Ostracodermi
The division of living beings into systematics is a continuous subject of research. Different systematic classifications exist side by side and one after the other. The taxon treated here has become obsolete due to new research or is not part of the group systematics presented in the German-language Wikipedia.
As ostracoderm (ostracoderms; Greek ostrakon , shard ',' cup '; derma , skin') is a group of extinct, pine loser "fish" refers to ( "Agnatha"). These primeval vertebrates first appeared in the early Ordovician and became extinct in the Devonian . The mouth of the ostracodermi is small and without a jaw , the pectoral fins (if any) were immobile. The head and the front trunk are surrounded by massive bone armor, the rear trunk is covered with bone scales. In this they resemble the later Placodermi , fish-like vertebrates with jaws, which also produced heavily armored forms.
Systematic position
In the past the ostracoderms were placed together with the round mouths (Cyclostomata) in the taxon of the "jawless" (Agnatha), which is no longer in use today . The round mouths included the lampreys (Petromyzonta) and the hagfish (Myxinoidea), also known as Inger. In modern biological systematics , the taxa ostracodermi and cyclostomata are regarded as paraphyletic and no longer used.
The "Ostracodermi" are divided into the following sub-taxa:
Individual evidence
- ^ Ulrich Lehmann : Paleontological Dictionary . 4th edition. Ferdinand Enke Verlag, Stuttgart 1996, p. 164 .
literature
- Steven M. Stanley: Historical Geology , Spectrum Academic Publishing House, Heidelberg, Berlin 2001, ISBN 3-8274-0569-6
- Oskar Kuhn: The prehistoric fish and fish , A. Ziemsen Verlag, 1967, Wittenberg