October 31, 2016:

We report on a paired set of manus and pes tracks from the lower part of the Upper Cretaceous Cantwell Formation in Denali National Park, Alaska, USA. The tridactyl track is bi-lobed in the ‘heel' and the morphology allows attribution to a hadrosaurid. While adult hadrosaurs typically reached body lengths of 1200 cm, the length of this Alaskan pes impression is approximately 11 cm, which provides a hip height estimate of approximately 44–45 cm for this trackmaker. The manus impression is approximately 3.6 cm wide and 2.75 cm long. While hypothesized through studies of skeletal anatomy, given the small body size of the hadrosaur that made these tracks, this paired set of impressions indicates that at least some juvenile hadrosaurs were facultative quadrupeds rather than obligatory bipeds.

Anthony R. Fiorillo & Ronald S. Tykoski (2016)
Small hadrosaur manus and pes tracks from the Lower Cantwell Formation (Upper Cretaceous) Denali National Park, Alaska: implications for locomotion in juvenile hadrosaurs.
PALAIOS (advance online publication)
DOI: 10.2110/palo.2016.049