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1 March 2008 Partial Dentition of a Chimaeroid Fish (Chondrichthyes, Holocephali) from the Upper Cretaceous Niobrara Chalk of Kansas, USA
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Abstract
A specimen collected in 2006 from the Smoky Hill Chalk of central Kansas, USA, represents a rare occurrence of a chimaeroid fish from the Niobrara Chalk. The associated material includes associated right and left vomerine plates, and the right palatine plate. Comparison of the Kansas vomerines with the type of “Edaphodon” laqueatus, a right vomerine from Lower Campanian strata of eastern Mississippi, indicates that the remains are conspecific. However, our analysis also shows that these vomerine plates are distinct from Edaphodon, principally because of a massive, hammer-like beak, and overall modification of the oral surfaces into flat crushing plates, rather than oblique shearing surfaces as seen in Edaphodon. In addition, whereas there are three large tritors on an Edaphodon palatine, the Niobrara palatine has four very small tritors, with two inner tritors, a middle tritor, and an outer tritor. Our conclusion is that the original taxonomic designation, Eumylodus laqueatus Leidy, 1873, is valid, and the geographic distribution of the taxon extended from the Mississippi embayment to the central portion of the Western Interior Seaway, U.S.A.
David J. Cicimurri, David C. Parris and Michael J. Everhart "Partial Dentition of a Chimaeroid Fish (Chondrichthyes, Holocephali) from the Upper Cretaceous Niobrara Chalk of Kansas, USA," Journal of Vertebrate Paleontology 28(1), (1 March 2008). https://doi.org/10.1671/0272-4634(2008)28[34:PDOACF]2.0.CO;2
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