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Biogeography (was Re: Biggest predators)



At 05:38 PM 3/17/99 +0800, Raymond Thaddeus C. Ancog wrote:

>Let me get my paleogeography straight. S. America was connect to N. America
>via a Carribean connection, right?

Well, only fleetingly if at all: this would have been a very brief
connection sometime in the Late Cretaceous as what are now the Greater
Antilles got swept between North America and South America from the Pacific
to the Atlantic.

(Oh, and to be pedantic, North America didn't exist in the Mesozoic.  Since
modern Greenland and North America didn't separate until sometime in the
Cenozoic, the proper name for that joined landmass is Laurentia).

>N. America was in turn, connected to
>Europe (through Greenland?), which itself was connected to Africa (via
>Gibraltar, the Atlas range?).

EEK!  Don't try and place Late Cenozoic geography on the Cretaceous: a lot
of what is now southern Europe were still isolated blocks during the latest
Cretaceous, and only accreted onto the European Cretaceous during the Cenozoic.

>So if the _Gig._ and _Carch._ clade evolved
>in either S. America or Africa, the beasts must have traversed N. America
>and Europe to reach the other continent.

Actually, no: South America and Africa were still connected in the Early
Cretaceous, and very close (with a possible land or island chain connection)
into the earliest Late Cretaceous, the time of _Gig._ & _Carch._.
Furthermore, if Rauhut is correct in allying some of the teeth from
Tendaguru to the carcharodontosaurs, then this clade was already around
during the Late Jurassic, when faunal interchange between continents still
seems to have been very high.

>So, are there genera in N. America
>and Europe that would belong to this clade and provide evidence for this
>transcontinental migration?

Well, _Acrocanthosaurus_ seems to be part of this clade, and is only
slightly older and North American.  Our knowledge of post-Wealden large
theropods in Europe is, sad to say, very very poor at present.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661