Saurodontidae
| Saurodontidae | ||||||||||||
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Saurodon , life reconstruction |
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| Temporal occurrence | ||||||||||||
| Campanium to Cenomanium (Upper Cretaceous) | ||||||||||||
| 100.5 to 72 million years | ||||||||||||
| Locations | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Saurodontidae | ||||||||||||
| Cope , 1871 | ||||||||||||
The Saurodontidae ( Syn .: Saurocephalidae, Berg , 1940 ) are an extinct bony fish family from the Upper Cretaceous of North America. The family comprises three genera found in deposits of the Western Interior Seaway and stratigraphically ranging from the Campanium to the Cenomanium .
features
The Saurodontidae were elongated, laterally flattened predatory fish that could reach a length of two to three meters. The spine was well ossified and could contain up to 100 vertebrae. The head length was usually one sixth of the standard length . The temporomandibular joint sat below the posterior margin of the orbit . The crack in the mouth was pointed slightly upwards. A characteristic feature of the family was a so-called "predentary bone", a toothless extension of the lower jaw, which ended in a triangular tip and whose function is still unknown today. Thus the lower jaw protruded far beyond the upper jaw. The teeth of the Saurodontidae were flat and blade-like, and sat in a single row in each jaw. In Saurocephalus and Saurodon , the teeth were close together and vertical. A keyhole-like pit was found at its base. In Prosaurodon this pit was missing, the teeth were further apart and pointed backwards. The first ray of the pectoral fins was blade-like and undivided.
Genera
- Prosaurodon Stewart, 1999
- Saurocephalus Harlan, 1824
- Saurodon Hays, 1829
A noun dubium is Gwawinapterus , whose fossil remnant consists only of a partially preserved jawbone including teeth, and was described as a pterosaur fossil in the first description . Vullo and colleagues later interpreted the fossil as an incompletely isolated maxillary of a saurodontid fish, but could not identify any unique features that could be used to distinguish the fossil from known saurodontid genera.
A similar controversy concerns teeth from Uzbekistan , which Lev Nessov described in 1995 as Asiamericana asiatica . Nessov stated that the teeth could belong to a theropod dinosaur belonging to the Spinosauridae group or to a saurodontid. Two later studies supported classification as Saurodontidae, while a third study preferred classification as Spinosauridae. Hans-Dieter Sues and Alexander Averianov (2012) observed, however, that the teeth show a fine sawing of their incisal edges, which suggests classification as a theropod; these authors tentatively attributed Asiamericana to the theropod Richardoestesia .
literature
- David Bardack & Gloria Sprinkle. 1969. Morphology and relationships of saurocephalid fishes . Fieldiana Geology 16 (12): 297-340.
- Colin Patterson , Donn Eric Rosen : Review of ichthyodectiform and other Mesozoic teleost fishes, and the theory and practice of classifying fossils. Bulletin of the American Museum of Natural History ; Volume 158, article 2
Individual evidence
- ↑ Hans-Dieter Sues, Victoria M. Arbor, Philip J. Currie: An istiodactylid pterosaur from the Upper Cretaceous Nanaimo Group, Hornby Island, British Columbia, Canada . In: Canadian Journal of Earth Sciences . 48, No. 1, 2010, pp. 63-69. doi : 10.1139 / e10-083 .
- ^ A b Romain Vullo, Éric Buffetaut , Michael J. Everhart: Reappraisal of Gwawinapterus beardi from the Late Cretaceous of Canada: a saurodontid fish, not a pterosaur . In: Journal of Vertebrate Paleontology . 32, No. 5, 2012, pp. 1198-1201. doi : 10.1080 / 02724634.2012.681078 .
- ↑ Hans-Dieter Sues, Alexander Averianov: Enigmatic teeth of small theropod dinosaurs from the Upper Cretaceous (Cenomanian-Turonian) of Uzbekistan . In: Canadian Journal of Earth Sciences . 50, No. 3, March 1, 2013, pp. 306-314. doi : 10.1139 / e2012-033 .
