Re: Equids

whittet (
29 Dec 1994 04:25:53 GMT

In article <>, (Phillip Bigelow) says:
> (whittet) writes:
>>If you have a firm date for the extinction of the horse in the
>>New World, I would be delighted to see have you cite your sources.
> The references you seek that show the extinction of the North American
>Equus within the late Pleistocene are:
> MacFadden, B.J., 1985. Patterns of phylogeny and rates of evolution in
> fossil horses: Hipparions from the Miocene and Pliocene of North
> America. _Paleobiology_ v. 11, pp. 245-257.
> MacFadden, B.J., 1988. Horses, the fossil record, and evolution.
> _Evolutionary Biology_, v. 22, pp. 131-158.
> <pb>
The reason I have a problem with the "Late Pleistocene" date is that it
is intended to cover a range of possible dates which have been proposed.

It could mean 10,000 BC, It could mean 6,500 BC, it could have a range of
error of plus or minus 10,000 years. The extinction of some species does
not usually mean the extinction of all species unless there is an associated
catastrophic occurence.

There are still some other "big game" mammals, predators like the wolf and
the grizzly, which once roamed extensive areas, who have managed to survive
even though the extent of their range is greatly reduced.Some species, like
the Bison, even have been known to go from the edge of extinction to
sizable herds.

The horse may very well have survived the ice age
in the Americas, certainly the horse did survive the ice age somewhere.

If the ice age is not the catastrophic occurence, then possibly it is the
arrival of man. Elsewhere the arrival of man does not mean
the extinction of the horse. What's different about the Americas?

>>> The fossil evidence I've heard /read about says that the
>>>Pleistocene American Horse was about the same as the Polish Wild
>>>Horse that still survives.
> The North American fossil horse (the Pleistocene species) was of a
>different species than the Eurasian species. The Eurasian species is the
>horse we have today, including all of the breeds. Where are your sources on
>your claim?
> <pb>
although the above is not my quote, the sources I have speak to it;
see the quotes from Edwards I tacked onto Kathleen Hunts post.

One other interesting tidbit is that as late as 35 million years ago
there was still intermitent contact between Africa and South America.
Earlier versions of equus, now extinct themselves, would have had
a much easier route for getting to the Old World, than would equus c.