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

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
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
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
This is the end of the preview. Sign up to access the rest of the document.

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....
View Full Document

Page1 / 2

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

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online