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

CANALE, JUAN IGNACIO; APESTEGUÍA, SEBASTIÁN; GARRIDO, ALBERTO

Trelew, Chubut

Jornada; XXIII Jornadas Argentinas de Paleontología de Vertebrados; 2007

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 allows us 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, cacharodontosaurid (EC-LB), abelisauroid (LB) and deinonychosaurian (LB) theropods, and dryolestoids (LB). On the other hand, ceratodontiforms (LB), posible goniofolids (EC), rebbachisaurid (EC-LB) and titanosaurian (EC) sauropods, and abelisaurid (EC) and deinonychosaurian (EC) theropods occur in the basal section of the Huincul Formation. The distinct lithofacial features observed in both localities, respond to different environmental conditions of sedimentation. In this sense, it is posible that the dissimilar paleoenvironmental particularities occurred at EC  and LB areas, should have conducted to a different 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 abundante of eilenodontine skeletons: more than 200 specimens at LB and barely 4 at EC. Considering that both faunas are relatively abundant the absence of ornithischians in both localities is remarkable.