Thursday, January 26, 2006

Ghost Ranch archosaur: Effigia

Well as some of you may already know, a crocodylian fossil was just identified as a new species after 60 years of collecting dust in the basement of the American Museum of Natural History. The species was part of a collection of fossils excavated from the famous Ghost Ranch quarry in northern New Mexico and supposedly misidentified as just another Coelophysis dinosaur, which were also collected by the thousands in the same area.

Now whilst this animal may seem fairly similar to that of the ostrich-mimicking dinosaurs, I find the media might be overstating the direct similarities between the two parties mentioned. When visually comparing the two side by side it is easy to say they look alike. However it would be incorrect to state that the “ostrich body plan” actually developed within this species.

Effigia okeeffeae lacks the characteristic long, cursorial legs and the arctometatarsus found in the Ornithomimosauria. And while Effigia might be bipedal like the “ostrich dinosaurs”, the proportions of its legs and anklebones are much more crocodilian like. Another feature more prominent in crocs (as with this new species) is a more flexible back and tail typical of the semi-aquatic beasties. On the other hand, “ostrich mimics” --like birds-- have much more rigid backs and tails used for balance and speedy maneuverability.

What exactly is my point to all of this? I honestly can’t think of one…

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