First Ordovician vertebrate from south America

The first Ordovician vertebrate from South Americais described from the Anzaldo Formation (Caradoc, Upper Ordovician) of Central Bolivia. It is referred to a new taxon, Sacabambaspis janvieri nov. gen. nov. sp., within the jawless vertebrate group Heterostraci, and displays some resemblance to both Astraspis and Arandaspis. It differs from all other known heterostracans by having very broad sensory-line grooves on the exoskeleton. Consideration of the palaeobiogeography of Ordovician vertebrates suggests that the early forms have been restricted to warm regions.