EVERYDAY SCIENCE

Detailed explanation-1: -Anapsid reptiles are characterized by a primitive skull with no temporal openings. Turtles are the only living representatives of this clade and belong to one order variously referred to as Testudines, Testudinata, or Chelonia. Thus, when we refer to chelonians, we refer to turtles, tortoises, and terrapins as a group.

Detailed explanation-2: -The order testudines is a monophyletic clade containing 260 species of extant turtles, terrapins and tortoises in 13 families. Tortoises include just a single family (Testudinidae), which is phylogenetically embedded within the turtles.

Detailed explanation-3: -turtle, (order Testudines), any reptile with a body encased in a bony shell, including tortoises. Although numerous animals, from invertebrates to mammals, have evolved shells, none has an architecture like that of turtles. The turtle shell has a top (carapace) and a bottom (plastron).