Data from: Eocene Pachynolophinae (Perissodactyla, Palaeotheriidae) from China and their paleobiogeographic implications

The Eocene Palaeotheriidae was traditionally considered a nearly endemic
European group within Equoidea, but a few palaeotheres have been reported
from Asia. Here I reanalyze a maxilla containing M1-3 from the Lunan
Basin, Yunnan Province, China. This element was initially assigned to a
new tapiromorph species, Lophialetes yunnanensis, but I erect a new genus
Lophiohippus within Pachynolophinae for the Yunnan specimen based mainly
on the absence of mesostyles, the strongly inclined metalophs, the strong
development of lophodonty, parastyles overlapping metastyles of preceding
teeth and situated mesial to the paracone, and the fact that M3 is longer
than wide and has a large and buccally deflected metastyle. L. yunnanensis
differs from European Anchilophus and Paranchilophus in that the
parastyles are situated mesial or even slightly lingual, rather than
mesiobuccal, to the paracones, and M3 is relatively pronouncedly larger
than M1. I further reanalyze Qianohippus magicus from the Shinao Basin of
Guizhou Province, China, in which the complete dentition is known.
Qianohippus is characterized by a molariform P2 and non-molariform P3-4; a
relatively high degree of lophodonty; the absence of mesostyles; an
angular bending in the protoloph on P3-M3 and the metaloph on M1-3 at the
paraconule and metaconule, respectively; and weakly developed “metastylid”
on the lower cheek teeth. A cladistic analysis supports a close
relationship between Lophiohippus yunnanensis and Paranchilophus, and
suggests that Qianohippus is closely related to some derived pachynolophs.
The appearance of the pachynolophins Lophiohippus and Qianohippus in China
supports the existence of a biogeographic connection between Europe and
Asia in the Middle-Late Eocene, and the dispersal route was probably along
the Tethyan micro-continents in the south.