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Palaeostomata
Palaeostomata is a superorder of extinct stenolaemate bryozoans, including all extinct orders within Stenolaemata and excluding the order Cyclostomata Cyclostomi, often referred to as Cyclostomata , is a group of vertebrates that comprises the living jawless fishes: the lampreys and hagfishes. Both groups have jawless mouths with horny epidermal structures that function as teeth called cer ..., which is the only extant stenolaemate order. Palaeostomates are sometimes called "stony bryozoans" because they are heavily calcified, making them ideal candidates for fossilization. They are distinct from cyclostomes because they lack calcified exterior walls above the basal lamina and because their zooecial tubes are transected by calcitic partitions, such as diaphragms (which serve as the "floor" for the individual zooids that live in the zooecial tubes). References Stenolaemata Fossil taxa described in 2014 {{bryozoan-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stenolaemata
Stenolaemata are a class of exclusively marine bryozoans. Stenolaemates originated and diversified in the Ordovician, and more than 600 species are still alive today.Stenolaemata. The Digital Atlas of Ordovician Life. All extant (living) species are in the order , the third-largest order of living bryozoans.Ramalho, L. V., G. Muricy, and P. D. Taylor. (2009) Cyclostomata (Bryozoa, Stenolaemata) from Rio de Janeiro State, Brazil. ''Zootaxa'' 2057 32-52. These animals are stationary [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclostomata
Cyclostomi, often referred to as Cyclostomata , is a group of vertebrates that comprises the living jawless fishes: the lampreys and hagfishes. Both groups have jawless mouths with horny epidermal structures that function as teeth called ceratodontes, and branchial arches that are internally positioned instead of external as in the related jawed fishes. The name Cyclostomi means "round mouths". It was named by Joan Crockford-Beattie. Possible external relationships This taxon is often included in the paraphyletic superclass Agnatha, which also includes several groups of extinct armored fishes called ostracoderms. Most fossil agnathans, such as galeaspids, thelodonts, and osteostracans, are more closely related to vertebrates with jaws (called gnathostomes) than to cyclostomes. Cyclostomes seem to have split off before the evolution of dentine and bone, which are present in many fossil agnathans, including conodonts. Biologists disagree on whether cyclostomes are a c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |