Eggshell Taphonomy: Environmental Effects on Fragment Orientation

Dinosaur eggshell is abundant in the fossil record but only during the last several decades has this reproductive product been considered more than a novelty. Recent work has provided evidence that both whole eggs and fragmented eggshell represent a rich source of information related to paleoecology and dinosaur reproductive biology. In this paper, we report the effects of environmental variables on modern eggshell fragment orientation. Non-transported eggshell fragments at hatching and predation sites favoured concave-up over concave-down orientations. Trampled fragments and fragments transported by wind and water favoured concave-down over concave-up orientations. Although differences in orientation between nontransported and transported eggshell fragments were usually obvious and significant under the chosen experimental conditions, paleontologists are cautioned to interpret the taphonomy at fossil eggshell sites with care and within their sedimentological context.