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Re: Paper on drepanosaurids



Silvio Renesto wrote:

Simiosauria sounds appropriate, in fact if they are really so basal, they mimic very well lots of characters of more advanced diapsids, pterosaurs included.

And birds too! But all of these bird-like ("avimorph") characters appear to be superficial, such as the triangular bird-like head. Wouldn't it be funny if _Protoavis_ (or part of _Protoavis_) ended up in the Avicephala?


More seriously, an applause to Phil Senter for stating that no drepanosaurid is aquatic, something I stated since 1994, but few believed (guess why?).

I can't begin to guess.

Perhaps some more people will now consider it as feasible.

Colbert and Olsen (2001) were so convinced that their new drepanosaurid from New Jersey was aquatic that they named it _Hypuronector limnaios_ ("deep tailed swimmer from the lake"). However, the authors did support the idea that other drepanosaurids may have been arboreal:


"_Hypuronector_ has a very deep tail, superficially comparable in shape to that of gymnotid or gymarchid fishes (figs. 6, 15 ). No other tetrapod has such elongate chevrons, or a tail with a strongly similar structure. The similarity at least superficially to the deepened tails in aquatic tetrapods such as newts and crocodilians, however, strongly suggests that the tail of _Hypuronector_ was adapted for sculling in water. [snip] There is no evidence that _Hypuronector_ could lift its tail so that it was at an acute angle to the dorsal series; all of the articulated specimens found thus far have the caudal series in line with the dorsal vertebrae. Thus, it appears unlikely that it could have been a balancing organ for arboreal life, as might be suggested by its relationship with _Megalancosaurus_ and _Drepanosaurus_. Evidently, _Hypuronector_ had a beak anteriorly, as judged from the pointed but toothless anterior mandible, the functional significance of which is obscure."

Reference:

Colbert, E.H. and Olsen, P.E. (2001). A new and unusual aquatic reptile from the Lockatong Formation of New Jersey (Late Triassic, Newark Supergroup). Am. Mus. Novit. 3334: 1?24.

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