Asiomys dawsoni Qi, 1987
|
publication ID |
https://doi.org/ 10.4202/app.00292.2016 |
|
persistent identifier |
https://treatment.plazi.org/id/03E687D4-FFFD-FFC5-FCD5-7AE0FE252555 |
|
treatment provided by |
Felipe |
|
scientific name |
Asiomys dawsoni Qi, 1987 |
| status |
|
Fig. 12 View Fig .
Material.—Left P4 (V20828.1), left M1 (V20828.2–3), right M1 (V20828.4), right M2 (V20828.5), left dp4 (V20828.6), left m3 (V20828.7) from Wulanhuxiu, Erlian Basin, Nei Mongol, China, middle and upper part of horizon 4, middle Eocene.
Description.—P4 ( Fig. 12A View Fig ) lacks the hypocone, but has a prominent protocone. On M1 ( Fig. 12B, C View Fig ) and M2 ( Fig. 12D View Fig ) the four main cusps are prominent, the crests are low, and the paracone and metacone are subequal in size and widely separated from one another. The hypocone is less-developed, being smaller than the protocone. The protoloph is complete, and the metaloph is weaker than the protoloph. The metaconule is large and V20828.5 has two metaconules ( Fig. 12D View Fig ). The anterior and posterior cingula on M1 and M2 are prominent, and the entoloph is distinct. The sinus is shallow.
The trigonid of dp4 is narrower than the talonid. In dp4 Fig. 12E View Fig ) the metaconid is close to the protoconid and is slightly anteriorly placed, the entoconid is separated from the hypoconulid by a notch, the distinct hypoconulid extends transversely along the posterior margin of the tooth, and the short hypolophid extends from the entoconid. The m3 ( Fig. 12F View Fig ) has a weak hypoconulid, and a short hypolophid. The protocristid on m3 is absent, so that the trigonid basin is open posteriorly.
Asiomys dawsoni was first described by Qi (1987) based on three teeth from the Irdin Manha area. Li and Meng 2013) reported many specimens of Asiomys from the Irdin Manha Formation of the Huheboerhe area, which adds substantially to our knowledge of this ischyromyid. The new specimens from Wulanhuxiu show several diagnostic features, including the absence of a hypocone on P4, the presence of a small hypocone on M1–M2, a complete protoloph, an enlarged (or dual) metaconule on M1–M2, and a short hypolophid on dp4 and m3. All of these features identify these specimens as Asiomys dawsoni . The size of the new specimens also falls within the range of variation of A. dawsoni ( Li and Meng, 2013) (see Table 5).
Stratigraphic and geographic range.—Middle Eocene, Irdinmanhan, Nei Mongol, China.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
