Pachyrhizodus is an extinct
genus of
ray-finned fish that lived during the
Cretaceous to
Paleocene[1] in what is now Europe, North America, South America, and Oceania. Many species are known, primarily from the Cretaceous of England and the midwestern United States.[2]
History and discovery
Pachyrhizodus fossils were first collected from
Cambridgeshire, England in the 1840s and were very fragmentary, only a partial maxilla (SMB.9097) and were described as a species of Raphiosaurus in 1842 by
Richard Owen. The type remains of Pachyrhizodus consisted of a maxilla (BMNH 49014) from the Lower Cretaceous of
Sussex, England and was originally thought to be a mandible that
Louis Agassiz dubbed Pachyrhizodus in 1850,[3] with Frederick Dixon creating the species name basalis for the specimen.[3] Over the next few years, many Pachyrhizodus species would be named only from England until in 1872,
Edward Drinker Cope described large remains from the
Smoky Hill Chalk of
Kansas of several new species.[4] During the 19th century, several complete and partial skeletons of Pachyrhizodus were collected from England, many of which belonging to P. basalis and P. subulidens.[2] In 1899, Alban Stewart described the mandibles of another species, P. minimus, from Kansas and it is the most commonly discovered species of Pachyrhizodus.[5][6] Since the 19th century, many complete skeletons and species have been described from many regions.[7][8]P. caninus specifically has been discovered in the United States, Mexico, and New Zealand.[9][10][8]
References
^Cope, K. H., Utgaard, J.E., Masters, J.M., and Feldmann, R., 2005, The fauna of the Clayton Formation (Paleocene, Danian) of southern Illinois: A case of K/P survivorship and Danian recovery: Bulletin of the Mizunami Fossil Museum, v. 32, p. 97–108.