Paleontology Glossary
Essential Terminology
A
Ammonite
An extinct group of cephalopod mollusks with coiled shells, closely related to modern nautiluses but more closely related to octopus and squid. Ammonites are important index fossils for Mesozoic rocks and were extraordinarily diverse from the Devonian through the end-Cretaceous mass extinction.
B
Biostratigraphy
The branch of stratigraphy that uses fossil organisms to correlate and date rock layers. Certain species that lived only during specific time intervals serve as index fossils, allowing geologists to match strata across widely separated locations.
C
Cladistics
A method of biological classification that groups organisms based on shared derived characteristics (synapomorphies) inherited from a common ancestor, resulting in a tree-like diagram called a cladogram.
Coprolite
Fossilized feces. Coprolites provide direct evidence of diet, gut contents, and feeding behavior in ancient organisms, and can preserve pollen, bones, scales, and other ingested material.
D
Diagenesis
The physical, chemical, and biological changes that affect sediment and fossil material after burial. Diagenetic processes include compaction, cementation, recrystallization, and mineralization.
E
Extinction
The complete disappearance of a species or higher group from Earth. Mass extinctions are global events in which a substantial proportion of all species disappear in a geologically short interval. The fossil record documents five major mass extinctions and numerous smaller events.
H
Holotype
The single physical specimen upon which the formal scientific description and naming of a new species is based. The holotype serves as the definitive reference specimen for that taxon in perpetuity.
I
Ichnofossil
A trace fossil: the preserved record of an organism's activity, such as footprints, burrows, feeding marks, or trackways. Ichnofossils provide behavioral evidence distinct from body fossils.
L
Lagerstätte
A sedimentary deposit that preserves fossils in exceptional quality or abundance. Plural: Lagerstätten. Famous examples include the Burgess Shale (British Columbia), the Solnhofen Limestone (Germany), and the Yixian Formation (China).
M
Morphology
The study of the form and structure of organisms, including both external features and internal anatomy. In paleontology, morphological analysis of fossil specimens is fundamental to identifying species and inferring function and phylogeny.
P
Paleoecology
The study of the relationships between ancient organisms and their environments, including community structure, predator-prey interactions, habitat preferences, and ecosystem function through geological time.
Phylogeny
The evolutionary history and relationships among groups of organisms, typically represented as a branching tree diagram (phylogenetic tree or cladogram). Phylogenetic analysis integrates fossil and living taxa.
Paleobiology
An approach to paleontology that applies biological principles and quantitative methods to understand the ecology, physiology, and evolution of ancient organisms. Paleobiology bridges geology and biology.
Permineralization
A common fossilization process in which mineral-laden groundwater infiltrates pores in bone, shell, or wood and deposits minerals, preserving the original structure in stone. Most dinosaur bones are permineralized.
R
Radiometric Dating
A suite of techniques for determining the absolute age of rocks and fossils using the known decay rates of radioactive isotopes. Common methods include uranium-lead dating, potassium-argon dating, and radiocarbon dating (the last being limited to the last ~50,000 years).
S
Stromatolite
Layered sedimentary structures formed by communities of cyanobacteria and other microorganisms that trap and bind sediment. Stromatolites represent some of the oldest evidence of life on Earth, dating back more than 3.5 billion years.
Stratigraphy
The study of rock layers (strata) and their relationships. Stratigraphic context is critical in paleontology: knowing the precise geological layer from which a fossil comes is essential for understanding its age and environment.
T
Taphonomy
The study of how organisms decay and become fossilized, including the processes of death, decomposition, burial, and diagenesis that determine what is preserved and what is lost from the fossil record.