Molecular preservation in Late Cretaceous sauropod dinosaur eggshells

Abstract

Exceptionally preserved sauropod eggshells discovered in Upper Cretaceous (Campanian) deposits in Patagonia, Argentina, contain skeletal remains and soft tissues of embryonic Titanosaurid dinosaurs. To preserve these labile embryonic remains, the rate of mineral precipitation must have superseded postmortem degradative processes, resulting in virtually instantaneous mineralization of soft tissues. If so, mineralization may also have been rapid enough to retain fragments of original biomolecules in these specimens. To investigate preservation of biomolecular compounds in these well-preserved sauropod dinosaur eggshells, we applied multiple analytical techniques. Results demonstrate organic compounds and antigenic structures similar to those found in extant eggshells.

The importance of microscopic examinations of eggshells: Discrimination of bioalteration and diagenetic overprints from biological features

“…Schweitzer et al (2005) report molecular chemistry from these eggshells, yet, our analysis would suggest that caution should be exercised when interpreting the chemical data, because the CL signature clearly indicates the postdepositional movement of fluids through these structures and recrystallization that has been biomediated in several occasions (Grellet-Tinner, 2005). A number of these eggs from Auca Mahuevo were recently diagnosed as pathological by Jackson et al (2004).…”

Dinosaur Integument

“…Here, we will look at how in recent years dinosaur eggs are providing an increasing source of information on the biology and lifestyles of these fascinating reptiles. Schweitzer et al (2005) investigated the possibility of molecular preservation in Late Cretaceous titanosaurid sauropod dinosaur eggshells. The quality of morphological preservation of the fossil shells was demonstrated using transmitted light and scanning electron microscopy.…”

“…The nesting site dates from the late Cretaceous and is approximately 70-90 million years old. In addition to tiny embryonic bones, Schweitzer et al (2005) many of the eggs contain patches of delicate fossilized skin, providing the first glimpse of the soft tissue covering embryonic dinosaurs (Fig. 7.14).…”

“…This implies that as the dinosaurs matured, their necks and hind limbs grew much faster than their forelimbs and head. Schweitzer et al (2005) note that the preservation of embryonic soft tissues is highly significant because it indicates unique depositional and geochemical conditions that resulted in rapid and complete mineralization of these very labile soft tissues before degradation could occur. These taphonomic conditions extend to the eggshell, and as a result, both eggs and their contents represent a unique opportunity to elucidate taphonomic conditions resulting in exceptional preservation.…”

Will current technologies enable dinosaur proteomics?

“…When these eggshells were subjected to demineralization, an extremely strong petroliferous odor was released, indicating the association of degraded organics complexed within the mineral lattice of the shells. Rabbits immunized with titanosaurid eggshell extracts produced antibodies that reacted with chicken ovalbumin [20].…”