Los Rastros Formation

The formation overlies the Chañares Formation (and/or the Ischicuca Formation), and is overlain by the Ischigualasto Formation. The formation belongs to the Agua de la Peña Group of the Ischigualasto-Villa Unión Basin, where it is exposed in the Ischigualasto Provincial Park, a World Heritage Site in Argentina. The up to thick formation of claystones, mudstones and sandstones was deposited in a deltaic to lacustrine environment during the first post-rift sequence in the basin. A CA-TIMS U-Pb zircon age of 234.47 ± 0.44 Ma from the lower Los Rastros Formation was published in 2020. The acquired age demonstrates that most of the overlying lacustrine strata within the basin were deposited during or after the Carnian Pluvial Event (CPE). == Paleobiota ==

The only tetrapod body fossil reported from the Los Rastros Formation is a poorly-preserved temnospondyl amphibian. Most of the trackways are symmetrical prints created by animals with a narrow bipedal stance, three toes contacting the ground, and a raised fourth toe. They were presumably early dinosaurs or dinosauromorphs, the generalized nature of Triassic dinosaurs and their relatives prevent a precise referral. Another form of trackway consists of numerous non-overlapping sets of broad rounded depressions on a heavily trampled wackestone surface. They may have been left by a herd of dicynodonts walking down to the lakeshore. Palaeophycus tubularis invertebrate burrows are also abundant. Other insects Plants A wide variety of plant fossils are known from the Los Rastros Formation, including both microfossils Most species from the formation have been listed by Lutz et al. (2011) and Pedernera et al. (2020). • Calamitales • Coniferales • Cycadales • Equisetales • Osmundales • Rhexoxilales Seed ferns Other gymnosperms Other plants == See also ==