Mammalline

Mammalline is a term encountered primarily in speculative biology and some science fiction writings to describe a hypothetical lineage or organizing principle for mammalian diversity. It is not a formal taxonomic category and has no official standing in taxonomic nomenclature.

In the speculative uses, mammalline denotes either a conceptual continuum of mammalian traits along a functional or developmental axis, or a simplified schematic for teaching trait evolution. Proponents use it to illustrate how certain features reappear or persist across lineages due to convergent evolution, pleiotropy, or ecological constraints. Critics argue that it risks conflating diverse clades under a single axis and that it lacks clear criteria for delimitation.

Because it is not adopted in formal biology, there is no standard definition of what constitutes a mammalline or how it would be diagnosed in a real organism. It may appear as a thought experiment, a narrative device, or a heuristic aid in classrooms.

Origin and usage of the term are varied, and documentation is sparse; it is not widely cited in peer-reviewed literature. Readers encountering mammalline should note its status as a nonstandard, speculative concept rather than a recognized taxonomic entity.

See also: Mammalia, Taxonomy, Phylogeny, Evolution, Speculative biology.