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Urodela sp. - vertebra

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Description

amphicelic salamander vertebra, cm 1.8 x 1.5 x 1.4.

Amphibians were the first vertebrates to colonize the terrestrial environment (tetrapods), and as such have ever had a remarkable expansion and diversification, between 416 and 360 million years ago in the Devonian. Around 300 million years ago in the Carboniferous, amphibians spread all over the world and diversified into a multitude of shapes, becoming the dominant organisms on land. Primitive amphibians, however, were quite different from those of today. Among these, the most diverse of the group was temnospondyla, which included tiny and gigantic forms, aquatic and terrestrial elements and provided with "sail" back. Many scientists believe that some forms of small low-skilled temnospondyla may have given rise to today's frogs and toads. The group of lepospondyla, however, included only small animals, some of them looking snake. Currently, most scholars agree in classifying all amphibians present as part of a group evolved, the lissamphybia, separated from the previous two. The monophyly of the group, however, remains to be shown, due to the lack of intermediate fossil forms can all be described as "ancestors" of the group. Some pose lissamphybia as descendants of the temnospondylia, other approach amphibians current to lepospondylia. The position of the current Apoda, then, is yet to be clarified. Caudata or Urodela, in particular, are an order of amphibians, to which belong newts and salamanders. They have short legs adapted for swimming or walking, have a long tail, they also live out of water. Are known cases of tails that keep the gills as adults (this phenomenon is called neoteny).

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