Hyolitha
| Hyolitha Fossil range: Cambrian–Permian1 |
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| Hyolithes cerops, Spence Shale, Idaho (Middle Cambrian) | |
| Scientific classification | |
| Kingdom: | Animalia |
| Subkingdom: | Metazoa |
| Superphylum: | Lophotrochozoa |
| Phylum: | Mollusca?2 |
| Class: | Hyolitha |
Hyolitha are ambiguous animals with baby conical shells accepted from the Palaeozoic Era.
Contents |
Shell morphology
The calcareous shells accept a awning (operculum) and two arced supports accepted as helens. A lot of are one to four centimeters in breadth and are triangular or egg-shaped in cantankerous section. Some breed accept rings or stripes.
Taxonomy & ecology
Because hyoliths are abolished and do not acutely resemble any extant group, it is cryptic which active accumulation they are a lot of carefully accompanying to. They may be molluscs; authors who advance that they deserve their own phylum do not animadversion on the position of this phylum in the timberline of life.1 Deposit traces assuming a twisted, looped, civil buck some affinity to the gut of sipunculan worms.3
Despite the actuality that hyolithid shells are accepted as fossils, little is accepted about their ancestry, centralized structures, and activity mode. They were apparently benthic (bottom-dwellers).
Fossil record
The aboriginal hyolith fossils appeared about in the Purella antiqua Zone of the Nemakit-Daldynian Stage of Siberia and in its alternation the Paragloborilus subglobosus–Purella squamulosa Zone of the Meishucunian Stage of China. Hyolith affluence and assortment attain a best in the Cambrian, followed by a accelerating abatement up to their Permian extinction.4
References
- ^ a b Malinky, j. 2009 "Permian Hyolithida from Australia: The Last of the Hyoliths?" Journal of Paleontology 83(1):147-152.
- ^ Wotte, T. 2006. "New Middle Cambrian mollucs from the Láncara Formation of the Cantabrian Mountains (north-western Spain)". Revista Española de Paleontología 21(2):145-158
- ^ Introduction to Sipuncula
- ^ Michael Steiner, Guoxiang Li, Yi Qian, Maoyan Zhu and Bernd-Dietrich Erdtmann (2007). "Neoproterozoic to aboriginal Cambrian baby shelly deposit assemblages and a revised biostratigraphic alternation of the Yangtze Platform (China)". Palaeogeography, Palaeoclimatology, Palaeoecology 254: 67–99.
