This paper deals with B. onoideus specimens from Portugal. This species occurs in the Lisbon area (in the upper part of the lower
Miocene, ca.18 to 17.6 Ma) in a very accurate stratigraphic framing (age, lithostratigraphic, climatic and palaeoecologic control being most complete). Some mandibular dental size variation, sex characters, functional interpretation, ecology and predation, chemical corrosion, and extinction are discussed
