Tetrapod tracks in a sand sea at the Carboniferous-Permian transition in southern Gondwana

MARSICANO, CLAUDIA A.; KRAPOVICKAS, VERONICA

Puerto Escondido

Simposio; V SLIC 2023; 2023

SLIC

Several beds containing tetrapod footprints have recently been discovered from the eolian (erg) succession of the De la Cuesta Formation (Catamarca, Paganzo Basin, northwestern Argentina), considered to encompass the Carboniferous- Permian boundary in the region. The track-bearing horizons correspond to the top of the unit and represent interdune deposits. The new fossil tetrapod assemblage comprises several tracks and trackways mostly representing the quadrupedal progression of a plantigrade homopod trackmaker. The manus and pes imprints are nearly of the same size and equally orientated; the digit impressions are sub-parallel and anteriorly directed. They are tentatively assigned to the same ichnotaxon (cf. “Chelichnus”) showing the presence of a quite diverse arrangement of trackmakers with anteroposterior length of the autopodium impressions ranging from 1 cm to 10 cm approximately. Particularly, one large surface shows the presence of oblique up-dune progressions with downslope sand crescents, a recurrent behaviour of “Chelichnus” trackmakers preserved in eolian facies. According to recent proposal of colonization trends and evolutionary turnovers displayed by eolian ichnofaunas, the De la Cuesta assemblage corresponds to the third phase of desert colonization: the tetrapod colonization of sand seas. It also shows that this colonization was already underway by the Carboniferous-Permian transition in the high latitudes of Gondwana also supported by the already described early Permian tetrapod ichnofaunas from eolian deposits of the Paganzo Basin and the San Rafael succession of Argentina.