The Maastrichtian L’Espinau hadrosauroid bonebed (NE Iberian Peninsula)

摘要: The L’Espinau hadrosauroid bonebed was discovered in 2010 in the Àger Syncline (southern Pyrenees, Catalonia) in the Tremp Formation. The unit records a transition from lacustrine to fluvial environment, which took place during the Maastrichtian (Riera et al., 2009). More than 500 complete and fragmented hadrosauroid bones have been excavated between 2010 and 2014, the majority of which belongs to postcranial and appendicular skeleton. Also, the site yields crocodile (teeth and vertebrae), fish and invertebrate remains, as well as megaloolithid and prismatoolithid eggshells (Sellés et al., 2014). The fossiliferous layer is deposited within ochre and reddish marls and consists of a 40 cm-thick layer of homogeneous grey marl (45% of CaCO3) with no sedimentary structures. This bed contains abundant plant remains (often in the form of coals) and charophytes and exhibits signs of plant bioturbation or mottling towards the top. The recovered bones are not found in anatomical connection and they are covered with grey and white carbonate crusts. They occur floating within the matrix instead of being deposited at the base of the grey layer. A preliminary study of the remains found during the 2010-2012 campaigns shows that virtually all the bones are characterized by fractures and they are eroded at the edges. A macroscopic study of samples from the first three excavations revealed a predominance of transverse fractures (65%) attributable to diagenetic causes rather than biostratinomic (Behrensmeyer, 1975). Very few bones are affected by bite marks and scavenging, and there are no signs of cracking or flacking. This fact suggests a rapid …