Phylloctenus

Phylloctenus is a genus of extinct marine reptiles belonging to the order Ichthyosauria. These animals lived during the Late Triassic period, approximately 235 to 221 million years ago. The genus was first described in 1978 based on fossil remains found in the United States. Phylloctenus fossils are relatively rare and are primarily known from fragmentary skeletons.

The defining characteristic of Phylloctenus, as suggested by its name which means "leaf comb," is its unusual dentition. The teeth were arranged in a comb-like fashion along the jaws, a feature distinct from many other ichthyosaurs. This arrangement may have been an adaptation for a specialized feeding strategy, though its exact diet remains a subject of scientific debate. It is hypothesized that Phylloctenus may have fed on soft-bodied prey or filtered small organisms from the water.

Reconstructions of Phylloctenus suggest it was a medium-sized ichthyosaur, with an elongated body and paddle-like limbs, typical of the group's adaptations for a fully aquatic lifestyle. Its exact phylogenetic position within Ichthyosauria is still being investigated, but it is generally considered to be an early or basal member of the group. The discovery of Phylloctenus has contributed to our understanding of the early evolution and diversification of ichthyosaurs during the Triassic, a crucial period for the emergence of marine reptiles.