Research paper
Ophiomorpha irregulaire and associated trace fossils from the Upper Cretaceous of Patagonia, Argentina: Palaeogeographical and ethological significance
MARÍA I. LÓPEZ CABRERA
Laboratorio de Geología Andina, Centro Austral de Investigaciones Científicas, CADIC-CONICET, B. A. Houssay 200, 9410 Ushuaia, Tierra del Fuego, Argentina.
EDUARDO B. OLIVERO
Laboratorio de Geología Andina, Centro Austral de Investigaciones Científicas, CADIC-CONICET, B. A. Houssay 200, 9410 Ushuaia, Tierra del Fuego, Argentina; emolivero@gmail.com
Corresponding author
ABSTRACT
There are two contrasting opinions on the stratigraphic and palaeogeographic distribution of the relatively rare trace fossil Ophiomorpha irregulaire: 1) the trace is mostly restricted to the Upper Cretaceous of the Western Interior Seaway, or 2) it has a post-Palaeozoic record and a worldwide geographic distribution. In this study we document the finding of O. irregulaire in Upper Cretaceous turbidites of the Alta Vista Formation, southern Patagonia, providing additional evidence on the morphology and composition of its pelletal masses, the ethology of its producer and the palaeogeographical and palaeoenvironmental distribution of the trace fossil. The burrow walls are lined with dark mud and their elongate, spiky pellets are formed by a sand core that is also lined with mud. The association with typical fodinichnia, such as Halopoa, Spirophyton, and Zoophycos and the common presence of O. irregulaire in sediments with abundant plant detritus, suggest that the producer was a deposit feeder. Crosscutting relationships and occurrences at several levels within thick-bedded turbidites, suggest a relatively deep tier emplacement of the trace. The finding of the trace in the Southern Hemisphere supports its envisaged worldwide palaeogeographic distribution.
Keywords: Upper Cretaceous, southern Argentina, ichnology, Ophiomorpha irregulaire, slope deposits.
How to cite: López Cabrera, M.I. & Olivero, E.B. 2014. Ophiomorpha irregulaire and associated trace fossils from the Upper Cretaceous of Patagonia, Argentina: Palaeogeographical and ethological significance. Spanish Journal of Palaeontology, 29 (1), 33-44.
Received 25 April 2013, Accepted 08 November 2013, Published 30 June 2014
https://doi.org/10.7203/sjp.29.1.17486
