 Rather, they were a sister group that remained in the ecological niche of their common ancestor.The number of species in the genus is disputed.The species "P. ambiguus" was found in Middle Oligocene to Middle Miocene (c. 29-12 mya) deposits of Western and Central Europe, being rare in Oligocene and much more common in Miocene strata; there is also a probably record from the Oligocene/Miocene of Taubaté Basin in São Paulo, Brazil.