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Re: Tiny dinosaur on verge of swearing off meat



----- Original Message ----- From: "Jaime A. Headden" <qilongia@yahoo.com>
Sent: Monday, October 27, 2008 7:32 PM


Augusto Haro wrote:

<Except for the enlargement of the canines, the basal position within Ornithischia now hypothesized for Heterodontosaurus by Butler et al. (2007) suggests that these theropod-like tooth may be just plesiomorphic retentions, unless Silesaurus and Azendohsaurus (with basally constricted teeth) turn out to be successive outgroups of Ornithischia and Dinosauria. That the serrations of the crown are perpendicular instead of oblique would represent a further plesiomorphy.>

I overlooked this. *Azendohsaurus* is in fact the sister-group to Archosauriformes:


John Flynn, Sterling Nesbitt, Michael Parrish, Lovasoa Ranivoharimanana & André Wyss: A new species of basal archosauromorph from the Late Triassic of Madagascar, supplement to JVP 28(3), 78A (September 2008)


A remarkable fossil vertebrate assemblage including traversodonts, a dicynodont, rhynchosaurs, and other reptile remains has been recovered from the Late Triassic "Isalo II" (Makay Formation) of southwestern Madagascar over the past 10 years. This assemblage includes nearly a dozen, well-preserved, associated and partially articulated reptile skeletons recovered from a single apparently monotypic bone-bed. Originally considered a "prosauropod" (based on fragmentary gnathic remains), and closely resembling *Azendohsaurus* specimens from Morocco, this material is now referred to a new species of *Azendohsaurus*. This extends the geographic range of *Azendohsaurus* and aids in temporal correlation of this assemblage. Although *Azendohsaurus* has consistently been considered an early dinosaur (based on dental and gnathic features resembling those present in basal sauropodomorphs), the abundant skeletal material now available from Madagascar argues strongly against its sauropodomorph, and even dinosaurian, affinities. Instead the new taxon was analyzed within the context of an extensive archosauromorph character matrix, was found to represent a close relative of the archosauriforms rather than a member of Dinosauria. Features previously considered diagnostic of the "prosauropods" (= basal sauropodomorphs) thus are revealed here to occur homoplastically in at least one clade of non-dinosaurian archosauromorphs, indicating a complex evolution and distribution of features traditionally considered to be derived within archosaurs. Tooth morphology and our microwear studies indicate that *Azendohsaurus* was an herbivore, feeding on soft plants and that its jaw motion was simple and orthal. Herbivory thus evolved early within basal archosauromorphs, and appeared multiple times within this clade, including within the Dinosauria in taxa with similar tooth morphologies. The presence of teeth resembling those of early sauropodomorphs and ornithischians in a taxon marked by inarguably basal archosauromorph cranial and postcranial attributes highlights the risks of uncritically referring isolated, Middle-Late Triassic (or even later), "leaf-shaped" teeth to Dinosauria.
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Unfortunately, I have only now stopped to think if this fascinating discovery tells us anything about *Eshanosaurus*.

I am thinking here that a comparison is in order, and would bring attention to Darren Naish once calling this animal a sort of suine analogue. At one point, this animal was compared favorably with *Anthracotherium,* an animal that as a juvenile have finely serrated canines and ate meat, but matures into much more of an omnivore and opportunistic feeder, as are most extant suines.

I think you mean *Archaeotherium* and the other entelodonts ("killer pigs"), not *Anthracotherium* and its fellow hippo-like animals that probably were stem-hippos.