Palaxius chosmalalensis n. isp., a new crustacean microcoprolite from the Lower Cretaceous of Argentina and new criteria for the classification of Palaxius ichnospecies

KIETZMANN, D.A.; OLIVO, M.S.

REVISTA DE LA ASOCIACIÓN GEOLÓGICA ARGENTINA

Asociación Geológica Argentina

Lugar: Ciudad Autónoma de Buenos Aires; Año: 2020 vol. 77 p. 352 - 365

1853-7138

Crustacean microcoprolites are abundant constituents in the Upper Jurassic?Lower17 Cretaceous of the Neuquén Basin. A new record of these particles is described from the lowermost Olcostephanus (O.) atherstoni ammonite Zone (lower Valanginian) in the Mulichinco Formation at Puerta Curaco section, north of the Neuquén province. Coprolites come from shallow-water oyster-dominated biostromes and belongs to a new ichnospecies, Palaxius chosmalalensis n. isp., which was previously described as P. decemlunulatus (Paréjas) from the Upper Cretaceous of Egypt. As a consequence of the description of the new ichnospecies, we proposed to incorporate quantitative criteria regarding the angle with which the canals are oriented, as well as its position with 24 respect to the center of symmetry of the coprolite.