Argillotherium toliapicum

Argillotherium toliapicum

Davies, 1884

Common name Oxyaenid predatory mammal
Fossil group Mammals
Order Oxyaenodonta
Family Oxyaenidae
Genus Argillotherium
Taxonomic status Accepted
Geological age Ypresian

Summary

Argillotherium toliapicum is a very poorly known early Eocene mammal traditionally placed with oxyaenids, an extinct radiation of predatory placentals separate from modern Carnivora. A largely faunivorous way of life is therefore plausible from that relationship, but it is not demonstrated by the preserved dentition: the known skull has lost its tooth crowns.

The type is part of a cranium preserving portions of the parietals, maxillae, palatals, pterygoids and presphenoid. In the upper jaw, alveoli mark the positions of the third and fourth premolars and first molar; if a second molar was present, it was very small. With no complete dentition or postcranial skeleton, its body form, locomotion and detailed feeding mechanics remain uncertain, so these should not be reconstructed more precisely than the fossil allows.

Quick Identification

Look for: a partial mammalian skull or palate in which the rear upper jaw preserves a short cheek-tooth row of sockets for P3, P4 and M1, followed by no socket for a normal-sized M2. The type has lost the tooth crowns, so an isolated tooth cannot be confidently recognised as A. toliapicum from crown shape.

Diagnostic Features

  • The preserved upper-jaw tooth row shows alveoli for P3, P4 and M1.
  • Behind the M1 alveolus there is no socket for a normal-sized M2; if M2 was present, it must have been very small.
  • The fossil preserves portions of both maxillae together with the palatal bones, retaining the architecture of the posterior palate.
  • Pterygoid elements are preserved immediately behind the palate, with part of the presphenoid on the midline.
  • Fragments of the parietal region remain with the palatal and skull-base elements, showing that the type is cranial material rather than an isolated jaw or tooth.

Fossil Details

Typical size
Not defensibly estimable from the very limited London Clay material.
Preservation
The type is an incomplete skull in which the tooth crowns are absent and the cheek teeth are represented by alveoli. Fracture or loss of the posterior maxilla can therefore remove the most useful visible feature—the short P3–M1 alveolar sequence and the reduced or absent M2 position. Isolated teeth cannot presently be tied securely to the species from the type specimen alone.

Recorded Fossil Sites

References

  • Davies, W. (1884). Notes on some new carnivores from the British Eocene formations. Geological Magazine, 1(10), 433–438 View reference
  • Lydekker, R. (1885). Catalogue of the Fossil Mammalia in the British Museum (Natural History), Part I. 1–268. British Museum (Natural History), London View reference
  • Solé, F.; Gheerbrant, E.; Godinot, M. (2011). New data on the Oxyaenidae from the Early Eocene of Europe; biostratigraphic, paleobiogeographic and paleoecologic implications. Palaeontologia Electronica, 14(2), 1–41 View reference
Last Reviewed
16 August 2026 Reviewed by Sam Harris