Thursday, July 19, 2007

Undeserved self-promotion and the protracted rise of dinosaurs

The cover art from today's Science. From front to back:
- the new basal dinosauromorph Dromomeron romeri
- a basal dinosauriform similar to the Polish Silesaurus
- the herrerasaurid Chindesaurus bryansmalli
- a coelophysoid theropod

Today was a good day for the Padian lab. Current Padianite Randy Irmis, former Padianite Sterling Nesbitt, and Kevin himself (plus some other folks) got the cover of Science today for their paper on basal dinosaurs and dinosauromorphs from New Mexico (Irmis et al. 2007).

The UC Berkeley press release is here, and a good overview is here. The latter site also includes super-humongous versions of the cover art and a nice comparative skeletal reconstruction, both of which I've stolen for this post. I recommend going there for the real story, but here's the short version:

The big news here is that basal dinosauromorphs, basal dinosauriforms, basal dinosaurs, and basal theropods--all the critters shown above and below--have all been found together at the Hayden Quarry in New Mexico. The age of the quarry is not wonderfully constrained, but it is probably about 215 million years old. The oldest dinosaurs are about 230 million years old, from Argentina. This is the first time that early dinosaurs have been found alongside their collateral ancestors (the dinosauromorphs and dinosauriforms), and the coexistence of all of these animals for ~15 Ma after the first appearance of dinosaurs shows that dinosaurs did not immediately replace their close relatives.

Randy and company describe a new genus and species of basal dinosauromorph, Dromomeron romeri (Romer's running femur), which is the sister taxon to Lagerpeton from the Chanares fauna in Argentina; Lagerpeton was described by A.S. Romer in the early '70s (Romer 1971, 1972).

Same critters, same order:
, 'silesaurid', Chindesaurus, coelophysoid.

Today was also a good day for me. Randy is out in the field, and Kevin is out of town, so I got to talk to the reporters instead. Totally unfair, but what are you going to do? The local ABC and Fox affiliates ran the story on the evening news; videos are here and here. Try not to laugh at my ultra-informal description of Postosuchus.

Naturally, they got some stuff wrong. I am not on this project and I've never been to the quarry; as I took pains to point out, I was just the closest available dino-doc. I don't think Postosuchus has been identified from the Hayden Quarry, I was describing it as an example of what a big predator was for that area and time. Still, I can't complain too much about making the evening news for work I didn't even do.


Irmis, R.B., Nesbitt, S.J., Padian, K., Smith, N.D., Turner, A.H., Woody, D., and Downs, D. 2007. A Late Triassic dinosauromorph assemblage from New Mexico and the rise of dinosaurs. Science 317:358-361.

Romer, A.S. 1971. The Chanares (Argentina) Triassic fauna. X. Two new and incompletely known long-limbed pseudosuchians. Breviora 378:1-10.

Romer, A.S. 1972. The Chanares (Argentina) Triassic fauna. XV. Further remains of the thecodonts Lagerpeton and Lagosuchus. Breviora 394:1-7.

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Anonymous Anonymous said...


Thanks for stepping in and doing this. All of us authors really appreciate it! Though, I was sad to see you didn't work in post-cranial pneumaticity.

Postosuchus sensu stricto is not known from the quarry, though an un-named relative is. (see our Table 1 under "Rauisuchia")


11:57 AM  

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