Analysis of Asteriacites von Schlotheim 1820 from Mulichinco Formation (Lower Cretaceous, Neuquén Basin) and ichnotaxonomic implications

GIACHETTI, L.; FERNÁNDEZ D. E.; COMERIO M.

Revista de la Asociación Geológica Argentina

Asociación Geológica Argentina

Año: 2020

1853-7138

The last review of Asteriacites (Knaust and Neumann 2016) dismissed sculpture as an ichnotaxobase for this ichnogenus and usedsimple morphometric parameters to differentiate the ichnospecies, reducing them to three: A. lumbricalis, A. stelliformis, and A. quinquefolius.In this work, ichnotaxonomic tools are discussed through the analysis of trace fossils assigned to this ichnogenus from theMulichinco Formation (Valanginian) of the Neuquén Basin, northern Patagonia. New Asteriacites-bearing levels from different localitiesare described, and specimens that were previously assigned to A. lumbricalis are reassigned to A. stelliformis. Taking into account thismaterial and previous works where Asteriacites were analysed, we observed that some problems arise in the ichnospecific assignmentwhen applying the methodology of Knaust and Neumann (2016). Therefore, in this work, three simple criteria were incorporated to facilitatethe ichnospecific assignment through this morphometric approach. It is also noted that the specimens with epirelief preservationare challenging to identify because the delineation of the edge of the trace, necessary for the morphometric analysis, depends on theused methodology. Additionally, examples of previous works are analysed, allowing discussion of proposed ichnospecific ichnotaxobasesand the relevance of sculpture