NEOTAPHONOMIC ANALYSIS OF GALLOANSERAE EGGS: A MODERN PERSPECTIVE FOR PRESERVATIONAL CHARACTERISTICS OF DINOSAUR EGGS

This neotaphonomic study documents biogenic and geogenic mechanisms driving destruction in eggs and compares soil degradation during burial and microbiome development of over six months of domestic fowl (Superorder Galloanserae) eggs as analogs for dinosaur eggs.

Twelve chicken (Gallus gallus domesticus) and ten duck (Anas platyrhynchos domesticus) eggs were buried in two types of substrates: organic-rich topsoil from the Vegetable Systems Trial (VST) of Rodale Institute and commercial potting soil. FESEM analysis of eggshells sampled periodically over the course of six months revealed a progressive increase in microbially-induced corrosion of eggshell cuticle and membrane. Microbial communities developed more rapidly in terms of population and biodiversity in the VST than the commercial potting soil both. Eggshell exterior cuticle developed a biofilm consisting of Bacillus sp., Streptobacillus sp., coccus bacteriaand fungi. In addition, patches of biofilm dominated by diverse suite of fungi occurred around month 5. In later specimens, coccus and Bacillus sp. bacteria and fungus were found to be embedded within the individual collagen fibers of shell membrane. Collogen fibers were more frayed with time and in places the exterior sheath was missing. In addition to bacteria, numerous fungal spores and hyphae, plant debris, putative fowl mites, and nematodes were found in association with the buried eggs. The thinner shelled chicken eggs experienced vertical compression due to the drainage of amniotic fluid into the surrounding substrate coupled with consumption by decomposers. Compaction continued for the entire 6 months. The microbiome and degradational deformation observed in the modern Galloanserae eggs closely resembles observations made of fossilized fragmented dinosaur eggs.