Distinctly Montana Magazine

52 D I S T I N C T LY M O N TA N A M A G A Z I N E • FA L L 2 0 2 4 Formation in Montana. Combining the two datasets, 42 of 53 T. rex specimens were excavated from exposures of the Hell Creek Formation: 26 in Montana, three in North Dakota, and 13 in South Da- kota. These sites are most highly concentrated in Garfield (10) and Carter (6) counties in Montana, as well as Harding County (7) in the extreme northwestern corner of South Dakota. Additionally, six skeletons described in Lar- son's essay were disinterred from exposures of the Lance For- mation in northeastern Wyoming. Both formations were depos- ited along what was then the eastern coast of Laramidia and the western shores of the Western Interior Seaway. Numerous outcroppings of these formations contribute sig- nificantly to the accessibility and geographic patterning of discovery sites, but they do not accurately reflect the immense breadth of Tyrannosaurus rex habitat. In addition to the areas listed above, the fossilized remains of this carnosaur have been recovered from sites in southwestern New Mexico, northeastern Colorado, Utah, and the southwestern corners, respectively, of Alberta and Saskatch- ewan. The Hell Creek Formation is typi- cally interpreted as a forested, sub- tropical floodplain. However, based on the enormous landmass delineated by discovery sites elsewhere, Larson characterizes the territori- al range of T. rex as encompassing "habitats from wet lowland coastal plain environments to cooler alluvial plain settings and semi-arid, upland intermontane basins." To take full advantage of its potential for paleontological re- search, the Hell Creek Project was launched in 1998. Due, in large measure, to fieldwork conducted by consortium insti- tutions, the Museum of the Rockies (Bozeman) became the foremost repository of dinosaur fossils from the Hell Creek Formation. Indeed, its collections include portions of 12 T. rex skeletons, the largest assemblage of its kind. "Wankel rex" HELL CREEK FORMATION Early paleontologists were as rugged as the Montana environment they explored Barnum Brown in the Hell Creek Formation wearing his trademark fur coat

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