Agnotocastor is an extinct member of the beaver family Castoridae. Unlike its modern relative, this species took the place of muskrats in the rivers of North America during the Oligocene epoch.
Species taxanomy provided by GBIF Secretariat (2022). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2023-06-13; License: CC BY 4.0