Amiidae

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Amiidae
Northern pike (Amia calva)

Northern pike ( Amia calva )

Temporal occurrence
Kimmeridgian (Upper Jurassic) to this day
155.7 to 0 million years
Locations
  • North America, Europe, Asia, South America, Africa
Systematics
Class : Ray fins (Actinopterygii)
Subclass : Neuflosser (Neopterygii)
Subclass : Bone organoids (holostei)
Halecomorphi
Order : Amiiformes
Family : Amiidae
Scientific name
Amiidae
Bonaparte , 1832

The Amiidae are a family of primeval bony fish that are extinct with the exception of the North American bald pike ( Amia calva ). In the upper Mesozoic , the family with numerous species and genera also occurred in Europe and other continents, especially the northern hemisphere. Most of the Amiidae were freshwater fish, but there were also some marine representatives. The last European representatives lived 48 to 40 million years ago in the Lutetian (Eocene) and have been found in the Messel mine in Hesse and the Geiseltal in Saxony-Anhalt .

features

The Amiidae are elongated predatory fish that are almost round in cross section. The dorsal fin of today's bald pike and some fossil forms is long, occupying more than half the length of the body and is the main driving organ. However, there were also numerous genera with short dorsal fin.

The Amiidae display a pattern of primitive and advanced features. Their caudal fin is short and outwardly almost symmetrical and rounded or forked, but the caudal fin skeleton is heterocerk . The neural arches of the caudal vertebrae are not converted to uroneuralia . The number of urodermalia is two or less. The ratio of fin carriers and hypuralia in the tail fin skeleton is around 1: 1.

In the upper jaw there is only a single supramaxillary and no supraoccipital in the skull. The premaxillary is not protractile (cannot be extended), but is firmly attached to the skull. On the lower side of the gill region there are some Branchiostegal rays . In addition, it is protected by a large throat-bone plate (gularia). Similar to almost all real bony fish (Teleostei), the Amiidae have an additional ventral element in the jaw joint with the symplecticum . The joint for the lower jaw is formed together with the quadratum , but is designed differently than that of the teleostei. The vertebral anatomy is also primitive, the vertebral bodies never hollowed out at the back. The scales have no ganoin layer and are no longer rhombic but cycloid.

External system

The Amiidae form the order of the Amiiformes with three other extinct families from the Mesozoic Era , the Caturidae , the Liodesmidae and the Asian Sinamiidae . The three families lived mostly in the sea, while the Amiidae are mostly freshwater inhabitants.

Cyclurus kehreri from the Messel pit in the State Museum for Natural History Karlsruhe
Amiopsis lepidota from Solnhofen
Calamopleurus cylindricus

Internal system

literature

Web links

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