Teilhardia
Extinct genus of mammals
From Wikipedia, the free encyclopedia
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.
| Teilhardia | |
|---|---|
| |
| 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[2] |
| Species: | †T. pretiosa |
| Binomial name | |
| †Teilhardia pretiosa Matthew & Granger, 1926[2] | |
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.[2] AMNH 20299 preserves much of the cheek teeth, from the third premolar to the third molar.[2] In 1927, the formation of the relevant rock layers was reassessed as the distinct Tukhum Formation.[3] The correct horizon of AMNH 20299 is disputed, since the fossil was reportedly found associated with "typical Sharamurunian taxa".[3] Teilhardia is nevertheless typically dated the Irdinmanhan land mammal age, preceding the Sharamurunian age of the Shara Murun Formation.[1][4]
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.[5] 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.[3]
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).[2] It had primitive rhinocerotoid teeth;[2] 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.[2]
Classification
Matthew and Granger interpreted Teilhardia as a hyracodont, possibly an ancestral form to Ardynia.[2] 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.[6] 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.[7]
Later researchers have consistently maintained Teilhardia as a distinct genus.[1][3][4][8] Bai et al. (2018) classified Teilhardia as a hyracodont.[3] 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.[1][4][5][8]