Symmoriida

from Wikipedia, the free encyclopedia
Symmoriida
Live reconstruction of Symmorium sp.

Live reconstruction of Symmorium sp.

Temporal occurrence
Oberdevon to Oberkarbon
Systematics
Superclass : Jaw mouths (Gnathostomata)
Class : Cartilaginous fish (Chondrichthyes)
Subclass : Euselachii
Subclass : Plate gill (Elasmobranchii)
Superordinate : Cladoselachimorpha
Order : Symmoriida
Scientific name
Symmoriida
Zangerl , 1981

The Symmoriida or Symmoriiformes are an extinct order of shark-like cartilaginous fish whose fossil remains were found in marine deposits of the Upper Paleozoic Era .

features

The fish are similar to the Cladoselachia . Like these, the Symmoriida lacked the anal fin , their caudal fin was fork-shaped and also externally symmetrical. The pectoral fins were drawn out like a whip. In contrast to the Cladoselachia, they only had one dorsal fin , which stood over the pelvic fins , and no normally developed fin spines. Her teeth were cladodont. The Symmoriida were only scaled along the lateral line organ . The clasps were already well developed but differed from those of modern sharks.

Subtaxa

  • Symmoriidae , without fin spines.
  • Falcatidae , the dorsal fin spine of males, is formed into a forward-facing hook-shaped organ with a tooth-covered surface.
  • Stethacanthidae , the dorsal spine of males, is formed into a brush-shaped organ with a tooth-covered surface.

literature

Web links

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