Daspletosaurus, Russell, 1970

Carr, T. D. & Williamson, T. E., 2000, A review of Tyrannosauridae (Dinosauria, Coelurosauria) from New Mexico, New Mexico Museum of Natural History and Science Bulletin 17, pp. 113-146 : 131-133

Late Campanian

In the northern Rocky Mountain region, the tyrannosaurid fauna was dominated by Albertosaurus libratus and Daspletosaurus spp. during the late Campanian ( Russell, 1970; Horner et al., 1992). In New Mexico, Daspletosaurus appears to have been the resident tyrannosaurid.

The partial skull and skeleton ( OMNH 10131 ; Figs. 5 , 6A- K, 10A-I , 11 M-U , 12F- I , 13A- J ) described by Lehman and Carpenter (1990) was collected from either the upper Fruitland Formation or lower Kirtland Formation (Bisti, Hunter Wash, or Farmmgton Sandstone Members) as well as the partial skeleton USNM 365551 ( Fig. 9I -L ). Tyrannosaurid body fossils definitely occur in the Hunter Wash Member (~75.2-74.2 Ma: Fassett and Steiner, 1997). These include an isolated glenoid and acromial region of a large right scapula ( NMMNH P-25073 ; Fig. G-J), an isolated right femur ( NMMNH P-22976 ; Figs. 7K-P , 11 A-F ), and an incomplete skull and skeleton of a large individual ( NMMN H P- 27469 ; fig. 7A-F ). To our knowledge, the latter specimen is the largest late Campanian tyrannosaurid collected in western North America. Linear measurements of the dentary exceed those of the three largest Daspletosaurus specimens ( CMN 8506 , CMN 11594 , FMNH PR308 ; Table 5 ).

An incomplete skull and skeleton of a juvenile tyrannosaurid ( NMMNH P-25049 ; Figs. 8 , 13K-O ) recovered from the overlying unit, the Farmington Member of the Kirtland Formation (~74.2-73.5 Ma; Fassett and Steiner, 1997), represents a new species of Daspletosaurus ( Carr and Williamson, 1999). Tyrannosaurid skeletal material from the succeeding unit, the Dena-zin Member (~73.0-73.5 Ma; Fassett and Steiner, 1997) of the Kirtland Formation, is represented by numerous isolated elements and partial skeletons including the dentary collected by Reeside ( USNM 8346 ; Fig. 3A-C ), isolated caudal vertebrae ( NMMNH P- 30014 ; Fig. 3LL), the distal end of a right femur ( NMMNH 13-25071 ; Fig. 3V-W ), an isolated right tibia ( NMMNH P-25085 ; Figs. 3D-G , 12A-E ), and a partial skeleton (N MMNH P-27470 ; Fig. 3H-S ) consisting of an incomplete dentary, ilium, and caudal vertebrae. The Ringbone Formation is Campanian in age ( Lawton et al., 1993; Lucas et al., 1990), and it contains indeterminate Tyrannosauridae consisting of an incomplete tooth and an incomplete vertebra.

A new species of Daspletosaurus ( Carr and Williamson, 1999; in prep.) represents another distinct dinosaur taxon together with lambeosaurine hadrosaurids ( Wiman, 1931; Sullivan and Williamson, 1999), hadrosaurine hadrosaurids ( Brown, 1910), chasmosaurine ceratopsids ( Osborn, 1923), pachycephalosaurids (lNilliamson and Sealey, 1999), and ankylosaurs ( Sullivan, 1999) from the late Campanian members of the Kirtland Formation of New Mexico. This distinct fauna implies that there was a northern and southern faunal province among late Campanian dinosaurs in western North America because it overlaps in time with the Dinosaur Park Formation of Alberta and the upper Two Medicine Formation of Montana ( Lehman, 1987, 1997; Fig. 2 ).

However, characterization of "northern” and ” southern" dinosaur faunas (sensu Lehman, 1996, 1997) is Weakened by the unique dinosaur faunas from the Oldman Formation (the unit that underlies the Dinosaur Park Formation) in Alberta ( Ryan et al., 1999) and the upper Two Medicine Formation of Montana (Horner etal., 1992). The tyrannosaurid Daspletosaurus torosus is unique to the Oldman Formation as well as a new taxon of centrosaurine ceratopsian (Currie, pers. comm., 1999; Ryan et al., 1999). Also, the Two Medicine Formation dinosaur fauna is characterized by unique dinosaur species (e. g., Daspletosaurus , Hypacrosaurus , centrosaurine ceratopsians) ( Horner et al., 1992; Horner and Currie, 1994; Sampson, 1995; Carr, pers. obs.). Thus, the presence of two species-distinct faunas from chronologically successive units in southern Alberta and another distinct fauna in a chronostratigraphically consecutive horizon in northwestern Montana undermines the hypothesis of a north-south dichotomy among late Campanian dinosaur faunas.

Alternatively, the evidence suggests that faunal turnover may have been rapid among dinosaurs or that the different faunas were ecologically or geographically specific. Unfortunately, the majority of late Campanian tyrannosaurids are collected from a narrow chronostratigraphic interval (ranging from 78 to 73 Ma) and are not all contemporaneous, preventing comparison between successions of faunas in different geographic regions.

Figures

FIGURE 2. Stratigraphic correlation of the Fruitland and Kirtland formations to the Judith River and Edmonton groups of Montana and southern Alberta, Canada.

FIGURE 3. Tyrannosaurid fossils collected from the De-na-zin Member of the Kirtland Formation. A-C, USNM 8346, left dentary in A, lateral, B, dorsal, and C, medial views. D-G, NMMNH P-25085, right tibia in D, rostral, E, medial, F, caudal, and G, lateral views. H-S, NIVIMNH P-27470, partial skeleton with distal end of dentary in H, lateral and I, medial views; pubic peduncle of left ilium in], lateral, K, rostral, and L, medial views; proximal caudal neural arch in M, dorsal, N, leftlateral, O, right lateral, and P, ventral views; proximal caudal Centrum in Q, dorsal, R, left lateral, and S, right lateral views. T-U, NMIVINH P-26276, manual ungual (D I) in lateral views. V-W, NMIVINH P-25071, distal right femur in V, roslral and W, caudal views. X-Z, AA-BB, NMIVINH P-27276, left metatarsal IV in X, lateral, Y, medial, Z, ventral, AA, dorsal, and BB, distal views. CC-FF, NNIMNH P-20879, left pedal phalanx (D IV, PH HI) in CC, dorsal, DD, proximal, EE, medial, and FF, distal views. GG-HH, NIVIMNH P-27287, proximal caudal vertebra in GG, right lateral and HH, left lateral views. II-JJ, NMNINH P27287, proximal caudal vertebra in II, right lateral, and JJ, left lateral views. KK, NMIMNH P-22722, proximal caudal centrum in left lateral view. LL, NMMNH 13-30014, distal caudal vertebrae in right lateral view. MM-NN, NMMNH P-28923, distal caudal vertebra in MM, left lateral, and NN, right lateral views. OO-PP, NMMNH P-12999, isolated tooth in OO, lingual, and PP, labial views.

FIGURE 5. Daspletosaurus sp. (OMNH 10131) from the upper Fruitland or Kirtland (exclusive of Naashoibito Member) formations. Left postorbital in A, lateral, B, caudal, C, medial, and D, dorsal views; frontoparietal region in E, dorsal, F, ventral, G, right lateral, and H, rostral views; partial left dentary in I, lateral, and I, medial views; left femur in K, proximal, L, rostral, M, medial, N, caudal, and O, lateral views; right femur in P, proximal, Q, rostral, R, medial, S, lateral, and T, caudal views; distal half of right tibia in U, rostral, V, medial, W, lateral, and X, caudal views.

FIGURE 6. Daspletosaurus sp. (ONINH 10131) from the upper Fruitland or Kirtland (exclusive of Naashoibito Member) formations. Right metatarsal H in A, rostral, D, distal, E, lateral, G, caudal, and I, medial views; right metatarsal HI in B, rostral, C, distal, F, lateral, and I JI, medial views; K, various ribs in rostral and caudal views. L-Q NMIVINH P250891, indeterminate tyrannosaurid femur from the De-na-zin Member of the Kirtland Formation in L, rostral, M, medial, N, proximal, O, caudal, P, distal, and Q, lateral views.

FIGURE 7. Tyrannosaurid fossils collected from the Hunter Wash Member of the Kirtland Formation. A-F, NMIVINH P-27469, left premaxilla in A, medial view; left ectopterygoid in B, dorsal, and C, ventral views; right dentary in D, lateral view; and left thoracic rib in E, rostral and F caudal views G-I NMNINH 13-25073, partial left scapula in G, lateral,,, rostlal, M, distal, N, lateral, O, medial, and P, caudal views.

FIGURE 8. Daspletosaurus sp. nov. (NMMNH P-25049) collected from the Farrníngton Member of the Kirkland Formation Formation. A-D skull in A, righ right lateral, B, dorsal, C, ventral, D, caudal views; right scapula in E, lateral view; F-G right femur in F, rostral and G, caudal viws; H-I right tibia in H, medial and I, rostral views; J-K right fibula in J, medial and K, lateral views; L-O right metatarsus in L; rostral, M, caudal, N, lateral, and O, medial views; and P, caudal vertebral series in left lateral view.

FIGURE 9. Tyrannosaurid fossils collected from the upper Fruitland or Kirtland (exclusive of Naashoibito Member) formations. A-F, NMMNH P- 29164, right tibia in A, medial, B, proximal, C, rostral, D, distal, E, caudal, and F, lateral views. G-H, PMU.R1235, distal end of right dentary in G, lateral, and H, medial views. I-L, USNM 365551, partial Skeleton with?left femur in I,?medial view, I, left tibia in rostral view, K, metatarsal in?rostral view, and L,?right pubis in?lateral view. M, NMMNH P-27296, right pedal phalanx (D D1, PH D1) in dorsal, ventral, medial, proximal, and lateral views. N, NMMNH P-27281, left pedal phalanx (D IV, PH III) in dorsal, ventral, distal, lateral, and proximal views. O, NMMNH P-27773, pedal phalanx (D II) in lateral and distal views. P, NMMNH P-27773, '?left pedal phalanx (D I, PH I) in?lateral, proximal,?medial, and distal views. Q, NMMNH P—22908, distal end of?left metatarsal IV in rostral,?lateral, ventral, and distal views. R, NMMNH P-22908, distal end of metatarsal III in caudal,?lateral, rostral, and distal views. S, NMMNH P-27744, distal end of pedal phalanx (D IV, PH IV) in dorsal, ventral, and distal views. T, NMMNH P-27744, distal end of pedal phalanx (D III, PH II) in dorsal, ventral, and distal views.

FIGURE 10. Tyrannosaurid skull bones. A-I, Daspletosaurus sp. (OMNH 10131), with left postorbital in A, lateral, B, dorsal, and C, caudal views; frontoparietal region in D, dorsal, E, ventral, F, right lateral, and G, left lateral views; and left dentary in H, medial and I, lateral views. I-M, Tyrannosaurus rex (NMMNH P-3698), with vomerine process of rightpalatine in], medial, and L, lateral views; and basal portion in K, medial and M, lateral views. Scale bars equal 10 cm.

FIGURE 11. Comparison of tyrannosaurid femora. A-F, P-22976, right femur in A, lateral, B, medial, C, rostral, D, caudal, E, proximal, and F, distal views. G-L, P—25083, right femur in G, lateral, H, medial, I, rostral, I, caudal, K, proximal, and L, distal views. M-U, OMNH 10131, right femur in M, lateral, O, medial, Q, roslral, S, caudal, and V, proximal views; left femur in N, lateral, P, medial, R, rostral, T, caudal, and U, proximal views. Scale bar equals 10 cm.

FIGURE 12. Comparison of tyrannosaurid tibiae. A-E NMMNH P-25085, right tibia in A, lateral, B, medial, C, rostral, D, caudal, and E, proximal views. F-I OMNH 10131, distal end of right tibia in F, rostral, G, caudal, H, lateral, and I medial views. Scale bar equals 10 cm.

FIGURE 13. Comparison of tyrannosaurid metatarsals. A-J, OMNH 10131, right metatarsal II in A, rostral, C, caudal, E, medial, G, lateral, and J, distal views; metatarsal III in B, rostral, D, caudal, F, medial, H, lateral, and I distal views. K-O, NMMNH P—25049, right metatarsus in K, rostral, L, lateral, M caudal N medial and O, distal views. Scale bars in I and J equal 5 cm, all others equal 10 cm.