Osteology of the Basal Hadrosauroid Eolambia caroljonesa (Dinosauria: Ornithopoda) from the Cedar Mountain Formation of Utah

BACKGROUND: Eolambia caroljonesa is known from copious remains from the lower Cenomanian Mussentuchit Member of the Cedar Mountain Formation in eastern Utah; however, the taxon has been only briefly described. Thus, we present herein a complete osteological description of Eolambia. METHODOLOGY/PRINCIPAL FINDINGS: The description of Eolambia presented here is based upon the holotype partial skeleton (CEUM 9758), paratype partial skull (CEUM 5212), and abundant disarticulated elements from two bonebeds that contain juvenile individuals. These remains allow the skeletal anatomy of Eolambia to be documented almost fully and a revised diagnosis to be proposed. CONCLUSIONS/SIGNIFICANCE: The description provided here facilitates comparisons between Eolambia and other iguanodontians and allows Eolambia to be coded for additional characters in phylogenetic analyses. The close affinity between Eolambia and Probactrosaurus gobiensis from the Early Cretaceous of China supports previous hypotheses of faunal interchange between Asia and North America in the early Late Cretaceous.