The Dinosaur Hadrosaurus Foulkii, from the Campanian of the East Coast of North America, with a Reevaluation of the Genus

The dinosaur Hadrosaurus foulkii, from the Campanian of the East Coast of North America, with a reevaluation of the genus ALBERT PRIETO−MÁRQUEZ, DAVID B. WEISHAMPEL, and JOHN R. HORNER Prieto−Márquez, A., Weishampel D.B., and Horner J.R. 2006. The dinosaur Hadrosaurus foulkii, from the Campanian of the East Coast of North America, with a reevaluation of the genus. Acta Palaeontologica Polonica 51 (1): 77–98. Hadrosaurus foulkii was the first dinosaur known outside Europe from partially complete skeletal elements. It is the holotype of the family Hadrosauridae and the subfamily Hadrosaurinae. The history of its discovery and taxonomy is re− viewed, and the holotype of H. foulkii is redescribed. The holotype of H. foulkii lacks distinguishing characters; therefore, this taxon is a nomen dubium. It is not synonymous with species of Gryposaurus and/or Kritosaurus. We also reevaluate the taxonomy and osteology of H. tripos, H. minor, H. cavatus, H. breviceps, H. paucidens, and Ornithotarsus immanis. In agreement with previous studies, these taxa are considered nomina dubia due to the absence of distinguishing charac− ters and are therefore referrable only to Hadrosauridae indeterminate; H. paucidens is referrable to Lambeosaurinae inde− terminate. Finally, our phylogenetic analysis indicates that the holotype of H. foulkii belongs to a member of Euhadro− sauria and, tentatively, of Hadrosaurinae. Key words: Hadrosauridae, Cretaceous, East Coast, North America, phylogeny. Albert Prieto−Márquez [[email protected]], Department of Biological Science, Florida State University, Tallahas− see, Florida, 32306−1100, U.S.A.; David B. Weishampel [[email protected]], Center for Functional Anatomy and Evolution, Johns Hopkins Uni− versity, School of Medicine, Baltimore, Maryland 21205, U.S.A.; John R. Horner [[email protected]], Museum of the Rockies, Montana State University, Bozeman, Montana 59717, U.S.A. Introduction where in the world and provided key information about dino− saurian lifestyles. Thus, due to its historical importance, this During the summer of 1858, William Parker Foulke, a natural− taxon is doubtless one of the most celebrated dinosaurs. It is ist from Philadelphia, learned of the discovery some 20 years the state fossil of New Jersey (Gallagher 1994) and also the before of fossil bones in the Cretaceous marls of the Wood− first dinosaur skeleton to be mounted for exhibition, at the bury Formation, in Haddonfield, New Jersey (Foulke 1859; Museum of the Academy of Natural Sciences in Philadelphia see also Weishampel and White 2003). Subsequent excava− (Ruschenberger and Tryon 1879; Anonymous 1922). How− tions at the edge of the old marl pit, on a small tributary of the ever, the unprecedented richness of the dinosaur discoveries south branch of Cooper Creek where the bones had originally made in the Western Interior of North America and else− been found, uncovered a new deposit of bones. Many were where in the world during the 19th and 20th centuries pro− large and Foulke contacted Joseph Leidy at the Academy of duced a shift in the focus of research towards those new find− Natural Sciences in Philadelphia (ANSP). Excavations contin− ings. The only exceptions are the monograph by Lull and ued, as did exploration elsewhere in the area (Weishampel and Wright (1942), a study of new hadrosaurid material from Young 1996; Warren 1998). Foulke and Leidy joined forces in New Jersey (Colbert 1948), and an often−cited abstract by the first description of the bones from Haddonfield at the De− Baird and Horner (1977). cember 14, 1858 meeting of the ANSP. Foulke (1859) pro− Hadrosaurus is also important for being the type genus of vided some indication of the Late Cretaceous environments the family Hadrosauridae Cope, 1869 and the subfamily there, while Leidy (1859) described the teeth, fragmentary Hadrosaurinae Cope, 1869 (Lambe 1918). Hadrosaurids are jaw, numerous vertebrae, and partial forelimb and hindlimb among the most diverse, specialized, and successful herbi− from the Haddonfield material for which he proposed the vores in the vertebrate communities of the latest stages of the name Hadrosaurus foulkii, in honor of his collaborator. Mesozoic Era. Furthermore, they are probably among the H. foulkii was the first dinosaur known from partially best−understood dinosaurs today in terms of anatomy and complete skeletal remains discovered in the New World. It evolutionary history (Lull and Wright 1942; Hopson 1975; rivaled the best−known dinosaurs then recorded from else− Ostrom 1961), behavior and life−history strategies (Horner Acta Palaeontol. Pol. 51 (1): 77–98, 2006 http://app.pan.pl/acta51/app51−077.pdf 78 ACTA PALAEONTOLOGICA POLONICA 51 (1), 2006 and Makela 1979; Horner 1982), functional morphology tebral column of living crocodiles and iguanas to estimate (Weishampel 1981; Norman and Weishampel 1985), paleo− that his new dinosaur was probably 25 feet (8 m) in length. ecology (Chin and Gill 1996), and taphonomy and sedimen− He also noted the resemblance of this animal’s teeth and ver− tology of their fossil occurrences (Dodson 1971). tebrae with those of Iguanodon, a more basal taxon from Yet the taxonomic status and phylogenetic position of H. England. More importantly for paleobiological inferences, foulkii remains enigmatic because this taxon has not been Leidy also pointed out the great disparity in length between properly diagnosed nor phylogenetically assimilated within the forelimb and hindlimb in H. foulkii and suggested that Hadrosauridae. This is principally because its remains, con− this dinosaur browsed on foliage in a kangaroo−like posture, sidered fairly complete and diagnostic in the 1850s, are actu− using its hindlimbs and tail as a tripodal support. At the same ally poorly documented and incomplete in comparison with time, he regarded it as most probably an amphibious animal later discoveries. Therefore, this material has been difficult with fresh−water habits. The presence of H. foulkii in marine to interpret in the context of the modern knowledge of these sediments suggested that its remains were transported by animals. In particular, is H. foulkii really based upon diag− rivers to be deposited at the bottom of the Cretaceous sea. nostic material? Is Hadrosaurus cogeneric with Gryposau− Before the discovery of H. foulkii, hadrosaurid dinosaurs rus and/or Kritosaurus, as has been proposed by several au− were only known from several isolated teeth discovered in the thors (Baird and Horner 1977; Brett−Surman 1979)? Will a badlands of Montana (Trachodon mirabilis Leidy,1856a) and phylogenetic analysis support the inclusion of H. foulkii from two caudal vertebrae and a phalanx from the Lance For− within Hadrosaurinae? With these questions in mind, we re− mation of Nebraska (Thespesius occidentalis Leidy, 1856b). evaluate the holotype of H. foulkii from historical, taxo− Still, after the discovery of H. foulkii, so little was known nomic, and phylogenetic perspectives. We redescribe in de− about dinosaurs on either side of the Atlantic before the great tail its osteology and make comparisons with the current discoveries of the late 19th and 20th centuries, that H. foulkii known hadrosaurid material, showing that Hadrosaurus is was much discussed and figured for several decades after its probably not cogeneric with Kritosaurus or Gryposaurus. original description (Leidy 1868a; 1870; Cope 1868, 1869, We will show that the holotype of H. foulkii lacks distin− 1874, 1883; Hawkins 1874, 1875; Lydekker 1888). For exam− guishing characters, but that it shares apomorphies with ple, Leidy returned to H. foulkii in a monograph on the Creta− Euhadrosauria (sensu Weishampel et al. 1993; the clade ceous reptiles of the United States (Leidy 1865), which sum− formed of Lambeosaurinae and Hadrosaurinae within Hadro− marized the available information on the geology of the Upper sauridae) and, tentatively, with Hadrosaurinae. Finally, we Missouri, New Jersey, Alabama, Texas, and elsewhere in the conclude this study with a review of the taxonomy of other U.S. Crocodilians, plesiosaurs, mosasaurs, turtles, and dino− species previously referred to Hadrosaurus and other taxa saurs were compared with extinct and living forms from the from the East Coast of North America. Old and New World. H. foulkii and two other dinosaurs [Astrodon johnstoni and Tomodon horrificus—later to be re− Institutional abbreviations.—AEHM, Amur Natural History named Diplotomodon by Leidy (1868b)]—were described. Museum, Blagoveschensk, Russia; AMNH, American Mu− This contribution represented Leidy’s most detailed and com− seum of Natural History, New York City, New York, USA; prehensive osteology of H. foulkii. Comparisons were made ANSP, Academy of Natural Sciences of Philadelphia, Phila− not only with modern iguanas and Iguanodon in the context of delphia, Pennsylvania, USA; CMN, Canadian Museum of their relationship to herbivory, but also with the teeth of Nature, Ottawa, Canada; MOR, Museum of the Rockies, Trachodon (Edmontosaurus). Without having the benefit of Bozeman, Montana, USA; NMMNH, New Mexico Museum knowing that all hadrosaurids had a dental battery, Leidy ar− of Natural History and Science, Albuquerque, New Mexico, gued for the close apposition of each functional tooth and its USA; OTM, Old Trail Museum, Choteau, Montana, USA; successors. But beyond these claims about its teeth, Leidy PMU, Museum of Evolution, Uppsala University, Uppsala, made no effort to infer anything about the paleobiology of H. Sweden; ROM, Royal Ontario Museum,

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