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Cycadeoids - to a maximum of 11 during the Cretaceous...

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Cycadeoids The cycadeoids superficially resemble cycads in having recurrent leaf bases on soft- wood stems. Unlike the cycads, however, the cycadeoids have bisexual reproductive structures and structure of their stomates more like what is found in angiosperms and gnetophytes. Their reproductive structures were at one time interpreted as flowers and the cycadeoids were suggested as ancestors to the flowering plants. Cladistic analyses, such as Doyle and Donoghue (1986), suggest the cycadeoids and the flowering plants belong to the same clade, the anthophyte clade, but that cycadeoids are not the sister group for the angiosperms. Ginkgophytes The ginkgoes, like the cycads, originated during the late Paleozoic and diversified during the Mesozoic. Beginning during the Jurassic the number of species increased
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Unformatted text preview: to a maximum of 11 during the Cretaceous before the decline to the single species, Ginkgo biloba , that remains today. Othe Gymnosperms The Mesozoic saw the spread of true conifers, including forms similar to Metasequioia and Sequoia , as well as numerous types of pines. A wide variety of extinct gymnosperms were present, including Caytonia and Pentoxylon . Flying Reptiles The flying reptiles of the Triassic underwent diversification during the Jurassic. The pterosaurs (literally winged-lizard) consisted of the earlier forms with long tails, like Rhamphorhynchus shown below, and the later forms that ruled the Cretaceous period, the pterodactyls. The long tailed formns died out by the close of the Jurassic. Pterosaurs had hollow bones, large brains and possibly some had endothermy....
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Cycadeoids - to a maximum of 11 during the Cretaceous...

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