A comparison between “La Buitrera” and “El Chocón” local faunas.

CANALE, J. I., APESTEGUÍA, S. Y GARRIDO, A. C.

Trelew

Jornada; XXIII Jornadas Argentinas de Paleontología de Vertebrados; 2007

Museo Egidio Feruglio

Along the last decades, the fossil findings around the Ezequiel Ramos-Mexía lake has improved the list of cretaceous tetrapods, particularly by two local faunas: “El Chocón” (EC) and “La Buitrera” (LB), representing the boundary between the Candeleros and the Huincul formations. An attempt to compare both localities allow to recognize the faunal composition of the Limayan assemblage. The upper Candeleros Formation provided ceratodontiforms (LB), pipoids (EC) and possible leptodactyloids (LB), chelids (EC-LB), eilenodontines (EC-LB), iguanids (LB), snakes (LB), araripesuchids (EC-LB), neosuchians (LB), pterosaurs (LB), rebbachisaurid (EC-LB) and basal titanosaur (EC) sauropods, carcharodontosaurid (EC-LB), abelisauroid (LB) and deinonychosaurian (LB) theropods, and dryolestoids (LB). On the other hand, in the basal section of the Huincul Formation occur ceratodontiforms (LB), possible goniofolids (EC), rebbachisaurid (EC-LB) and titanosaurian (EC) sauropods, and abelisaurid (EC) and deinonychosaurian (EC) theropods. The distinct lithofacial features observed between both localities, respond to different environmental conditions of sedimentation. In this sense, is possible that the dissimilar paleoenvironmetal particularities occurred at EC and LB areas, should have conducted to a different distribution and habitat preferences of the biota, as well as in the taphonomical mode of preservation. This sittuation is not absolute, but a trend, which can be clearly shown in the relative abundance of eilenodontine skeletons: more than 200 specimens at LB and barely 4 at EC. Considering that both faunas are relatively abundant is remarkable the total absence of ornithischians in both localities.