Pachyrhizodus is an extinctgenus ofray-finned fish that lived during theCretaceous toPaleocene[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]
Pachyrhizodus fossils were first collected fromCambridgeshire, England in the 1840s and were very fragmentary, only a partial maxilla (SMB.9097) and were described as a species ofRaphiosaurus in 1842 byRichard Owen. The type remains ofPachyrhizodus consisted of a maxilla (BMNH 49014) from the Lower Cretaceous ofSussex, England and was originally thought to be a mandible thatLouis Agassiz dubbedPachyrhizodus in 1850,[3] with Frederick Dixon creating the species namebasalis for the specimen.[3] Over the next few years, manyPachyrhizodus species would be named only from England until in 1872,Edward Drinker Cope described large remains from theSmoky Hill Chalk ofKansas of several new species.[4] During the 19th century, several complete and partial skeletons ofPachyrhizodus were collected from England, many of which belonging toP. basalis andP. subulidens.[2] In 1899, Alban Stewart described the mandibles of another species,P. minimus, from Kansas and it is the most commonly discovered species ofPachyrhizodus.[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]
^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.
