page_title: Tetrapod
section_title: Living tetrapods
hierarchical_section_title: Tetrapod / The tetrapod clade / Living tetrapods
caption_attribution_description: English: Metoposaurus skull - dorsal view. University of Alberta Laboratory for Vertebrate Paleontology (UALVP).
context_page_description: Tetrapods are vertebrate tetrapodomorph land animals. The basic tetrapod plan is four legs and feet. This kind of locomotion is quadrupedal. Amphibians, reptiles, dinosaurs, birds, and mammals are all tetrapods. Even though snakes do not have limbs, they are tetrapods because they evolved from animals with four limbs.
  The earliest tetrapods evolved from the Sarcopterygii, or lobe-finned fish, into air-breathing amphibians, perhaps in the Upper Devonian period. This means the transition took place in fish, before the land was the main habitat. This is typical of transitional fossils undergoing mosaic evolution.
context_section_description: There are three main groups of living ("crown group") tetrapods. Each group also includes many extinct groups:
  Amphibia 
  frogs and toads, newts and salamanders, and caecilians
  Sauropsida 
  birds and modern reptiles
  Synapsida 
  mammals
  Snakes and other legless reptiles are tetrapods because they are evolved from ancestors who had four limbs. This is also true for caecilians and aquatic mammals.
caption: Flat skull of a typical early amphibian, Metopsaurus.
exif: {"Image Make": "Panasonic", "Image Model": "DMC-FZ5", "Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Ver.1.0", "Image DateTime": "2007:11:01 11:05:10", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "418", "Image PrintIM": "[80, 114, 105, 110, 116, 73, 77, 0, 48, 50, 53, 48, 0, 0, 14, 0, 1, 0, 22, 0, ... ]", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail Orientation": "Horizontal (normal)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "6804", "Thumbnail JPEGInterchangeFormatLength": "5601", "Thumbnail YCbCrPositioning": "Co-sited", "EXIF ExposureTime": "1/30", "EXIF FNumber": "14/5", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "80", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2007:11:01 11:05:10", "EXIF DateTimeDigitized": "2007:11:01 11:05:10", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "4", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "3", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire, auto mode", "EXIF FocalLength": "6", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "2560", "EXIF ExifImageLength": "1920", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "6652", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "0", "EXIF FocalLengthIn35mmFilm": "36", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "None", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal"}