Circothecida

Belongs within: Hyolitha. The Circothecida are a group of hyoliths in which the dorsum and venter are undifferentiated or weakly differentiated (Kruse 2002). <==Circothecida | i. s.: Conotheca Missarzhevksy in Rozanov et al. 1969D94, KB09 | |–C. australiensis Bengtson in Bengtson et al. 1990K02 | |–C. circumflexa Missarzhevksy in Rozanov et al. 1969KB09 | `–C.… Continue reading Circothecida

Published
Categorised as Hyolitha

Sulcavitida

Belongs within: Hyolitha. The Sulcavitida are a group of hyoliths defined by Kruse (2002) to include those species with a ligula present on the venter, and in which the dorsoventral and lateral transitions coincide such that the dorsum perimeter is equal to or greater than the venter perimeter. The type family Sulcavitidae includes less differentiated… Continue reading Sulcavitida

Published
Categorised as Hyolitha

Orthothecida

Belongs within: Hyolitha. The Orthothecida are a group of hyoliths defined by Kruse (2002) as including those species in which the dorsum and venter were clearly differentiated, but without a ligula along the venter. Families of Orthothecida are primarily distinguished by the shape of the cross-section. Orthothecidae have the transverse section triangular or subtriangular with… Continue reading Orthothecida

Published
Categorised as Hyolitha

Hyolithidae

Belongs within: Hyolitha. The Hyolithidae were a family of hyoliths found during the Cambrian and Ordovician. Though the circumscription of the family has varied widely over the years (and the type genus, Hyolithes, seems to have long been the default repository for almost any hyolith), it was defined by Kruse (2002) as including those species… Continue reading Hyolithidae

Published
Categorised as Hyolitha

Hyolitha

Belongs within: Brachiozoa.Contains: Circothecida, Orthothecida, Sulcavitida, Hyolithidae, Crispatellidae. Hyoliths were a group of small shelled animals that mostly lived during the Cambrian and Ordovician (though probable hyoliths remained alive as late as the Permian—Peel & Yochelson 1984). They possessed a bilaterally symmetrical conical shell that was open at one end only and closed by an… Continue reading Hyolitha

Published
Categorised as Hyolitha