Protosphyraena

Taxobox
name = "Protosphyraena"
fossil_range = Late Cretaceous

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image_width = 200px
image_caption = Skull of "Protosphyraena" from the Niobrara Chalk of Kansas.
status = fossil
regnum = Animalia
phylum = Chordata
classis = Actinopterygii
ordo = Perciformes
familia = Xiphiidae
genus = "Protosphyraena"
genus_authority = Leidy, 1857

"Protosphyraena" is a genus of primitive swordfish which thrived worldwide during the Upper Cretaceous Period (Coniacian-Maastrichtian). Though fossil remains of this taxon have been found in both Europe and Asia, it is perhaps best known from the Smoky Hill Member of the Niobrara Chalk Formation of Kansas (Late Coniacian-Early Campanian). "Protosphyraena" was a largish fish, averaging 2-3 meters in length. "Protosphyraena" shared the Cretaceous oceans with aquatic reptiles, such as mosasaurs and plesiosaurs, as well as with many other species of extinct predatory fish. The name "Protosphyraena" is a combination of the Greek word "protos" ("early") plus "Sphyraena", the genus name for barracuda, as paleontologists initially mistook "Protosphyraena" for an ancestral barracuda.

History and Taxonomy

As is the case with many fossil vertebrates discovered by Victorian paleontologists, the taxonomy of "Protosphyraena" has had a confusing history. Fossil pectoral spines belonging to this taxon were first recognized in 1822, from chalk deposits in England, by Gideon Mantell, the physician and geologist who also discovered the dinosaur "Iguanodon". In 1857, the fish was named "Protosphyraena ferox" by the renowned American naturalist and paleontologist, Joseph Leidy, based on Mantell's English finds. Earlier, Leidy had published an illustration of a "Protosphyraena" tooth from the Cretaceous-aged Navesink Formation of New Jersey (Maastrichtian), but mistakenly identified is as having come from a dinosaur. During the 1870s, B. F. Mudge, a fossil collector supplying material to rival paleontologists Edward Drinker Cope and Othniel Charles Marsh, discovered a number of specimens of "Protosphyraena" in Niobrara exposures in Rooks and Ellis counties in Kansas and sent them back east. Between 1873 and 1877, Cope named three species of based on Mudge's specimens, all of which would eventually be recognized as belonging to the genus "Protosphyraena": "Erisichte nitida", "Portheus" gladius", and "Pelecopterus" pernicciosus". Between 1895 and 1903, paleontologists in America and England, including Arthur Smith Woodward (1895), Loomis (1900), O. P. Hay (1903), in a series of important works, reviewed the genus, adding much to our understanding of this fish.

Today, four species of "Protosphyraena" are recognized from the Niobrara Chalk of the western United States: "P. nitida", "P. perniciosa", and "P. gladius". An additional species, "P. bentonianum" was named by Albin Stewart in 1898, based on a specimen from the older Lincoln Member of the Greenhorn Limestone (Upper Cenomanian). Perhaps the oldest remains of "Protosphyraena" in North America have come from the upper beds of the Dakota Sandstone (middle Cenomanian) in Russell County, Kansas (Everhart, 2005; p. 91).

Anatomy

In its general body plan, "Protosphyraena" resembled a modern sawfish, though it was smaller with a shorter rostrum, was somewhat less hydrodynamic, and adults possessed large blade-like teeth (adults of living swordfish species are toothless). Complete skeletons of "Protosphyraena" are relatively rare, but in parts of the Niobrara Chalk, the Mooreville Chalk of Alabama, and other geological formations, fragmentary specimens are quite common and most often include isolated teeth, the distinctive rostrum, and fragments of the long saw-edged pectoral fin first described by Mantell. Usually, portions of the skull and postcranial skeleton are found separately. This preservational bias can be explained by the fact that the skeleton of "Protosphyraena" was less ossified than that of most bony fishes and tended to be torn apart by scavengers or decay before burial and fossilization (Everhart, 2005; p. 93). Like most of the Cretaceous marine fauna, "Protosphyraena" became extinct at the end of the Mesozoic, though it has left modern descendants in the form of living swordfish.

References

*Cope, E. D. 1873. [On an extinct genus of saurodont fishes] . "Proceedings of the Academy of Natural Sciences of Philadelphia" 24:280-281.
*Cope, E. D. 1873. On two new species of Saurodontidae. Proceedings of the Academy of Natural Sciences of Philadelphia" 25:337-339.
*Cope, E. D. 1874. Review of the vertebrata of the Cretaceous period found west of the Mississippi River. U. S. Geolological Survey of the Territories, Bulletin" 1(2):3-48.
*Cope, E. D. 1875. " [http://hdl.handle.net/1813/5393 The Vertebrata of the Cretaceous Formations of the Wes] t". Report of the U. S. Geological Survey of the Territories. 2 (Washington, D.C.: Government Printing Office):302 pp.
*Everhart, M. J. 2005. "Oceans of Kansas: A Natural History of the Western Interior Sea". Indiana University Press: 323 pp.
*Hay, O. P. 1903. "On certain genera and species of North American Cretaceous Actinopterous Fishes. "Bulletin of the American Museum of Natural History" 19:1-95.
*Leidy, J. 1857. Remarks on "Saurocephalus" and its allies. "Transactions of the American Philosophical Society" 11: 91-95.
*Loomis, F. B. 1900. Die anatomie und die verwandtschaft der Ganoid-und Knochen-fische aus der Kreide-Formation von Kansas, U.S.A. "Palaeontographica" 46: 213-283.
*Mantell, G. 1822. "The fossils of the South Downs; or illustrations of the geology of Sussex". London: Lupton Relfe. xiv + 327 pp.
*Stewart, A. 1900. Teleosts of the Upper Cretaceous. "The University Geological Survey of Kansas" 6:257-403.
*Woodward, A. S. 1895. "Catalogue of the fossil fishes in the British Museum. Part 3". British Museum of Natural History, London. pp. i-xliii, 1-544.

External links

* [http://www.oceansofkansas.com/Protosphyr.html "Protosphyraena": A Late Cretaceous "Swordfish"] at the "Oceans of Kansas" website. Includes detailed taxonomic history, life restorations, bibliography, many photos of fossil remains.
* [http://www.oceansofkansas.com/RMDRC/Protosph4.jpgThe most complete skeleton of "Protosphyraena pernicosa" yet found] , on display at the Rocky Mountain Dinosaur Resource Center.