Re-evaluation of Chelichnus tazelwürmi, a non mammalian therapsid-grade track from the Upper Permian Arenaria di Val Gardena

Abstract

In this paper, a revision of tracks referred to as Chelichnus tazelwürmi is reported. The performed analysis, consisting of a holistic approach by means of a mainly morphological analysis, and a secondarily functional one, led to the proposal of a new ichnogenus, named as Contiichnus tazelwurmi. The three dimensional morphology of the tracks allows for the inference of a complex cycle of locomotion by the trackmakers. The tracks were formed in the main phases (i.e. touch-down, weight-bearing and kick-off) by different axes of body load and transference, indicating that the whole fore autopod was involved in the cycle of locomotion and actively contacted the substrate, while for the hind autopod the functional prevalence was markedly centro-medial. Some track features suggest a therapsid-grade synapsid as potential trackmaker. However, the reconstructed autopodial structure does not correlate with known autopods from the Late Permian body fossil record. These observations stress the importance of tetrapod ichnology studies in improving knowledge in the field of vertebrate palaeontology. http://www.zoobank.org/urn:lsid:zoobank.org:pub:B4EB4D42-1A3B-48EC-B83F-6942F741AF30

http://www.zoobank.org/urn:lsid:zoobank.org:pub:B4EB4D42-1A3B-48EC-B83F-6942F741AF30

Keywords:

• Ichnology
• footprint
• Contiichnus
• trackmaker
• therapsids
• Late Permian

Acknowledgements

PC acknowledges the staff of the Dumfries Museum and Camera Obscura and the Elgin Museum for their help during his visit. Marco Romano is kindly thanked for fruitful discussion during the preparation of the manuscript and for a revision of an early version of the manuscript. Angelo Cipriani and Scilla Roncacé are warmly thanked for their technical support during museum operations. Silvina de Valais is kindly acknowledged for valuable comments and suggestions on the final version of the manuscript. We are indebted with Richard T. McCrea for his suggestions and corrections that have consistently improved the manuscript. Finally, we thank the editor Gareth Dyke, two anonymous reviewers and Martin Lockley for their careful reviews and insightful comments that considerably improved the manuscript.