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Re: Dinos in the Southern Hemisphere: Sereno et al. and the VII Mesozoic Terrestrial Ecosystems Symposium

Thomas R. Holtz, Jr. wrote:

 The authors [Sereno et al.] suggest that _Nigersaurus_ belongs in
the clade Rebbachisauridae with _Rayososaurus_, _Rebbachisaurus_, and a
dentary from the Campanian of Argentina referred to _Antarctosaurus_ by
Huene (in fact, the specimen that I think they are talking about is part of
the type of "_A." wichmannianus_: plate 29 Figs. 5a-d of Huene 1929 (Anales
del Museo de La Plata, Ser. 2)).

I think you're right. I haven't seen or read the _Science_ paper yet, but Sereno and co. may be in agreement with Upchurch on the matter of this _Antarctosaurus_ dentary.

Huene (1929) included a braincase and anterior mandible in the type specimen of _A. wichmannianus_. The occiput closely resembles that of _Saltasaurus_, so probably comes from a titanosaurid (Salgado and Calvo, 1997).

However, based on the mandible fragment, the width of the mandible is greater than the width of the occiput (26 vs 20cm), so _Antarctosaurus_ has an unusually wide snout for a sauropod. Most likely, as Upchurch suggests (in his recent JVP paper on nemegtosaurids), the partial mandible and braincase come from two different sauropods. Sereno et al provide a possible identity for the mandible (rebbachisaurid).

The hypodigm of _Antarctosaurus wichmannianus_ is problematic since the postcranium too may be a chimera. Huene had an irritating habit of pooling unassociated material together into single taxa, and separating associated material into different taxa. _Laplatasaurus_ is problematic for much the same reason.

While on the topic of possibly chimeric sauropods, _Janenschia robusta_ is about to be re-described in a paper in _Palaeontographica_ ("in press"). The paper may include a new genus of sauropod from the Tendaguru Beds.

Also, I just got a copy (actually, an electronic download) of the abstracts
volume of the VII International Symposium on Mesozoic Terrestrial
Ecosystems, held in Buenos Aires shortly before SVP this year (hence I could
not go... bummer). Lots of good stuff in there.

Is there some way anyone could "download" this too, or get a hold of the volume through the post?


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