If you read the ceratosaurid article from yesterday (here), you'll understand what's going on here. I drew it in a diary in 1992 (specifically, on Wednesday 29th April 1992, the day I learnt that Toby the cat had died, and also the day on which the borg [of Star Trek: The Next Generation] made their first appearance on British TV). The caption reads 'Ceratosaurus and Thylacinus contemplate their predicament'. Anatomical errors abound, but I can live with that.
- Log in to post comments
Following the link to Toby the Cat, I was flipping through your pics at Flickr and came across a drawing of Carnotaurus. Mark Whitton remarked that it probably would have been slow in a turn because of the lateral inertia of the long torso. I've seen this elsewhere as well. Does anyone know if these dinos could flick their tails to the side as a way of making turns quicker the way some cats can? Wouldn't necessarily make them quick, but quicker than if the tail and torso are always aligned.
Mike, you need to see...
Carrier, D. R., Walter, R. M. & Lee, D. V. 2001. Influence of rotational inertia on turning performance of theropod dinosaurs: clues from humans with increased rotational inertia. The Journal of Experimental Biology 204, 3917-3926.
Henderson, D. M. & Snively, E. 2004. Tyrannosaurus en pointe: allometry minimized rotational inertia of large carnivorous dinosaurs. Proceedings of the Royal Society of London B 271, S57-S60.
Both papers present arguments as to how big theropods coped with inertia when turning. Carrier et al. argued that big theropods tucked in their forelimbs and ran with their tails semi-erect in a comical jack-knife posture in order to minimize inertia. This is - so far as I can tell from discussion - not regarded as likely by anyone who knows dinosaurs as it results in various anatomical violations. Henderson & Snively argued that, as theropods increased in size, their body shapes become more compact, apparently in an effort to minimize inertia. The maths indicate that big theropods were in fact highly manoeuvrable for their size. If you're really interested in this question you'd do well to hunt down pdfs of these papers - does anyone have copies they can send?
One more thing - we know that small theropods, at least, could use their tails in dynamic turning, as a tracksite at Crayssac (France) shows a small theropod doing just this. The animal made a 180°; turn; as it executed the turn, the distal part of its tail contacted the ground and actually cut into the sediment. A report on this trackway - it was spoken about at SVPCA 2002 by Peter Griffiths - has yet to be published (to my knowledge), but you can read a little bit more on it here.
you can download the pdf version of the henderson/snively Tyrannosaur enpointe paper here
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1809988
Cheers,
Mike Skrepnick
I was in Crayssac in 2004 and touched that print with my own fingers! Let me just say it's real. :-) And it's next to the track of the landing pterosaur. :-)
Do you know who suffered the most from Predatory Dinosaurs of the World? That poor woman who's being chased by theropods through all the scale drawings.
Shameless self-promotion: a little more on turning dinosaurs here (not Ceratosaurus though):
Hutchinson, J.R., V. Ng-Thow-Hing, F.C. Anderson. 2007. A 3D interactive method for estimating body segmental parameters in animals: application to the turning and running performance of Tyrannosaurus rex. Journal of Theoretical Biology 246:660-680.
pdf-able here:
http://www.rvc.ac.uk/AboutUs/Staff/jhutchinson/Publications.cfm
Henderson and Snively didn't contradict Carrier et al's notion that theropods were relatively slow in turning (compared with, say, ostriches/humans), but did note that they were better off than a typical archosaur. In the paper above we agreed with their general points and added some (very rough) estimates of absolute turning times (to be administered with NaCl ad libitum).
Thanks guys. Plenty to chew on. That there's a trackway showing a dinosaur making just the sort of turn we'd be interested in is too marvelous for words so I'll shut up and go read papers.
Darren, that's a frightening ceratosaur. :-)
Did Ceratosaurus and Thylacinus really have only one predicament between them? What was it?
I haven't yet seen this question answered to my satisfaction: were theropod tail vertebrae articulated such that the tail could swing freely enough to be useful as an aid to turning? If so, I can't imagine them not doing it.
I note in passing that that mummified hadrosaur demonstrates that the hadrosaurs, at least, had substantially looser vertebral articulation than had been surmised. Of course it was no theropod, but it gives us some idea of the degree of uncertainty in estimates of this sort. It makes me wonder, though: must some analog of rigor mortis be presumed to have have cinched tight the spines of all the other more-or-less articulated specimens previously dug up? Or is there some plausible complementary process that could have loosened that one speciment?
Nathan: the imaginary predicament supposedly shared by Ceratosaurus and Thylacinus is that, while good at doing what they did, they are 'archaic' taxa that found themselves competing against more recently evolved, more 'sophisticated' species. Of course, being 'archaic' doesn't mean than you're less good than the new kids on the block - in the long run you might out-live them, but still...
All theropods had tail bases that were, almost certainly, flexible enough to allow the tail to be used as an aid in turning (even relatively stiff-tailed forms, like the dromaeosaurs with their hyper-elongate zygapophyses). So, yes, it is almost certain that they did use the tail in this way.