Trogontherium

Trogontherium is an extinct genus of Eurasian giant beavers that lived from the Late Pliocene to the Late Pleistocene. Fossils of Trogontherium have been found across northern Eurasia, from Western Europe to China and Siberia.

== Taxonomy == Trogontherium was originally described in 1809 from a skull given to Gotthelf Fischer von Waldheim from the collection of Russian aristocrat Alexander Sergeyevich Stroganov found near Taganrog on the coast of the Sea of Azov in southern Russia, suggested to be Early Pleistocene in age. Originally, no species name was given. In 1823, Georges Cuvier cited the type species name as being T. cuvieri, attributing the species name to von Waldheim, which has been followed by later authors.'' Although the origin of the name was previously obscure, a 2024 study confirmed that the species name T. cuvieri was first used in a previously overlooked 1814 publication by von Waldheim. Cuvier had previously named the species Castor trogontherium in an 1809 publication, which is recognised as a synonym of Trogontherium cuvieri but because C. trogontherium was last used in 1884, it is considered a nomen oblitum, and thus T. cuvieri remains the valid name for the species. T. cuvieri is known from the Late Pliocene to Pleistocene of Eurasia. A distinctly smaller species, T. minus, named by Edwin Tulley Newton in 1890, is known from the Late Pliocene-earliest Pleistocene of Europe, where it co-existed with T. cuvieri. T. boisvilletti is generally considered a synonym of T. cuiveri. Some authors also include the species T. minutus from the Late Miocene of Europe, though this species has also been included in the genera Steneofiber or Euroxenomys, although it is clearly closely related to Trogontherium. Trogontherium has been placed as part of the subfamily Castoroidinae, which notably also includes North American giant beavers (Castoroides), though the large body size seems to have developed independently in both lineages.