Re: Abelisaur & Titanosaur migratory routes

[Dinogeorge@aol.com]

In a message dated 96-01-24 09:39:38 EST, Thomas_R_HOLTZ@umail.umd.edu (th81)
writes:

>>And the "oldest" Titanosauridae i know Atlantosaurus montanus, is from the
>>Late Jurassic Tithonian (152.1 145.6 MYA) from the US and Canada while all
>>the South American Titanosauridae are from the Late Cretaceous.
>>
>The titanosaurian nature of Atlantosaurus is subject to debate, to say the
>least.  Furthermore, almost all the dinosaur bearing horizons of the
>Morrison are now known to be Kimmeridgian (a recent development,
>though, not widely reported yet).  However, Janenschia of the Tendaguru, IS
>a Late Jurassic titanosaurian.

Don't confuse _Atlantosaurus montanus_, originally named _Titanosaurus
montanus_, with titanosaurids. Marsh's 1877 genus _Titanosaurus_ was
preoccupied by Lydekker's _Titanosaurus_ (the typical titanosaurid), proposed
a few months earlier in 1877. That's the only connection between
_Atlantosaurus_ and titanosaurids. The type sacrum of _Atlantosaurus
montanus_ is indeterminate but probably belonged to an _Apatosaurus_. Other
possibilities are _Diplodocus_, _Barosaurus_, and even _Camarasaurus_, but by
no means a titanosaurid.