Gol'din P. Heterochronies in cetacean evolution

This work is focused on analysis of regularities and functions of heterochronies in evolution of cetaceans (Cetacea). Phylogeny of fully aquatic cetaceans (Pelagiceti) is reconstructed; it was shown their divergence comes back to the Middle Eocene. Slowing ontogeny rate was found to cause increase in body size of cetaceans: it is seen in the earliest Pelagiceti and explains their differentiation in body size. A phylogenetic tree was built for Neogene and modern baleen whales (Mysticeti), and origins and phylogeny were suggested for the family Cetotheriidae and the groups closely related to it. The new family of Tranatocetidae was described during the work, as well as four new mysticete genera. Manifestations of paedomorphosis were studied across cetacean lineages, including toothed whales, baleen whales and stem cetaceans (early Pelagiceti). Endemic Neogene fauna of dwarf Paratethyan cetaceans was studied, and some of adaptations developed in its members were found to be similar to adaptations in modern cetaceans living in the Mediterranean and Black Seas. Explanation of feeding mechanisms in dwarf baleen whales was provided. Drivers of development of peramorphic sexually dimorphic bizarre structures in beaked whales (Ziphiidae) were assessed, and novel hypothesis for their unique function was provided. Evolutionary study of paedomorphic development of forelimb skeleton was conducted, and it was found to lead to evolutionary novelty. Pelvic and hindlimb evolution and the role of heterochrony in it were studied.