Malcolm C. McKenna

Susan K. Bell

Above the Species Level

Classification of Mammals

Frederick S. Szalay

Michael J. Novacek

The roots of this book and its sister volume, Mammal Phylogeny: Placentals, go back to discussions and plans, shelved for a while, between F. S. Szalay and W. P. Luckett during the international and multidisciplinary symposium on rodent evolution sponsored by NATO, July 2-6, 1984, in Paris. That conference, orga nized by W. P. Luckett and J. -L. Hartenberger, the proceedings of which were published in 1985, proved an inspiring experience to all of the participants, as this was repeatedly expressed both during and after the meetings. In addition to issues relating to rodents, general theoretical topics pertaining to the evolutionary biol ogy and systematics of other groups of mammals regularly surfaced during the presentations and discussions. M. J. Novacek, who was also a participant in the rodent symposium, shared with Luckett and Szalay the enthusiasm acquired there, and he also expressed strong interest for a meeting on mammal evolution with a general focus similar to that of the rodent gathering. In 1988, Szalay and Luckett, after having planned in detail a program, direc tion, and core list of participants, were awarded a $30,000 grant by the Alfred P. Sloan Foundation through the Research Foundation of the City University of New York. The grant was contingent upon obtaining additional funds sufficient to assure that the symposium would be held. Raising the remaining funds proved to be a problem.

Mesozoic Differentiation, Multituberculates, Monotremes, Early Therians, and Marsupials

Mammal Phylogeny

Daryl P. Domning

Clayton Edward Ray

A new genus, comprising two new species of desmostylians, is described from marine Oligocene deposits of the Pacific Northwest. Behemotops proteus, new genus, new species, is based on an immature mandibular ramus and apparently associated skeletal fragments from the middle or (more likely) upper Oligocene lower part of the Pysht Formation of Clallam County, Washington. A related new species, Behemotops emlongi, is founded on a mandibular ramus of an old individual and a mandibular fragment with canine tusk from the uppermost Oligocene (early Arikareean equivalent) Yaquina Formation of Lincoln County, Oregon. The two new species are the most primitive known desmostylians and compare favorably with the primitive Eocene proboscideans Anthracobune and Moeritherium, and to the still more primitive tethythere Minchenella from the Paleocene of China.For many years the Desmostylia were widely regarded as members of the mammalian order Sirenia before being accepted as a taxon coordinate with the Sirenia and Proboscidea (Reinhart, 1953). On the basis of cladistic analysis we go a step further and regard the Desmostylia as more closely related to Proboscidea than to Sirenia because the Desmostylia and Proboscidea are interpreted herein to share a more recent common ancestor than either order does with the Sirenia. This analysis also suggests that the common ancestor of the Proboscidea and Desmostylia (but not the Sirenia) had suppressed P5 and the original last molar. These characters may be convergent with some other mammals. The Superorder Tokotheria McKenna, 1975, was originally thought to be characterized by loss of both P5 and M3. However, because early sirenians do not show these losses, they may have occurred independently in the common ancestor of proboscideans and desmostylians and in various other tokotheres.The late Paleocene genus Minchenella Zhang, 1980, from China, is a suitable candidate to be the common ancestor of both the Desmostylia and the Proboscidea. It possesses a small entoconid II on M3. The Eocene genus Lammidhania Gingerich, 1977, from Pakistan, and the late Paleocene and/or early Eocene Chinese and Mongolian phenacolophids had not acquired an entoconid II on M3 but are otherwise similar to Minchenella and the anthracobunids. The Asiatic occurrence of phenacolophids, Lammidhania, Minchenella, and anthracobunids suggests an Asian origin for the Proboscidea and is in accord with the exclusively Pacific distribution of the Desmostylia.We believe that desmostylians were amphibious herbivores that fed on marine algae and angiosperms, and that at least the earlier taxa depended to a large extent on plants exposed in the intertidal zone.

Two New Oligocene Desmostylians and a Discussion of Tethytherian Systematics

Malcolm C. McKenna

About

Books

Join the club