TETRAPOD TRACKS TAPHONOMY IN AEOLIAN FACIES FROM THE PERMIAN OF ARGENTINA

MANCUSO, A.; KRAPOVICKAS, V.; MARSICANO, C.A.; BENAVENTE, C. ; BENEDITO, D; DE LA FUENTE, M.; OTTONE, E.G.

PALAIOS

SEPM-SOC SEDIMENTARY GEOLOGY

Lugar: Lawrence; Año: 2015

0883-1351

Unexpectedly, ancient desert deposits preserve a copious ichnofossil record. Particularly during the Permian, the record of tetrapod footprints is abundant and present in almost all desert setting. We propose to analyze, from a taphonomic perspective, Permian footprints preserved in aeolian deposits from Argentina with a detailed sedimentological study of the trackway-bearing levels, in order to find evidence of processes that could have enhanced their preservation. We defined four taphonomic modes based on preservation quality, and morphological and extra-morphological features of the footprints. Mode 1 includes footprints with detailed impressions of the palm, digits and claws. Mode 2 includes tracks with palm and digit impressions associated with small bulbous-shape marginal rims. Mode 3 includes tracks characterized by large, bulbous, marginal rims and randomly preserved palm impressions. Mode 4 includes footprints with shallow digit and palm impressions associated to sand-crescent marginal rims. The Los Reyunos footprints suggest preservation in: (1) dry sand, evidenced by sediment shipping down-slope structures; (2) subsurface damp sand, evidenced by digit impressions and claw drag marks. Also, we found (3) vertical water content variations alog the dune forests, evidenced by a varying amount of sediment slipping down-slope in the same trackway. Moreover, (4) differences in the time of entombment are suggested by the morphology of rims (bulbous-shape or sand-crescent). The stratigraphic genetic framework resulted from the Los Reyunos taphonomic analysis supports changes in the water table and the rise of moisture from groundwater. Additionally, the rapid entombment of the tracking surface due to a high rate sediment supply, was the main factor for footprint preservation.