Proschismotherium Explained

Proschismotherium is an extinct genus of ground sloth of the family Megalonychidae, endemic to Argentina during the Early Miocene. It lived from 17.5 mya — 16.3 mya, existing (as a genus) for approximately .^[1] The type, and only, species, P. oppositum, was named in 1902 by Florentino Ameghino based on a single specimen found in the Santacrucian-aged Colpodon Beds of Argentina.^[2] Ameghino in 1902 placed Proschismotherium in the Megatheriidae, alongside Hapaloides, which was its sister taxon.^{[3] [4] [5]}

The holotype jaw was compared to that of Schismotherium fractum and was found to be roughly the same size, indicating that Proschismotherium weighed roughly 45kg (99lb) and grew up to 1m (03feet);^[6] the size estimate was loosely based on Hapalops and also Schismotherium.^[7]

Notes and References

1. R. L. Carroll. (1988). Vertebrate Paleontology and Evolution 1-698
2. F. Ameghino. (1902). Première contribution à la connaissance de la fauna mammalogique des couches à Colpodon [First contribution to the knowledge of the mammalian fauna of the Colpodon Beds]. Boletin de la Academia Nacional de Ciencias de Córdoba 17:71-141
3. McKenna & Bell (1997) Classification of Mammals Above the Species Level
4. Web site: Hapaloides. Fossilworks. 11 August 2022.
5. Web site: Proschismotherium. Fossilworks. 11 August 2022.
6. Toledo . Néstor . 2012-09-07 . Mass estimation of Santacrucian sloths from the Early Miocene Santa Cruz Formation of Patagonia, Argentina . Acta Palaeontologica Polonica . 10.4202/app.2012.0009. free . 11336/20506 . free .
7. Book: The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. Marshall Editions. 1999. 978-1-84028-152-1. Palmer, D.. London. 207.