Paradi2s: PARAsitic DIversity, vectors, host and transfers in Early Cretaceous DInosaur-aSsociated vertebrates (Paradi2s)

Over geological times, biological crises and diversification events have fashioned the evolutionary history of plants and animals. Palaeontologists usually interpret the evolutionary success of a lineage and its demise in direct relation to environmental variations, including its food web and climate changes. The impact of interspecific associations, like parasitism, is usually completely neglected by palaeontologists, although parasitism and zoonotic diseases are well known to constrain the sustainable settlement of human and animal populations in historical periods. The soft body of ancient parasites is indeed extremely rarely preserved in the fossil record. However, since a dozen of years, evidences started to accumulate, showing examples of overlooked ectoparasites that were fossilized on their host (mites and fleas), fossil stools preserving digested structural inclusions, organic molecules and above all, cysts and eggs of parasites.

This project aims at

(1) analysing the parasitic content of fossilized stools of dinosaurs' associated faunas (dinosaurs and other terrestrial vertebrates) from Early Cretaceous deposits of Belgium (Bernissart), France, Lebanon, and China, focusing on non- destructive methods (micro- and nano-CT scannings). The studied fossils are 140-100 Ma in age and have been selected for (a) the already-existing knowledge about the potential stool producers, (b) their potential for parasites’ preservation from published/unpublished preliminary observations.

(2) examining for the first time large collection of dinosaurs, birds and mammals from the Lower Cretaceous of Liaoning (China) with exceptionnally-preserved plumages and furs, and of Early Cretaceous amber (fossilized tree resin) from Lebanon, for the preservation of external parasites (insects and arachnids). In parallel, the material of likely hematophagous insects (mostly dipterous) recovered from these deposits will be reexamined, focusing on their buccal appendages and relevant host range.

(3) improving our understanding of fossil feces in proposing a novel technic to image their food/parasitic content at high resolution; compare the level of preservation of some original organic molecules in and out of fossil feces (RAMAN and FTIR spectroscopy); link the fossil stools elementary composition to paleotemperatures and climate (LIBS spectroscopy).

This project will document for the first time the distribution of parasitic groups (and vectors) among terrestrial vertebrates, including dinosaurs, during the Mesozoic; and will evidence interspecific transfers of parasites, with their possible impacts on host fitness and communities as early as the Cretaceous. This would allow to decipher how parasite transfers have actually occured and affected groups of ecologically-dominant terrestrial vertebrates in the History of Life.