Contents lists available at ScienceDirect Journal of South American Earth Sciences journal homepage: www.elsevier.com/locate/jsames Late early Miocene caviomorph rodents from Laguna del Laja (~37° S), Cura-Mallín Formation, south-central Chile Andrés Solórzano a,∗ , Alfonso Encinas b , Alejandro Kramarz c , Gabriel Carrasco d , Germán Montoya-Sanhueza e , René Bobe f a Programa de Doctorado en Ciencias Geológicas, Facultad de Ciencias Químicas, Universidad de Concepción, Víctor Lamas, 1290, Concepción, Chile b Departamento de Ciencias de la Tierra, Facultad de Ciencias Químicas, Universidad de Concepción, Víctor Lamas, 1290, Concepción, Chile c Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales Bernardino Rivadavia, Av. Ángel Gallardo 470 (C1405DJR), Ciudad Autónoma de Buenos Aires, Argentina d Servicios Científicos Educativos y Turismo Científico Chile, Pedro León Ugalde 254, San Bernardo, Chile e Department of Biological Sciences, University of Cape Town, Cape Town, South Africa f School of Anthropology, University of Oxford, UK ARTICLE INFO Keywords: Santacrucian SALMA Neogene fossils rodents Echimyids Dasyproctids “Eocardiids” Lagostomines Early Miocene paleoenvironments ABSTRACT Despite recent efforts, the paleodiversity of the Neogene mammals in Chile remains poorly known, with several putative new species awaiting description. For example, previous studies suggest that the early to late Miocene mammalian assemblages from the Laguna del Laja fossiliferous locality (Cura-Mallín and Trapa-Trapa forma- tions), which crop out in the Andean Cordillera of Chile (~37°), comprise dozens of undescribed taxa. A better understanding of the taxonomic affinities of the Laguna del Laja faunas is needed, as it represents one of the few faunas known from the early to late? Miocene of the south-central Andean main range. Several specimens of caviomorphs recently recovered in late early Miocene beds of the Cura-Mallín Formation at Laguna del Laja are here described in detail, and a brief discussion of their chronological, biogeographical, and paleoenvironmental significance is also provided. Based on fragments of mandible, maxilla and isolated teeth five taxa were re- cognized, Phanomys mixtus Ameghino, Prolagostomus sp., Neoreomys sp., Maruchito nov. sp.?, and Luantus som- pallwei nov. sp. The radiometric ages of the fossil-bearing horizons, constrained between 17.7 and 16.4 Ma, as well as the common species (P. mixtus) and genera (Prolagostomus and Neoreomys) indicate that the fauna here reported belongs to the Santacrucian SALMA. Finally, our finding preliminary suggests the predominance of rather open habitats in the Cura-Mallín Formation during this time, but also a widely distributed late Early Miocene caviomorph fauna along the southern Andes, in both intra-arc and foreland basins. 1. Introduction Caviomorpha is a taxonomically and ecomorphologically diverse clade of hystricognath rodents endemic to the Americas and Caribbean islands that comprises nearly 250 extant species distributed among 52 genera and 10 families (Álvarez et al., 2011; Patton et al., 2015; Upham and Patterson, 2015). Caviomorphs have a long evolutionary history, and their representation in the South American fossil record begins in the late middle Eocene deposits of Contamana, Peru (Antoine et al., 2012; Boivin et al., 2017). Slightly younger assemblages indicate an early diversification of the group since the late Eocene? and early Oli- gocene as exemplified by the Santa Rosa (Peru), Tinguiririca (Chile) and La Cantera (Argentina) faunas (Álvarez et al., 2017; Arnal et al., 2019a; Bertrand et al., 2012; Frailey and Campbell Jr, 2004; Vucetich et al., 2010b). Early Miocene caviomorphs were also diverse with 36 genera recognized in the Colhuehuapian and Santacrucian SALMA faunas, mostly recognized in several localities in the Argentinean Pa- tagonia (Ameghino, 1889, 1894; Arnal et al., 2019b; Kramarz et al., 2010; Kramarz and Bellosi, 2005; Scott, 1905; Vucetich et al., 2010a, 2015). However, in contrast with neighboring geographical areas such as Argentina, work focused on Chilean caviomorph paleodiversity is still scarce. Recent findings indicate the presence of several distinctive early Miocene rodent assemblages in Chile (Bostelmann et al., 2013, 2012; Charrier et al., 2015; Croft et al., 2008; Flynn et al., 2002b, 2002a), but some of them are poorly studied. This is the case of the rodent assemblages of the Cura-Mallín Formation in south-central Chile. The Cura-Mallín Formation consists of a series of upper Oligocene to https://doi.org/10.1016/j.jsames.2020.102658 Received 14 February 2020; Received in revised form 15 May 2020; Accepted 19 May 2020 ∗ Corresponding author. E-mail address: solorzanoandres@gmail.com (A. Solórzano). Journal of South American Earth Sciences 102 (2020) 102658 Available online 31 May 2020 0895-9811/ © 2020 Elsevier Ltd. All rights reserved. T