BAI Bin QI Tao

(1 Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences Beijing 100044)

(2 CAS Center for Excellence in Life and Paleoenvironment Beijing 100044 baibin@ivpp.ac.cn)

Qi (1990a) named a new hyracodontid genusUlaniafrom the Middle Eocene deposits of Nei Mongol (Inner Mongolia), China. However, the generic name has been preoccupied byUlaniaLin & Zhang, 1979, a Cambrian trilobite (Zhu, et al., 1979). We therefore propose a new generic nameUlanodonnom. nov. to replaceUlaniaQi, 1990.

Type speciesUlanodonwilsoni(Qi, 1990).

Included speciesOnly the type species.

Etymology“Ulan” means red in color in Mongolian language, and also refers to the so called “Ulan Gochu Formation” where the type species was found; the Greek “-odon” is a common root in hyracodontid names meaning teeth.

DiagnosisAs for the type and only species.

HolotypeIVPP V 8922-1–28, a juvenile individual including associated mandibles,maxilla, isolated teeth, distal end of Mc IV, scaphoid, unciform, phalanges, and sesamoids.

EtymologyThe specific name honors Dr. John A. Wilson, for his contributions to the study of perissodactyls.

DiagnosisMedium-sized hyraodontids, M1–2 length 44.5 mm; M1–2 with a flat,straight ectoloph, long metacone, and oblique protoloph and metaloph; M3 metacone reduced and labially deflected; p1 absent; p3–4 with a low, complete hypolophid; lower molars relatively long with oblique protolophids and hypolophids, and U-shaped trigonids.

Type locality and horizonErden Obo, Nomogen, Siziwangqi, Nei Mongol, China; the base of “Ulan Gochu Formation”, Middle Eocene.

CommentsQiu and Wang (2007) doubted the association of the maxilla (IVPP V 8922-1) with mandibles (V 8922-2–3) based on their different worn stage, and further suggested that the maxilla may belong to amynodontCaenolophus, while the mandibles were designated as the holotype ofUlanodon(=Ulania)wilsoni. However, we still consider all specimens are from the same individual, because they are from the same horizon at Erden Obo as shown by “1P14H17” marked on the specimens, and the worn stages are similar between the upper and lower molars with both M3 and m3 still in the socket. As pointed out by Qi (1990a) and Qiu and Wang (2007), the M1–2 of V 8922 is similar to that ofCaenolophus obliquusin having a flat, straight ectoloph and oblique protoloph and metaloph, which are often regarded as characters of amynodonts, but the flat ectolophs on the upper molars are also known from hyracodontidHyracodon. Furthermore, the M3 of V 8922 has a more lingually placed metacone and a trapezoid rather than quadrate outline, suggesting its hyracodont affinity as indicated by the mandibles. The P4 rather than P3 (IVPP V8922-4) is premolariform (sens.Qiu and Wang, 2007) with the hypocone discriminated from the endoprotocrista at the top,and the metaconule (metaloph) is short and posterolingually extended from the paracone as inCaenolophusobliquus. The mandibles show clear hyracodontid affinity, especially the three spatulate incisors increasing in size anteriorly and a small canine appressed to i3(Radinsky, 1967). The scaphoid and unciform of V 8922 are relatively high and narrow as in hyracodonts. Thus, the specimens of IVPP V 8922 represent a same individual of hyracodontUlanodonwilsoni, which is probably descended fromCaenolophusobliquus. If the specimens were discovered from the base of the “Ulan Gochu Formation” as defined by Qi (1990b), theUlanodon-bearing horizon is equal to the “Lower White” at Erden Obo.

We thank Mr. John Ponting for bringing this issue to our attention, and Dr. Wang Yuan-Qing for the suggestion of the new generic name and review of the manuscript.