homeomorfa

Homeomorfa (plural homeomorfas) is a biological term used to describe two or more organisms that bear a strikingly similar external form or body plan despite not being closely related. The resemblance is typically the result of convergent or parallel evolution driven by similar ecological roles, environmental pressures, or functional constraints rather than a shared recent ancestry. In such cases the similarities are superficial at the level of morphology rather than due to homologous structures.

Etymology and scope: The word derives from Greek roots meaning “same form.” In practice, the concept is most often encountered in paleontology and comparative anatomy, where researchers compare fossil and living forms to understand how similar shapes can evolve independently. The term helps distinguish parallel appearances from true homology, which reflects common ancestry, and from mimicry driven by other evolutionary forces. It is closely related to the idea of homoplasy, where similar traits arise independently.

Examples: Classic cases include the fusiform, streamlined bodies of ichthyosaurs (extinct marine reptiles) and dolphins (mammals), which show remarkable functional similarity despite distant kinship. Other examples include independent adaptations for burrowing or gliding in unrelated groups, such as fossorial mammals that converge on a similar compact form or flying mammals and flying squirrels that share a gliding membrane albeit from different lineages.

See also: Convergent evolution, analogy, homology, homoplasy.