Friday, January 1, 2010

Yet more extreme Triassic weirdness: Vancleavea


Congrats yet again to Sterling Nesbitt and colleagues on the publication of another one of those insane Triassic hellasaurs, this time the surreal archosauriform* Vancleavea campi (Nesbitt et al. 2009) [adjacent life restoration by Sterling Nesbitt]. Vancleavea was named by Long & Murry (1995) and is well represented by various bits and pieces from the Upper Triassic of the southwestern USA (interestingly, it seems to have been around for a long time: like, 20 million years or so). Its affinities were initially unclear: all that was clear was that it was a weird, armoured diapsid reptile, with relatively small limbs and a covering of assorted osteoderms. But, as everyone knows, a new, very well preserved, articulated skeleton was later discovered at Ghost Ranch Quarry in New Mexico, and this is the specimen described in the new paper. Finally, we know what Vancleavea is, and what it looked like...

* Archosauriformes corresponds with Archosauria of tradition, with Archosauria now being restricted to the archosauriform crown-group (the crocodilian-bird clade).
Vancleavea was about 1.2 m long and, as is clear from the reconstruction shown here (from Nesbitt et al. 2009) was long-bodied and short-limbed. It was covered in rows of osteoderms, and 30 particularly tall osteoderms formed a vertical fin along the top of the tail. The latter is totally unique (archosauriformes, and reptiles [and tetrapods!] in general, tend to use elongated neural spines to increase the depth of the tail) and suggests that Vancleavea was a semi-aquatic swimming animal, and thus very different ecologically from other basal archosauriforms.

The skull is also really weird...

The rest at Tetrapod Zoology

Posted via email from Garth's posterous

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