Holocephali

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Holocephali
Chimaera cubana is found in the waters around Colombia, Cuba and Puerto Rico.

Chimaera cubana is found in the waters around Colombia, Cuba and Puerto Rico.

Temporal occurrence
Upper Devonian to date
385.3 to 0 million years
Locations
  • Worldwide
Systematics
Over trunk : Neumünder (Deuterostomia)
Trunk : Chordates (chordata)
Sub-stem : Vertebrates (vertebrata)
Superclass : Jaw mouths (Gnathostomata)
Class : Cartilaginous fish (Chondrichthyes)
Subclass : Holocephali
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

Orodus sp. from the carbon
Sarcoprion edax † (Eugeneodontiformes) from the Permian

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.

literature

Web links

Commons : Holocephali  - collection of images, videos and audio files