Polytomy: When an ancestral branch has just two descendants, we call that splitting pattern a dichotomy. This group is subdivided into two subgroups: Palaeognathae and Neognathae. Amniotes – these are tetrapods whose embryo grows inside a waterproof membrane called an amnion, which enables life outside of the water. However, the modern definition of reptiles generally refers to tetrapods such as crocodiles, lizards, turtles, and tuataras. Adaptations to dry terrestrial environments-waterproof skin ... all tetrapods are ECTOthermic except... mammalia & aves. Amniote Clade. Contains membranes that protect the embryo. More than 10000 species of reptiles are known to live on earth with the first reptiles observed about 312 million years ago. Modern Classification of Birds. Amniotic egg. Reptiles lay on land eggs enclosed in shells. According to modern classification, birds are part of the group Aves. Reptiles – these are amniotes with thick skin and bony epidermal scales whose eggs have a mineralised shell. Amphibians, reptiles (including dinosaurs and birds) and mammals are the major groups of the Tetrapoda. Amniotes evolved during the late Paleozoic era.The characteristic that sets amniotes apart from other tetrapods is that amniotes lay eggs that are well-adapted to survive in a terrestrial environment. Limbless reptiles (snakes and other squamates) have vestigial limbs and, as with caecilians, are classified as tetrapods because they are descended from four-limbed ancestors. Understanding that reptiles are a monophyletic group containing birds helped us find out that feathers evolved from scales, which were present in other reptiles but are absent in amphibians. birds: internal fert.-cloacas-no … This clade is known as the "Tetrapods." Reptiles are land-dwelling tetrapods that have scales and lay amniotic eggs. Reptiles are cold-blooded, air-breathing vertebrates that have skin covered in scales as opposed to hair or feathers. Tetrapod, (superclass Tetrapoda), a superclass of animals that includes all limbed vertebrates (backboned animals) constituting the classes Amphibia (amphibians), Reptilia (reptiles), Aves (birds), Mammalia (mammals), and their direct ancestors … This group includes warm-blooded birds and scaly cold-blooded reptiles. Modern reptiles are divided into four orders based on their physical appearance. The origin of tetrapods. Tetrapods include all land-living vertebrates, such as frogs, turtles, hawks, and lions. reptiles, birds, mammals. Amniotes (Amniota) are a group of tetrapods that includes birds, reptiles, and mammals. Most reptiles are tetrapods with two pairs of limbs, and they are exclusively terrestrial and do not have an aquatic larval stage. Even aquatic reptiles return to … Reptiles are tetrapods. -reptiles-birds-mammals. Reptiles are tetrapod animals in the class Reptilia / r ɛ p ˈ t ɪ l i ə /, a paraphyletic grouping comprising all amniotes except synapsids (mammals and their extinct relatives) and birds.Properly, reptiles and birds are grouped together in the monophyletic group known as sauropsids.The class Reptilia comprises turtles, crocodilians, snakes, amphisbaenians, … Reptiles are ‘tetrapods’ (vertebrate animals that have four feet, legs or leg like appendages) and amniotes, animals whose embryos are surrounded by an amniotic membrane and members of the class Sauropsida. all tetrapods.... breath air w/ lungs. 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