Lower Ordovician- Upper Devonian
Dichoporita is an extinct order of stationary intermediate-level epifaunal suspension feeders
Characteristics of the Order
- Thecal-pores are in pairs
- Pores are situated vertically across suture lines
- 20-30 plates
- Dichoporite rhombiferans include the two superfamilies Glyptocystitida and Hemicosmitida [Kesling, 1967; Paul, 1972a]. Dichoporites are characterized by a theca with endothecal pore-structures, and consisting of a reduced number of plates (usually 20-30), organized into three (hemicosmitids) or five rows (glyptocystitids). Their stem is well-differentiated, with a flexible proximal portion, and a more rigid, holomeric, distal region.
- Diploporita are blastozoan echinoderms characterized by exothecal pore-structures corresponding to diplopores (paired pores opening in a shallow depression) [Kesling, 1967; Paul, 1972a; Bockelie, 1984]. Diplopores are usually extensive and occur on most or all thecal plates. Most diploporites are characterized by a relatively globular theca, consisting of numerous (several tens to hundreds), unorganized, polygonal plates. A stem is sometimes present (e.g. Destombesia, Eumorphocystis), but it is absent in most forms [Kesling, 1967; Paul, 1972a; Bockelie, 1984; Chauvel, 1969]. Diploporites are usually subdivided into the four superfamilies Aristocystitida, Asteroblastida, Protocrinitida, and Sphaeronitida [Bockelie, 1984; Paul, 1984].
Treatise on Invertebrate Paleontology, Part T, Vol. 2(1) (1978):
- Rhombifera with endothecal pore structures composed of dichopores and only developed across certain plate sutures; theca comprising a small number of plates arranged in 3 to 5 circlets; well-developed stem throughout life.
- Dichoporita are Cystoidea whose thecal-pores are in pairs, each pair divided between two plates, situated vertically across the suture lines, slit or tubular-form, arranged parallel and combined into pore-rhombs, their ambulacral radial-grooves in special skeletal elements supported by the theca.