LAUSR

The recent article published by Pazos et al. (2019) consists of a description of one tyreophoran track in deltaic deposits of the Middle Jurassic Lajas Formation, Neuquén basin, Argentina. In their sedimentological interpretation of the succession, the authors referred to several aspects of previous contributions (Zavala and González, 2001; Zavala, 2002; Canale et al., 2015), incurring in omissions and incorrect statements that we consider should be clarified, in order to avoid generating confusion in one of the classic Lajas Formation section in the Neuquén basin. 1Pazos et al. (2019) made serious omissions about the origin and previous studies in the Lajas Formation mentioning that “A robust sedimentary facies model is based on the study of a series of outcrops belts situated onto or to the south of Huincul High (e.g. McIlroy et al., 2005; Rossi and Steel, 2016; Gugliotta et al., 2015a,b; 2016a,b; Kurcinka et al., 2018; Steel et al., 2018).” Pazos et al. (2019) cannot ignore the excellent and detailed work performed by Yacimientos Petrolíferos Fiscales (YPF) during the eighties and nineties, summarized in Gulisano and Pando (1981), Gulisano et al. (1984), Legarreta and Gulisano (1989), and Gulisano and Gutiérrez Pleimling (1995). In particular, the first detailed facies characterization of deltaic deposits in Puesto Seguel area was performed by Gulisano and Hinterwimmer (1986). Zavala (1993) measured and analyzed in detail more than 6 km of stratigraphic sections located southward of the Huincul Arch, discussing facies, sequence stratigraphy and also the interaction between fluvial and tide-dominated deltas (Zavala, 1996a, b). 2Pazos et al. (2019) mentioned “... while Canale et al. (2015a,b) for the locality studied in this paper suggested hyperpycnal fluvial discharges to the base (prodelta) and wave action to the top.” This is not correct. Canale et al. (2015a,b) interpreted the deposits of the Lajas Formation in the areas of Arroyo Covunco (AC) and Sierra de la Vaca Muerta (SVM) as accumulated in a fluvio-dominated deltaic system, frequently affected by hyperpycnal discharges and reworked by wave action. Hyperpycnites have been recognized not only within prodelta facies, but in all analyzed subenvironments. Hyperpycnal channels and lobes in AC and SVM were also documented by Zavala and González (2001) for the first time. Alternatively, Canale et al. (2015a,b) highlighted the fluvio-dominated character of the system over tide and wave influences, suggesting that hyperpycnal deposits were common all along the deltaic succession. 3Pazos et al. (2019) also indicated, “Contrarily, in outcrops to the north of the Huincul High, in both Sierra de la Vaca Muerta and Covunco area (Fig. 1, area 1) there are only a few and less detailed studies ...” Pazos et al. (2019) omitted the existence of highly detailed sedimentological and ichnological studies that determined for the first time the fluvio-dominated character of the deltaic deposits exposed in AC and SVM (Canale and Ponce, 2012; Ponce et al., 2012; Canale et al. 2015a,b, 2016). Curiously, the work of Canale et al. (2015a,b) is later recurrently discussed. In addition, the authors ignored a large number of contributions related to detailed palynological analyses, which provided significant paleoenvironmental information of the Lajas Formation in these localities (Volkheimer, 1970, 1978; Quattrocchio and Sarjeant, 1992; Martínez et al., 2001, 2016; Quattrocchio et al., 2001; Martínez and Quattrocchio, 2005). 4Pazos et al. (2019) stated that their paper “... confirms the original idea of Zavala (2002) and invertebrate palaeontologists (see below) that the Covunco section is Bathonian–Callovian in age.” This is incorrect. Zavala (2002) never mentioned that age for the