Page 11 - whistler1967

Phillips Ranch fauna (Buwalda and Lewis, 1955) contain
similar oreodont species,
Therefore, two local lineages appear to be present in
the Mojave Desert region, One of these lineages,~- (~.)
calaminthus, and similar or large species, displays very
little change except for an increase in size and appears to
die out in the Hemingfordian.
The other lineage is best represented by the species of
Merychyus at Boron which was referred to the subgenus
Metoreodon, This Boron form has a shallow antorbital fossa
and paired infraorbital foramina, both of which are developed
in ~- (~.) jahnsi. A specimen from the Mojave Arikareean
site also bears paired infraorbital foramina~ Merychyus
(Metoreodon) relictis fletcheri Schultz and Falkenbach, a
much ~arger and only questionably related form, occurs low
in the Barstow Formation. The Barstow record is the last
occurrence of the subfamily Merychyinae in Southern
Caiifornia.
It is premature to say with certainty, but it appears
that there may be one or more endemic lineages of merychyine
oreodonts~ evolving in the Mojave Desert region during the
Miocene.
I would like to thank Mr. Karoly Fogassy who prepared
the illustrations and Richard H. Tedford who supplied
financial assistance and critical discussion of the
manuscript.

10