Brownstein—On the theropods of the Ellisdale Site (Campanian) 92(6):1115–1129


Measurement and anatomical methodology.—The proposed standardized nomenclature for theropod teeth described by Hendrickx et al. (2015) was followed. Tooth dimensions are described using: (1) crown height (CH), measured from the middle of the base of the tooth to the apex; (2) crown base length (CBL), measured from the middle of the mesial to the middle of the distal faces of the tooth; and (3) crown base width (CBW), measured at the greatest labiolingual width of the base of the tooth. Because many of the Ellisdale specimens are fractured and all are very fragile, measurements of small teeth and their denticles were taken using digital calipers and rounded to the nearest tenth of a millimeter.


Institutional abbreviation.—NJSM, collections of the New Jersey State Museum, New Jersey, USA.


Systematic paleontology


Theropoda Marsh, 1881 Tetanurae Gauthier, 1986


Coelurosauria von Huene, 1914 Tyrannosauroidea Osborn, 1905 Tyrannosauroidea indet. Figures 1, 2.1–2.5


Description.—NJSM 14682 is a slightly eroded pedal phalanx of a tyrannosauroid dinosaur measuring 113mm proximodis- tally and has a circumference of 123mm at its diaphysis. This bone is identified as a phalanx III-1 or III-2 because it is not proximodistally elongate and mediolaterally compressed (con- ditions in the pedal phalanges of digit II) or proximodistally compressed (as in the pedal phalanges of digit IV or III-3). The


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phalanx is robustly built, with a strongly arched ventral surface in medial and lateral view. The collateral ligament pits are both deep and teardrop-shaped, both reaching their deepest point proximally. The lateral collateral ligament pit is better preserved than the medial. The proximal and distal surfaces are moderately worn, yet the preserved bone indicates that only a very slight sulcus separated the distal hemicondyles. On the dorsal surface, a deepened, teardrop-shaped fossa sits just proximal to the distal hemicondyle, identified as the extensor fossa for the insertion of the M. extensor digitorum longus (Carrano and Hutchinson, 2002). The shaft of the bone is arched dorsoventrally and pinched mediolaterally between the mediolaterally expanded proximal and distal ends of the bone. The middle portion of the bone is slightly less abraded than the proximal and distal ends, the former semi-rectangular in proximal view due in part to erosion. In medial and lateral views, the dorsal surface of the shaft is flattened. In lateral and medial views, the shaft expands dorsoventrally towards the proximal end, unlike the pinched morphology seen in dorsal view. The shaft is slightly rounded dorsally, ventrally, medially, and laterally. Towards the ventral part of the proximal most portion of the lateral and medial sur- faces of the bone, there are slight depressions. The proximal surface, like the distal, is eroded. However, enough bone is preserved to show the presence of a lip around the proximal articular surface with its most distally outstretched point at the dorsal apex of the bone. The proximal surface is semi- rectangular in shape, and there is no vertical inflection on the proximal articular facet. Measurements of this bone may be found in Table 1. NJSM 14682 is most parsimoniously placed within


Figure 1. Tyrannosauroid pedal phalanx NJSM 14682 in lateral (1), medial (2), dorsal (3), ventral (4), proximal (5), and distal (6) views. Scale bar=50mm.


Tyrannosauroidea based on several features of the bone. First, the bone’s dimensions are much larger than those of definite ornithomimosaur phalanges known from the Late Cretaceous of the Atlantic Coastal Plain (e.g., AMNH FARB 2553, NJSM 14686) (Table 2). NJSM 14682, at 113mm proximodistally, is also longer than the largest of any of the pedal phalanges of Gallimimus by more than 10mm (e.g., Osmólska et al., 1972, table 2). Thus, the bone is appreciably larger than the corresponding element in any Cretaceous ornithomimid (e.g., Makovicky et al., 2004; Kobayashi and Barsbold, 2005a, table 6.3; Longrich, 2008b, fig. 13) excluding Deinocheirus and Beishanlong, which have pedal phalanges of similar length (e.g., Makovicky et al., 2009, fig. 3; Lee et al., 2014, extended data fig. 5). However, the author regards it as unlikely that NJSM 14682 comes from a deinocheirid, given that the group is currently only represented by Cretaceous genera from Asia (e.g., Lee et al., 2014). NJSM 14682 may further be distinguished from those of ornithomimids by the lack of proximally projecting ridges that extend past the proximal end of the bone and form a concavity on the ventral surface, a robust distal end that has approximately the same mediolateral width as the proximal (Table 1), having a deeper flexor fossa relative to the pedal phalanx III-1 of ornithomimosaurs, having a deeply concave proximal surface, and having a mediolaterally “pinched,” as opposed to gently arched, diaphysis (e.g., Osborn, 1921, fig. 3a; Osmólska et al., 1972, fig. 17; Kobayashi and Barsbold, 2005a, fig. 6.10G, 6.10H, 2005b, fig. 17B; Choiniere et al., 2012, fig. 14; Cullen et al., 2013, figs. 2, 3; McFeeters et al., 2016, fig. 11; Tsogtbaatar et al., 2017, fig. 4). NJSM


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