A MIXED VERTEBRATE EGGSHELL ASSEMBLAGE FROM THE TRANSYLVANIAN LATE CRETACEOUS

MARIELA S. FERNÁNDEZ; XIA WANG; MATYAS VREMIR; CHRIS LAURENT; GARY KAISER; GARETH DYKE

Caparica

Simposio; VI Symposium of Eggs and babies; 2017

To date, the vertebrate oological record is dominated by single-oospecies egg and nest assemblages, with few rare exceptions of mixed fossil eggs and eggshell assemblages. Among the extant fauna, however, there are numerous examples of disparate taxa sharing nesting areas or even the same nests. Based on these occurrences, it is parsimonious to predict similar behaviours in the past.A Late Cretaceous-aged multi-taxon nesting site from Romania, preserved in three dimensions, reveals the earliest example of nest site sharing in the vertebrate fossil record. Eggshell and osteological evidence, mixed in a single accumulation, show that at least four vertebrate taxa including enantiornithine and neornithine birds, crocodylomorphs, and gekkotan squamates were nesting at the same site. Communal nesting in enantiornithines was previously described from this site; we present the first fossil evidence that other vertebrates also nested in the same area, perhaps exploiting the presence of a large bird colony. We describe the four different eggshell types present at this site and draw palaeoecological inferences based on this inter-class nesting association.The Od accumulation is thus unique in the vertebrate fossil record: it is a multi-species nesting assemblage which reveals the earliest record of disparate animals sharing the same nesting area. We speculate that perhaps a plain area, created by seasonal flooding, offered the birds safety from predators and that the nest environments themselves offered shelter to smaller reptiles that benefitted from the security provided by those birds guarding their own nests, as is often the case in extant mixed-nesting assemblages.Acknowledgments: We would like to thanks PICT 2013-1901 for funding this investigation. Paula Troyon from CNEA, who took the pictures at SEM.