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Velociraptor wrists

Posted by tigerhawkvok on February 19, 2009 02:49 in biomechanics , dinosaurs , biology , paleontology

The promised science post!

Rewatching Jurassic Park, I wanted to correct a rather small, but important and understated error.

There's a hint in the URL, of course. The answer? The claws — they're held horribly, horribly wrong.

Jurassic Park Velociraptors are named after Velociraptor mongoliensis, and modeled after a hybrid between the genera Deinonychus and Utahraptor. At the time the novel was written, there was some talk of moving Deinonychus into the genus Velociraptor, which was the convention followed by Micheal Crichton, though this didn't play out. However, all of these were dromaeosaurids, which are eumaniraptorans. In fact, Dromaeosauridae is the group closest to but outside of Aves. So, all members of eumaniraptora have a synapomorphy list that includes a "semilunate carpal".

Sinoris manus

Sinornis santensis manus

Tanycolagreus manus

Tanycolagreus topwilsoni manus. Scale in cm.

Cathayornis manus

Cathayornis sanctis manus.

All three of the pictures above show this semilunate carpal in other maniraptorans. Unlike most mammalian wrists, it cannot flex perpendicular to the radius-ulna plane (ie, what we would most commonly accept as perpendicular to the groud). Instead, its motions were restricted to that plane, giving a jacknifing motion, much like a flight stroke. This was an optimal grasping motion for prey, and good for grappling large prey, and was easy to adapt into a flight stroke (particularly given the presence of primary feathers on some dromaeosaurids).

Sadly, this does mean that the raptors couldn't open doors. They would have broken their wrists trying to make the motion!

Image citations:

  • Carpenter K., Miles C., Cloward K. New Small Theropod from the Upper Jurassic Morrison Formation of Wyoming. In "The Carnivorous Dinosaurs" (ed. Kenneth Carpenter), 2005.
  • Sereno PC., Chenggang R., Jianjun L. Sinornis santensis (Aves: Enantiornithes) from the Early Cretaceous of Northeastern China. In "Mesozoic Birds: Above the Heads of Dinosaurs" (ed. Luis M. Chiappe and Lawrence M. Witmer), 2002.
  • Zhonghe Z. and Lianhai H. Mesozoic Birds in China. In "Mesozoic Birds: Above the Heads of Dinosaurs" (ed. Luis M. Chiappe and Lawrence M. Witmer), 2002.

Update and Shell-less turtles

Posted by tigerhawkvok on November 29, 2008 20:59 in evolution , biology , news , paleontology

Hm, I've not blogged in a bit. Well, I'm working on the graduate school apps with a bit of a mix of physics, astrophysics, paleontology and biomechanics. Some dual applications, some single. We'll see how it plays out.

I've also finally submitted my paper to Proceedings B, and hopefully it will be accepted (or conditionally accepted).

Nah, the real trick is money. The economy sucks, finding a job has been hard, and well, not quite enough money to make rent. Ugh. Well, perhaps I'll blog on science tomorrow at the airport. In particular, Science and Nature have had a few interesting articles as of late, such as one on a new turtle find -- it has a plastron, but no upper shell -- and with teeth! Dubbed Odontochelys, it is placed phylogentically basal to all all extant and extinct testudines. While I find the use of "Ontology recapitulates phylogeny" a bit problematic, its still a very interesting read, and I feel that its sparing use in this context is justified.

Odontochelys

It seems I blogged on science accidentally anyway. Huh. Perhaps not much, but nevertheless.

The full paper can be found here: Nature.com (DOI: 10.1038/456450a , Reisz & Head ).

Update 03/15/09: Link repair

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