Late Devonian Bothriolepidids (Placodermi, Antiarchi) of the Tver Oblast

The species Livnolepis heckeri (Lukševičs, 2001) which had been assigned to the genus Bothriolepis at first description, was described from the Famennian sediments (Upper Devonian) of the Tver oblast. New materials collected from a type locality near the village of Bilovo enabled considerable expansion of the morphological description of the species. The plates of the entire head shield and almost the entire trunk shield, as well as the plates of the proximal segment of the pectoral fin, are known for L. heckeri. Specimens from different ontogenetic stages were available for some plates. The genus Livnolepis currently includes two species: L. zadonica (H. Obrucheva, 1983) from the Lower Famennian of the Central Devonian Field and L. heckeri (Lukševičs, 2001) from the middle Famennian of the southwestern margin of the Main Devonian field. A large preorbital recess of the head shield and weakly conspicuous anterolateral corners of the oticooccipital depression on the internal surface of the head shield are the most characteristic structural features of the Livnolepis exoskeleton.