tetroodids

Tetroodids are a proposed, informal grouping of tetrapods that includes all extinct tetrapods and extant amphibians, reptiles, birds, and mammals. The term is sometimes used in discussions about evolutionary relationships, particularly when contrasting with amniotes, which comprise reptiles, birds, and mammals. This grouping highlights the broad evolutionary divergence that occurred early in tetrapod history, separating lineages that would eventually lead to the diverse forms of modern vertebrates. Amphibians, representing a more basal lineage within tetrapods, often serve as a point of comparison for understanding the evolutionary transitions that occurred as tetrapods moved from aquatic to terrestrial environments. The concept of tetroodids is not a formal taxonomic rank but rather a descriptive term used to encompass the vast array of tetrapod diversity outside of the amniote clade. Understanding this grouping helps in tracing the evolutionary history and diversification of terrestrial vertebrates from their fish ancestors.