Contents lists available at ScienceDirect Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo Middle Triassic Pentasauropus-dominated ichnofauna from western Gondwana: Ichnotaxonomy, palaeoenvironment, biostratigraphy and palaeobiogeography Abdelouahed Lagnaoui a,d, ⁎ , Ricardo N. Melchor a,b , Eduardo S. Bellosi c , Pablo M. Villegas a , Nahuel Espinoza a , Aldo M. Umazano a,b a Instituto de Ciencias de la Tierra y Ambientales de La Pampa (CONICET and Universidad Nacional de La Pampa), Mendoza 109, 6300 Santa Rosa, La Pampa, Argentina b Departamento de Geología, Universidad Nacional de La Pampa, Av. Uruguay 151, 6300 Santa Rosa, La Pampa, Argentina c CONICET, Museo Argentino de Ciencias Naturales, Av. Ángel Gallardo 470, C1405DJR, Buenos Aires, Argentina d Laboratory of Stratigraphy of Oil-and-Gas Bearing Reservoirs, Institute of Geology and Petroleum Technologies, Kazan (Volga Region) Federal University, Kazan, Russia ARTICLE INFO Keywords: Pentasauropus argentinae nov. isp. Dicynodont trackmaker Behaviour Chirotherian track Anisian-Ladinian Argentina ABSTRACT Quadruped trackways of large pentadactyl footprints are reported from the Middle Triassic (Anisian-Ladinian) Cerro de las Cabras Formation of the Cuyo Basin, Mendoza Province, central-western Argentina. The track- bearing strata are interpreted as deposited by sheetfloods in a mixed flat where water was ponded in a playa-lake setting. The vertebrate trackways are assigned to the ichnogenus Pentasauropus, originally described from the Upper Triassic Elliot Formation of South Africa, based on the presence of five equally spaced digit imprints that form an anteriorly convex broad arcuate pattern. A new ichnospecies, Pentasauropus argentinae nov. isp., is erected for the Argentinian material because of the distinct heteropody, inward rotation of the pes and outward rotation of the manus imprints, and the presence of palm/sole traces, and the diagnosis of the ichnogenus is emended. Pes/manus set arrangement and trackway patterns indicate a sprawling limbed trackmaker with an abducted posture for the fore-limbs and at least a semi-abducted posture for the hindlimbs, which suggests that the trackmaker was a kannemeyeriiform dicynodont. Associated archosaur ichnotaxa (Chirotherium barthii, Chirotherium cf. C. rex, Isochirotherium cf. I. coureli) point to a Middle Triassic age for the trackway-bearing strata in agreement with bracketing geochronological data. The rare occurrence of the therapsid footprint Dicynodontipus isp. is also compatible with the inferred age. The moderate abundance and oldest occurrence of Pentasauropus from three areas in Argentina suggest an origin for this ichnogenus in southwestern Gondwana, and presumably this area was a faunal exchange gate between southeastern and southwestern Gondwana and south Gondwana and North America. 1. Introduction Argentina is an important area to understand the evolution of Early Mesozoic fossil ecosystems, due to the relative large basins, the oc- currence of corresponding body- and trace-fossils and its connection with southeastern Gondwanan faunal provinces (Bonaparte, 1969a,b; Goñi and Goin, 1988; Goñi and Abdala, 1989). The faunal links be- tween Triassic terrestrial vertebrate assemblages from South America and Africa are still rare (Abdala and Smith, 2009; Abdala et al., 2013). The Triassic vertebrate track record is relatively poor considering the geographical extent of the continental basins in Argentina, although several ichnoassemblages have been described (Casamiquela, 1964; Melchor et al., 2001a, 2003; Melchor and De Valais, 2006; Marsicano and Barredo, 2004; Marsicano et al., 2004, 2010). Moreover, the record of Middle Triassic tetrapod footprints from Argentina is rare in com- parison to numerous occurrences in North America, Africa and Europe. Worldwide, the most abundant vertebrate ichnofaunas during that time are chirotheriid-dominated, belong to a wide range of groups, including therapsids, parareptiles, lepidosauromorphs, non-archosauriform arch- osauromorphs, non-archosaurian archosauriforms, crocodilian-stem and dinosauromorph archosaurians (i.e., Avanzini and Lockley, 2002; Haubold and Klein, 2002; Avanzini and Mietto, 2008; Klein and Haubold, 2007; Klein and Lucas, 2010a,b; Klein et al., 2011, 2018; Díaz-Martínez et al., 2015; Santi et al., 2015; among others). https://doi.org/10.1016/j.palaeo.2019.03.020 Received 22 December 2018; Received in revised form 12 March 2019; Accepted 13 March 2019 ⁎ Corresponding author at: Instituto de Ciencias de la Tierra y Ambientales de La Pampa (CONICET and Universidad Nacional de La Pampa), Mendoza 109, 6300 Santa Rosa, La Pampa, Argentina. E-mail address: abdelouahedlagnaoui@gmail.com (A. Lagnaoui). Palaeogeography, Palaeoclimatology, Palaeoecology 524 (2019) 41–61 Available online 20 March 2019 0031-0182/ © 2019 Elsevier B.V. All rights reserved. T