Hilarcotherium
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Hilarcotherium Temporal range: 12 Ma Middle Miocene |
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| Reconstructed skull of Hilarcotherium: the brown parts represents the fossils found. | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | †Astrapotheria |
| Family: | †Astrapotheriidae |
| Subfamily: | Uruguaytheriinae |
| Genus: |
Hilarcotherium Vallejo-Pareja et al.,2015 |
| species | |
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Hilarcotherium castanedaii Vallejo-Pareja et al., 2015 (type species) |
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Hilarcotherium castanedaii Vallejo-Pareja et al., 2015 (type species)
Hilarcotherium is an extinct genus of astrapotheriid mammal that lived in South America during the middle Miocene. The type and only known species is H. castanedaii, found in sediments of the La Victoria Formation in the Tolima Department in Colombia.
The remains of Hilarcotherium were discovered by José Alfredo Castañeda, who found them in the Malnombre Creek in the Hilarco village located near the town of Purificación, in Tolima. This area, in the valley of the Upper Magdalena River, correspond to the La Victoria Formation, that along the Villavieja Formation makes the Honda Group, dating from the Middle Miocene, made between 13-11.8 million years ago and it has provided a remarkable fossil site known as La Venta, although the lack of key fossil does not allow establish accurately the membership of the Hilarco site to the formation. The remains of Hilarcotherium were collected by dr. María Páramo and Gerardo Vargas, who took them to the Geological Museum José Royo y Gómez of Ingeominas (former name of Colombian Geological Service) in Bogotá for study and preservation. In February 2015 these remains were officially named, although the name Hilarcotherium castanedaii was released earlier and informally in conference abstracts. The genus name is derived from the Hilarco site and the term in Latinized Greek therium, meaning "beast", while the species name castanedaii is in recognition to Castañeda, by finding and reporting the find.
The only known specimen of Hilarcotherium is the holotype, IGM p881231. This consists of fragments of skull, a partial jaw, the vertebral ramus of a dorsal rib, a complete left humerus and an incisor tooth associated. The skull includes the rostrum area, the palate with the fourth premolar (P4) and the three upper molars (M1-M2-M3) plus part of the zygomatic arch and the braincase, but lacks of the upper canines and the top portion of the skull. The premaxilla shows no sign of having teeth, as in other astrapotheres. The jaw missing the incisors, the crown of the fourth premolar and the left mandibular ramus, but has the roots of the teeth of the right side and a broken canine with an oval cross section. It has however the sockets for three incisors on each side of the jaw, which is a plesiomorphic feature, as his other relatives as Xenastrapotherium had two.
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