An Early Late Cretaceous Dinosaur Tracksite in Central Yukon Territory, Canada

Abstract

Dinosaur tracks were first reported from the coal-bearing clastic sequences of the Ross River Block in 1999 by members of a University of Alaska Museum field party, and track sites were confirmed by a joint Alaska-Yukon team in 2000. This fault-bounded sedimentary block is 3 kilometers west of Ross River, in the Yukon Territory. The discovery was followed by two years of field mapping and collection. This research has resulted in the documentation of 251 individual tracks at two separate but stratigraphically related sites, as well as a short (four-footprint) trackway at one of the sites. Six ichnogenera were identified. Ornithomimipus, Amblydactylus, and Gypsichnites were recognized at one site. At a stratigraphically higher site, four ichnogenera were documented including Tetrapodosaurus, Irenesauripus, Amblydactylus, and Columbosauripus. This ichno-assemblage is compared with those of Aptian to Cenomanian age from Alberta, British Columbia, and Alaska.

The discovery of unequivocal dinosaur evidence in a small structural inlier in the Tintina Trench that was previously assumed to be Eocene in age resulted in a restudy of the palynology and biostratigraphy of this coal-bearing sequence and the recent assignment of a middle Albian to early Cenomanian age to the upper part of the dinosaur-bearing interval.

Keywords:

• Late Cretaceous
• Yukon Territory
• Canada
• dinosaur tracks

ACKNOWLEDGEMENTS

We are grateful to Richard McCrea for helpful discussions and for making his thesis and research available. Lizzie May Williams and Judy Scotchmoor are thanked for their tireless work in the field. The Ross River Station, Departments of Economic Development and Environment, Yukon Territorial Government provided assistance with equipment and personnel. Monetary support was provided by a fellowship granted through the Northern Research Institute, Yukon College, and an appropriation from Heritage Resources, Yukon Tourism and Culture, Yukon Territorial Government. The project was done in cooperation with the Ross River Dena Council.