Figure 1. Structural changes between fish and tetrapods. A in Thermal physiology and the origin of terrestriality in vertebrates

Figure 1. Structural changes between fish and tetrapods. A, Eusthenopteron, the most thoroughly known Upper Devonian choanate sarcopterygian (from Andrews & Westoll, 1970). B, Panderichthys, an Upper Devonian fish intermediate between Eusthenopteron and the Upper Devonian amphibians (from Vorobyeva & Schultze, 1991). C, the Upper Devonian amphibian Acanthostega (Coates & Clack, 1995). D, the Upper Devonian amphibian Ichthyostega (from Coates & Clack, 1995). More details of the forelimb have since been discovered (Clack, Blom & Ahlberg, 2003). Animals are reproduced at approximately equal head/trunk lengths.Published as part of Carroll, Robert L., Irwin, Jason & Green, David M., 2005, Thermal physiology and the origin of terrestriality in vertebrates, pp. 345-358 in Zoological Journal of the Linnean Society 143 (3) on page 347, DOI: 10.1111/j.1096-3642.2005.00151.x, http://zenodo.org/record/543274