kingdom animalia - Blue Valley Schools
... – lose lots of water through skin and must keep it continually moist to prevent lethal desiccation – must reproduce in the water since eggs would dry up on land – aquatic larval stage more closely related to fish than terrestrial animals ...
... – lose lots of water through skin and must keep it continually moist to prevent lethal desiccation – must reproduce in the water since eggs would dry up on land – aquatic larval stage more closely related to fish than terrestrial animals ...
Animals, part 3
... earliest verts resembled lampreys – jawless fishes Jawed Vertebrates -- jawbones evolved from bones supporting gill slits Cartilaginous fishes – sharks and rays endoskeleton is cartilage, not bone. This is a derived character – these creatures lost a bony skeleton Bony fishes – most fish have a bony ...
... earliest verts resembled lampreys – jawless fishes Jawed Vertebrates -- jawbones evolved from bones supporting gill slits Cartilaginous fishes – sharks and rays endoskeleton is cartilage, not bone. This is a derived character – these creatures lost a bony skeleton Bony fishes – most fish have a bony ...
Document
... • The most diverse vertebrates – Lungfishes – Lobe-finned fishes (coelacanth) – Ray-finned fishes ...
... • The most diverse vertebrates – Lungfishes – Lobe-finned fishes (coelacanth) – Ray-finned fishes ...
Tetrapod
The superclass Tetrapoda (Ancient Greek τετραπόδηs tetrapodēs, ""four-footed""), or the tetrapods /ˈtɛtrəpɒd/, comprises the first four-limbed vertebrates and their descendants, including the living and extinct amphibians, reptiles, mammals, birds, and some extinct fish. Tetrapods evolved from the lobe-finned fishes around 390 million years ago in the middle Devonian Period, with modern tetrapod groups having appeared by the late Devonian, 367.5 million years ago. The specific aquatic ancestors of the tetrapods, and the process by which land colonization occurred, remain unclear, and are areas of active research and debate among palaeontologists at present.While most species today are terrestrial, the first tetrapods were fully aquatic. Amphibians today generally remain semiaquatic, living the first stage of their lives as fish-like tadpoles. Amniotes evolved about 340 million years ago (crown amniotes 318 mya), and their descendants drove most amphibians to extinction. One population of amniotes diverged into lizards, dinosaurs, birds and their relatives, while another diverged into mammals and their extinct relatives. Several groups of tetrapods, such as the caecilians, snakes, cetaceans, sirenians, and moas have lost some or all of their limbs. In addition, many tetrapods have returned to partially aquatic or fully aquatic lives throughout the history of the group (modern examples of fully aquatic tetrapods include cetaceans and sirenians). The first returns to an aquatic lifestyle may have occurred as early as the Carboniferous Period, whereas other returns occurred as recently as the Cenozoic, as in cetaceans, pinnipeds, and several modern amphibians.The change from a body plan for breathing and navigating in water to a body plan enabling the animal to move on land is one of the most profound evolutionary changes known. It is also becoming increasingly well-understood as a result of more transitional fossil finds and improved phylogenetic analysis.