Nanoscopic imaging of ancient protein and vasculature offers insight into soft tissue and biomolecule fossilization.

Fossil bones have been studied by paleontologists for centuries. Despite this, empirical knowledge regarding the progression of biomolecular (soft) tissue diagenesis within ancient bone is limited; this is particularly the case for specimens spanning Pleistocene directly into pre-Ice Age strata. A nanoscopic approach is reported herein that facilitates direct imaging, and thus empirical observation, of soft tissue preservation state. Presented data include the first extensive nanoscopic (up to 150,000× magnification), three-dimensional (3D) images of ancient bone protein and vasculature; chemical signals consistent with collagen protein and membrane lipids, respectively, are also localized to these structures. These findings support the analyzed permafrost bones are not fully fossilized but rather represent subfossil bone tissue as they preserve an underlying collagen framework. Extension of these methods to specimens spanning the geologic record will help reveal changes biomolecular tissues undergo during fossilization and is a potential proxy approach for screening specimen suitability for molecular sequencing.