Palaeoxyris is the prehistoric shark egg capsule morphotype of the family Hybodontidae with a predominant occurrence in ancient freshwater environments.
Vertebrates present here at the time of Oligokyphus included hybodont sharks, bony fish known as osteichthyes, lungfish, salamanders, the frog Prosalirus, the caecilian Eocaecilia, the turtle Kayentachelys, a sphenodontian reptile, various lizards.