Our boot-shaped ancestors in Wales

The marine Palaeozoic fossils called calcichordates, although traditionally regarded as echinoderms, were in fact chordates. They were ancestral to living chordates in general and to vertebrates in particular. The most primitive calcichordates were boot-shaped. Recent discoveries of calcichordates in the Cambrian and Ordovician of Wales suggest they are commoner than has generally been thought. Geologists should look out for them.