Ortotherium fossil map
Where fossils of Ortotherium have been found, shown on the Earth as it looked about 5 million years ago and on today’s map.
Dots are fossil collections recorded in the Paleobiology Database. The “then” view moves today’s fossil sites back to their positions 5 million years ago (the time slice nearest the median age of the fossils) using the Merdith et al. (2021) plate model; positions are approximate. Open on the timeline map →
| Group | Early mammals |
|---|---|
| Lived | 8–5 million years ago (Tortonian to Zanclean) |
| Periods | Neogene |
| Family | Megalonychidae |
| Named by | Ameghino 1885 |
| Fossil records | 12 occurrences at 2 locations (PBDB) |
| Found in | Argentina |
| Rock formations | Ituzaingo |
About Ortotherium
Ortotherium ("upright beast") is a genus of megalonychid ground sloth from the Late Miocene (Huayquerian SALMA, around 9 to 6.8 million years ago) Ituzaingó Formation of Entre Rios Province, Argentina. Although many species were described, the only valid species of the genus is Ortotherium laticurvatum, with many species being junior synonyms. Ortotherium is known from very fragmentary material, all of which is material from the mandible (lower jaw) and teeth. The holotype (specimen a scientific name is applied to) of O. laticurvatum consists of an incomplete left dentary that had been unearthed from a series of sediments known as 'Conglomerado osifero' in Paraná, Argentina. Argentina paleontologist Florentino Ameghino named the species in 1885, though he would go on to name four more, invalid, species of the genus. One species however, O. brevirostrum, has been reclassified as Mesopotamocnus.
Text in “About” is quoted from the Wikipedia article Ortotherium (revision 1373239974), licensed under CC BY-SA 4.0; introduction excerpted verbatim, formatting removed. Ages, family, authority and fossil records: Paleobiology Database, accessed 23 October 2026. Ages are those of the rock layers the fossils were found in. Wikidata: Q118145239.
