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Re: New review of bird origins and evolution in Naturwissenschaften



> The same issue also features a short communication that describes a new
> titanosaur.
>
> Sebastián Apesteguía (2004) _Bonitasaura salgadoi_ gen. et sp. nov.: a
> beaked sauropod from the Late Cretaceous of Patagonia

A very surprising animal!!!

> The posited beak of _Bonitasaura_ would have been present
> *behind* the front of the snout, not at the tip of the snout
> as in beaked ornithischians and theropods.

Except *Pelecanimimus*.

I've just read the paper. *Bonitasaura* is surprisingly small -- just 7 m or
so in length. Interesting quotes:

"*Bonitasaura* differs from *Antarctosaurus* in having the guillotine crest,
a less straight angle of symphysis, and a rather flat instead sinuous
posterior surface of the parietal. *Rapetosaurus* substantially differs in
having a dentigerous region more extended backwards and an even more gently
curved symphysis [...]. The presence in *Antarctosaurus* of an extensive
edentulous region (although devoid of a tall crest) and the *Rapetosaurus*
short, rugose postalveolar ridge and the bizarre post-dentigerous corner of
the maxilla, suggest that incipient guillotine-like structures could have
been developed in other titanosaurs.

The unresolved phylogenetic relationships of *Antarctosaurus*, and the fact
that the record of Late Cretaceous sauropods is only composed of derived
titanosaurs and basal diplodocoids (i.e., Rebbachisauridae), led Upchurch
(1999) to propose two possibilities for the status and evolutionary
relationships of this species: a chimera of bones from different lineages,
or a diplodocoid that acquired a postcranium largely convergent with that of
derived titanosaurs. The discovery of *Bonitasaura* has shed light on the
systematic affinities of *Antarctosaurus*, showing that its bizarre lower
jaw features are not unusual in advanced titanosaurs, which can bear a
squared snout convergent to that of diplodocoids, as originally proposed
[...]. This is also supported by the clear titanosaur affinities of the
remaining *Antarctosaurus* bones."