Plesiotypotherium
From Wikipedia, the free encyclopedia
| Plesiotypotherium Temporal range: Middle-Late Miocene ~. | |
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| Skull of Plesiotypotherium | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | †Notoungulata |
| Family: | †Mesotheriidae |
| Subfamily: | †Mesotheriinae |
| Genus: | †Plesiotypotherium Villarroel, 1974 |
| Type species | |
| †Plesiotypotherium achirense Villarroel, 1974 | |
| Species | |
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Plesiotypotherium is an extinct genus of notoungulate, belonging to the suborder Typotheria. It lived from the Middle to the Late Miocene, and its fossilised remains were discovered in South America.
This animal was somewhat similar to modern wombats, but was slightly larger-sized. Plesiotypotherium, like its relatives Trachytherus and Mesotherium, was characterized by a postcranial skeleton suited for burrowing. Its scapula was characterized by a distally located suprascapular fossa; the deltoid crest was well developed. The humerus of Plesiotypotherium was slightly thinner than in Trachytherus, and had a characteristic perforation in the olecranon fossa. The entepicondyle, ectepicondyle and supracondylar crest were well developed. The ulna was characterized by a well developed olecranon, while in the proximal area of the radius a sesamoid bone was articulated with the main bone; the distal part of the radius had particular grooves for the tendons of the extensor muscle. The hand was strong; the carpal bones, the metacarpals and the phalanges were particularly strong. The pelvic area of Plesiotypotherium was characterized by its five vertebrae firmly fused with each other. The transverse processes of the penultimate vertebra were fused solidly with the ischium. The talus had a characteristic asymmetrical trochlear keel; the lateral keel was much wider than the middle one and evocative of those of ground sloths.
The skull was characterized by its large anterior incisors, separated from the posterior teeth by a large diastema; in the species Plesiotypotherium casirense, there was a bony process in the lacrimal bone, and a large infraorbital foramen.
