''Echinosphaerites'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of rhombiferan cystoid

echinoderm An echinoderm () is any animal of the phylum Echinodermata (), which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". While bilaterally symmetrical as ...

s that lived in the Early to Middle

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...

of North America and Europe (Bockelie, 1981).

Biology

Echinosphaerites had branched biserial brachioles which is rare for species belonging to the Class

Rhombifera The Eocrinoidea were an extinct class of echinoderms that lived between the Early Cambrian and Late Silurian periods. They are the earliest known group of stalked, brachiole-bearing echinoderms, and were the most common echinoderms during the Cam ...

. Echinosphaerites had a skeletal meshwork like many other blastozoan echinoderms, with a fine outer mesh layer and an inner coarse mesh layer. During evolution the number and location of these brachioles, including the branching patterns, increased in the number of brachioles and complexity of the branching pattern. The exothecal pore structures increased in the complexity of patterns of tangential canals (Bockelie, 1981).

References

* Bockelie, J.F., 1981. Functional morphology and evolution of the cystoid ''Echinosphaerites''. Lethaia 14: 189–202.

External links

*
Echinosphaerites
' in the

Paleobiology Database The Paleobiology Database (PBDB) is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms. History The Paleobiology Database originated in the NCEAS-funded Phanerozoic Marine Pale ...

Functional morphology and evolution of the cystoid ''Echinosphaerites''
in the Wiley Online Library Cystoidea Blastozoa genera Ordovician echinoderms of Europe Fossils of the Czech Republic Letná Formation Ordovician echinoderms of North America Early Ordovician first appearances Middle Ordovician extinctions {{paleo-echinoderm-stub