Updated March 15, 2019 and March 20, 2020
with a new interpretation of the skull sutures of the stem tetrapod Tiktaalik. Now, with the addition of more closely related taxa, Koilops is a finned fish that nests basal to Elpistostege, Spathicephalus and Tiktaalik off the main lineage of the fin to finger transition.
Koilops herma (Clack et al. 2016; NMS G. 2013.39/14) Tournasian, early Carboniferous ~375 mya) is a temnospondyl with a flat skull and large orbits nesting between Greererpeton and Spathicephalus. The nares were close to the rim of the short rorstrum. The pineal foramen was enormous. The teeth were small and sharp. The nasals were broad.
Clack et al. (14 other authors) 2016. Phylogenetic and environmental context of a Tournaisian tetrapod fauna. Nature ecology & evolution 1(0002):1-11.