|
by Phil Robinson A limestone shale slab from the Green River Formation, USA, has incredibly ‘captured’ a mass of 257 fish swimming together in a school. The fish, each just under 1 in (2.5 cm) long, belong to an extinct species, Erismatopterus levatus. Just before being fossilised they were swimming in the same direction. Swimming together in a school is a dynamic process and this slab amazingly preserves, in ‘freeze frame’ as it were, this coordinated collective motion. Such discoveries are rare. As pointed out in the New York Times, “It’s difficult, for instance, to find evidence of schooling fish in the fossil record. You need just the right circumstances to fossilize something like a school of fish in place within a rock. Then, that rock has to survive intact long enough for a paleontologist to discover it and study it”. The right circumstances? While the study did not conclusively give an answer as to how the fish were fossilized the authors suggested that a, “Rapid fixation of the fish shoal might be possible by sand dune collapse on shallow water, which can produce a bed in only seconds or minutes”. It is clear that they recognised that the fish school’s fossilisation …
|
