[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: various & sundry



>>What, pray tell, was the largest known crocodilian from the Hell Creek
>>locale?  Do you know?  How big was it?
>
>
>Hell Creek locale or beds? Locale I have no idea but some vertebrae referred
>to Deinosuchus have been recovered from the Hell Creek Beds. As far as I
>recall anyway. Am I right Chris?
>

Deinosuchus doesn't make it into the Maastrichtian.  It's known from the
Judith River Group (or equivalents) in the northern Rocky Mountain region,
Aguja Formation in Texas, and several Campanian (or Judithian NALMA) units
out east.


I have no doubt that Deinosuchus material has been listed in Hell Creek or
Hell Creek equivalent faunal lists, but none of it is demonstrably
Deinosuchus - someone finds a tooth, sees that it's fairly large, and says
"Aha - Deinosuchus!"  But the teeth are the least diagnostic aspect of
Deinosuchus, unless you have a dagger-sized specimen.

As for Hell Creek crocs - basically, you've got Borealosuchus (formerly
Leidyosuchus) sternbergii, Brachychampsa montana, and a new alligatorid
currently under description.  This third taxon was fairly small (2 m) at
maturity, but the other two would have been "average-sized" crocs, up to
three meters in length.  I believe Thoracosaurus has also been described
from Hell Creek or HC equivalent units, but the material is not as well
preserved as eastern Thoracosaurus, and again we're talking about a 3 m
animal.

Further south, we still get "goniopholids" in Maastrichtian units - San
Juan Basin, Big Bend, and even Missouri.  Roughly equivalent in size to
their northern ecological counterparts, and no Borealosuchus in the region
until the Paleocene.

Out east, we get Thoracosaurus (one species, which is the same as
"Holops"), a dyrosaur (not a crocodylian sensu stricto), and one or more
derived alligatoroids.  None were giant.



chris





Christopher Brochu
Department of Geology
Field Museum of Natural History
Roosevelt Road at Lake Shore Drive
Chicago, IL 60605

312-922-9410 x469