Holocephali
Holocephali | ||||||||||||
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Chimaera cubana is found in the waters around Colombia, Cuba and Puerto Rico. |
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Temporal occurrence | ||||||||||||
Upper Devonian to date | ||||||||||||
385.3 to 0 million years | ||||||||||||
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Systematics | ||||||||||||
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Scientific name | ||||||||||||
Holocephali | ||||||||||||
Bonaparte , 1832-41 |
The Holocephali (= "Euchondrocephali" Grogan & Lund, 2000) are the second subclass of cartilaginous fish , next to the Euselachii , to which sharks and rays belong . The only recent order among them are the sea cats (Chimaeriformes). The animals appeared in the Upper Devonian and were particularly numerous in the fish fauna of that time in the Carboniferous . Most taxa became extinct during the Permian , especially towards the end of this period . After the Jura, only the sea cats remained as the only surviving group.
features
In contrast to the Euselachians, who have several (mostly five) gill openings, the gills of the Holocephali are covered by a gill cover that leaves only one gill opening free (unlike in the picture of the extinct Sarcoprion edax, which is reconstructed here in life ). The skin of the sea cats and some fossil forms is bare. In many extinct Holocephali, however, like the Euselachians, the skin was covered by placoid scales. Holocephali have no ribs and they also lack a stomach. Many of the subtaxa are only known from tooth and tooth plate finds, as the fossil record was made difficult by the soft cartilage skeleton of the fish. It is therefore uncertain whether the characteristics apply to all subtaxa.
Systematics
The systematics of the Holocephali is still very uncertain. The classification according to Nelson (2016) is reproduced here. Other scientists classify some taxa, e.g. B. the Eugeneodontiformes , outside the Holocephali as basal Chondrichthyes.
The extinct basal holocephali have shark-like teeth that are constantly being replaced.
- Order Orodontiformes †
- Order Petalodontiformes †
- Order Helodontiformes †
- Order Iniopterygiformes †
- Order Debeeriiformes †
- Order Eugeneodontiformes † (assignment very uncertain)
- Superorder Holocephalimorpha, the members of the superorder Holocephalimorpha (= "Holocephali" Grogan & Lund, 2000) have a few large tooth plates that are used to crush solid food. All orders of the Holocephalimorpha except for the recent sea cats are extinct.
- Order Psammodontiformes †
- Order Copodontiformes †
- Order Squalorajiformes †
- Order Chondrenchelyiformes †
- Order Menaspiformes †
- Order Cochliodontiformes †
- Order sea cats (Chimaeriformes)
literature
- Joseph S. Nelson , Terry C. Grande, Mark VH Wilson: Fishes of the World. John Wiley & Sons, 2016, ISBN 978-1118342336 .
Web links
- Holocephali at Palaeos.com