Andrewsarchus

Andrewsarchus
Temporal range: Middle Eocene, 47.8–37.71 Ma
Holotype skull of A. mongoliensis, held at the American Museum of Natural History
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Clade: Cetancodontamorpha
Family: †Andrewsarchidae
Szalay & Gould, 1966[2]
Genus: †Andrewsarchus
Osborn, 1924[1]
Type species
†Andrewsarchus mongoliensis
Osborn, 1924
Other species
  • †Andrewsarchus crassum
    Ding, Zheng, Zhang, & Tong, 1977[3]
Synonyms
Genus synonymy
Species synonymy
  • A. mongoliensis
      • Paratriisodon henanensis
        Chow, 1959[5]
      • Paratriisodon gigas
        Chow, Li, & Chang, 1973[6]

Andrewsarchus (/ˌændruːˈsɑːrkəs/), meaning "Andrews' ruler", is an extinct genus of artiodactyl that lived during the Middle Eocene in what is now China. The genus was first described by Henry Fairfield Osborn in 1924 with the type species A. mongoliensis based on a largely complete cranium. A second species, A. crassum, was described in 1977 based on teeth. A mandible, formerly described as Paratriisodon, does probably belong to Andrewsarchus as well. The genus has been historically placed in the families Mesonychidae or Arctocyonidae, or was considered to be a close relative of whales. It is now regarded as the sole member of its own family, Andrewsarchidae, and may have been related to entelodonts. Fossils of Andrewsarchus have been recovered from the Middle Eocene Irdin Manha, Lushi, and Dongjun Formations of Inner Mongolia, each dated to the Irdinmanhan Asian land mammal age (Lutetian–Bartonian stages, 48–38 million years ago).

Andrewsarchus has historically been reputed as the largest terrestrial, carnivorous mammal given its skull length of 83.4 cm (32.8 in), though its overall body size was probably overestimated due to inaccurate comparisons with mesonychids. Its incisors are arranged in a semicircle, similar to entelodonts, with the second rivalling the canine in size. The premolars are again similar to entelodonts in having a single cusp. The crowns of the molars are wrinkled, suggesting it was omnivorous or a scavenger. Unlike many modern scavengers, a reduced sagittal crest and flat mandibular fossa suggest that Andrewsarchus likely had a fairly weak bite force.

  1. ^ Osborn, H.F. (1924). "Andrewsarchus, giant mesonychid of Mongolia". American Museum Novitates (146): 1–5. hdl:2246/3226.
  2. ^ Szalay, F.S.; Gould, S.J. (1966). "Asiatic Mesonychidae (Mammalia, Condylartha)". Bulletin of the American Museum of Natural History. 132 (2): 127–174. hdl:2246/1112.
  3. ^ Ding, S.; Zheng, J.; Zhang, Y.; Tong, Y. (1977). "The age and characteristic of the Liuniu and the Dongjun faunas, Bose Basin of Guangxi" (PDF). Vertebrata PalAsiatica. 15 (1): 35–45.
  4. ^ Chow, M.M. (1959). "A new arctocyonid from the Upper Eocene of Lushih, Honan" (PDF). Vertebrata PalAsiatica. 3 (3): 133–138.
  5. ^ Cite error: The named reference O'Leary 1998 was invoked but never defined (see the help page).
  6. ^ Chow, M.M.; Li, C.; Chang, Y. (1973). "Late Eocene mammalian faunas of Honan and Shansi with notes on some vertebrate fossils collected therefrom" (PDF). Vertebrata PalAsiatica. 11 (2): 165–181.