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Amphibians have soft bodies with thin skins, and lack claws, defensive armour, or spines. Nevertheless, they have evolved various defence mechanisms to keep themselves alive. The first line of defence in salamanders and frogs is the mucous secretion that they produce. This keeps their skin moist and makes them slippery and difficult to grip.
A neural spine sail is a large, flattish protrusion from the back of an animal formed of a sequence of extended vertebral spinous processes and associated tissues. Such structures are comparatively rare in modern animals, but have been identified in many extinct species of amphibians and amniotes. Paleontologists have proposed a number of ways ...
Temnospondyli (from Greek τέμνειν, temnein 'to cut' and σπόνδυλος, spondylos 'vertebra') or temnospondyls is a diverse ancient order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carboniferous, Permian and Triassic periods, with fossils being found on every continent.
Generally, males have been found to possess larger bodies and longer heads compared to the female sex, which normally is indicative of male-male combat observed within the population. [21] [22] There has been, however, no other physical indicating factors for male-male combat as in other species of amphibians, such as horns or spines. [22]
Amphibamus is a genus of amphibamid temnospondyl amphibians from the Carboniferous (middle Pennsylvanian) of North America. [1] [2] [3] This animal is considered to have been close to the ancestry of modern amphibians. Its length was about 20 centimetres (7.9 in). [4]
Class Amphibia (amphibians, some ancestral to the amniotes)—now a paraphyletic group; Class Synapsida (mammals and their extinct relatives) Class Sauropsida (reptiles and birds) While this traditional taxonomy is orderly, most of the groups are paraphyletic, meaning that the structure does not accurately reflect the natural evolved grouping. [47]
The largest living amphibian is the 1.8 m (5 ft 11 in) South China giant salamander (Andrias sligoi), but this is dwarfed by prehistoric temnospondyls such as Mastodonsaurus which could reach up to 6 m (20 ft) in length. The study of amphibians is called batrachology, while the study of both reptiles and amphibians is called herpetology.
Persistence of notochordal cells within the vertebra may cause a pathologic condition: persistent notochordal canal. [17] If the notochord and the nasopharynx do not separate properly during embryonic development, a depression (Tornwaldt bursa) or Tornwaldt cyst may form. [18] The cells are the likely precursors to a rare cancer called chordoma ...