Iniopterygia

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Iniopterygia
Iniopterygian.jpg

Iniopterygia

Temporal occurrence
Upper Carboniferous ( Pennsylvania ) to Perm
Locations
  • North America, Europe, China
Systematics
Trunk : Chordates (chordata)
Sub-stem : Vertebrates (vertebrata)
Superclass : Jaw mouths (Gnathostomata)
Class : Cartilaginous fish (Chondrichthyes)
Subclass : Holocephali
Order : Iniopterygia
Scientific name
Iniopterygia
Zangerl & Case , 1973

The Iniopterygia ("neckfloss") or Iniopterygiformes are an extinct taxon of the cartilaginous fish . The fossils of this group of cartilaginous fish are known from ancient times and come mainly from the Upper Carboniferous ( Pennsylvania ) of North America. Overall, however, the Iniopterygia are also found in Paleozoic sediments of Central Europe and China from the Devonian to the Permian .

features

The Iniopterygia were about 50 cm long. Their head is large and short, mostly scaly on the dorsal side. The structure and arrangement of the teeth are particularly important for the classification of cartilaginous fish. With the Iniopterygia they were used partly to grab, partly (as plates; with Sibyrhynchidae) to bite. The jaws are dia- or holostyle connected to the skull. The gills are under the skull, gill covers (with radii and cartilage plate) may be present.

The shoulder girdle is wide ventrally and articulated at the front of the gill basket, dorsally it is narrower and reaches up to the back. The pectoral fins are very high, curved, or broad; the pterygium is very large. The front ray is covered with thorny scales in males, the trunk is otherwise bare. The male's pelvic fins are equipped with long clusters (mixipterygias, for internal fertilization). The caudal fin is round or absent as in the sea ​​cats (Chimaeroidea). The dorsal fin, if present, sits in the middle of the back. It has no fin spike.

Due to the density of radiation at that time , it is currently difficult to specify the systematic position of the Iniopterygians within the cartilaginous fish "somewhere between sharks and sea cats". Nelson assigns them to the Holocephali ; they are said to be the sister group of all other holocephali.

They apparently lived sociable near the surface and the coast and (when escaping) they might jump out of the water like the Exocoetidae , but some (like Cervifurca ) like rays in the Benthal .

Genera

literature

  • Richard Lund and Eileen D. Grogan, Relationships of the Chimaeriformes and the Basal Radiation of the Chondrichthyes , Reviews in Fish Biology and Fisheries 7: 65-123. 1997
  • Rainer Zangerl: Handbook of Paleoichthyology 3 A. Chondrichthyes I. Paleozoic Elasmobranchii. Gustav Fischer Verlag, New York 1981 (unchanged new edition January 2004) ISBN 3-89937-045-7
  • Rainer Zangerl and Gerard Ramon Case: Iniopterygia: a new order of Chondrichthyan fishes from the Pennsylvanian of North America. Fieldiana Geology Memoirs, v. 6, Field Museum of Natural History, 1973 Biodiversity Heritage Library (full text)
  • Joseph S. Nelson : Fishes of the World . John Wiley & Sons, 2006, ISBN 0-471-25031-7 .

Web links