Climatiiformes
| Climatiiformes | ||||||||||||
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Climatius macnicoli |
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| Temporal occurrence | ||||||||||||
| middle Silurian to Serpukhovian ( Lower Carboniferous ) | ||||||||||||
| ? up to 323.2 million years | ||||||||||||
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| Scientific name | ||||||||||||
| Climatiiformes | ||||||||||||
| Berg , 1940 |
The Climatiiformes ( Syn .: Diplacanthiformes Berg, 1940 ) are an extinct fish order from the group of Acanthodii ("barbed sharks"). She lived from the middle Silurian to the Mississippium (Lower Carboniferous). Climatiiformes fossils have been found in Europe, North and South America, Greenland, South Africa, Asia, Australia, New Zealand and Antarctica. They were named after Climatius from the British Old Red sandstone .
features
The Climatiiformes are considered to be the most primitive Acanthodii and differ from other forms mainly by the two or more pair of fin spines between the pectoral and ventral fins. The fin spines have broad bases and were fluted. They had two dorsal fins. In most cases, an ornamented skin bone is found below her shoulder girdle. The scales were small, thick, and high-crowned and did not overlap. The Diplacanthidae family was toothless, most of the remaining Climatiiformes had spirals of small teeth that were not firmly attached to the jaws. Like other “spiny sharks”, they were mostly small fish with a length of 15 cm or less. Gyracanthus, a common form from the Carboniferous, is mainly known for its fossil fin spines, which could be up to 40 cm long. For this genus a length of about 1.5 meters is assumed.
External system
The Climatiiformes are counted among the Acanthodii , also called "Stachelhaie" in German. The monophyly and with it the systematic position of the Acanthodii is uncertain. Traditionally they are regarded as the sister group of the bony fish (Osteichthyes). This systematic position shows the following cladogram :
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According to more recent phylogenetic investigations, the Climatiiformes are a poly- and paraphyletic taxon, which comprises various forms, which have to be classified in the basal eugnathostomata (all jaws except for the placodermi ) or in the tribe group of cartilaginous fish (Chondrichthyes) or bony fish (Osteichthyes) ) belong.
The following diagram shows the Climatiiformes as a poly- and paraphyletic taxon:
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literature
- Robert L. Carroll : Paleontology and Evolution of the Vertebrates , Thieme, Stuttgart (1993), ISBN 3-13774-401-6 .
- John A. Long: The Rise of Fishes . The Johns Hopkins University Press, 1995, ISBN 0801849926 .
- Joseph S. Nelson : Fishes of the World . John Wiley & Sons, 2006, ISBN 0-471-25031-7 .
Individual evidence
- ↑ Brazeau, MD 2009. The braincase and jaws of a Devonian 'acanthodian' and the origin of modern gnathostomes. Nature Vol. 457, January 15, 2009 doi : 10.1038 / nature07436
- ^ A b Samuel P. Davis, John A. Finarelli & Michael I. Coates: Acanthodes and shark-like conditions in the last common ancestor of modern gnathostomes. Nature Vol. 486, pp. 247-250, June 14, 2012, doi : 10.1038 / nature11080
Web links
- Palaeos: Climatiiformes
- Mikko's Phylogeny Archive: Climatiiformes