Background Eolambia caroljonesa is the most abundant dinosaur in the lower Cenomanian Mussentuchit Member of the Cedar Mountain Formation of Utah, and one of the most completely known non-had rosa urid iguanodontians from North America. In addition to the large holotype and paratype partial skulls, copious remains of skeletally immature individuals, including three bonebeds, have been referred to E. caroljonesa. Nevertheless, aspects of the postcranial anatomy of this taxon, particularly the pelvic girdle, have remained ambiguous due to the lack of associated postcranial material of larger, more mature individuals. Methodology/Principal findings Here we describe a recently discovered associated partial postcranial skeleton of a large Eolambia caroljonesa. This specimen, FMNH PR 3847, provides new anatomical data regarding the vertebral column and pelvic girdle, supplementing previous diagnoses and descriptions of E. caroljonesa. A new phylogenetic analysis incorporating information from FMNH PR 3847 places E. caroljonesa as a basal hadrosauromorph closely related to Protohadros byrdi from the Cenomanian Woodbine Formation of Texas. Histological analysis of FMNH PR 3847 reveals that it represents a subadult individual eight to nine years of age. Taphonomic analysis indicates that FMNH PR 3847 was preserved in a crevasse splay deposit, along with an unusual abundance of small crocodylomorph material. Conclusions/Significance FMNH PR 3847 provides a wealth of new morphological data, adding to the anatomical and systematic characterization of Eolambia caroljonesa, and histological data, revealing new information on growth history in a basal hadrosauromorph. Taphonomic characterization of FMNH PR 3847 and associated vertebrate material will allow comparison with other vertebrate localities in the Mussentuchit Member of the Cedar Mountain Formation.
Bibliographical noteFunding Information:
TNT is provided free by the Willi Hennig Society. We thank Jim Kirkland and Martha Hayden of the Utah Geological Survey and Randall Irmis and Janaki Krishna of the Natural History Museum of Utah for assistance with permits. We are grateful to Akiko Shinya, Bill Simpson, Connie van Beek, Lisa Herzog, James Holstein, Debbie Wagner, Josh Ostergaard, Erin Fitzgerald, Christian Kammerer, Michael Eklund, Will Adams, Allie Weil, and Odin for excavation and fieldwork. Akiko Shinya, Kurt Zahnle, Tim Nelson, Lis Meeker, Eric Ahlgren, Steve Clawson, Debbie Wagner, Jim Holstein, Joanne Kluger, Bill Zandrew, Magdalena Garczynska, and Janice Kelly ably prepared the material described herein. ATM thanks the following people for access to specimens under their care: Carl Mehling (AMNH); Ted Daeschler (ANSP); Jeff Bartlett and John Bird (CEUM); Amy Henrici and Matt Lamanna (CM); Ken Carpenter (DMNS); Annelise Folie and Hugo du Potter (IRSNB); Steve Hutt (MIWG); Ronan Allain (MNHN); Robert McCord (MSM); Paul Barrett, Sandra Chapman, and Lorna Steel (NHMUK); Sally Shelton (SDSM); Louis Jacobs (SMU); Don DeBlieux, Jim Kirkland, and Scott Madsen (Utah Geological Survey); Michael Brett-Surman and Matt Carrano (USNM); Douglas Wolfe (White Mountain Dinosaur Exploration Center); and Dan Brinkman (YPM). ATM is grateful to Paul Barrett, Ken Carpenter, Matt Lamanna, Chloe Marquart, David Norman, and Christopher Noto for discussions and correspondence on iguanodontian taxonomy. ATM also thanks Hailu You for providing additional images of Xuwulong and Luis Alcalá for providing additional images of Proa. ATM’s research on iguanodontians was supported by grants from the Jurassic Foundation, Evolving Earth Foundation, Utah Friends of Paleontology, and University of Pennsylvania Paleobiology Summer Stipend. PJM thanks The Field Museum Women's Board for their generous support to acquire equipment used in the excavation of FMNH PR 3847. LEZ was supported by the John Caldwell Meeker postdoctoral fellowship at The Field Museum over the span of the fieldwork that resulted in collection of FMNH PR 3847. Finally, we thank Mark Spigelman, the Academic Editor, and Glenn Storrs for reviewing the manuscript.
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