Fish Out of Water 235tetrapods. Panderichthys had both gills and well-developed lungs with nostrils, so it could
breathe either way. Most importantly, like tetrapods, Panderichthys has lost the dorsal fins
and anal fins, leaving only the remarkably footlike lobed pectoral and pelvic fins. This is
a classic fishibian: tetrapod-like skull and body and braincase and lungs, all the rest of the
fishy fins lost, but still retaining true fins that become the hands and feet.
Another important recent discovery is several nearly complete skeletons of Acanthostega
(figs. 10.6–10.8) by Jenny Clack, Michael Coates, Per Ahlberg, and others. Acanthostega still
had a well-developed fin on the tail, large gill openings, and even gills preserved on the
FIGURE 10.5. The evolutionary modifications of the skull, limbs, and the rest of the skeleton from a rhipidistian
like Eusthenopteron to a tetrapod like Ichythyostega. (Drawing by Carl Buell).