New ref. on Scleromochlus

[Adam Yates <A.Yates@zoo.latrobe.edu.au>]

The latest issue of Philosophical Transaction of the Royal Society of London
contains a new paper titled "Scleromochlus taylori and the origin of
dinosaurs and pterosaurs" by Mike Benton.
New anotomical information and a new reconstruction based on multiple
specimens of this little beast are provided. The basic conclusion is
Scleromochlus is the sister group to the Ornithodira (Pterosauria +
Dinosauromorpha). There is quite a bit of interesting stuff in the paper,
perhaps the one that will generate the most discussion are the two new
higher level taxa that he erects. The first is a new node-based name for the
crown-group Archosauria, which is dubbed the Avesuchia. Benton clearly
rejects the notion of restricting the Archosauria to the crown-group. The
second is the Avemetatarsalia, which is the stem group containing all taxa
more closely related to birds than to crocodiles. Under strict priority for
PT names this would be a junior objective synonym of Ornithosuchia, but that
name is presumably rejected on the basis that Ornithosuchus itself is not a
member of the clade,though Benton does not mention this in the paper.
Sharovopteryx and Longisquama also get a mention. Niether can be
convincingly demonstrated to be a close relative of Scleromochlus.