Foundations of Taphonomy

Understanding Taphonomy What is Taphonomy? Taphonomy is the study of all processes that affect objects after they leave living contexts, become buried, and are later recovered. The term comes from the Greek words "taphos" (burial) and "nomos" (law), literally meaning "the laws of burial." Understanding taphonomy is essential for paleontologists and archaeologists because it helps explain how organisms transform from living animals into fossils, and what happens to them during that journey. When you find a fossil in the field, it's rarely a pristine snapshot of an ancient organism—it's the product of many overlapping natural processes. Taphonomy helps us decode what actually happened. The Two Major Phases of Taphonomy Taphonomic processes are organized into two broad phases that describe when different changes occur relative to burial. Biostratinomy: Before Burial Biostratinomy encompasses all events that occur between an organism's death and its burial. Think of this as what happens to remains while they're still exposed on the surface (or in shallow water). During this phase, several important processes occur: Disarticulation: Bones and body parts separate from each other as connective tissues decay Scattering and dispersal: Flowing water, predators, or scavengers move bones away from the original death site Exposure to weathering: Sun, wind, and temperature changes begin breaking down bone These processes can spread the remains across a wide area, making it difficult to reconstruct the original organism or understand how it died. Diagenesis: After Burial Diagenesis includes all physical and chemical changes that occur after burial of the remains. Once bones are covered by sediment and protected from surface weathering, a different set of processes takes over: Chemical alteration: Groundwater carries minerals that can replace or fill the internal structure of bone Physical compaction: Weight of overlying sediments squeezes and deforms remains Mineralization: New minerals can form within the bones, making them harder and more preservable The key difference between these phases is protection: biostratinomy is about exposure and degradation, while diagenesis is about transformation in a protected burial environment. The Five Main Stages of Taphonomy While the two major phases describe when changes occur, taphonomists also recognize five specific types of changes that can happen at various stages: 1. Disarticulation: The separation of connected bones. When an animal dies, its skeleton holds together through ligaments and cartilage. As these tissues decay (especially in the first few weeks to months), joints fall apart. This is why you rarely find a complete skeleton with all bones in their original positions. 2. Dispersal: The movement and scattering of remains. Water currents, gravity on slopes, and animal activity can carry bones far from their original position. A single skeleton can end up scattered across meters or even kilometers. 3. Accumulation: The gathering of bones in specific locations. Sometimes bones are transported and redeposited in areas where they concentrate—like on a river bar or in a cave. This can create bone beds containing the remains of many individuals. 4. Fossilization: The process of bones being replaced or filled with minerals, hardening them and making them last millions of years. Without fossilization, bones would simply crumble to dust. 5. Mechanical Alteration: Physical damage to bones from transport, pressure, or interaction with other objects. Bones can be cracked, scratched, or broken during any stage of taphonomy. Chemical Changes Throughout Taphonomy An important concept that cuts across all stages: chemical changes caused by bacteria occur at every stage of taphonomy, beginning immediately at death and continuing even after burial. When an organism dies, its cells begin releasing enzymes that break down proteins and other organic compounds. Bacteria colonize the tissues and accelerate this breakdown. This process: Starts the moment death occurs (during biostratinomy) Continues after burial (during diagenesis) Eventually leads to mineralization, where remaining organic material is replaced by minerals from groundwater This is why taphonomy isn't simply divided into "surface processes" and "burial processes"—biological decay is always happening, everywhere, gradually transforming the remains at a chemical level. Why Taphonomy Matters for Reconstructing the Past Knowledge of taphonomic processes provides essential contextual information for reconstructing ancient ecological, cultural, and environmental conditions. Here's why this matters: For Ecology: If you find bones scattered and disarticulated, you need to know whether that represents an actual ancient community that lived together, or whether water current scattered them. Taphonomy tells you the difference. For Behavior: If bones show scratch marks and damage, was that caused by a predator during the kill, or by sediment transport afterward? Understanding taphonomy helps you distinguish genuine evidence of animal behavior from diagenetic artifacts. For Environment: Taphonomic patterns can reveal information about ancient climates, water levels, and sediment conditions. For example, bones preserved in anoxic (oxygen-free) mud are better preserved than those exposed to oxidation, telling you something about the burial environment. Without understanding taphonomy, paleontologists could misinterpret their findings completely. With it, fossil remains become a reliable window into the deep past.