Bones and Rocks of the Upper Cretaceous Two Medicine-Judith River Clastic Wedge Complex, Montana

Route

Start point

No route given.

End point

No route given.

Roads

Total distance

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Geology

Summary

The purpose of this field trip is to provide an overview of the paleontologic, stratigraphic, and paleoenvironmental aspects of the Upper Cretaceous Two Medicine-Judith River clastic wedge in western Montana. Strata of the Two Medicine Formation yielded the first evidence of such dinosaur social behavior as nest construction and parental care, and have provided important information concerning the processes of bonebed formation in the fossil record. The correlative Judith River Formation in Montana has yielded an abundant and diverse dinosaur fossil record primarily preserved as transported and concentrated accumulations of vertebrate remains ("microsites"). The geology and paleontology of four fossil localities [Seven Mile Hill, Shield's Crossing, Willow Creek Anticline (Egg Mountain), and the Badger Creek/Two Medicine River confluence] are described, but precise details concerning the locations of the sites are not given in the field guide.

Key Lithologic Features

• various terrigenous, lacustrine, and marine sedimentary rocks of the Two Medicine-Judith River clastic wedge complex (sanstones and shales) documenting several transgressions and regressions

Structures

Landforms

Other Features

• significant fossil locality which documents dinosaur paleoecology and processes of bonebed fossilization

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Reference

Horner, J.R., Schmitt, J.G., Jackson, F., and Hanna, R., 2001, Bones and rocks of the Upper Cretaceous Two Medicine-Judith River clastic wedge complex, Montana, in, Hill, C.L., ed., Guidebook for the fieldtrips: Mesozoic and Cenozoic paleontology in the western plains and Rocky Mountains : Museum of the Rockies Occasional Paper No. 3, p. 3-13.

Availability

Order from the Museum of the Rockies. Go to their website' to contact the museum bookstore to order.