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Re: Re: "No Bolides!"

>       What do people think about the Pleistocene extinctions in North 
>America? They seem comparable to the Late Cretaceous. We've lost wooly 
>mammoths, sabertooths, dire wolves, teratorns, lions, giant lions, 
>horses, ground sloths, phorusrhacids, cheetahs, rhinos, those dog-bear 
>things, and plenty of other animals. As for niches not refilled, we've lost 
>large grazers like mammoths, rearing browsers like sloths, big-game 
>predators like sabertooths, etc. etc. The Late Cretaceous saw groups like 
>Centrosaurines on the way out, but we did lose elephants, rhinos, etc., 
>so it was not merely at the generic level.

[The mid-Maastrichtian extinction of the centrosaurines was global as well
as regional, since this taxon was restricted to western North America.
Proboscideans and rhinoceratids, however, experienced a regional extirpation
in the New World, but presist to this day.]

More importantly, the Pleistocene-Holocene extinctions are very different
from most (all) previous mass extinctions because we have not lost major
clades of marine invertebrates.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661