What is palaeontology?
‘The study of ancient life through fossil remains or traces of its activity recorded in ancient sediments.’
Paleo (old) + ontology (life/beings)
Rocks = age & environment
Biology = life/lifestyle & environment
Taphonomy: “the study of the transition (in all its details) of animal remains from the biosphere into the lithosphere”
The fossil record is incomplete. Most organisms do not become fossils. Study of organisms from death to fossils is termed taphonomy
Information from fossils
1. Time: organisms live for specific periods of time. Vertical ranges in layers of rock. Time zones.
2. Evolutionary relationships: fossil record shows large-scale patterns of evolutionary change. Shape of life on Earth.
3. Biotic information (palaeoecology): relationship between ancient organisms and environments. Evolutionary palaeoecology studies large-scale trends in ecological processes through time.
4. Abiotic information (palaeoenvironment): physical nature of the Earth through time, e,g., a) radiations linked to O2 increase in atmosphere, b) changes in 16O/18O ratio.
5. Biogeography: Changes in patterns of faunal provinces through time. E.g. tectonic plates as evidence for continental drift.
Types of fossils
Body fossils: remains of living organisms. Usually hard tissues e.g. bones, shells.
Trace fossils: preserved impressions of biological activity. Direct indicators of fossil behaviour, e.g., burrows, footprints, tooth marks, cut marks, fossil faeces (coprolites)
Chemical fossils: chemical signature left by some organisms after decomposition, e.g. in some plants chlorophyll breaks down into distinctive molecules.
Biases in the fossil record