New Ichnotaxa of Mammal and Reptile Tracks from the Upper Paleocene of Alberta

Abstract

Only two vertebrate trackways are known from the Paleocene of western Canada and are among the few Paleocene vertebrate trackways known worldwide.

A natural cast trackway consisting of five prints (three pes, two manus) on a fallen block was found along the Red Deer River, near the town of Red Deer, Alberta, in 1927. The discoverers, Ralph Rutherford and Loris Russell, identified the strata the track block had fallen from as belonging to the Paskapoo Formation (upper Paleocene: middle Tiffanian). The trackway was attributed to a mammalian track-maker in two subsequent publications. However, the prints are more characteristic of a reptilian (crocodylian) track-maker.

A natural cast track-bearing block was discovered on Signal Hill in the city of Calgary during the preparation of a new residential subdivision in 1990. The large track-bearing block was found in a rock pile but is suspected to have originated from strata belonging to the Porcupine Hills Formation (Upper Paleocene: late Torrejonian), which was being excavated at the time. This large slab contains twelve prints (six pes, six manus) and is associated with extensive mud cracks. The mammalian affinity of the trackmaker was recognized by researchers from the Royal Tyrrell Museum of Palaeontology.

Keywords:

• Mammal trackway
• crocodylian trackway
• Paskapoo Formation
• Porcupine Hills Formation
• upper Paleocene

ACKNOWLEDGEMENTS

This project was originally proposed by the first author in the spring of 2002 to William (Bill) A. S. Sarjeant (University of Saskatchewan), a former supervisor and a well-known and respected authority of fossil footprints, especially those of mammals. However, Bill was diagnosed with terminal cancer, to which he succumbed in July 2002. The authors respectfully dedicate this work to the memory of Bill's significant contributions to vertebrate ichnology.

We thank Dr. Mark V. H. Wilson and Dr. Michael Caldwell (University of Alberta) for providing access to UALVP 134, and to Al Lindoe for helping move the heavy specimen to a favorable location for photographic purposes. We appreciate the efforts of Dr. James Gardner and the Royal Tyrrell Museum of Palaeontology for arranging access to TMP 90.131.01 and for providing us with a replica peel. Thanks to Dan Spivak (Royal Tyrrell Museum of Palaeontology) and Dr. Richard Fox (University of Alberta) for discussions on Paleocene vertebrates of Alberta. Dr. Martin G. Lockley was generous in providing access to an unpublished manuscript on crocodile ichnotaxonomy (this volume) that he co-authored and which was of great assistance in the systematic section of this paper.

Thanks to George White and Darren Tanke for giving first-hand information on the circumstances of the discovery and collection of the TMP 90.131.01 specimen. The first author is grateful to Stacey Gibb who accompanied the first author into the field in an attempt to locate additional footprint material in the Paskapoo Formation near Red Deer, Alberta; she discovered the only fossil track from that expedition. The first author wishes to acknowledge the wonderful assistance of Randy Pakan (University of Alberta—EAS Digital Imaging Facility) for giving instruction and advice on the art of stereo photography.

The majority of this research was undertaken through the Department of Earth and Atmospheric Sciences, University of Alberta and the Royal Tyrrell Museum of Palaeontology.