Siamosorex, Peigné & Chaimanee & Yamee & Marandat & Srisuk & Jaeger, 2009

Peigné, Stéphane, Chaimanee, Yaowalak, Yamee, Chotima, Marandat, Bernard, Srisuk, Paladej & Jaeger, Jean-Jacques, 2009, An astonishing example of convergent evolution toward carnivory: Siamosorex debonisi n. gen., n. sp. (Mammalia, Lipotyphla, Soricomorpha, Plesiosoricidae) from the latest Oligocene of Thailand, Geodiversitas 31 (4), pp. 973-992 : 976

Genus Siamosorex n. gen.

TYPE SPECIES. — Siamosorex debonisi n. sp. by monotypy and present designation.

ETYMOLOGY. — The genus name refers to Siam, old name of Thailand, and -sorex, Latin for mouse.

DIAGNOSIS. — Plesiosoricid of large size that differs from most other plesiosoricids in being larger to much larger (except compared to some species of Plesiosorex Pomel, 1848 ) and having a shallow masseteric fossa; i2 enlarged, not procumbent but upright and caniniform, with a deep, mesiolingual groove; p3 and p4 elongated, double-rooted, of similar length; p3 with simple crown and p4 semimolariform with a reduced paraconid, a high, distinct metaconid, and a short talonid; molars show a strong decrease in size from m1 to m3; molars elongated with talonid markedly narrower and shorter than the trigonid, trigonid tall and open, especially in m1, entoconid and hypoconid not individualized, entocristid lower than oblique cristid, and metaconid taller than paraconid in m1, subequal to it in m2.

DISTRIBUTION AND AGE. — Nong Ya Plong, Thailand, late Oligocene (see Marivaux et al. 2004; Fig. 1 ).

Figures

FIG. 1. — Geographical map of South-east Asia showing the vertebrate fossil locality of Nong Ya Plong.