Middle Triassic (Ladinian) amphibian tracks from the Lower Keuper succession of southern Germany: Implications for temnospondyl locomotion and track preservation

• Published in: Palaeogeography, palaeoclimatology, palaeoecology palaeoclimatology, palaeoecology, 2020-04, Vol.543, p.109625, Article 109625
• Main Authors: Mujal, Eudald, Schoch, Rainer R.
• Format: Article
• Language: English
• Subjects: Fossil footprints; Ladinian; Lagerstätte; Locomotion; Microbial mats; Vellberg
• ISSN: 0031-0182; 1872-616X
• DOI: 10.1016/j.palaeo.2020.109625

Triassic temnospondyl amphibian tracks are relatively rare, in contrast with the body fossil record. Herein we report temnospondyl tracks from the base of the Anthrakonitbank carbonate bed, within the upper Middle Triassic Lower Keuper succession (Erfurt Formation) in the Vellberg Fossil-Lagerstätte of southern Germany. The sedimentary succession comprises restricted marine deposits, and the track-bearing layer includes microbial mats covering thin bone-beds. The ichnological material includes >20 footprints, four of which are arranged in a trackway, and all footprints comprise manus impressions with no pes preserved. The combination of characters, such as tetradactyl clawless manus impressions, relative digit length and angulation, and trackway with low pace angulation, are different from any known tetrapod ichnotaxon. While the scarcity of material precludes a confident ichnotaxonomy, comparison with the autopodia in the body fossil record suggests capitosaur stereospondyls as the most probable trackmakers. Ichnological and sedimentological features indicate that the trackmakers displayed a walking-swimming locomotion, with a sprawling posture, only touching the substrate with the forelimbs, as seen in present-day swimming crocodiles. The Vellberg tetrapod tracks reported here contribute to our knowledge of the Triassic ichnological record, as well as the life style and habitats of temnospondyls. •The lowermost Triassic unambiguous temnospondyl tracks are recovered from Vellberg.•Capitosaur stereospondyls are the most probable trackmakers.•Only tetradactyl manus tracks: forelimbs prevailing over hindlimbs in locomotion•Locomotion of temnospondyls similar to present-day swimming crocodiles•Low probability of amphibian track preservation: environment and mode of locomotion