Siphonotretida

	Siphonotretida Siphonotretida is an extinct order of linguliform brachiopods in the class Lingulata. The order is equivalent to the sole superfamily Siphonotretoidea, itself containing the sole family Siphonotretidae. They were most abundant in the Late Cambrian and Early Ordovician (Furongian to Floian), and were traditionally considered to have gone extinct in the Upper Ordovician ( Ashgill). However, they may have been present as early as Cambrian Stage 4, and as late as the Silurian ( Ludlow). Siphonotretoids were originally placed as a superfamily of Acrotretida, before being raised to their own order. Siphonotretids had simple, rounded shells with an ornamentation of hollow spines. The shell is usually ventribiconvex (both valves convex, the ventral valve moreso) and composed of microscopic granules of apatite. The inner surface of the shell tends to be weakly mineralized, so many aspects of the musculature and other soft anatomy are difficult to estimate in most species. Available dat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
picture info	Brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan 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 brachiopods, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Lingulata Lingulata is a class of brachiopods, among the oldest of all brachiopods having existed since the Cambrian period (). They are also among the most morphologically conservative of the brachiopods, having lasted from their earliest appearance to the present with very little change in shape. Shells of living specimens found today in the waters around Japan are almost identical to ancient Cambrian fossils. The Lingulata have tongue-shaped shells (hence the name Lingulata, from the Latin word for "tongue") with a long fleshy stalk, or pedicle, with which the animal burrows into sandy or muddy sediments. They inhabit vertical burrows in these soft sediments with the anterior end facing up and slightly exposed at the sediment surface. The cilia of the lophophore generate a feeding and respiratory current through the lophophore and mantle cavity. The gut is complete and J-shaped. Lingulata shells are composed of a combination of calcium phosphate, protein and chitin. This is unlike most ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Lingulellotretidae Lingulellotretidae is an extinct family of brachiopods, with an extended pseudointerarea, including some soft-shelled representatives. The lingulellotretids are possibly close relatives of the Siphonotretida, Siphonotretids. Soft tissue is occasionally known.Zhang, Z., Han, J., Zhang, X., Liu, J., Guo, J., and Shu, D. (2007). Note on the gut preserved in the Lower Cambrian Lingulellotreta (Lingulata, Brachiopoda) from southern China. Acta Zool. 88, 65–70. References Brachiopod families {{paleo-protostome-stub Cambrian genus extinctions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]