Post by creature386 on Feb 13, 2013 1:23:55 GMT 5
Lycoptera middendorffi
©T. D. A. Cockerell
Temporal Range:
Upper Jurassic or Lower Cretaceous
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Family: Lycopteridae
Genus: Lycoptera
Species: Lycoptera middendorffi
Locations:
Mongolia, Gobi, Ondai Sair Formation/Transbaikal region of Siberia
Description:
Lycoptera middendorffi was a small fish, what was described by Johannes Müller in 1848. It is one of the sixteen Lycoptera species. Müller describes it as a jurassic fish, but this is debatable, because the exact correlation of the shales can be questioned. In the Ondai Sair Formation, details of Lycoptera middendorffi were preserved, like the very small, oval scales (1,2 mm across).
©T. D. A. Cockerell
The scales are pretty much identical with the scales of the European minnow Phoxinus phoxinus, there are hardly differences.
Classification:
Dr. A. S. Woodward reffered the Genus Lycoptera to the family Leptolepidae. Here what he writes about the family:
Other scientists don't agree, Boulenger seperates Leptolepidae from other soft finned fishes, due to central vertebra features, however, Lycoptera went trough similar life stages as Leptolepis. Due to it's similarities with Cyprinidae, Egerton wanted to place Lycoptera in the Genus Aspius. Lycoptera are indeed seen as ancestors of Cyprinidae, because there are too many differences to claim it to be a cyprinid yet. Differences like (as the Holotype in Sibearia shows) the presence of (small) teeth in the premaxilia, maxilia and dentary, scales in the near of the throat (gular scales) which are similar to those of Bowfins (but the other scales are different from those of Amia calva, as said, they're more similar to those of minnows), a turning upwards vertebral column and unmodified anterior vertebrae. Because of all these differences, the Genus got an own family called Lycopteridae. These are seen as minnow scales ancestors of cyprinids.
Sources:
digitallibrary.amnh.org/dspace/bitstream/handle/2246/1319//v2/dspace/ingest/pdfSource/bul/B051a08.pdf?sequence=1
digitallibrary.amnh.org/dspace/bitstream/handle/2246/832//v2/dspace/ingest/pdfSource/bul/B051a06.pdf?sequence=1
©T. D. A. Cockerell
Temporal Range:
Upper Jurassic or Lower Cretaceous
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Family: Lycopteridae
Genus: Lycoptera
Species: Lycoptera middendorffi
Locations:
Mongolia, Gobi, Ondai Sair Formation/Transbaikal region of Siberia
Description:
Lycoptera middendorffi was a small fish, what was described by Johannes Müller in 1848. It is one of the sixteen Lycoptera species. Müller describes it as a jurassic fish, but this is debatable, because the exact correlation of the shales can be questioned. In the Ondai Sair Formation, details of Lycoptera middendorffi were preserved, like the very small, oval scales (1,2 mm across).
©T. D. A. Cockerell
The scales are pretty much identical with the scales of the European minnow Phoxinus phoxinus, there are hardly differences.
Classification:
Dr. A. S. Woodward reffered the Genus Lycoptera to the family Leptolepidae. Here what he writes about the family:
The Leptolepidie differ from the two preceding families in the absence of fulcra on the fins, and are remarkable as being the earliest family in which intermuscular bones occur. These elements, forming so conspicuous a feature among modern fishes, appear to be arranged here only in a single series above the vertebral column in the abdominal region; though there may perhaps be traces of them sometimes also in the lower half of the caudal region. The vertebral centra of Leptolepis itself exhibit interesting gradations in the degree of development according to the geological age of the species, these centra never being more than delicate constricted rings or cylinders in the Upper Lias, and always strengthened by secondary peripheral calcifications in the Oxfordian and upwards. In Thrissops, which ranges as far at least as the Lower Cretaceous, the vertebral centra are still more robust. These fishes, it will be noticed, approach very closely the Clupeidie, among which they are sometimes included; but they are distinguished by the meeting of the parietal bones in the median line, by the non-fusion of the. haemal spines at the base of the tail, and by the presence of a thin film of ganoine on the scales.
Other scientists don't agree, Boulenger seperates Leptolepidae from other soft finned fishes, due to central vertebra features, however, Lycoptera went trough similar life stages as Leptolepis. Due to it's similarities with Cyprinidae, Egerton wanted to place Lycoptera in the Genus Aspius. Lycoptera are indeed seen as ancestors of Cyprinidae, because there are too many differences to claim it to be a cyprinid yet. Differences like (as the Holotype in Sibearia shows) the presence of (small) teeth in the premaxilia, maxilia and dentary, scales in the near of the throat (gular scales) which are similar to those of Bowfins (but the other scales are different from those of Amia calva, as said, they're more similar to those of minnows), a turning upwards vertebral column and unmodified anterior vertebrae. Because of all these differences, the Genus got an own family called Lycopteridae. These are seen as minnow scales ancestors of cyprinids.
Sources:
digitallibrary.amnh.org/dspace/bitstream/handle/2246/1319//v2/dspace/ingest/pdfSource/bul/B051a08.pdf?sequence=1
digitallibrary.amnh.org/dspace/bitstream/handle/2246/832//v2/dspace/ingest/pdfSource/bul/B051a06.pdf?sequence=1