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Smithsonian National Museum of Natural History

Draft Glossary of Paleoecological Terms and Phrases


Adaptation: characteristic of an organism that has been favored by natural selection.

Alpha diversity: biodiversity within a particular area, community or ecosystem at a particular time. It is often measured simply as species richness, but some measurements use a combination of richness and abundance.

Analytical time averaging:
the process of combining samples after collection for data analysis.

Beta diversity: turnover of diversity across multiple areas, communities or ecosystems or across time.

Binning: the process of categorizing samples (or species) using a continuous variable that has been divided into smaller divisions (e.g., million year time bins, or body size bins)

Biome: a persistent climate-vegetation system that covers a significant area.

Centrality (“keystoneness”)

Chance: something that happens unpredictably

Chronofauna/chronoflora: A geographically restricted, natural assemblage of interacting animal/plant populations that has maintained its basic structure over a geologically significant period.

Community: an operational subset of the living biota that exists in a given place and time.

Connectance: the fraction of all possible links that are realized in a network. typically used in food web analysis.

Contingency: typically refers to the role of history or phylogeny in shaping current circumstances.

Depositional environment: The area in which and physical conditions under which sediments are deposited, including sediment source.

Ecological disparity: measures the richness of functional types (or adaptive strategies) in an ecological unit (e.g., paleocommunity)

Ecological surprises:
Unexpected - and often disproportionately large - consequences of changes in the environment (such as change in climate or invasions of alien species). (

The study of the relationship between the ecological role of an individual and its morphological adaptations

Ecosystem: many functional and operations definitions; ecologists think in terms of dominant taxa, processes. We define in terms of patterns and composition because we can’t see the processes but assume that the same ones are at work as in modern analogues. We can see food webs, snapshot example of spatial distribution,

Emergence: refers to the way complex systems and patterns arise out of multiple relatively simple interactions.

Emergent property: An attribute of a population or system that cannot be measured in any individual unit at a lower hierarchical level.

Environment: Webster’s definition: the complex of physical, chemical, and biotic factors (as climate, soil, and living things) that act upon an organism or an ecological community and ultimately determine its form and survival

paleontological event horizons. Brett and Baird (1977) define as “pervasive, regional to occasionally global, thin (centimeter to meter) scale beds with an unusually high abundance of fossils that are normally rare or absent”

Escalation: increase in the intensity of a conflict. Typically used to describe the “arms race” between predators and their prey in the marine Mesozoic revolution.

Extinction: loss of all individuals and populations of a taxa (global extinction)

Extirpation: loss of all individuals and populations from a particular geographic area (local extinction).

Facies: band of sedimentary rocks of the same specific type (all characteristics of a particular rock type).

Fossil assemblage: a collection of individuals (or taxa) from a particular bed, collection or locality

Functional group: collections of organisms based on morphological, physiological, behavioral, biochemical, or environmental responses or on trophic criteria.

Habitat: the environment in which a species lives, the physical conditions that surround a species.

Gamma diversity: Paleoecology: typically refers to global biodiversity at a particular point in time. Ecology: overall diversity for multiple ecosystems within a region

Geohistory: historical evidence derived from the geological and paleobiological records.

Guild (in the paleoecology context):
Ecology: a group of species that exploit a resource in a similar way. paleoecology: typically defines groups of species based on similarities in morphological, trophic and spatial complexity.

History: all of history (all types of records)

Invasibility: susceptibility of a community (or environment) to colonization and establishment of individuals from species not currently part of the resident community.

the act of colonization and establishment in a community by individuals from species not currently part of the resident community

Life habit: characterization of a species mode of life incorporating information about substrate relationship or life position, feeding type, mobility, and shell fixation (attached vs. unattached).

Macroecology: study of relationships between organisms and their environment at large spatial or temporal scales to characterize and explain statistical patterns of abundance, distribution and diversity

Megaguild: collection of closely related guilds.

Metacommunity: set of local communities that are linked by dispersal of potentially interacting individuals of species within those communities.

Modern: many possible definitions; must define what you mean in context of the study; usually means before major human impact/disturbance. There are many modes/manifestations of this impact.

Niche: an N-dimensional hypervolume describing all the possible biotic and abiotic factors that affect an organism’s interaction with its environment.

Paleocommunity: an assemblage of species (or taxa) found together in a particular area at a particular time. It is generally assumed that a paleocommunity will include some degree of time averaging.

Persistence: often used in population or metapopulation ecology. Refers to the ability of a population or metapopulation to maintain itself in an environmental area.

Random: Webster’s defines as “without definite aim, direction or rule”. It is often used to refer to a process simulated by a uniform probability distribution.

Resistence: often used in food webs. refers to the ability of food webs to resist extinction as species are removed.

Robustness: often used in food web analyses. refers to the ability of food webs to maintain structure as species are lost. Has been quantified as the fraction of species that had to be removed in order to result in a total loss of more than 50% of the species in the food web (Dunne et al. 2002. Ecology Letters: 5:558-567).

Scale dependence: refers to the potential for observed patterns or processes to differ depending upon the scale at which they are observed.

Scale independence: refers to the potential for observed patterns of processes to remain the same no matter the scale at which they are measured.


Stability: Montoya and Solé (2003) define stability as the speed with which the system recovers after a disturbance. In the general ecology literature, “stability” usually has connotations of both resistance and resilience.

Static vs. Dynamic: refers to whether a model, process, pattern etc. is essentially a single snapshot or point in time (static) or changes over the course of time.

Stochastic: refers to patterns or processes that result from random factors. The occurrence of individual events cannot be predicted, although measuring the distribution of all observations usually follows a predictable pattern.

Taphonomic time averaging: the natural process of individuals accumulating over time in samples that are eventually fossilized, or for bioturbation to result in the accumulation of individuals in fossil samples that represent some span of time.

Taphonomy: the study of decaying organisms over time. it is often concerned with understanding how organisms make it into the fossil record and the biases imposed by that process.

Taxon-free: refers to analyses that do not use taxa as the operational units (e.g., analyses of functional groups or guilds).

Taxonomy of invasions (definition of invasions, types of invasions)

Time averaging types

exact definition depends upon the scale at which it is measured. In paleontology, it often refers to extinction and replacement of taxa over time. However turnover can also be across space (see beta diversity).


Compiled by S. K. Lyons, 10/24/07
Additions by A. K. Behrensmeyer 9/8/08


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