PALAXIUS CHOSMALALENSIS N. ISP., A NEW CRUSTACEAN MICROCOPROLITE FROM THE LOWER CRETACEOUS OF ARGENTINA AND NEW CRITERIA FOR THE CLASSIFICATION OF ICHNOSPECIES OF PALAXIUS

Diego A Kietzmann, Mariana Olivo

Resumen


Crustacean microcoprolites are abundant constituents in the Upper Jurassic–Lower Cretaceous of the Neuquén Basin (Argentina). 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 belong 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 propose to incorporate quantitative criteria regarding the angle with which the canals are oriented, as well as its position with respect to the center of symmetry of the coprolite.


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Revista de la Asociación Geológica Argentina. ISSN en línea 1851-8249.ISSN impreso 0004-4822. ISSN CD-ROM 2250-5571. Registro de la Propiedad Intelectual Nº 52500703. Asociación Geológica Argentina. Maipú 645 (1006), Buenos Aires, República Argentina. Teléfono y Fax:  (+54) 11 4325 3104. http://www.geologica.org.ar/ secretaria@geologica.org.ar