Figure 2
From: Do mudskippers and lungfishes elucidate the early evolution of four-limbed vertebrates?
Morphology, ontogeny and behaviour of the African lungfish, Protopterus annectens . Schematic drawing of an adult specimen (a), larval development with gills that resemble those of extant amphibians (b), and behaviour during periods of drought in their natural environment (c). Adult specimen of the African lungfish, Protopterus annectens (d). These large sarcopterygians are the sister group to living tetrapods and may be viewed as model organisms to understand the vertebrate water-to-land transition (original photograph).