Lophorhothon

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Lophorhothon atopus (Langston, 1960) is the first genus and species of dinosaur discovered in Alabama. Remains of this small, poorly known hadrosaurine euhadrosaurid dinosaur were first discovered during the 1940s from extensive erosional outcrops of the lower unnamed member of the Mooreville Chalk Formation (Selma Group; lower and middle Campanian) in Dallas County, west of the town of Selma, Alabama. The taxon has since been reported from Black Creek Formation (Campanian) of North Carolina. The holotype, which is housed in the collections of the Field Museum in Chicago, consists of a fragmentary and disarticulated skull and incomplete postcranial skeleton. The length on the holotype specimen has been estimated as 4.5 meters. The name Lophorhothon means "crested nose" (Greek lophos - 'crested' and rhothon - 'nose').

Taxonomic Status

Over the forty-six years since the publication of Langston's description of Lophorhothon atopus a number of workers have questioned the validity of this genus. It has been suggested, for example, that the material may actually represent a juvenile Prosaurolopus. Lamb (1998) has suggested the genus may actually represent a basal iguanodont, an idea that has failed to find widespread acceptance. More recent workers (Horner, Weishampel, and Forster, 2004) has classified Lophorhothon as a basal hadrosaurine and a sister taxon to all other hadrosaurines.

The Holotype

The specimen upon which Wann Langston, Jr. based his type description of Lophorhothon atopus consists of less than one half of the skull, a number of vertebrae, and significant portions of the fore- and hindlimbs. Preserved cranial material includes a partial quadrate, left maxilla, teeth, jugal, lacrimal, nasal (with the namesake crest), postorbital, frontal, prefrontal, parietal, squamosal, and parocciptal process, and a portion of the predentary bone. The specimen was likely washed out to sea by a river, where it eventually sank and was buried in the silty carbonate sediments of the Mississippi Embayment.

References

Horner, J. R., Weishampel, D. B., and Forster, C. A. 2004. Chapter Twenty: Hadrosauridae. in The Dinosauria (2nd edition), Weishampel, D. B., Dodson, P., and Osmólska, H., editors. University of California Press.
Lamb, J. P. 1998. Lophorothon, an iguanodontian, not a hadrosaur. Journal of Vertebrate Paleontology, 18 (3 Abstracts): 59A.
Langston, W. 1960. The vertebrate fauna of the Selma Formation of Alabama, part VI: the dinosaurs. Fieldiana: Geology Memoirs 3(5): 315-359.
Schwimmer, D. R. 1997. Late Cretaceous dinosaurs in eastern USA: a taphonomic and biogeographic model of occurrences, p. 203-211. In D. L. Wolberg, E. Stump, and G. D. Rosenberg (eds.), Dinofest International. The Academy of Natural Sciences, Philadelphia.
Thurmond, J. T. and Jones, D. E. 1981. Fossil vertebrates of Alabama. University of Alabama Press.

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