FIORELLI lucas Ernesto
congresos y reuniones científicas
Ciudad de Neuquén, Argentina
Congreso; III Congreso Latinoamericano de Paleontología de Vertebrados; 2008
Institución organizadora:
Universidad Nacional del Comahue
Bite mark and injuries by predations or aggressive social behavioral between conspecifics are not frequent in fossils vertebrate. Moreover, in the archosaurians fossil record such characteristic features are very extraordinary (Buffetaut, 1983; Tanke & Currie, 1998; Avila et al., 2004). Here is reported a peirosaurid crocodyliform –MUCPv-27– from the Bajo de la Carpa Formation, Upper Cretaceous beds of Neuquén Group, Argentina (Fiorelli et al., 2007) with abundant bite marks and injuries. These wounds there are practically in all preserved remains of the specimen, with a highest concentration (more than 70) of bite marks, perforations, punctures, fractures and “scratches” on the caudal section. In the articular dorsal sequence, there are some breakages in the vertebrae (lacking of their centra) and his neural spines are very damaged. Even so, there are aligning rows of circular big perforation located in both side of the dorsal paravertebral dermostea. Such characteristic is observed in the tail too that preserved the caudal axial skeleton enclosed completely by the articulated and imbricates dermostea. This caudal region is crushed in a direction that is coplanar with the axes that join the ventral and dorsal bite marks. Moreover, the perforations are directed from the outside towards the inside to the plates. The caudal vertebrae and hemal arches showing also several damages and aligned bite marks. All these perforations are extremely characteristic with circular or like-eye form; his diameter ranges varies of 3 mm to 20 mm. and are filled fully by sediment with radial grooves in the internal face of dermostea. The results shared that such injuries were not realized by social behaviors and conspecific fighting like was hypothesized by Avila et al (2004) for other related crocodyliforms. In this case, this marks were do it by a big predator (possibly a great theropod dinosaur) since the bite marks and punctures are numerous producing an enormous damage and the death to this peirosaurid. The remains were found in yellow quartz-rich sandstones on ephemeral fluvial currents of an interdune area from fluvio-eolian deposits at the universitary campus quarry. The biostratinomic attributes were the more than important taphonomic processes. Only displayed bite marks and a low dismemberment generated exclusively by the predator. Moreover, do not showing climatic damage, bioerosion, accumulated abrasion or corrosion, physic transport or other biostratinomic characteristics. The articulated vertebrae and imbricate osteodermal plates, the rows of bite marks filling on fully by sediments, the coplanar deformation by the bites, the low disarticulation and fragmentation are showing the absence of selective transport and a quick buried. Thus, these taphonomic attributes suggest that MUCPv-27 peirosaurid was exposed to weather inclemency on the order of some hours to a few days. Moreover, this attributes are highly homogeneous in all quarry (i.e., articulated and well preserved remains of Notosuchus and Dinilysia or several avian eggs in nests) and implies a very low time averaging.