Fossil range: Middle Eocene - Oligocene
| Scientific classification
Phareodus ((synonym - P. acutus) (meaning "to have tooth") is an extinct genus of fish commonly found in the Green River Formation of Wyoming, USA and Australia. These fish existed 50 million years ago during the Eocene epoch. Today their ancestors and close relatives, the "bonytongues", live throughout the world. Phareodus are well known for their long pectoral fins, large scales, and several pointy teeth. These fish are suggested to be active hunters due to their array of sharp teeth. Also, the remnants of Priscacara and Mioplosus percoid spines have been found in their stomachs. They may have had organs that enabled them to "breathe air" like today's Arowana and Arapaima. Their jaws are hinged at the bottom (like the Arowana's) which might mean they spent most of their time at the surface. Phareodus may have been mouth-brooders like most modern-day bonytongues. The average length of Phareodus fossils are 7 inches (17.8 centimeters) with a maximum size of 30 inches (76.2 centimeters). Phareodus fossils are labled uncommon. During life, Phareodus predated on Knightia, Priscacara, and other small fish.
There are two known species of the Phareodus genus, Phareodus testis and Phareodus encaustus.
Smallest of the two species, P. testis reaches a maximum length of 15 inches. Their body structure is thicker and more rounded then P. encaustus. Most differences of the species occurs in the skull. For example, the upper jaw structure is shorter then P. encaustus. The horizontal arm of preopercle is larger in testis than P. encaustus. The jaws are visably shorter and this species has few teeth. The scales of P. testis are larger and less numerous than P. encaustus.
P. testis was a freshwater fish with an oval outline, a small head, and a slightly pointed snout. Its dorsal and anal fins were situated posteriorly, with the anal fin being larger. Its caudal fin was slightly forked. It had small pelvic fins but long, narrow pectoral fins. It is synonymous with Dapedoglossus.
Phareodus encaustus is the largest of the genus with a maximum length of 30 inches. The body shape of Phareodus encaustustends to be more slender and longer compaired to P. testis. Some differences in cranial features include a parietal longer in P. encaustus than in P. testis, and the mouth corner of Phareodus encaustus is more posteriorly located than in Phareodus testis.
History of the Phareodus Genus Edit
The Phareodus genus was named by American paleontologist, Joseph Leidy, in 1873. Leidy based the genus on the genus Dapeoglossus coined by Cope in 1871. Sixty years later in 1938, Thorpe revised Cope's genus and rendered it "a subjective junior synonuym". The Dapeoglossus genus was discarded and the Phareodus genus became the accepted name. During the history of the Phareodus genus there have been at least five species that have been included or exluded. In 1934, Hills named an Asutralian species (Phareodus queenslandicus) of Phareodus from fossils in the Redbank Plains Formation. Phareodus queenslandicus was said to be very similar to Phareodus encaustus in North America. Later in 1958, Hills decided that P. queenslandicus belonged in the genus Scleropage which would be renamed Phareoidus in 1973 by Taverne. Once there was a European Phareodus species named muelleri but was later placed in the Brychaetus genus. Phareodus encaustus was once named Phareodus acutus by Cope in 1974. Finally, in 1984, Grande revised the genus to reconise the two species known today, the Phareodus testis and Phareodus encaustus.
- ^ Li et all. 1997 "The species of †Phareodus (Teleostei: Osteoglossidae) from the Eocene of North America and their phylogenetic relationships." Journal of Vertebrate Paleontology 17(3):487-505
- ^ a b Frickhinger, Karl Albert (1995). Fossil Atlas: Fishes. Trans. Dr. R.P.S. Jefferies. Blacksburg, Virginia: Tetra Press.
Sources and External LinksEdit
- JSTOR: Journal of Vertebrate Paleontology, Vol. 17, No. 3 (Sep. 4, 1997), pp. 487-505 Relationship between the species and history of the Phareodus genus.
- Osteoglossidae - Wikipedia, the free encyclopedia Characteristics of the Osteoglossidae family.
- Phareodus (Genus)
- Paleontology of the Green River Formation, With a Review of the Fish Fauna. 2nd ed. Laramie, Wyoming: Wyoming State Geological Survey, 1984.