water activity. Within this environment it has been hypothesized that P. rhombolepis was a large predator and fed upon dipterids, small and juvenile sarcopterygians, and Latvius. Associated vertebrates found in the same deposits include an armored jawless fish (Psammolepis), two placoderms (Asterolepis and Plourdosteus), an unidentified acanthodid acanthodian, a porolepiform lobe-fin (Laccognathus), a lungfish (Dipterus), and another elpistostegalian (Livoniana). During the Frasnian in which Panderichthys was extant, there was a drop in oxygen in the atmosphere as well as an increase in the abundance of plants. Due to the fact that oxygen is much less soluble in water than air, the decreased oxygen in the atmosphere would have caused the oxygen concentrations in any type of water to decrease substantially. This in turn would have caused any aquatic animal that could breathe air to have an advantage and be more likely to thrive. In addition to its ability to move in shallow water, Panderichthys could also breathe air. Its strong pectoral fins in theory could allow it to prop up its head in shallow water and take a breath. The enlargement of the spiracular chamber itself as well as its opening to the outside suggests that Panderichthys was part of a transition to an increased capacity for air breathing that was completed in tetrapods. See also Eusthenopteron Elpistostege Tiktaalik References External links Pharyngula Elpistostegalians Prehistoric lobe-finned fish genera Devonian fish of Europe Transitional fossils Fossil taxa described in 1941