Phyllolepida
| Phyllolepida | ||||||||
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Phyllolepis |
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| Temporal occurrence | ||||||||
| Middle Devon to Upper Devon | ||||||||
| ? to ? Million years | ||||||||
| Locations | ||||||||
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| Systematics | ||||||||
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| Scientific name | ||||||||
| Phyllolepida | ||||||||
| Stensio , 1934 |
The Phyllolepida (Phyllolepidae) are a group of the extinct Placodermi , fish-like, armored vertebrates from the Devonian . The animals lived in fresh water .
features
The fish were flattened and heavily armored in front, the middle bone plates are always considerably larger than those on the sides. The head is protected at the top by a single, central plate, which is surrounded by smaller ones on the sides. The bone plates have a striking pattern of concentric ribs on their outside. The shell is not closed behind the pectoral fins . The largest Phyllolepida were 50 to 60 centimeters long. The unarmored torso and tail are long and strong.
The phyllolepida were likely blind. They lack the openings in the head armor that are necessary for the eyes and the ring of small bones surrounding the eyes in other placoderms. The sensory channels on the head shield are well developed.
It is possible that the phyllolepida lived as ambulance hunters , buried in the muddy bottom of the water and waited for prey to swim past, which they captured with a wide open mouth and a few powerful blows of the long tail.
Systematics
The taxon was initially only known through the genus Phyllolepis and was placed among the jawless until Erik Stensiö in 1936 proved that it belonged to the placoderms. Possibly they are primitive arthrodesis . To date, only five genera have been described : Austrophyllolepis , Cobandrahlepis , Phyllolepis , Placolepis and Yurammia .
literature
- Joseph S. Nelson : Fishes of the World . John Wiley & Sons, 2006, ISBN 0-471-25031-7 .
- Robert L. Carroll: Paleontology and Evolution of the Vertebrates . Thieme, Stuttgart 1993, ISBN 3-13774-401-6 .
- John A. Long: The Rise of Fishes . The Johns Hopkins University Press, 1995, ISBN 0801849926 .
