Glyphyalinia Snails

North America (as with pretty much everywhere in the world outside the coldest regions) is home to a wide diversity of small, terrestrial snails that tend to pass unnoticed. Among the more diverse of these is the zonitid genus Glyphyalinia. Glyphyalinia carolinensis, copyright John Slapcinsky. Glyphyalinia species are often found in forest leaf-litter in the… Continue reading Glyphyalinia Snails

Icthyocrinidae

Clidochirus springeri, from the Smithsonian National Museum of Natural History. Belongs within: Inadunata. The Icthyocrinidae are a group of crinoids known from the early Silurian to the early Carboniferous in which the crown lacks a marked boundary between cup and arms (Moore 1978). Characters (from Eckert & Brett 2001): Crown ovoid to pyriform without demarcation… Continue reading Icthyocrinidae

Acrocrinidae

Springeracrocrinus conicus, from Webster et al. (2003).Belongs within: Compsocrinina. The Acrocrinidae are a group of crinoids known from the Carboniferous, characterised by the possession of a tall calyx containing intercalary plates (Ubaghs 1978). Characters (from Ubaghs 1978): Crown ovoid to pyriform, with height exceeding greatest width; arms (where known) erect or pendent, biserial, pinnulate; calyx… Continue reading Acrocrinidae

Dolatocrinidae

Calyx of Dolatocrinus lacus in (left to right) A-ray, basal and tegminal views, from Ubaghs (1978). Belongs within: Glyptocrinina. The Dolatocrinidae are a group of crinoids known from the Lower to Middle Devonian that commonly exhibit a markedly pentaradial calyx (Ubaghs 1978). Characters (from Ubaghs 1978): Basals three, unequal or commonly fused; fixed primibrachs one… Continue reading Dolatocrinidae

Hexacrinitidae

Hexacrinites sp., from Lithos Harelbeke.Belongs within: Compsocrinina. The Hexacrinitidae are a group of crinoids known from the Upper Silurian to the Upper Devonian with a further possible record in the Middle Carboniferous (Ubaghs 1978). Characters (from Ubaghs 1978): Calyx medium conical to bowl-shaped, with low to moderately high tegmen; basals three, subequal; primibrachs typically not… Continue reading Hexacrinitidae

Dichocrinidae

Dichocrinus cinctus, from Fossilcrinoids.com.Belongs within: Compsocrinina. The Dichocrinidae are a group of crinoids known from the Carboniferous and Permian periods that commonly bore hypertrophied wing plates on the tegmen (Ubaghs 1978b). Characters (from Ubaghs 1978b): Calyx small; basals two, equal, with A–CD interbasal suture; radials five, separated on posterior side by primanal. Tegmen variable in… Continue reading Dichocrinidae

Carpocrinidae

Carpocrinus simplex, from Akiyasu Shimizu.Belongs within: Compsocrinina. The Carpocrinidae are a group of crinoids with simple arms known from the Middle Silurian to the Middle Devonian (Ubaghs 1978). Characters (from Ubaghs 1978): Fixed secundibrachs one to three in each half-ray, exceptionally more; interprimibrachs one to many, connecting with or separated from tegmen; CD interray primitively… Continue reading Carpocrinidae

Batocrinidae

Eretmocrinus, copyright Hectonichus.Belongs within: Compsocrinina. The Batocrinidae are a group of crinoids bearing a crown of numerous unbranched arms, known from the Early Carboniferous (Ubaghs 1978b). Characters (from Ubaghs 1978b): Theca variable in shape; basals three, equal; one to fifteen interprimibrachs in each interray may or may not be in contact with tegmen; primanal in… Continue reading Batocrinidae

Patelliocrinidae

Macrostylocrinus pristinus, from the Smithsonian National Museum of Natural History. Belongs within: Glyptocrinina. The Patelliocrinidae are a group of crinoids with large radial plates known from the Upper Ordovician to the Middle Devonian (Ubaghs 1978b). Characters (from Ubaghs 1978b): Calyx conical or subglobose to subcylindrical; basals usually three, unequal, azygous one in AE or ED… Continue reading Patelliocrinidae

Eucalyptocrinitidae

Eucalyptocrinites, copyright Wilson44691. Belongs within: Glyptocrinina. The Eucalyptocrinitidae are a group of crinoids known from the Middle Silurian to the Middle Devonian (Ubaghs 1978b). Characters (from Ubaghs 1978b): Calyx typically with narrow, moderately deep basal concavity having sides composed of four basals and proximal parts of radials; fixed primibrachs one or two, fixed secundibrachs two,… Continue reading Eucalyptocrinitidae