BIOSTRATINOMIC PROCESSES ACTING ON KATEPENSAURUS GOICOECHEAI: INTRINSIC AND EXTRINSIC FACTORS ANALYSIS. BAJO BARREAL FORMATION (UPPER CRETACEOUS), PATAGONIA, ARGENTINA Procesos bioestratinómicos actuantes en Katepensaurus goicoecheai: Análisis de factores intrínsecos y extrínsecos. Formación Bajo Barreal (Cretácico Superior), Patagonia, Argentina

CASAL, GABRIEL A.; IBIRICU, LUCIO M.; ALVAREZ, BRUNO N.; CARDOZO, NOELIA V.; CAGLIANONE, JULIETA; LUNA, MARCELO; FOIX, NICOLÁS

Publicacion Electronica de la Asociacion Paleontologica Argentina

Asociacion Paleontologica Argentina

Año: 2023 vol. 23 p. 1 - 26

Intrinsic and extrinsic factors that controlled the preservation of the rebbachisaurid sauropod Katepensaurus goicoecheai, from the Bajo Barreal Formation (Chubut Group-Upper Cretaceous) in south-central Chubut, Golfo San Jorge Basin, central Patagonia, Argentina, are analyzed. The remains were preserved in a non-channelized overbank deposit of lobed geometry, a thickness of 30 cm, and related to sandy fluvial channels. Lithologically, it is formed by coarse sandstones with an abundant pelitic and tuffaceous matrix which characterized it as a hyperconcentrated flow. The recovered elements, which comprehend mainly the axial skeleton, were found lying on pelitic deposits of a poorly-drained distal floodplain. They were partially covered for the overbank deposit; therefore, leaving expose structures which were strongly eroded. The materials are incomplete, disarticulated, and evidence a long subaerial exposure. They were not strongly mobilized by hydrodynamic processes, and reoriented normally to the direction of the overbank deposit. Lateral dispersion of the elements shows that some of them were grouped together because of hydraulic traps which in turn were produced by the larger elements located in the central position of the lobe. Smaller elements are located towards the lateral sections of the deposit, in accordance with the energy of the lobe. The scarce overbank deposit thickness did not completely bury the remains. Finally, a new overbank deposit entirely covered the materials. Katepensaurus bones accumulations would be a residual bone concentration, representing a parautochthonous accumulation of sedimentology origin.