English: Figure 1 Simplified phylogeny spanning the fish–tetrapod transition, illustrating the major anatomical changes. Note the enormous enlargement of the ribcage and pelvis. Ribs are present in Eusthenopteron, but so small that they are difficult to see. The taxa are arranged from most aquatically adapted at the top to most terrestrially adapted at the bottom. In the colour coding, blue denotes an aquatic adaptation, and yellow to red colours represent adaptations for walking and weight support. The placement of Acanthostega crownward to Ichthyostega reflects its possession of a deltopectoral crest (see Fig. 2). Eusthenopteron modified from Jarvik (1980), Tiktaalik from Shubin et al. (2014), Acanthostega and Ichthyostega from Ahlberg et al. (2005a, b).