Blastoids ( sea buds , lat. Blastoidea ) - a class of extinct invertebrates from the group Echinoderms .
| † Blastoideas | ||||||||
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 Pentremites | ||||||||
| Scientific classification | ||||||||
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| Latin name | ||||||||
| Blastoidea Say, 1825 |
Length up to 35 cm. Lived from Ordovik to Perm . About 300 species are described.
Characterized by a bud-shaped calyx of a five-beam structure [1] . They were stocked with a short stalk, which served to attach to underwater objects. The cup consists of 13 interconnected calcareous plates arranged in three belts with five ambulacral fields. Blastoids are most common in coal limestone ( Mississippi River area ), less common in Devonian sediments ( Eifel , Spain , etc.) and in the form of rare representatives in Upper Silurian sediments.
Notes
- ↑ Yu. A. Orlov. Basics of paleontology. Volume 10. Echinoderms, hemichord, pogonofory, bristle maxillary. M., "Nedra", 1964
Literature
- Blastoidea // Brockhaus and Efron Encyclopedic Dictionary : 86 t. (82 t. And 4 add.). - SPb. , 1890-1907.