Sphenocephalus
| Sphenocephalus | ||||||||||||
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Fossil of Sphenocephalus fissicaudus in the Teylers Museum in Haarlem |
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| Temporal occurrence | ||||||||||||
| Campanium (Upper Cretaceous) | ||||||||||||
| 83.6 to 72 million years | ||||||||||||
| Locations | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name of the order | ||||||||||||
| Sphenocephaliformes | ||||||||||||
| Rosen & Patterson , 1969 | ||||||||||||
| Scientific name of the family | ||||||||||||
| Sphenocephalidae | ||||||||||||
| Patterson , 1964 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Sphenocephalus | ||||||||||||
| Agassiz , 1838 | ||||||||||||
Sphenocephalus is an extinct genus of fish that lived in the Upper Cretaceous. Fossils of the only species Sphenocephalus fissicaudus have been found in Europe, including in the Baumberger sand-lime stone in Münsterland . They lived predatory on small animals.
features
Sphenocephalus was a small, just over 10 cm long freshwater fish with a stocky shape, broad head and large eyes. The crack in the mouth was moderately long and reached under the eyes. A horn-like sting on the back of the head was characteristic. The only dorsal fin sat about the middle of the body, began high and fell backwards. The anal fin that began further back had the same shape. The pectoral fins were unusually small, the pelvic fins were far forward. The caudal fin was moderately indented. There was no adipose fin .
Like the recent and possibly related to Sphenocephalus North American percussion fish (Percopsidae), Sphenocephalus shows a mixture of primitive and advanced characteristics. In terms of skull morphology, Sphenocephalus is less derived than the perch fish.
Systematics
The systematic position of Sphenocephalus is uncertain due to its mosaic features . Today the genus is the only representative in the monotypical family Sphenocephalidae. Robert L. Carroll and Charles Albert Frickhinger refer the family to the order of perch-like salmon (Percopsiformes) within the paracanthopterygii . Carroll also noticed similarities with the mucus-like head (Beryciformes).
The American ichthyologist Don Rosen and the paleontologist Colin Patterson place the Sphenocephalidae in the monotypical order Sphenocephaliformes within the Paracanthopterygii, where it forms a sister group to the Anacanthines, a clade of all other Paracanthopterygii except Sphenocephaliformes and Percopsiformes. Common features of Sphenocephaliformes and Anacanthines are a notch in the premaxillary and some characteristics of the first five vertebrae. Joseph S. Nelson , author of the standard work on fish systematics Fishes of the World , adopts this systematic classification. Jack Sepkoski considers Sphenocephalus to be one of the first genera of perch and assigns it to the perch-like (Perciformes).
literature
- Robert L. Carroll : Paleontology and Evolution of the Vertebrates. Thieme, Stuttgart 1993, ISBN 3-13774-401-6 , p. 137.
- Karl Albert Frickhinger: Fossils Atlas Fishes. Mergus-Verlag, Melle 1999, ISBN 3-88244-018-X , p. 672.
- Joseph S. Nelson : Fishes of the World. John Wiley & Sons, 2006, ISBN 0-471-25031-7 .
- Jack Sepkoski : A compendium of fossil marine animal genera. Bulletins of American paleontology. Volume 363, Paleontological Research Institution, 2002, ISBN 0-8771-0450-6 .
