A tyrannosaur trackway at Glenrock, Lance Formation (Maastrichtian), Wyoming

During the Campanian and Maastrichtian ages (86-66 million years ago), tyrannosaurids were the predominant large carnivorous dinosaurs throughout the Northern hemisphere. Despite the abundance of skeletal material, the fossil-footprint record of tyrannosaurids has been limited. Here we report a tyrannosaurid trackway in the Lance Formation, Wyoming. The trackway consists of three sequential tracks on a sandstone surface. Based on the age and size of the footprints, the trackmaker can be identified as either a sub-adult Tyrannosaurus rex or a Nanotyrannus lancensis. The trackway offers a record of a tyrannosaurid pace length, which permits the speed of the trackmaker to be calculated at 4.5-8.0 km/h. This result discounts previous speculation that tyrannosaurid walking speeds were notably slower than those of other large theropods. (C) 2016 Published by Elsevier Ltd.