The earliest known (Namurian A, E1) haplolepids (Osteichthyes: Actinopterygii)

Abstract

ABSTRACTTwo new genera and species of haplolepids (Chondrostei), Protohaplolepis scotica and Blairolepis loanheadensis, are described from the ironstones of Loanhead, Midlothian (Namurian A, E1); this represents the earliest known record of the family. Protohaplolepis scotica (= Traquair's nomen nudum “Eurylepis scoticus”) shows many features in common with Westoll's hypothetical haplolepid “common ancestor X”, and is possibly ancestral to the Haplolepis–Microhaplolepis line within the family. Blairolepis loanheadensis, known only from a skull roof, shows greater similarities to Parahaplolepis and Pyritocephalus, but differs from these genera in having separate dermopterotics and parietals. Two subfamilies, the Haplolepinae and the Parahaplolepinae, are suggested to reflect the distinct evolutionary lines within the family.A new species, Parahaplolepis westolli, is also described from Newsham, Northumberland (Westphalian B). This species shows a close resemblance to the American species Parahaplolepis tuberculata from Linton, Ohio.A brief discussion of the evolutionary history of the family is presented, along with a summary of its stratigraphical and geographical distribution.