Reptilian coprolites in the Eocene of central Patagonia, Argentina

Abstract

Biogenic structures, herein interpreted as coprolites, were recorded in the ?upper Paleocene–Eocene Las Flores Formation, southeast Argentina. The coprolite origin is supported by several features, such as recurrent extrusive external morphology, longitudinal wrinkles, flattening of the ventral side, concentric and radial cracks, cryptocrystalline groundmass, and a phosphatic composition. A detailed comparative study with modern fecal masses, based on morphology, surface texture, micromorphology, mineralogical and chemical composition, suggest a crocodylian as the most probable producer, an interpretation also supported by the Patagonian paleontological record. This discovery, the first record on coprolites from Central Patagonia, provides new paleoenvironmental and paleoecological information for the studied successions.

New age constraints for early Paleogene strata of central Patagonia, Argentina: Implications for the timing of South American Land Mammal Ages

“…We note that the association frequently made in the literature of the Ernestokokenia faunal zone and Riochican SALMA with the Koluel-Kaike Formation (Legarreta et al, 1990;Legarreta and Uliana, 1994;Bond et al, 1995;Woodburne et al, 2014a) is somewhat misleading because no rocks assignable to the Koluel-Kaike Formation (e.g., silicified and pedogenized tuffs) are actually found along the coast where the relevant fossil sites are located. In the coastal area where the Ernestokokenia faunal zone fossils were recovered, the upper Río Chico Group is composed of sandstones and mudstones that are lithostratigraphically assignable to the Peñas Coloradas and Las Flores Formations (Krause et al, 2010;Raigemborn et al, 2010;Krause and Piña, 2012), with the Ernestokokenia faunal zone restricted to beds from the Las Flores Formation in this area.…”

“…1B), the Las Flores Formation becomes sandier (e.g., Pico Salamanca area, close to Bajo Palangana; Fig. 1B; Krause and Piña, 2012) and thicker, with sections of more than 100 m thickness (Krause, 2010). Similar sandy and muddy facies in sections with thicknesses of ~140 m, including both the Peñas Coloradas and Las Flores Formations (= Riochiquense sensu Feruglio, 1949), were recorded in the Punta Peligro area by Feruglio (1949).…”

“…Similar sandy and muddy facies in sections with thicknesses of ~140 m, including both the Peñas Coloradas and Las Flores Formations (= Riochiquense sensu Feruglio, 1949), were recorded in the Punta Peligro area by Feruglio (1949). Sedimentary facies of the Las Flores Formation have been interpreted to have been deposited in lacustrine and fluvial floodplain and channel environments (e.g., Raigemborn et al, 2009Raigemborn et al, , 2010Krause and Piña, 2012). The muddy facies contain evidence of pedogenic processes, such as mottles and rhizo liths.…”

“…Fossils in the study area include vertebrate remains that are attributed to the Itaboraian SALMA (Bond et al, 1995;Goin et al, 2009;Woodburne et al, 2014b) and phyto lith remains (Brea et al, 2008;Raigemborn et al, 2009). Crocodilian coprolites were also described from the Las Flores Formation in the coastal area of Pico Salamanca, 4-5 km to the east of Bajo Palangana (Krause and Piña, 2012).…”

“…At the Las Flores Formation type locality, this white tuff is absent, but the orange-reddish mudstones are present, allowing lithostratigraphic correlation of tuff sample 12CB01 to the Las Flores Formation type section. The muddy facies exposed as badlands constitute the middle-upper section of the Las Flores Formation at Las Flores and Cerro Blanco, but more sandy facies are recognized to the east, for instance, in the coastal area (e.g., Krause and Piña, 2012). Las Flores Formation facies correspond to distal floodplain deposits (massive mudstones) and sinuous channels (sandstone, tuffs, and tuffaceous sandstones; e.g., Krause and Piña, 2012).…”