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Many cladistic systems therefore redefine Reptilia as a clade (monophyletic group) including birds, though the precise definition of this clade varies between authors. Others prioritize the clade Sauropsida, which typically refers to all amniotes more closely related to modern reptiles than to mammals.
- Crocodilia
- Sphenodontia
- Squamata
- Testudines
Crocodilia(“small lizard”) arose as a distinct lineage by the middle Triassic; extant species include alligators, crocodiles, gharials, and caimans. Crocodilians (Figure 1) live throughout the tropics and subtropics of Africa, South America, Southern Florida, Asia, and Australia. They are found in freshwater, saltwater, and brackish habitats, such ...
Sphenodontia (“wedge tooth”) arose in the early Mesozoic era, when they had a moderate radiation, but now are represented by only two living species: Sphenodon punctatus and Sphenodon guntheri,both found on offshore islands in New Zealand (Figure 2). The common name “tuatara” comes from a Maori word describing the crest along its back. Tuataras hav...
The Squamata(“scaly or having scales”) arose in the late Permian, and extant species include lizards and snakes. Both are found on all continents except Antarctica. Lizards and snakes are most closely related to tuataras, both groups having evolved from a lepidosaurian ancestor. Squamata is the largest extant clade of reptiles. Most lizards differ ...
The turtles, terrapins, and tortoises are members of the clade Testudines (“having a shell”) (Figure 5), and are characterized by a bony or cartilaginous shell. The shell in turtles is not just an epidermal covering, but is incorporated into the skeletal system. The dorsal shell is called the carapace and includes the backbone and ribs; the ventral...
Amniota, a group of limbed vertebrates that includes all living reptiles (class Reptilia), birds (class Aves), mammals (class Mammalia), and their extinct relatives and ancestors. The amniotes are the evolutionary branch (clade) of the tetrapods (superclass Tetrapoda) in which the embryo develops.
What is a clade? What is cladistics, and what is it used for? Explain why reptiles and birds are placed in the same clade. Dogs and wolves are more closely related to each other than either is to cats. Draw a phylogenetic tree to show these relationships.
Squamata is the largest extant clade of reptiles (Figure \(\PageIndex{8}\)). Most lizards differ from snakes by having four limbs, although these have been variously lost or significantly reduced in at least 60 lineages.
Feb 28, 2021 · Squamata is the largest extant clade of reptiles (Figure 3). Most lizards differ from snakes by having four limbs, although these have been variously lost or significantly reduced in at least 60 lineages.
Jun 12, 2024 · A reptile is any member of the class Reptilia, the group of air-breathing vertebrates that have internal fertilization, amniotic development, and epidermal scales covering part or all of their body. The major groups of living reptiles are turtles, tuatara, lizards, snakes, and crocodiles.
