PanTetrapoda

PanTetrapoda is a total-group clade used in some vertebrate paleontology frameworks to designate the lineage that includes all members more closely related to Tetrapoda than to lungfish. In this sense, PanTetrapoda encompasses the crown group Tetrapoda and the stem tetrapodomorphs lying on the tetrapod lineage.

Membership is not fixed across studies. Typical inclusions are late Devonian stem tetrapodomorphs such as Eusthenopteron, Panderichthys, and Tiktaalik, as well as early tetrapods like Acanthostega and Ichthyostega. The exact composition depends on phylogenetic definitions and available fossils.

Evolutionary context: PanTetrapoda marks the transition from fish to land-dwelling vertebrates during the Devonian (roughly 385 to 360 million years ago). It covers key innovations such as fin-to-limb transformation, digits, strengthened girdles, a neck joint, and the emergence of lungs and changes in sensory systems.

Relationship to other groups: PanTetrapoda is a total-group concept within Tetrapodomorpha, the larger lineage including Tetrapoda and its stem relatives. Lungfish are a close out-group; PanTetrapoda comprises lineages more closely related to tetrapods than to lungfish.

Usage: The term PanTetrapoda is not universally adopted; some authors prefer Pan-Tetrapoda or simply refer to Tetrapodomorpha for the stem lineages. When used, it emphasizes inclusive phylogenetic scope over a strict crown-group definition.