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

publication ID

https://doi.org/ 10.5281/zenodo.3373655

DOI

https://doi.org/10.5281/zenodo.3483116

persistent identifier

https://treatment.plazi.org/id/03BB5A05-EA45-FFE6-F2CF-F5C50C92AEDD

treatment provided by

Jeremy

scientific name

Daspletosaurus
status

 

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 View FIGURE 5 , 6A- K, View FIGURE 6 10A-I View FIGURE 10 , 11 M-U View FIGURE 11 , 12F- I View FIGURE 12 , 13A- J View FIGURE 13 ) 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 View Materials ( Fig. 9I -L View FIGURE 9 ). 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 View FIGURE 7 , 11 A-F View FIGURE 11 ), and an incomplete skull and skeleton of a large individual ( NMMN H P- 27469 ; fig. 7A-F View FIGURE 7 ). 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 View TABLE 5 ).

An incomplete skull and skeleton of a juvenile tyrannosaurid ( NMMNH P-25049 ; Figs. 8 View FIGURE 8 , 13K-O View FIGURE 13 ) 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 View Materials ; Fig. 3A-C View FIGURE 3 ), isolated caudal vertebrae ( NMMNH P- 30014 ; Fig. 3LL), the distal end of a right femur ( NMMNH 13-25071 ; Fig. 3V-W View FIGURE 3 ), an isolated right tibia ( NMMNH P-25085 ; Figs. 3D-G View FIGURE 3 , 12A-E View FIGURE 12 ), and a partial skeleton (N MMNH P-27470 ; Fig. 3H-S View FIGURE 3 ) 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 View FIGURE 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.

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