A new brontothere (Brontotheriidae, Perissodactyla, Mammalia) from the Eocene of the Ily Basin of Kazakstan and a phylogeny of Asian "horned" brontotheres

Related Titles

Series: American Museum novitates, no. 3439

By

Lucas, Spencer G.
Emry, Robert J.
Bayshashov, Bolat

Mihlbachler, Matthew C.

Type

Book

Material

Published material

Publication info

New York, NY American Museum of Natural History c2004

Notes

Title from caption.

"May 14, 2004."

A new genus and species of 'horned' brontothere, Aktautitan hippopotamopus, from the Ily Basin of Kazakstan is described from three skulls and nearly complete postcranial material. This material occurs in fluvio-lacustrine red beds of the upper part of the Eocene (Irdinmanhan) Kyzylbulak Formation at Aktau Mountain. Trackways occurring in the overlying layers are also attributed to this new brontothere. Additionally, several misleading problems in the taxonomy of Asian horned brontotheres are addressed. We conclude that Protitan khaitshinus Yanovskaya, 1980 is a junior objective synonym of Metatitan relictus Granger and Gregory, 1943. Protitan reshetovi Yanovskaya, 1980 is removed from the genus Protitan and possibly belongs within Metatitan. Brachydiastematherium transylvanicum Böckh and Maty, 1876, the only bona fide European brontothere, known from a single partial mandible, is morphologically consistent with Metatitan Granger and Gregory, 1943. Although B. transylvanicum is known from very fragmentary material, it is possible that Metatitan is a junior synonym of Brachydiastematherium. The first cladistic phylogeny of middle and late Eocene Asian horned brontotheres was constructed with 40 characters and 17 taxa. Aktautitan, Metatitan, Brachydiastematherium, and Embolotherium form a monophyletic clade, with Aktautitan hippopotamopus as the most basal member of this clade. Within this clade, there are two monophyletic trichotomies: a Metatitan relictus, M. primus, Brachydiastematherium transylvanicum clade and a 'Metatitan' progressus, Embolotherium andrewsi, E. grangeri clade. The cladogram topology suggests that the elevated frontonasal horns shared by Aktautitan and Metatitan represent the ancestral morphology of the bizarre 'battering-ram' of Embolotherium. We extend the subfamily name Embolotheriinae to include these taxa. The unusually shortened distal limb segments of A. hippopotamopus resemble those of a phylogenetically disparate group of large ungulates that have convergently evolved hippolike limb proportions. We conclude that these limb proportions probably do not indicate a semiaquatic lifestyle, as had been previously surmised.

Subjects

Aktautitan hippopotamopus , Asia , Brontotheriidae , Eocene , Ili River Region (China and Kazakhstan) , Kazakhstan , Mammals, Fossil , Paleontology , Perissodactyla, Fossil , Phylogeny

Call Number

QL1 .A436 no.3439 2004

Language

English

Identifiers

DOI: https://doi.org/10.1206/0003-0082(2004)439<0001:ANBBPM>2.0.CO;2
OCLC: 55129363