Mindy Boland
Applied Science, Life Science, Biology
Material Type:
Community College / Lower Division, College / Upper Division
Rice University
Provider Set:
OpenStax College
Acanthostega, Actinopterygii, Allantois, Amnion, Amniote, Amniote Evolution, Amphibian, Amphibian Evolution, Ampullae of Lorenzini, Anapsid, Anthropoid, Anura, Apocrine Gland, Apoda, Archaeopteryx, Archosaur, Australopithecus, Bird, Bird Evolution, Bony Fish, Brachiation, Brumation, Caecilian, Cartilaginous Fish, Casineria, Catarrhini, Cephalochordata, Chondrichthyes, Chordata, Chordate, Chorion, Contour Feather, Craniata, Craniate, Cranium, Crocodilia, Cutaneous Respiration, Dentary, Diphyodont, Dorsal Hollow Nerve Cord, Down Feather, Eccrine Gland, Enantiornithes, Eutherian Mammal, Fish, Fishes, Flight Feather, Frog, Furcula, Gnathostome, Hagfish, Heterodont, Hominin, Hominoid, Homo, Homo Sapiens, Homo Sapiens Sapiens, Hylobatidae, Hylonomus, Jawed Fish, Jawless Fish, Lamprey, Lancelet, Lateral Line, Lepidosaur, Lobe-finned Fish, Mammal, Mammal Characteristics, Mammal Evolution, Mammary Gland, Marsupial, Monotreme, Myxini, Neognathae, Neornith, Notochord, Ornithorhynchidae, Osteichthyes, Ostracoderm, Paleognathae, Pan, Paranthropus, Petromyzontidae, Pharyngeal Slits, Platyrrhini, Plesiadapis, Pneumatic Bone, Pongo, Post-anal Tail, Primary Feather, Primate, Primate Characteristic, Primate Evolution, Prognathic Jaw, Prosimian, Pterosaur, Ray-finned Fish, Reptile, Reptile Characteristics, Salamander, Sarcopterygii, Sauropsid, Sebaceous Gland, Secondary Feather, Sphenodontia, Squamata, Stereoscopic Vision, Swim Bladder, Synapsid, Tachyglossidae, Tadpole, Temporal Fenestrae, Testudines, Tetrapod, Therapod, Tunicate, Urochordata, Urodela, Vertebral Column, Vertebrata, Vertebrate, Vertebrate Evolution, Vertebrates, Veterinarian
Creative Commons Attribution Non-Commercial

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Photos show a wolf (a), a gorilla (b), and an eagle (c).
Examples of critically endangered vertebrate species include (a) the Siberian tiger (Panthera tigris), (b) the mountain gorilla (Gorilla beringei), and (c) the Philippine eagle (Pithecophega jefferyi). (credit a: modification of work by Dave Pape; credit b: modification of work by Dave Proffer; credit c: modification of work by "cuatrok77"/Flickr)

Vertebrates are among the most recognizable organisms of the animal kingdom. More than 62,000 vertebrate species have been identified. The vertebrate species now living represent only a small portion of the vertebrates that have existed. The best-known extinct vertebrates are the dinosaurs, a unique group of reptiles, which reached sizes not seen before or after in terrestrial animals. They were the dominant terrestrial animals for 150 million years, until they died out in a mass extinction near the end of the Cretaceous period. Although it is not known with certainty what caused their extinction, a great deal is known about the anatomy of the dinosaurs, given the preservation of skeletal elements in the fossil record.

Currently, a number of vertebrate species face extinction primarily due to habitat loss and pollution. According to the International Union for the Conservation of Nature, more than 6,000 vertebrate species are classified as threatened. Amphibians and mammals are the classes with the greatest percentage of threatened species, with 29 percent of all amphibians and 21 percent of all mammals classified as threatened. Attempts are being made around the world to prevent the extinction of threatened species. For example, the Biodiversity Action Plan is an international program, ratified by 188 countries, which is designed to protect species and habitats.