Sclerorhynchidae

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Sclerorhynchidae
Head and front body of Libanopristis hiram in the Museo Civico di Storia Naturale di Milano in Milan.

Head and front body of Libanopristis hiram in the Museo Civico di Storia Naturale di Milano in Milan .

Temporal occurrence
Barremium to Maastrichtium ( chalk )
83.5 to 70.6 million years
Locations
  • North and South America
  • North africa
  • middle East
  • Uzbekistan
  • Japan
Systematics
Plate gill (Elasmobranchii)
Euselachii
Neoselachii
Stingray (batoidea)
Sclerorhynchiformes
Sclerorhynchidae
Scientific name of the  order
Sclerorhynchiformes
Kriwet, 2004
Scientific name of the  family
Sclerorhynchidae
Cappetta , 1974

The Sclerorhynchidae , the Germans also Scheinsägerochen or Pseudosägerochen called, are an extinct Roche family from the Cretaceous period . Outwardly they looked similar to the recent saw rays (Pristidae), but remained much smaller with a maximum length of 100 cm. They are likely the result of a convergent evolution , not closely related to the sawfish, nor their ancestors. They were spread all over the world, the main focus of the spread and probably the place of their origin was the Tethys . They reached their greatest biodiversity at the end of the Cretaceous Period in Maastricht , at the end of which they disappeared along with the dinosaurs and many other groups in the course of a great mass extinction .

features

Like the sawfish, the Sclerorhynchidae had an elongated, slightly disc-shaped and more shark-like body, a long rostrum with teeth on the sides, and lived near the coast as inhabitants of the seabed. They reached lengths of 70 to 100 cm. The two dorsal fins were positioned further back than those of the saw rays and the fiddle rays . The saw-like rostrum arose in the Sclerorhynchidae by lengthening the basal section of the rostral cartilage, whereas in the sawfish, the anterior part of the rostral cartilage lengthened. Propterygium, Mesopterygium and Metapterygium, the three basal, the fin rays transmitted cartilage of the pectoral fins are formed substantially larger than the Sägerochen and Propterygium and Mesopterygium contributed most fin rays. In addition, the jaw teeth of the pseudo-saw rays are generally relatively highly specialized, whereas those of the saw rays, like those of the fiddle rays, are unspecialized. The transition from the head to the rostrum took place more gently in the Sclerorhynchidae and is not as distinct as in the sawfish. The rostrum tapered from the base to the tip, while that of the saw ray is about the same width over the entire length. Another difference concerns the internal anatomy of the rostrum. There is a cavity in the rostrum that is a continuation of the brain cavity. The Sclerorhynchidae have only one unpaired, centrally located channel, a feature that is also found in the saw sharks (Pristiophoridae), which are not rays. The saw- ray genus Pristis , on the other hand, has another pair of channels on the side of the central cavity, Anoxypristis even has two paired channels. This contains nerves and the rostral artery.

Genera

To date, 23 genera with 40 species have been described, some of them only on the basis of their jaw teeth, so it is unclear whether they are pseudo-saw rays, saw rays or fiddle rays.

literature

  • H. Capetta. 1974. Sclerorhynchidae nov. fam. Pristidae et Pristiophoridae: un exemple de parallelisme chez Selaciens. Comptes rendus de Academie de Sciences Paris Series D 278: 225-228
  • Barbara E. Wueringer, Lyle Squire Jr., Shaun P. Collin: The biology of extinct and extant sawfish (Batoidea: Sclerorhynchidae and Pristidae). Reviews in Fish Biology and Fisheries. 05/2009; 19: 445-464. DOI: 10.1007 / s11160-009-9112-7

Web links

Commons : Sclerorhynchidae  - Collection of images, videos and audio files