Re: Sauropod Biology

[Tim Williams <twilliams_alpha@hotmail.com>]

Sim Koning wrote:

> There were probably specialist sauropods such as Brachiosaurus and
> Dicraeosaurus. With its high shoulders, Brachiosaurus was likely a high 
> browser like giraffes and Indricotherium,
[snip]
> As with all specialists, these forms were prone to extinction, which is 
> probably why the Brachiosaurs died out not long after the Jurassic.

David's already mentioned _Sauroposeidon_ (Aptian), and there was also 
slightly earlier post-Jurassic forms like _Pelorosaurus_.  Also, although 
the Brachiosauridae (sensu stricto) appears to have died out by the end of 
the Early Cretaceous, the titanosauriforms as a whole thrived in the Late 
Cretaceous.  The 'brachiosaurs' of traditional usage comprise forms that we 
know recognize as basal titanosauriforms, including (but not limited to) 
true brachiosaurids (e.g., _Brachiosaurus_, _Sauroposeidon_, probably 
_Pelorosaurus_, _Atlasaurus_).  Complicating things further is the fact that 
some titanosaurs ate grass (based on coprolite contents), which suggests 
they were low grazers - at least some of the time.

> Well... *Sauroposeidon*, which was bigger rather than smaller than 
> *Brachiosaurus*, is... how old? Aptian? That would be, like, 120 Ma... 
> that's 25 Ma after the end of the Jurassic... Dicraeosaurids 
> (*Amargasaurus*) and rebbachisaurids survived for a similar length of time.

Rebbachisaurids persisted into the Late Cretaceous.  If the teeth named 
_"Titanosaurus" rahiolensis_ belong to a rebbachisaurid, then the group 
survived until close to the end of the Cretaceous period.  (This is a big 
"if" though.)

Cheers

Tim

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