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Colleplax
Colleplax – a structure present in chileate brachiopods Brachiopods (), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the fron .... It is a triangular plate in the umbonal region of the ventral valve, covering an area that is otherwise externally exposed through the resorption of a part of the ventral valve. This aperture is supposed to have been covered by adhesive tissue, but no similar structure exists in any living brachiopod, so other interpretations have also been proposed. References {{Reflist Brachiopods ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chileata
Chileata Wiliams ''et al.'', 1996 is a class of rhynchonelliform brachiopods, characterised, among others, by the presence of a perforation in the umbonal region of the ventral valve, usually (partly) covered by a colleplax. They are known from the Cambrian to the Lower Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the s .... ''Salanygolina'' may represent the chileate stem group. References Brachiopods {{paleo-protostome-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brachiopod
Brachiopods (), phylum (biology), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the front can be opened for feeding or closed for protection. Two major categories are traditionally recognized, articulate and inarticulate brachiopods. The word "articulate" is used to describe the tooth-and-groove structures of the valve-hinge which is present in the articulate group, and absent from the inarticulate group. This is the leading diagnostic skeletal feature, by which the two main groups can be readily distinguished as fossils. Articulate brachiopods have toothed hinges and simple, vertically oriented opening and closing muscles. Conversely, inarticulate brachiopods have weak, untoothed hinges and a more complex system of vertical and oblique (diagonal) muscles used to keep the two valves aligned. In many brachio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
