Brownstein—On the theropods of the Ellisdale Site (Campanian) 92(6):1115–1129 Table 1. Measurements for Ellisdale theropod specimens (in mm). Element


NJSM 14682 NJSM 14686


Assignment


Tyrannosauroidea indet.


Ornithomimosauria indet.


Proximodistal length


113 67


Mediolateral width


(proximal) 47


31


Mediolateral width (distal)


43 25


Dorsoventral width


(proximal) 53


25


Dorsoventral width (distal)


33 19


Circumference (diaphysis)


125 74


1119


Table 2. Measurements for Ellisdale theropod teeth (in mm). Specimen


Assignment NJSM 16601


NJSM 12436 (partial crown) NJSM 13095 NJSM 13734


NJSM 14158 (larger) NJSM 14158 (smaller)


Tyrannosauroidea indet.


NJSM 12436 (complete crown) Dromaeosauridae indet. (morphotype A) 26 16+ 8 NJSM 14404 (larger) NJSM 14404 (smaller) NJSM 16623 NJSM 15319 NJSM 16611


2004; Norell and Makovicky, 2004). NJSM 14682 is also considerably more elongate than the extremely proximodistally shortened pedal phalanges of some therizinosauroids (e.g., Clark et al., 2004). However, large size, a mediolaterally “pinched diaphysis” on III-2, robust morphology, a deepened proxi- mal articular facet, a subtle sulcus separating the distal hemicondyles, and deepened collateral ligament pits are also found in tyrannosauroids, especially the larger species of the Late Cretaceous (e.g., Table 2; Lambe, 1917, fig. 49; Carr and Williamson, 2000, figs. 3, 4, 8, 15; Holtz, 2004; Farlow et al., 2013). Indeed, the deep hyperextensor pit on NJSM 14682 unites the bone with the corresponding element in Appalachio- saurus montgomeriensis (Red Mountain Museum specimen 6770; personal communication, R.K. Denton, 2017). Thus, it may be confidently referred to Tyrannosauroidea based on the aforementioned presence of features. Several morphologies on the bone, however, suggest


against it being a tyrannosaurid. The ratio of the mediolateral width of the diaphysis to the proximodistal length of NJSM 14682 is greater than 3.0 (=3.3) (Table 2) (e.g., Brusatte et al., 2010; Brusatte and Carr, 2016), the hyperextensor pit is deepened, unlike tyrannosaurids, where it is shallow, but as in Appalachiosaurus montgomeriensis (e.g., Lambe, 1917, fig. 49; Carr and Williamson, 2000, figs. 3, 4, 8, 15; Holtz, 2004; Farlow et al., 2013; personal communication, R.K. Denton, 2017). The phalanx could only be coded for one character in the Theropod Working Group Matrix (Brusatte et al., 2014), and thus was not included in a phylogenetic analysis. However, the morphology of the specimen makes it confidently assignable to Tyrannosauroidea. NJSM 16601(Fig. 1.7–1.11) is the eroded tooth of a large


theropod dinosaur. The tooth measures 13mm long mesiodis- tally and 4mmwide labiolingually at its base. The tooth’sCH is 33mm, and the specimen does not preserve denticles. The tooth is worn, with several vertical cracks in the enamel visible in labial and lingual views. The specimen bears a striation-filled


Tyrannosauroidea indet. (morphotype B) 25 n/a 6 Dromaeosauridae indet. (morphotype A) 25 10 5 Dromaeosauridae indet. (morphotype A) 25 14 6 +


cf. Dryptosaurus (morphotype A) cf. Dryptosaurus (morphotype A)


27.5 n/a 6 27 15 8


Dromaeosauridae indet. (morphotype B) n/a n/a n/a 16 7 2


Dromaeosauridae indet. (morphotype A) 16 8.0 4.0


CH CBL CBW distal denticles/5 mm mesial denticles/5 mm CBW/CBL 35 13 7


n/a 12


?12 17 16


n/a n/a n/a


Dromaeosauridae indet. (morphotype B) n/a n/a n/a ~ 17+(6 d/1.8mm) Theropoda indet. Theropoda indet.


5 0.5 0.25


n/a n/a n/a


n/a n/a n/a n/a n/a n/a n/a


n/a n/a n/a n/a 19


0.54 n/a


0.53 n/a


0.43+ 0.5


0.5


n/a n/a


0.29 0.50 0.50


elliptical wear facet, 10mm long and 4mm wide, on its lingual surface. The wear facet follows the long axis of the crown in orientation, contains homogeneously oriented striations offset from the major axis of the facet by ~15˚, and has worn away edges, matching the facets on tyrannosaurid teeth described by Schubert and Ungar (2005). Though barely visible due to the presence of vertical cracks in the specimen, the tooth bears a ridge that curves toward the apex, suggesting the tooth to be from a tyrannosaur more derived than basal taxa like Eotyrannus (e.g., Zanno and Mackovicky, 2011; Krume- nacker et al., 2017). NJSM 16601 is nearly symmetrical labiolingually in mesial and distal views. This tooth is eroded basally on its mesial and distal ends, but nevertheless has a CBW/CBL ratio of 0.53, just under the cutoff (0.60) for the incrassate condition (Brusatte et al., 2010, 2014). Nevertheless, the ziphodont nature of this specimen suggests it may belong to Dryptosaurus or a close relative because Dryptosaurus is unusual among derived tyrannosauroids in having ziphodont dentition (Brusatte et al., 2011).


Materials.—NJSM 14682, a pedal phalanx III-2 (Fig. 1.1–1.6), NJSM 16601, maxillary or dentary tooth crown (Fig. 2.1–2.5).


Remarks.—NJSM 14682 is referred to Tyrannosauroidea based on the following combination of features: massive size, med- iolateral width of phalanx at the distal hemicondyles equal to that at the proximal articular facet leading to a robust, prox- imodistally shortened morphology, a mediolaterally “pin- ched” diaphysis in dorsal and ventral views, a deeply concave proximal articular facet, and a deepened extensor fossa on the dorsal surface just proximal to distal hemicondyles (see below). NJSM 16601 is referred to Tyrannosauroidea based on the following combination of features: size, rectangular- ovoid cross-section in labial-lingual view, gentle curvature towards the apex, and labial-lingual width that is tapered distally.


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