Menaspiformes
| Menaspiformes | ||||||||||||
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Menaspis armata and Deltoptychius , two Menaspiformes |
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| Temporal occurrence | ||||||||||||
| Mississippian to Permian Triassic border | ||||||||||||
| 345 to 254 million years | ||||||||||||
| Locations | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Menaspiformes | ||||||||||||
| Nelson , 2006 |
The Menaspiformes are an extinct order of the cartilaginous fish (Chondrichthyes) that appear from the lower carbon to the upper perm in the fossil record .
Taxonomy
The order of the Menaspiformes includes three families (with a total of six taxa), the Deltoptychiidae , the Menaspidae and the Traquairiidae . However, Carroll (1988) does not regard the Deltoptychiidae as a separate family, but counts their only genus Deltoptychius among the Menaspidae. The Traquairiidae with their only genus Traquairius also cause taxonomic difficulties in their assignment to the Menaspiformes due to their special characteristics .
The exact taxonomic breakdown of the Menaspiformes is generally difficult and controversial. For example, Ortlam does not see any cartilaginous fish in Menaspis , but an arctolepid Arthrodira . If this were to be the case, this ancient taxon would have continued into Zechstein 1 ( copper slate ).
features
In their dentition, the Menaspiformes are very similar to the Chimaeriformes (sea cats), but otherwise show very different characteristics. In the back of the jaw there are large tooth plates, which are accompanied by a number of small teeth towards the front end. As with today's sharks, the latter are used for dentures. Your body is flattened dorsoventrally. There are no dorsal fins because the supporting bones, unlike other cartilaginous fish, are missing. On the back of the head, the animals have a skin armor (roughly comparable to that of the Placodermi / Arthrodira ), which is reinforced with very small conical appendages. The skin armor forms a pair of wing-like extensions at its front end. In Menaspis there are three pairs of backward-curved spinous processes ( English cephalic spines ), which probably had defensive tasks. In addition to the skin armor, the animals are covered by overlapping scales, which are arranged in a rather complicated pattern. Two rows of very large scales run across the back. The individual scales have a cyclomorial structure. With Traquairius , the armor is limited to the skull area.
Note: There are clear differences in the interpretation of the wing and thorn processes. These are based on the difficulty of determining the correct position of the fossil (whether it is on the underside or on the top).
Way of life
The Menaspiformes were quite small, nectobenthic animals (in free water close to the ground), Menaspis, for example, did not grow larger than 25 centimeters and Traquairius agkistrocephalus should have reached 45 centimeters. They probably stayed in not too great a depth, chasing after small vertebrates.
Occurrence
literature
- Bendix-Almgreen, SE: The anatomy of Menaspis armata and the phyletic affinities of the menaspid bradydonts . In: Lethaia . tape 4 , 1971, p. 21-49 .
- Carroll, Robert L .: Vertebrate Paleontology and Evolution . WH Freeman and Company, New York 1988, ISBN 0-7167-1822-7 .
- Hartmut Haubold and Günther Schaumberg: The fossils of copper slate . Wittenberg 1985.
- Josef Paul: The copper slate: lithology, stratigraphy, facies and metallogenesis of a black slate . In: Journal of the German Geological Society . tape 157 (1) , 2006, pp. 57-76 .
- Stahl, B .: Chondrichthyes III. In: HP Schultze and P. Kuhn (Eds.): Handbook of Palaeoichthyology . Vol. 4 Holocephali. Gustav Fischer Verlag, Stuttgart - New York 1999, p. 164 .
- Zangerl, R .: Chondrichthyes I. Paleozoic elasmobranchs . In: HP Schultze (Ed.): Handbook of Paleoichthyology . Vol. 3 Elasmobranchi. Gustav Fischer Verlag, Stuttgart 1981.
Individual evidence
- ↑ a b Ortlam, D .: New aspects for the interpretation of Menaspis armata Ewald (Kupferschiefer, Zechstein 1, Germany) with the help of stereoscopic X-ray technology . In: Geological Yearbook . A 81, 1986, p. 3-57 .
- ^ Patterson, C .: The philogeny of the chimaeroids . In: Phil. Trans. Roy. Soc. London . B 249, 1965, p. 101-219 .
- ↑ Friedrich Bachmayer and Erich Malzahn: The first evidence of a decapod cancer in the Lower Rhine copper schist . In: Ann. Naturhist. Mus. Vienna . 85 / A. Vienna 1983, p. 99-106 .