Paleopsephurus
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Reason: Description is missing
| Paleopsephurus | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Temporal occurrence | ||||||||||||
| Maastrichtium | ||||||||||||
| 72 to 66 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Paleopsephurus | ||||||||||||
| MacAlpin , 1941 | ||||||||||||
Paleopsephurus is a prehistoric genus of ray fins that is closely related to today's paddlefish . It has so far only beenreliably provenfrom the late Cretaceous Hell Creek Formation in the northwest of the USA . The only known species is Paleopsephurus wilsoni .
Occurrence
The type and so far only known material of the genus was recovered from the deposits of the Hell Creek Formation of McCone County in Montana . These layers are dated to the most recent Upper Cretaceous (Upper Maastrichtian ). Paleopsephurus is one of only two known fossil paddlefish genera in North America. The second is Crossopholis with the only species Crossopholis magnicaudatus from the Eocene of the Green River Formation . A third extinct species of paddlefish is Protopsephurus with the only species Protopsephurus liui , which was described in 1994 from China. Even in the present (more recently) there are only two species of paddlefish : Polyodon spathula , in the Mississippi river system in North America , and the possibly extinct Psephurus gladius in the Yangtze River in China.
History and systematics
The list of the genus Paleopsephurus and the first description of its type species P. wilsoni were formally made in 1941 in the dissertation of the paleontologist and ichthyologist Archie Justus MacAlpin . It was not until 1947 that MacAlpin published a detailed description of the material. The descriptions were based on originally three, today four incomplete fossil specimens, which are kept in the collection of the University of Michigan Museum of Paleontology (UMMP) in Ann Arbor .
The holotype , the specimen with the collection number UMMP 22206, comprises a largely complete, somewhat crushed skull with shoulder girdle and pectoral fins (the lower jaw that was originally recovered, however, was lost sometime between 1947 and the late 1980s). The specimen with the collection number UMMP 22207 is part of the Caudal region, while UMMP 22208 originally comprised a fragment of a shoulder girdle with an enclosed pectoral fin. However, the pectoral fin was subsequently cataloged separately under the number UMMP 22209. Although all the pieces were found in close proximity to each other, it is unclear whether they belong to the same individual. Brought to light they were in 1938, together with the later holotype of the extinct "real" Sturgeon -Art Protoscaphirhynchus squamosus (UMMP 22210) in a sandstone - disruption of the Hell Creek Formation, 39 km southeast of Fort Peck (Montana), while the exposure of the Skeleton of a hadrosaur ("large trachodont") by UMMP staff.
Individual evidence
- ↑ Kirk R. Johnson, Douglas J. Nichols, Joseph H. Hartman: Hell Creek Formation: A 2001 synthesis. Pp. 503-510 in: Joseph H. Hartman, Kirk R. Johnson, Douglas J. Nichols (Eds.): The Hell Creek Formation and the Cretaceous-Tertiary boundary in the northern Great Plains: An integrated continental record of the end of the Cretaceous. Geological Society of America Special Paper 361, Boulder (CO) 2002, doi: 10.1130 / 0-8137-2361-2.503 .
- ↑ a b c d Lance Grande, William E. Bemis: Osteology and Phylogenetic Relationships of Fossil and Recent Paddlefishes (Polyodontidae) with Comments on the Interrelationships of Acipenseriformes. Journal of Vertebrate Paleontology Memoir 1 (Supplementum 1 to the Journal of Vertebrate Paleontology, Vol. 11), 1991, doi: 10.1080 / 02724634.1991.10011424
- ^ Andrew C. Revkin: For Chinese Paddlefish, a Long Goodbye . In: The New York Times , September 30, 2009. Retrieved May 20, 2010.
- ↑ a b c d Archie MacAlpin: Paleopsephurus wilsoni , a new polyodontid fish from the Upper Cretaceous of Montana, with a discussion of allied fish, living and fossil . In: Contributions from the Museum of Paleontology, University of Michigan . 6, No. 8, 1947, pp. 167-234. ( online )
- ^ A b c Laurie J. Bryant: Non-Dinosaurian Lower Vertebrates Across the Cretaceous-Tertiary Boundary in Northeastern Montana. University of California Publications in Geological Sciences 134. University of California Press, Berkeley 1989, ISBN 978-0-520-09735-3 , p. 21