6533b7d3fe1ef96bd1260068

RESEARCH PRODUCT

Ammonoids and quantitative biochronology - A unitary association perspective

subject

description

Ammonoid evolutionary changes have long been recognized to be excellent time markers. They are the major macrofossil group to date and correlate Paleozoic and Mesozoic marine strata. Originations and extinctions of ammonoid species are commonly used to define GSSPs and build high resolution biozonations. Biochronology is now an advanced field with the recent development of computerized, quantitative methods yielding robust biochronological schemes. It has been demonstrated that such quantitative biochronological methods are very efficient to resolve (often complex) biostratigraphic contradictions and produce accurate and high resolution biozonations, thus enabling precise dating and correlations at various spatial scales. Among the available methods, Unitary Associations is the only one that does not violate the integrity of the data by breaking real coexistences or generating spurious coexistences of species. It has been most commonly applied to ammonoids and is thus reviewed here.