The Smallest Known Tetrapod Footprints: Batrachichnus Salamandroides from the Carboniferous of Joggins, Nova Scotia, Canada

Abstract

A new specimen of Batrachichnus salamandroides from the classic Carboniferous section at Joggins, Nova Scotia, is the smallest set of tetrapod footprints known in the fossil record. The trackmaker was a juvenile, quadrupedal temnospondyl or microsaur with a trunk length of 3.55 mm and an estimated body length of 8 mm (skull, presacral vertebrae, and caudal vertebrae). The 48 mm-long trackway preserves a high degree of extramorphological variation along its course, including a gait change associated with a change in direction along with an increased stride and pace, and the appearance of overstepped imprints, in the latter portion of the trackway. These morphological changes suggest the tetrapod changed from a walking gait to a running gait.

Keywords:

• Tetrapod footprints
• Batrachichnus
• Joggins
• Nova Scotia
• Carboniferous

ACKNOWLEDGMENTS

We thank Andrew MacRae, Caterina Corazza, Pam Dickinson, Diane Richard, Alexander Kaul, Brian Hebert, Martin Gibling, and John Calder for comments on early versions of the manuscript. Drs. Robert Carroll and Robert Holmes provided insightful discussions on the vertebrate paleontology of Joggins and measurements of the articulated skeletal remains of Dendrerpeton. The Nova Scotia Museum provided various Heritage Research Permits for the collection of fossil material from the Joggins Fossil Cliffs, and Don Reid collected the specimen under his Heritage Research Permit. The Joggins Fossil Centre gave continued support to our ichnological studies of the Joggins Fossil Cliffs. We thank Dr. Andrew MacRae and Saint Mary's University Department of Geology for use of lab space. We also thank Hendrik Klein and Sebastian Voigt for their careful peer review of the manuscript.