cystoids造句

• Cystoids of this age in Wisconsin were preserved in Racine County.
• Another Silurian resident of the Chicago region were cystoids.
• Superficially, cystoids resembled crinoids, but they had an ovoid, rather than cup-shaped, body.
• The most distinctive feature of cystoids was the presence of a number of pores in the rigid skeleton encasing the body.
• After a longer hiatus, up to 100 m of Caradocian ( Ordovician stage 5 and 6 ) benthic fauna ( brachiopods, bryozoans, cystoids ) as well as conodonts.
• About 340 million years ago Wisconsin was home to brachiopods, bryozoans, cephalopods, corals, crinoids, cystoids, gastropods, pelecypods, sponges, stomatoporoids, and trilobites.
• They include a variety of brachiopods, as well as trilobites, molluscs, echinoderms ( including starfish, crinoids, and the extinct blastoids and cystoids ), foraminifera and fish with jaws ( placoderms ).
• There are two competing hypotheses pertaining to the origin of the group : the traditional viewpoint holds that crinoids evolved from within the blastozoans ( the eocrinoids and their derived descendants the cystoids ), whereas the most popular alternative suggests that the crinoids split early from among the edrioasteroids.