Isastrea
| Isastrea Temporal range:
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|---|---|
| File:Isastrea richardsoni.jpg | |
| I. richardsoni showing calyces at various levels of magnification
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| Scientific classification Edit this classification | |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Subphylum: | Anthozoa |
| Class: | Hexacorallia |
| Order: | Scleractinia |
| Family: | †Montlivaltiidae |
| Genus: | †Isastrea Milne-Edwards & Haime, 1851[4] |
Isastrea is an extinct genus of corals that lived during the Jurassic and Cretaceous periods.[3] Its fossils have been found in Europe, Africa, North America,[2] Asia and South America.[4]
Description
[edit | edit source]Isastrea belonged to a group known as the hexacorals, so named for the shape of each individual polyp skeleton (corallite).[2] Each corallite was between 3 millimetres (0.12 in) and 15 millimetres (0.59 in) in diameter. In addition, 30–80 septa (walls dividing body cavities) were present in each animal.[3] Its walls were "weak, discontinuous or absent". In some species, adjacent septa would fuse. Dissepiments ("small blistery plates" serving the purpose of internal support) were plentiful in the animal. Columella (central "rod- or plate-like" structures) were present as well, but were not very strong.[1] The genus is believed to have lived in colonies (each of which could have been 39 inches (0.99 m) long) and formed coral reefs.[2] The colonies were "massive",[1] "encrusting, platey, dome-shaped or sometimes ramose".[3] It was a hermatypic coral, which require "warm, clear, shallow water" and live in symbiotic relationships with algae.[2] It is also likely that zooxanthellae (a kind of protozoa) lived on the coral.[3] It has been theorized that Isastrea could endure lower temperatures than most other hermatypic corals because it occurs farther north than them.[2]
Species and fossil sites
[edit | edit source]At least 49 species of Isastrea have been described.[4] Milne-Edwards and Haime originally described the following species of Isastrea:
- I. oblonga from the Portland stone[5]
- I. explanata and I. greenoughi from the coral rag[6]
- I. conybearii, I. limitata, I. explanulata, and I. serialis from the Great Oolite[7]
- I. richardsoni, I. tenuistriata, and I. lonsdalii from the Inferior Oolite[8]
References
[edit | edit source]Notes
[edit | edit source]Inline citations
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- ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Milne-Edwards & Haime 1850–1854, p. 74.
- ^ Milne-Edwards & Haime 1850–1854, pp. 94, 96.
- ^ Milne-Edwards & Haime 1850–1854, pp. 113–16.
- ^ Milne-Edwards & Haime 1850–1854, pp. 138–9.
General references
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- Scleractinia genera
- Prehistoric Hexacorallia genera
- Mesozoic invertebrates
- Jurassic animals of Europe
- Cretaceous animals of Africa
- Mesozoic animals of Asia
- Mesozoic animals of North America
- Mesozoic animals of South America
- Jurassic Argentina
- Jurassic Colombia
- Jurassic Peru
- Cretaceous Venezuela
- Fossil taxa described in 1851
- Taxa named by Henri Milne-Edwards
- Taxa named by Jules Haime