[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
RE: Late Cretaceous Giant Ceratopsians and Hadrosaurs
Vlad Petnicki wrote:
We know that the really large dinosaurs - the sauropods
- had disappeared from Western North America by the
mid-Cretaceous, as the conditions changed and animals
got smaller. They did not reappear until just at the
end, when Alamosaurus apparently migrated over a new
land bridge to South America, and made it as far as
Texas before the mass extinction.
This does appear to be the most parsimonious scenario. _Alamosaurus_ is
phylogenetically closer to the saltasaurines of South America than to North
American titanosauriforms such as _Cedarosaurus_ and _Venenosaurus_, which
are of Barremian age. Thus, _Alamosaurus_ was probably not home-grown, but
an immigrant from the south - based on current evidence. However, just to
muddy the waters: the various bones referred to _Alamosaurus_ over the years
appear to belong to at least two titanosaurian taxa. This would indicate
that more than one titanosaurian existed in the Campano-Maastrichtian of the
American Southwest, and these taxa may have had separate origins.
Get a FREE online computer virus scan from McAfee when you click here.