The gap in the tetrapod record has been progressively closed with the discoveries of such early Carboniferous tetrapods as "Pederpes" and "Crassigyrinus". There are a few sites where vertebrate fossils have been found to help fill in the gap, such as the East Kirkton Quarry, in Bathgate, Scotland, a long-known fossil site that was revisited by Stanley P. Wood in 1984 and has since been revealing a number of early tetrapods in the mid Carboniferous; "literally dozens of tetrapods came rolling out: "Balanerpeton" (a temnospondyl), "Silvanerpeton" and "Eldeceeon" (basal anthracosaurs), all in multiple copies, and one spectacular proto-amniote, "Westlothiana"", "Paleos" Project reports. In 2016, five new species were found across the Ballagan Formation: "Perittodus apsconditus", "Koilops herma", "Ossirarus kierani", "Diploradus austiumensis", "Aytonerpeton microps". These stem tetrapods and amphibians provide evidence for an early split between the two groups, and rapid diversification in the Early Carboniferous.