| Machaeroides | |
|---|---|
) | |
| Machaeroides eothen skull | |
) | |
| Machaeroides eothen head restoration | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | †Oxyaenodonta |
| Family: | †Oxyaenidae |
| Subfamily: | †Machaeroidinae |
| Genus: | †Machaeroides Matthew, 1909 |
| Type species | |
| Machaeroides eothen Matthew, 1909 | |
| Species | |
Machaeroides ("dagger-like") is a genus of sabre-toothed predatory mammal that lived during the Eocene (50.3 to 46.2 mya). Its fossils were found in the U.S. state of Wyoming.
Description
Both species bore a passing or superficial resemblance to a very small, dog-sized saber-toothed cat. Machaeroides could be distinguished from actual saber-toothed cats by their more-elongated skulls, and their plantigrade stance. Machaeroides species are distinguished from the closely related Apataelurus by the fact that the former genus had smaller saber-teeth. Despite its small size, the genus Machairoides was well-equipped to hunt prey larger than itself, such as the small, primitive horses and rhinoceroses present at the time, as it was equipped with saber teeth and powerful forelimbs to subdue prey.[3]
M. eothen weighed an estimated 10–14 kg (22–31 lb), thus matching in size a small Staffordshire Terrier. M. simpsoni was probably smaller.[4]
Taxonomic placement
Its position within the mammals has been in dispute. Experts have been equally divided over whether Machaeroides and its sister-genus, Apataelurus, belong in Oxyaenidae or Hyaenodonta, though the most recent studies favor the former.[5]
References
- ^ W. D. Matthew. (1909.) "The Carnivora and Insectivora of the Bridger Basin, middle Eocene." Memoirs of the American Museum of Natural History 9:289-567
- ^ M. R. Dawson, R. K. Stucky, L. Krishtalka and C. C. Black. (1986.) "Machaeroides simpsoni, new species, oldest known sabertooth creodont (Mammalia), of the Lost Cabin Eocene." Contributions to Geology, University of Wyoming, Special Paper 3:177-182
- ^ Antón, Mauricio (2013). Sabertooth. Indiana University Press. ISBN 978-0-253-01049-0.
- ^ Egi, Naoko1 (2001). "Body Mass Estimates in Extinct Mammals from Limb Bone Dimensions: the Case of North American Hyaenodontids". Palaeontology. 44 (3): 497–528. doi:10.1111/1475-4983.00189.
- ^ Zack, S. (2014). "Saber-tooth origins: a new skeletal association and the affinities of Machaeroidinae (Mammalia, Creodonta)". Journal of Vertebrate Paleontology, Program and Abstracts: 259–260.