That suborder of this class, Amphisbaenia, is thought to have evolved its thick fused skulls convergently with another order in this class, whose only family, Sphenodontidae, contains only two extant species, unique for their acrodont teeth fused to the top jawbone and now limited to a few islands around New Zealand.
Beta-keratin first evolved in this animal taxon and is an apomorphy of this class. One sorder in this class contains about 140 species of mostly legless, long-bodied creatures with reduced eyes and a central tooth on the upper jaw centered between two lower teeth to pierce through their rubbery prey. That suborder of this class, Amphisbaenia, is thought to have evolved its thick fused skulls convergently with another order in this class, whose only family, Sphenodontidae, contains only two extant species, unique for their acrodont teeth fused to the top jawbone and now limited to a few islands around New Zealand. That order, Rhynchnocephalia, roots the phylogenetic tree of subclass Lepidosauria in this class and was once thought to root this entire class before even older fossils were discovered of subclass Testudinia in this class. The tuatara is a member of, for 10 points, what vertebrate class often featuring temperature-dependent sex determination which includes turtles, lizards, and snakes?
Beta-keratin first evolved in this animal taxon and is an apomorphy of this class.
Reptilia or reptiles