. Other, more recently discovered, titanosaurs seem to be in the same size class: Puertasaurus, Futalognkosaurus, Dreadnoughtus and more. They they are hard to compare directly due to the paucity of overlapping material, or at least described overlapping material. (Scientists are working on getting more of this stuff properly described in the literature, which will help.)

But, sixth, the very biggest dinosaurs tend to be apocryphal. There’s Amphicoelias fragillimus, known only from E. D. Cope’s drawing of the upper half of a single vertebra. This may have been 50 m long and massed 80 tonnes; but other published estimates say 58 m and 122 tonnes. We really can’t say from the very poor remains.

So if you get asked this question in a pub quiz, your best bet is to roll a dice, pick an answer, close your eyes and hope. Roll 1 for Giraffatitan, 2 for Brachiosaurus, 3 for Apatosaurus, 4 for Argentinosaurus, 5 for Dreadnoughtus and 6 for Amphicoelias fragillimus. Good luck!

 

How light could a giant azhdarchid be?

I imagine that by now, everyone who reads this blog is familiar with Mark Witton’s painting of a giant azhdarchid pterosaur alongside a big giraffe. Here it is, for those who haven’t seen it:

Arambourgiania vs giraffe vs the Disacknowledgement redux Witton ver 2 low res

(This is the fifth and most recent version that Mark has created, taken from 9 things you may not know about giant azhdarchid pterosaurs.)

It’s one of those images that really kicks you in the brain the first time you see it. The idea that an animal the size of a giraffe could fly under its own power seems ludicrous — yet that’s what the evidence tells us.

But wait — what do we mean by “an animal the size of a giraffe”? Yes, the pterosaur in this image is the same height as the giraffe, but how does its weight compare?

Mark says “The giraffe is a big bull Masai individual, standing a healthy 5.6 m tall, close to the maximum known Masai giraffe height.” He doesn’t give a mass, but Wikipedia, citing Owen-Smith (1988), says “Fully grown giraffes stand 5–6 m (16–20 ft) tall, with males taller than females. The average weight is 1,192 kg (2,628 lb) for an adult male and 828 kg (1,825 lb) for an adult female with maximum weights of 1,930 kg (4,250 lb) and 1,180 kg (2,600 lb) having been recorded for males and females, respectively.” So it seems reasonable to use a mass intermediate between those of an average and maximum-sized male, (1192+1930)/2 = 1561 kg.

So much for the giraffe. What does the azhdarchid weigh? The literature is studded with figures that vary wildly, from the 544 kg that Henderson (2010) found for Quetzalcoatlus, right down to the widely cited 70 kg that Chatterjee and Templin (2004) found for the same individual — and even the astonishing 50 kg that seems to be favoured by Unwin (2005:192). In the middle is the 259 kg of Witton (2008).

It occurred to me that I could visualise these mass estimates by shrinking the giraffe in Mark’s image down to the various proposed masses, and seeing how credible it looks to imagine these reduced-sized giraffes weighting the same as the azhdarchid. The maths is simple. For each proposed azhdarchid mass, we figure out what it is as a proportion of the giraffe’s 1561 kg; then the cube root of that mass proportion gives us the linear proportion.

  • 544 kg = 0.389 giraffe masses = 0.704 giraffe lengths
  • 259 kg = 0.166 giraffe masses = 0.549 giraffe lengths
  • 70 kg =0.0448 giraffe masses = 0.355 giraffe lengths

Let’s see how that looks.

Arambourgiania vs giraffe vs the Disacknowledgement redux Witton ver 2 low res

On the left, we have Mark’s artwork, with the giraffe massing 1561 kg. On the right, we have three smaller (isometrically scaled) giraffes of masses corresponding to giant azhdarchid mass estimates in the literature. If Don Henderson (2010) is right, then the pterosaur weighs the same as the 544 kg giraffe, which to me looks pretty feasible if it’s very pneumatic. If Witton (2008) is right, then it weighs the same as the 259 kg giraffe, which I find hard to swallow. And if Chatterjee and Templin (2004) are right, then the giant pterosaur weighs the same as the teeny tiny 70 kg giraffe, which I find frankly ludicrous. (For that matter, 70 kg is in the same size-class as Georgia, the human scale-bar: the idea that she and the pterosaur weigh the same is just silly.)

What is the value of such eyeball comparisons? I’m not sure, beyond a basic reality check. Running this exercise has certainly made me sceptical about even the 250 kg mass range which now seems to be fairly widely accepted among pterosaur workers. Remember, if that mass is correct then the pterosaur and the 259 kg giraffe in the picture above weight the same. Can you buy that?

Or can we find extant analogues? Are there birds and mammals with the same mass that are in the same size relation as these images show?

References

  • Chatterjee, Sankar, and R. J. Templin. 2004. Posture, locomotion, and paleoecology of pterosaurs. Geological Society of America, Special Paper 376. 68 pages.
  • Henderson, Donald M. 2010. Pterosaur body mass estimates from three-dimensional mathematical slicing. Journal of Vertebrate Paleontology 30(3):768-785.
  • Witton, Mark P. 2008. A new approach to determining pterosaur body mass and its implications for pterosaur flight. Zitteliana 28:143-159.

Richard Butler: seeking volunteers for the SVPCA committee

Following on from his recent, and extensively discussed, offer to host SVPCA 2017, and a plan for the future, Richard Butler is now circulating his update, soliciting volunteers for the committee that virtually everyone agreed was a good idea.

Dear SVPCA/SPPC friends and colleagues,

We have identified you as a member of the SVPCA/SPPC community through having attended the meeting within the last five years. Many of you will doubtless be aware of the vibrant, lengthy, and occasionally fiery debate currently taking place about the future of the meeting on Mike Taylor and Matt Wedel’s SV-POW blog.

The least controversial proposal for change in the meeting has been my suggestion that we establish a ‘steering group’ to (i) try and solve some of the short-term and long-term logistical challenges (bank accounts, abstract submission and online registration issues etc.); (ii) provide support to meeting organisers and develop a comprehensive set of useful information; (iii) help identify and encourage future hosts to come forward; (iv) think about and discuss the future of the meeting, including discussing how best to make sure the meeting appeals to the entire community, from students to amateurs and from professors to preparators.

As there has been no opposition and plenty of support for a steering group, I propose we move forward with establishing this. No alternative to my proposal for the composition of this group has been put forward: I proposed a group of seven including past, current and future organisers (Gareth Dyke, Peter Falkingham, me as proposed host for a 2017 Birmingham meeting), and four elected members representing the student, early career academic (up to 10 years post-PhD), senior academic, and non-professional communities. This would not draw any museum/university distinction when it comes to students and academics. Although I have not heard formally from the GCG, I understand there is interest in one of their members being co-opted onto the steering group to represent SPPC. Elected steering group members could serve three-year terms, to match the terms served by meeting hosts.

At this stage we need volunteers: people willing to stand for election to this group and help secure and shape the future of the meeting! If you are a member of the SVPCA/SPPC community and are interested in serving, then please email me and Richard Forrest and let us know which of the four elected positions you wish to stand for. We would like volunteers by October 23rd. After this date, we will set-up online elections to allow the SVPCA/SPPC community to vote for each of the positions.

I look forward to hearing from you and to working together to shape the future of the meeting.