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Bahndwivici ammoskius

Paleontologists who don't specialize in dinosaurs or hominins have long since learned that, so far as the popular press is concerned, new discoveries rarely get much, if anything, in the way of media coverage. It isn't surprising, therefore, that the lay impression of prehistoric life and evolution generally involves that which is either titanic and scaly or somewhat furry and humanoid. Witness, for example, the recent attention received by new dinosaurs such as Erketu, Mapusaurus, Guanlong, and Juravenator. Likewise, the new hominins Homo floresiensis and Sahelanthropus tchadensis. Exceptions generally involve taxa which can be touted as dramatic "missing links" or examples of macroevolution and be used as fodder in the supposed evolution/creation "controversy."

And since such creatures make up only a tiny fraction of new fossil taxa described, most everything gets overlooked. For example, the truly wonderful lizard Bahndwivici ammoskius from the Eocene Green River Formation of Wyoming. The cover of the new issue of the Journal of Vertebrate Paleontology went to the baby Triceratops, which truly is a wonderful thing, but no less wondrous is this 20-25 cm. lizard:


FMNH PR 2260, the holotype of Bahndwivici ammoskius. I accidentally cropped the end of the tail when I scanned the image.


One of the most exciting things about this remarkable fossil is that it's almost indistinguishable from the semi-aquatic present-day Chinese crocodile lizard, Shinisaurus crocodilurus. Jack Conrad, who describes Bahndwivici in the new JVP, writes that "Bahndwivici and Shinisaurus share morphological details in nearly every aspect of their known osteologies, despite being separated by more than 48 million years of time and living on separate continents. This is a remarkable degree of stasis within a clade." Indeed.

Conrad also states, in a particularly cogent and honest bit of scientific writing:

Generic separation of any two morphologically similar taxa is a sticky undertaking and the current case is no exception. Taxonomy is a tool for discussing clades of organisms, a tool that will be used differently by different systematists. Shinisaurus and FMNH PR 2260 are similar in all known aspects of their osteology [skeletons]. The differences...are morphological features that may be used to identify and distinguish the two taxa. Geographic and temporal distance further help to separate these species and to justify their separation at the generic level. In the end, however, some researchers are likely to refer to both these shinisaurids as Shinisaurus and others will adopt the recommendation of generic distinctiveness given here.

Oh, here's a shot of a modern-day Chinese crocodile lizard:



By the way, the genus name of this new fossil lizard comes from Latinization of the Shoshoni Bah-n-dooi-vee-chee, or "handsome in the water." The species name is derived from two Greek words, Ammos ("sandy") and skia ("shade"). Hopefully, I have bored none of you to excess. It's just that sometimes I get very, very excited about these things. These stones and bones, this grand continuity of life, are my most reliable medicine against the black-and-white monotony of words...

Comments

sclerotic_rings
May. 11th, 2006 12:44 pm (UTC)
If it's any consolation, the "nothing but dinosaurs and hominims " syndrome is even worse with palaeobotany. A friend of mine currently works with early tetrapods, describing the condition of most of those fossils as "having been shotgunned", and he has nothing but sympathy for the amount of effort expended versus recognition received for anyone working with fossil plants.