Skip to content

Local Range of a Taxon (Teilzone)

Delimit the observed local stratigraphic span of one fossil taxon between its lowest and highest occurrences in a specified section or area, while treating those horizons as sampling- and ecology-conditioned observations rather than global origination or extinction.

Version
v3 · 2026-09-07 · History
Domain-specific #
2938
Origin domain
geology
Subdomain
biostratigraphic zonation
Aliases
Teilzone, Local-range zone, Local-range biozone

Core Idea

A local range of a taxon, historically called a Teilzone or local-range zone, delimits the part of a stratigraphic section, local area, or explicitly bounded region in which a selected fossil taxon has actually been recorded. Its lower boundary is the taxon's lowest observed stratigraphic occurrence in that locality; its upper boundary is the highest observed occurrence. The result is an empirical local span, not a claim that the organism originated at the lower surface or became globally extinct at the upper one.

Scope of Application

The construct applies wherever biostratigraphers, paleontologists, or stratigraphers record the vertical occurrence of fossils in a specified succession. It is useful in measured outcrop sections, cores, boreholes, mine sections, and mapped local areas, provided the ordering, locality, taxonomic identity, and occurrence criteria are explicit.

At the most basic level, the local range summarizes presence data. It converts a scattered list of finds into a bounded interval that can be compared with lithology, depositional environment, geochemical signals, radiometric dates, magnetostratigraphy, or ranges in other sections. It also supplies data for broader range charts and quantitative correlation methods.

Clarity

A clear local-range statement answers six questions.

  1. Where? Name and bound the section or area. 2. Which taxon? State the accepted identification and relevant taxonomic concept. 3. What observations count? Describe sampling, preservation, and indigenous-occurrence criteria. 4. Where are the limits? Report the horizons or sample positions of the local LO and HO, including uncertainty. 5. What lies between them? State whether internal gaps occur and whether they reflect noncollection, nonpreservation, or tested absence.

Manages Complexity

Fossil distributions combine biological history, depositional environment, preservation, rock exposure, collection effort, and taxonomic judgment. The local-range abstraction reduces this complexity without erasing it. It gives each taxon-section pair a compact lower limit, upper limit, and interval while retaining annotations for reliability and uncertainty.

This localization prevents a common category error: treating every first or last local find as a global event.

Abstract Reasoning

The abstraction licenses several conditional inferences.

  • If the same taxon has different local LOs in two sections, then at least one biological, environmental, preservational, sampling, or stratigraphic condition differs; synchronous origination does not follow from either observation alone.
  • If increased sampling adds a lower occurrence, the observed local range expands downward without implying that the organism's true history changed.
  • If a specimen above the prior HO is demonstrably reworked, it should not extend the indigenous local range; if it is indigenous and correctly identified, the HO must be revised.
  • If taxonomic concepts are split or synonymized, occurrences must be reassigned before comparing old and new range boundaries.
  • If a local range repeatedly coincides with independent chronological markers across sections, confidence in correlation can increase, but congruence requires evidence beyond the local-range definition.
  • If an internal absence occurs between positive samples, the outer range remains continuous as a range summary unless the study adopts a presence-only patch model or proves a stratigraphic break that changes the carrier.
  • If several local ranges are combined, their envelope may estimate a broader documented range, but the aggregation must retain locality provenance and cannot simply relabel one section's limits as global.

Knowledge Transfer

Within biostratigraphy, the abstraction transfers from one fossil group to another: ammonites, conodonts, foraminifera, pollen, spores, nannofossils, and other taxa can all supply local ranges if preservation and identification are suitable. It also transfers among carriers—outcrop, core, borehole, or composite local section—without changing its roles.

The local-range record can feed range charts, graphic correlation, constrained optimization, and probabilistic occurrence models. Those methods may estimate likely unseen extensions or order events across sections, but they begin from localized observations.

Relationships to Other Abstractions

Local relationship map for Local Range of a Taxon (Teilzone)Parents appear above the current abstraction, mutual partners to the right, and children below. Node labels state whether each abstraction is prime or domain-specific; colors identify relation types.Local Range of aTaxon (Teilzone)DOMAINPrime abstraction: Segmentation and Boundary Drawing — is a kind ofSegmentation andBoundary DrawingPRIME

Current abstraction Local Range of a Taxon (Teilzone) Domain-specific

Parents (1) — more general patterns this builds on

Hierarchy paths (2) — routes to 2 parentless roots

Neighborhood in Abstraction Space

Local Range of a Taxon (Teilzone) sits in a sparse region of the domain-specific corpus (85th percentile for distinctiveness): few abstractions share its structure, so a faithful description tends to retrieve it precisely.

Family — Unclustered & Miscellaneous (1565 abstractions)

Nearest neighbors

Computed from structural-signature embeddings · 2026-09-08