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An elongate hadrosaurid forelimb with biological traces informs the biogeography of the Lambeosaurinae

Published online by Cambridge University Press:  08 October 2020

Chase Doran Brownstein*
Affiliation:
Stamford Museum and Nature Center, Stamford, Connecticut Yale University, New Haven, Connecticut
Immanuel Bissell
Affiliation:
Yale University, New Haven, Connecticut
*
*Corresponding Author

Abstract

Although the fossil record of the Late Cretaceous eastern North American landmass Appalachia is poor compared to that from the American West, it includes material from surprisingly aberrant terrestrial vertebrates that may represent relictual forms persisting in relative isolation until the end of the Mesozoic. One intriguing question is to what extent eastern and western North American faunas interspersed following the closure of the Western Interior Seaway during the Maastrichtian Stage of the Late Cretaceous ca. 70 Ma. Isolated remains from the Atlantic Coastal Plain in New Jersey have been preliminarily identified as the bones of crested lambeosaurine hadrosaurids, a derived clade known from the Cretaceous of Asia, western North America, and Europe, but have not been formally described. We describe the partial forelimb of a large hadrosaurid from the late Maastrichtian New Egypt Formation of New Jersey. The ulna preserves multiple deep scores identifiable as shark feeding marks, and both bones show ovoid and circular marks attributable to invertebrates. This forelimb is very similar to another partial antebrachium from the same area that shows evidence of septic arthritis. Both these specimens and a complete humerus from the same unit are closely comparable to the lower forelimbs of lambeosaurines among hadrosaurid dinosaurs. Although the absence of lambeosaurine synapomorphies observable on the New Egypt Formation forelimbs precludes their definite referral to Lambeosaurinae, they show that a morphotype of large hadrosauromorph with distinctly elongate forelimbs existed in the latest Maastrichtian of eastern North America and allow for a revision of the latest Cretaceous biogeography of crested herbivorous dinosaurs.

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Articles
Copyright
Copyright © The Author(s), 2020. Published by Cambridge University Press on behalf of The Paleontological Society
Figure 0

Figure 1. Locality Context and Skeletal. (1) Location of the site of discovery of YPM 3216; (2) reconstruction of YPM 3216 as a lambeosaurine dinosaur.

Figure 1

Figure 2. Hadrosauridae indet. YPM 3216. Radius in (1) lateral, (2) dorsal, (3) ventral, and (4) medial views. Courtesy of the Division of Vertebrate Paleontology; Peabody Museum of Natural History, Yale University, New Haven, Connecticut, USA; peabody.yale.edu.

Figure 2

Figure 3. Hadrosauridae indet. YPM 3216. Ulna in (1) lateral, (2) dorsal, (3) ventral, (4) medial, and (5) proximal views, with a closeup (6) of the shark traces on the specimen. Courtesy of the Division of Vertebrate Paleontology; Peabody Museum of Natural History, Yale University, New Haven, Connecticut, USA; peabody.yale.edu.

Figure 3

Figure 4. Comparison of hadrosaurid forelimbs. Ulnae of (1, 2) Hadrosauridae indet. YPM 3216, (3, 6) Amurosaurus riabinini (after Godefroit et al., 2004), (4) Olorotitan arharensis (after Godefroit et al., 2012a), (5, 8) Kundurosaurus nagornyi (after Godefroit et al., 2012b), Edmontosaurus regalis (7, 9), (10) Hypacrosaurus (after Brown, 1913), and Tenontosaurus sp. YPM-PU 16514 (11) in lateral (1, 3, 5, 7, 10) and medial (2, 4, 6, 8, 9, 11) views.

Figure 4

Figure 5. Discriminant analysis of hadrosauromorph ulnae with Hadrosauridae indet., YPM 3216, included.

Figure 5

Table 1. Loadings for the discriminant analysis of hadrosauromorph ulna proportions after Maidment et al. (2012). B = ulna length; C = Anteroposterior width of the ulna; D = mediolateral width.