The Seed Ferns - The earliest terrestrial vertebrate...

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The Seed Ferns The seed ferns, fancy name pteridosperms (literally fern-seed), appeared during the late Devonian. One of the more important groups of seed ferns was the lyginopterids, small vine-like plants that probably grew on other plants. This group produced seeds in a cupule-like structure. Animals Perhaps the earliest animals ashore were the invertebrates, most likely groups of arthropods. The oldest known terrestrial arthropod is a trigonotarbid from the Silurian. Trigonotarbids superficially looked like spiders. The major groups of terrestrial arthropods were present during the Devonian: chelicerates including mites, spiders, and arachnids; and made the transition to land life, and uniramians including flightless insects, centipedes and millipedes.
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Unformatted text preview: The earliest terrestrial vertebrate fossils are from the late Devonian. These "stem tetrapods" as they are known, were essentially fish out of water. The late Devonian lungfish had two groups, the Dipnoi (which includes the living African, Auistralian, and South American lungfishes) and the Crossopterygii, whose sole living member is the coelacanth Latimeria . Comparison of the skull, forelimb, and tooth structure of Devonian crosspterygians such as Eusthenopteron with similar areas in a more specialized tetrapod such as Ichthyostega supports descent of amphibians from Devonian crossopterygians. However, some molecular studies point to descent of the amphibians from the lungfish, the Dipnoi....
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This note was uploaded on 11/29/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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