An unusual association of hadrosaur and therizinosaur tracks within Late Cretaceous rocks of Denali National Park, Alaska

Abstract

We report details of a unique association of hadrosaur and therizinosaur tracks found in the Late Cretaceous lower Cantwell Formation, Denali National Park, central Alaska Range, Alaska. This rock unit is now well-documented as a source of thousands of fossil footprints of vertebrates such as fishes, pterosaurs, and avialan and non-avialan dinosaurs. The lower Cantwell Formation in this area consists of numerous fining-upward successions of conglomerates and pebbly sandstones, cross-stratified and massive sandstones, interbedded sandstones and siltstones, organic-rich siltstones and shales, and rare, thin, bentonites, typically bounded by thin coal seams, and it contains a diverse fossil flora. We report the first North American co-occurrence of tracks attributable to hadrosaurs and therizinosaurs in the lower Cantwell Formation. Although previously un-reported in North America, this association of hadrosaur and therizinosaur tracks is more characteristic of the correlative Nemegt Formation in central Asia, perhaps suggesting that parameters defining the continental ecosystem of central Asia were also present in this part of Alaska during the Latest Cretaceous.

A New Hadrosaurine (Dinosauria: Hadrosauridae) from the Marine Deposits of the Late Cretaceous Hakobuchi Formation, Yezo Group, Japan

“…S28). The most recent common ancestor of Edmontosaurini was reconstructed as living in a widespread range in Asia and North America with faunal communications between these two continental areas through Beringia represented by present-day Alaska 58,59 , where Xing and others 30 documented a high probability of the group having originated in Asia. Vicariance event of Shantungosaurus and Edmontosaurus is suggested to have probably occurred during the early Campanian.…”

A mid-Cretaceous tyrannosauroid and the origin of North American end-Cretaceous dinosaur assemblages

“…Following previous TWiG protocols, we used the outgroup Allosaurus to root the tree. The following characters were ordered: 3, 16, 17,18,19,24,25,27,38,39,40,45,63,66,72,74,89,103,108,111,114,117,119,121,123,130,146,148,152,154,161,163,166,168,169,171,175,178,179,181,195,197,200,217,222,232,234,235,238,242,250,252,255,256,261,262,265,268,270,279,287,…”

The Biogeography of Coelurosaurian Theropods and its Impact on their Evolutionary History

“…Nothronychus) whose ancestors potentially dispersed from Asia via the Bering Land Bridge during its establishment in the later stages of the Early Cretaceous (Kirkland and Wolfe, 2001;Zanno, 2010;Fiorillo and Adams, 2012). This dispersal event receives further support in the form of a potential therizinosaurian track found in Alaska, USA, which is one side of the modern Bering Strait (Fiorillo and Adams, 2012;Fiorillo, et al, 2018).…”