ON A RECONSTRUCTION OF THE OLFACTORY SYSTEM AND BRAIN IN ANTIARCHS (PISCES: PLACODERMI)

The position of the nasal sacs and nostrils, as well as some features of the brain structure in antiarchs (placoderm fishes) are analyzed, based mainly on the examples of Bothriolepis and Asterolepis. A new possible reconstruction of the olfactory system and brain in antiarchs is proposed. The paired nasal sacs are closely located to the anterior wall of the telencephalon; tracti olfactorii are absent; telencephalon is situated anterior to the diencephalon, as it was reconstructed for other placoderms; and the epiphysis process is elongated. The mesencephalon, cerebellum and medula oblongata, bearing the fossa romboidea, are placed posterior to the diencephalon in the otico-occipital part of the endocranium.