A multi-ootaxic assemblage from the Lower Cretaceous of the Cameros Basin (La Rioja; Northern Spain)

MIGUEL MORENO AZANZA; JOSÉ MANUEL GASCA; IGNACIO DÍAZ MARTÍNEZ; BLANCA BAULUZ; JOSÉ IGNACIO CANUDO; ARTURO FERNÁNDEZ; FÉLIX PÉREZ LORENTE

Spanish Journal of Palaeontology

SEP

Lugar: Madrid; Año: 2016 vol. 31 p. 305 - 320

2255-0550

Here we describe the new fossil site of El Horcajo inthe vicinity of Trevijano (La Rioja, Spain). It is locatedin the palustrine facies of the Enciso Group (CamerosBasin). This new locality has provided dozens of eggshellfragments, together with other vertebrate remains andcharophyte fructifications, which allow dating of thelocality as Valanginian-Hauterivian. Five ootaxa have beingrecognized: 1) the Spheroolithidae Guegoolithus turolensis;2) a surprisingly thick Prismatoolithidae indet., with certainaffi nities to the oogenus Sankofa, that may represent a newoogenus and oospecies for this oofamily; 3) the KrokolithidaeKrokolithes sp.; 4) recrystallized ?Testudoolithidae eggshells;and 5) ?Geckoolithidae eggshells of uncertain affi nity. Thisoodiversity is similar to that of other eggshell microsites.The ootaxonomic list differs from the other Iberian localityof the same age, Pochancalo 1 (Villanueva de HuervaFormation, Zaragoza) in lacking sauropod and megalosauroidtheropod eggshells, but shares the presence the ornithopodand coelurosaurian theropod eggshells with other youngermicrosites found in similar facies. The age of the new localityhas immediate consequences for the tectono-sedimentaryframework of the Cameros Basin, and the new data will needto be considered in future stratigraphical works. Furthermore,the reliability of eggshells as biostratigraphic markers isquestioned, and the viability of Guegoolithus as a guide fossilfor the lower Barremian is rejected.