When feet had seven toes.When feet had seven toes Paleontologits have discovered something unexpected at the end of a 360-million-year-old leg: two extra toes. Since the 1930s, scientits have believed that Icthyostega, one of the earliest known amphibians amphibians members of the animal class Amphibia. Includes frogs, toads, newts, salamanders and cecilians all capable of living on land or in water. , crawled around on five-toed feet. But fossil finds from Greenland now indicate that Icthyostega had seven toes on each hind foot. What's more, fossils from Acanthostega, another primitive amphibian amphibian, in zoology amphibian, in zoology, cold-blooded vertebrate animal of the class Amphibia. There are three living orders of amphibians: the frogs and toads (order Anura, or Salientia), the salamanders and newts (order Urodela, or Caudata), and the , reveal it had eight fingers on each forelimb forelimb the front limb. forelimb paralysis see brachial paralysis. forelimb restraint hold restraint of a horse by holding a forelimb tightly flexed at the knee, either manually using an assistant, or by a tightly , according a report in the Sept. 6 NATURE by Michael I. Coates and Jennifer A. Clack Jennifer A. Clack is an English paleontologist, an expert in the science of evolution. She studies the "fish to tetrapod" transition— the origin, evolutionary development and radiation of early tetrapods and their relatives among the lobe-finned fishes. of the University of Cambridge in England. These early amphibians lived at the end of the Devonian period -- a time when vertebrates were first making the transition from water to land. In fact, the Acanthostega fossil is the most primitive known limb. Judging from their skeletons, these amphibians spent most of their time in the water, Coates says. Paleontologists have traditionally held that all land vertebrates followed a five-digit or pentadactyl pentadactyl having five digits. pattern. Though many vertebrates, such as horses, have fewer than five digits, they evolved from pentadactyl forms. The new fossil finds compleent a previous discovery by Soviet scientists of another six-digited Devonian amphibian. Taken together, these fossils indicate that development in early land vertebrates followed a more flexible patter pat·ter 1 v. pat·tered, pat·ter·ing, pat·ters v.intr. 1. To make a quick succession of light soft tapping sounds: Rain pattered steadily against the glass. . While some amphibians had seve-toed feet, other members of the same species might have sported feet with six or eight toes, Coates says. |
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