Teilhardia

Not to be confused with Teilhardina.

Teilhardia Temporal range: Middle Eocene (Irdinmanhan), Da. S T Ypr. Lut. B Pr. Rup. Ch. Possible Late Eocene record
Type jaw (AMNH 20299) of T. pretiosa
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Infraclass:	Placentalia
Order:	Perissodactyla
Superfamily:	Rhinocerotoidea
Family:	†Amynodontidae
Genus:	†Teilhardia Matthew & Granger, 1926
Species:	†T. pretiosa
Binomial name
†Teilhardia pretiosa Matthew & Granger, 1926

Teilhardia is an extinct genus of primitive amynodont that lived in East Asia during the Middle Eocene. A single species of Teilhardia is known, T. pretiosa, which lived in China during the Irdinmanhan land mammal age.

Research history

Teilhardia pretiosa was briefly described by William Diller Matthew and Walter W. Granger in 1926, based on a lower jaw (AMNH 20299), reportedly found at the base of the Shara Murun Formation in the "red layers" of Ula Usu in Inner Mongolia, China. AMNH 20299 preserves much of the cheek teeth, from the third premolar to the third molar. In 1927, the formation of the relevant rock layers was reassessed as the distinct Tukhum Formation. The correct horizon of AMNH 20299 is disputed, since the fossil was reportedly found associated with "typical Sharamurunian taxa". Teilhardia is nevertheless typically dated the Irdinmanhan land mammal age, preceding the Sharamurunian age of the Shara Murun Formation.

Fossils that might belong to T. pretiosa, and possibly an additional new species of Teilhardia, have been reported from the Late Eocene Lumeiyi Formation in Lunan, Yunnan, southwestern China. In 2018, Bai et al. reported that recent fieldwork in the "red layers" of Inner Mongolia had uncovered additional fossils from T. pretiosa, though they did not describe these new specimens.

Description

Teilhardia was a small rhinocerotoid. The series of premolar to molar teeth measures 55 millimetres (2.2 in), and the molar series by itself measures 35 millimetres (1.4 in). It had primitive rhinocerotoid teeth; all of the premolars were reduced in size, though the second premolar retained two roots and the third and fourth were submolariform (somewhat molar-like). The molars increased in size slightly from the first molar to the third molar.

Classification

Matthew and Granger interpreted Teilhardia as a hyracodont, possibly an ancestral form to Ardynia. In 1967, Leonard Radinsky suggested that Teilhardia's relatively short premolar series relative to its molar series could mean that it is a primitive amynodont, possibly ancestral to Caenolophus, another primitive amynodont. Caenolophus is slightly larger than Teilhardia, and also has a short premolar series. In 1986, William P. Wall and Earl Manning opinioned that AMNH 20299 was not sufficiently different from fossils assigned to Caenolophus to justify Teilhardia as a distinct genus.

Later researchers have consistently maintained Teilhardia as a distinct genus. Bai et al. (2018) classified Teilhardia as a hyracodont. Other than Bai et al. (2018), the consensus is that Teilhardia represents a primitive amynodont; Spencer & Emry (1996), Tsubamoto (2000), Missiaen (2011), and Bai et al. (2020) all classified Teilhardia as an amynodont.