Monday, July 30, 2007

What is your Cope-Marsh number?

Ho man. Just in case you care about where this crap comes from, here goes. I was over at TetZoo and saw a link on the sidebar to an Aetiology post on Danica McKellar's "Math Doesn't Suck". The third comment down states, "Danica McKellar has a Bacon-Erdos number of 6. Same as Feynmann." That embedded link (included above) takes you to the Wikipedia page on the Bacon-Erdos number.

What is the Bacon-Erdos number? From the Wikipedia article:
An individual's Erdős–Bacon number is the sum of one's Erdős number—which measures the "collaborative distance" in authoring mathematical papers between that individual and Hungarian mathematician Paul Erdős—and one's Bacon number—which represents the number of links, through roles in films, by which the individual is separated from actor Kevin Bacon.
Much like the Bristol Stool Scale, it's stuff like this that makes me proud to be a scientist.

As the title says, I wish we had something like this in paleo. Only maybe not tied to movies. It would be interesting to know who had the lowest Cope-Marsh number, which is the sum of one's collaborative distance from Edward Drinker Cope and Othniel Charles Marsh. It would be tough because although both Cope and Marsh published a buttload of papers (more than 1200 for Cope), they hardly ever collaborated and they hated each other's guts. So the immediate links to each would be few and probably distant from each other in collaboration space. Maybe their posthumous stuff would be a good place to start.

Can somebody get to work on this?

(Somebody else, I mean.)

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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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Tuesday, July 17, 2007

The largest land animal of all time*

* as of the Early Permian.

Darren's latest post, on Cotylorhynchus, inspired me to post some more pictures of this wonderfully bizarre animal. Above is the mounted skeleton at the Oklahoma Museum of Natural History. I recommend checking out Darren's post if you want to know about the biology and evolution of the critter. I'm just showing off its weirdness.

One commenter over at TZ asked how the animal got its head down far enough to drink. It's a fair question, but I can't help wondering if the reconstructed skeleton has the neck too high and the shoulders too low.

The real skeleton mounted on the wall behind looks like it has a longer neck, but I don't know how much of it might be reconstructed. This mount was in the old Stovall museum for decades, and I remember marveling at it when I was eight.

I know squat about the Early Permian, but it seems unlikely that this animal had any predators as an adult. First, because it really was the largest land animal of its time (which is a mind-blowing thought by itself), and second, because it looks like a big walking hamburger. I imagine these lardasses didn't last very long once something evolved that could eat them. They lived alongside Dimetrodon, though. Their life history was probably similar to that of turtles--tons of eggs, zillions of babies getting eaten by anything that can get a hold of them, and a few individuals squeaking by to becoming essentially invulnerable adults.

I suppose I am fascinated by Cotylorhynchus because I work on sauropods. These guys were the sauropods of their time--the biggest tetrapods that had evolved up until then. What a strange world they lived in. Compared to the present, or even the Mesozoic, the Early Permian is defined mostly by absences. No flowering plants, no flying vertebrates, no bipeds, no turtles, no crocs, no frogs, no marine reptiles, nothing on land larger than Cotylorhynchus, nothing faster or smarter than a lizard. I think about the desert islands off Baja that have no terrestrial denizens bigger than chuckwallas. I think about the rocky Galapagos coast with piles of marine iguanas. The whole world was like that.


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