primigenius

Primigenius is a Latin adjective used in biological taxonomy as a species epithet in the binomial names of living and extinct organisms. It derives from primus, meaning "first," and genitus, meaning "begotten" or "produced," and is typically translated as "first-born" or "primitive." It is employed to signal primitive, ancestral, or original characteristics, or to denote that a taxon was the first of its genus to be described.

In zoological nomenclature, primigenius appears in several species names across different genera. The most prominent example is Bos primigenius, the aurochs, an extinct wild cattle species that is considered an ancestor of domestic cattle (Bos taurus). The epithet is not unique to a single lineage and may be used independently by taxonomists to reflect perceived primitiveness rather than any specific phylogenetic claim; its exact meaning depends on the taxon and the author's intent.

Because it is only an epithet, primigenius is not a standalone taxon; a full scientific name requires a genus. The term is also encountered in paleontological or botanical contexts when describing primitive or early-form representatives of a group.