Classification of Reptilia
Based upon Zoological RecordVolume 138 (with modifications after Benton, J., Vertebrate Paleontology, 2015, pp. 438-441.)
Dinosaurs are classified as reptiles. A reptile is a cold-blooded, scaly, four-legged animal that lays eggs on land. Two formal orders: Saurischia (or lizard-hip) and Ornithischia (or bird-hip) encompass the creatures that have traditionally been called dinosaurs. Typically discussed alongside them as part of the great Age of Reptiles are the order Pterosauria (flying reptiles) and the orders Plesiosauria (great swimming reptiles). All of the animals that are highlighted in Genesis Park fit into the reptilian classification shown below.
Class ReptiliaInfraclass Diapsida Order Pareiasauromorpha Order Younginiformes Order Testudines (turtles) Family Chelydridae (Snapping Turtles) Family Emydidae (Pond Turtles/Box and Water Turtles) Family Testudinidae (Tortoises) Family Dermatemydidae (River Turtles) Family Kinosternidae (Mud and Musk Turtles) Family Carettochelyidae (Pig-nose Turtles) Family Trionychidae (Softshell Turtles) Family Cheloniidae (Sea Turtles) Family Dermochelyidae (Leatherback Turtles) Family Pelomedusidae (Afro-American Sideneck Turtles) Family Chelidae (Austro-American Sideneck Turtles) Infraclass Lepidosauromorpha Order Ichthyosauria (Dolphin-like marine reptiles) Order Thalattosauria (Large lizard-like marine reptiles) Order Placodontia (Marine reptiles-some with hard plates resembling turtles) Order Eosauropterygia Suborder Pachypleurosauria (Small, lizard-like aquatic reptiles) Suborder Nothosauria (Huge marine reptiles with a medium neck) Order Plesiosauria Suborder Plesiosauroidea (Huge marine reptiles with a long neck) Suborder Pliosauroidae (Huge marine reptiles with a short neck) Order Rhynchocephalia Family Sphenodontidae (Tuataras) Order Squamata ("scaled reptiles") Suborder Sauria (lizards) Family Agamidae (Agama Lizards) Family Chamaeleonidae (Chameleons) Family Iguanidae (Iguanas and Spinytail Iguanas) Family Corytophanidae (Casquehead Lizards) Family Crotaphytidae (Collared and Leopard Lizards) Family Hoplocercidae (Wood Lizards including the Dwarf Iguana) Family Opluridae (Madagascar Iguanids) Family Phrynosomatidae (Earless, Spiny, Tree, Side-blotched and Horned Lizards) Family Polychrotidae (Anoles) Family Tropiduridae (Neotropical Ground Lizards) Family Gekkonidae (Geckoes) Family Eublepharidae (Eyelid Geckoes) Family Pygopodidae (Legless Lizards) Family Dibamidae (Blind Lizards) Family Cordylidae (Spinytail Lizards) Family Gerrhosauridae (Plated Lizards) Family Gymnophthalmidae (Spectacled Lizards) Family Teiidae (Whiptails and Tegus) Family Lacertidae (Wall Lizards) Family Scincidae (Skinks) Family Xantusiidae (Night Lizards) Family Anguidae (Glass Lizards and Alligator Lizards; Lateral Fold Lizards) Family Anniellidae (American Legless lizards) Family Xenosauridae (Knob-scaled Lizards) Family Helodermatidae (Gila Monsters) Family Lanthanotidae (Earless Monitor lizards) Family Varanidae (Monitor Lizards) Family Mosasauridae (Huge Mosasaur marine lizard) Suborder Amphisbaennia Family Amphisbaenidae (Worm Lizards) Family Trogonophidae (Short head Worm Lizards) Family Bipedidae (Two-legged Worm Lizards) Suborder Serpentes (snakes) Family Anomalepidae (Dawn Blind Snakes) Family Typhlopidae (Blind Snakes) Family Leptotyphlopidae/Glauconiidae (Slender Blind Snakes) Family Aniliidae/Ilysiidae (Pipe Snakes) Family Anomochilidae (Dwarf Pipe Snakes) Family Boidae (Boas and Pythons) Family Bolyeridae (Round Island Boas) Family Cylindrophiidae (Asian Pipe Snakes) Family Loxocemidae (Mexican Burrowing Pythons) Family Tropidophiidae (Woodsnakes, Round Island "Boas") Family Uropeltidae (Short-tail Snakes) Family Xenopeltidae (Sunbeam Snakes) Family Acrochordidae (File Snakes) Family Atractaspididae (Mole Vipers) Family Colubridae (Colubrids) Family Elapidae (Cobras, Kraits, Coral Snakes) Family Hydrophiidae (Sea Snakes) Family Viperidae (Vipers and Pit Vipers) Infraclass Archosauromorpha Order Rhynchosauria (Stocky, herbivorous beaked reptiles) Order Protosauria (Amphibian-like reptiles) Order Phytosauria (Narrow-snouted, armored crocodilian) OrderCrocodyliaSuborderProtosuchidae (Ancient agile crocodilian) SuborderThalattosuchia (Ancient marine crocodilian) SuborderMetasuchia (Ancient huge crocodilian) SuborderEusuchiaFamilyCrocodylidae(Modern Crocodiles) FamilyGavialidae(Modern Gharials and False Gharials) FamilyAlligatoridae(Modern Alligators and Caimans) Order Pterosauria Suborder Rhamphorhynchoidea (Long-tailed pterosaurs) Suborder Pterodactyloidea (Short-tailed pterosaurs with a headcrest) SuperorderDinosauriaOrderSaurischia(“Lizard-hipped” dinosaurs) Suborder Theropoda (Bipedal, mostly carnivorous dinosaurs) Suborder Sauropodomorpha (Long-necked herbivorous dinosaurs) Order Ornithischia (“Bird-hipped” dinosaurs) Suborder Ornithopoda (Bipedal herbivorous dinosaurs like the hadrosaurs) Suborder Stegosauria (Huge, plated dinosaurs) Suborder Ankylosauria (Squat dinosaurs with club tails) Suborder Ceratopsia (Includes Triceratops)
Reptiles are vertebrates that have scales on at least some part of their body, leathery or hard-shelled eggs, and share a number of other features. Snakes, lizards, turtles, crocodilians, and birds are reptiles. Like all vertebrates, reptiles have bony skeletons that support their bodies.
Scales help prevent reptiles from losing water through their skin. The leathery or hard shells on their eggs protect the young from drying out while they grow inside the egg. Most reptiles can live their entire lives on land and reproduce in dry habitats. Some types of reptiles (such as sea turtles and penguins) are adapted to living in water, but even these species come onto land to lay their eggs. All reptiles also have lungs, so even those living in water must come to the surface to breath air. Reptiles are found living in all habitats but are more common in warm, tropical places.
So, why are birds considered reptiles? Birds look very different from other reptiles, they have feathers, fly, sing complex songs, and have many other unique features.
Animal groupings are most useful when they reflect the evolutionary history of the animals in that group. So, for example, "mammals" is the name of a group of animals that are all more closely related to each other than to other kinds of animals. It's not hard to imagine that a skunk is more closely related to you than it is to a turtle, because you and a skunk both have fur (yours is mostly on your head!), you both have mothers that fed you milk, and other features. Even though you and the skunk look very different, you share features that show you share an ancestor. The "mammals" group name reflects that shared history.
Snakes, lizards, turtles, crocodilians, and birds also all share an evolutionary history. Many years of research has proven that the ancestors of birds were bird-like dinosaurs (visit the Dinobuzz page for more on this). Even though birds look very different from other living reptiles, they’re most closely related to alligators and crocodiles and clearly belong in the reptile group.