Taphonomy

Traces and behaviour

Investigating the interval between death and discovery

How do remains end up together in the same layer? Taphonomy studies the processes and changes between an organism’s death and its discovery as a fossil.

Twenty more or less complete right ornithomimosaur tibiae found at Angeac-Charente; the figure alone does not establish why they accumulated. © Lilian Cazes and Lee Rozada. Dinosaures, les géants du vignoble, 2017, p. 206.

The method in practice

The investigation begins in the field: positions, relationships between fragments, sediments and surface traces are recorded before collection. In the laboratory, researchers study fractures, weathering, bite marks and scratches. They test these clues against hypotheses and may use experiments.

At Angeac and in regional comparisons

Angeac’s concentration of ornithomimosaur bones raises questions about transport, decomposition and activities that altered the remains. A trampling experiment in 2013 compared scratches on modern bones with those on the fossils. The spatial distribution of specimens is studied alongside their preservation.

Crocodile bite marks on an ornithomimosaur tibia. © Lilian Cazes. Dinosaures, les géants du vignoble, 2017, p. 222.

What this research reveals

Bone distribution and preservation help assess transport, trampling and feeding by other animals. They do not always provide a single explanation for death. The synthesis published by Rozada and colleagues in 2021 examines these questions using field data.

Examining the evidence

Reading marks on fossil surfaces

Shell plate ANG 14R-534a bears a puncture attributed to a goniopholidid crocodile bite (A–B). One ornithomimosaur bone fragment has hook-shaped grooves (C), while another bears multiple trampling marks (D).

Bite marks and trampling traces on bones — Photographs: L. Cazes, MNHN. Figure 12, Rozada et al., 2021. Scientific article · DOI 10.1111/let.12394 · Click to enlarge the figure.

How to read the evidence

A single mark does not reveal a fossil’s entire history. Its shape, recurrence and context must be compared before an interpretation can be proposed.

People and expertise

Lee Rozada studies the formation of the fossil assemblage and changes to the bones. This work combines evidence from specialists in animals, rocks, trace fossils and geochemistry.

Lee Rozada

All the people behind the project →