Paleontologists have examined 142 new specimens, including 160 teeth, of the extinct medium-sized beaver species Steneofiber depereti from the Late Miocene Hammerschmiede locality in the Northern Alpine Foreland Basin, Germany.
Castor sp. from the Viviparous Quadrupeds of North America by John Woodhouse Audubon.
Today, beavers are solely represented by the genus Castor, which includes two species: the North American beaver (Castor canadensis) and the Eurasian beaver (Castor fiber).
A much higher diversity of several dozen species in seven genera (Anchitheriomys, Chalicomys, Dipoides, Eucastor? (Schreuderia), Euroxenomys, Steneofiber, and Trogontherium) is known from the European Miocene epoch.
One of these extinct species, Steneofiber depereti, was little smaller than the modern beavers and lived in freshwater dominated river ecosystems of southern Germany more than 11 million years ago.
In a new study, Thomas Lechner and Professor Madelaine Böhme from the Senckenberg Centre for Human Evolution and Palaeoenvironment at the University of Tübingen analyzed the dental material of Steneofiber depereti from two fossiliferous layers of the Hammerschmiede locality in Germany.
The material represented beaver individuals of a large range of age classes, from juvenile to old.
“Beavers today have strong family ties. Parents and up to two generations of young take care of offspring together,” Lechner said.
“Eventually, mature animals leave the clan to seek out their own territory.”
“The ideal home for a beaver is normally on a major river, most of which are already taken, so young adult beavers are forced to travel upstream and settle in smaller waterways.”
“Survival is much harder here and the mortality rate is correspondingly higher in this age group than it is for older animals who occupy an optimal habitat.”
“It’s unusual to be able to make statements about the mortality and ecology of fossil species — mostly there are only single finds,” Professor Böhme added.
“Hammerschmiede, where the find was made, gives detailed insight into two different fossil habitats, a smaller rivulet — the habitat of the great ape Danuvius guggenmosi — and a larger river.”
“This made it possible to compare the mortality of the beavers in the river with those in the stream.”
“It seems that, similarly to contemporary examples of the genus, the optimal habitat for Steneofiber depereti was in larger river areas,” Lechner said.
“Moreover, beavers probably also lived in family clans with ongoing parental care 11 million years ago.”
“In addition to this, both the ecological similarities of this type of beaver and the morphological characteristics of the teeth indicate that Steneofiber depereti is in the line of the ancestors of today’s beaver.”
“The molars of our fossil beaver have similarities with the forerunner of the contemporary beaver. So this species fits into a small gap between previously clearly distinct species and prove that the beaver has steadily evolved into the present form.”
“The study once again shows how rewarding meticulous excavation is and the unique potential that fossils can have, because not only pure morphology but also statistical age distribution of finds can yield unexpected insights,” Professor Böhme said.
The study was published in the journal Acta Palaeontologica Polonica.
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Thomas Lechner & Madelaine Böhme. 2022. The beaver Steneofiber depereti from the lower Upper Miocene hominid locality Hammerschmiede and remarks on its ecology. Acta Palaeontologica Polonica 67 (4); doi: 10.4202/app.00997.2022
