Tomographic analysis of a fossilized fish reveals the oldest brain fossil yet
This iniopterygian fossil, discovered in Kansas, is an extinct relative of modern chimaeras, a distant relative of sharks and rays. Iniopterygians have unusual features, including large skulls and eye sockets, rows of shark-like teeth, clubbed tails, and fins tipped with spikes and hooks. Previously, only flattened fossils of this relatively small fish -- which averages around six inches in length -- were known to exist. The new finding, the first three-dimensional iniopterygian fossil, is remarkable for having the oldest fossilized brain ever found.