Development of the cetacean nasal skull.

1 Introduction.- 2 Materials and Methods.- 3 Synopsis of Structures of the Embryonic Nasal Skull...- 3.1 Cartilaginous Structures.- 3.2 Dermal Bones.- 4 Morphogeny of the Nasal Skull.- 4.1 Odontoceti.- 4.1.1 Spotted DolphinStenella attenuata.- 4.1.2 Common DolphinDelphinus delphis.- 4.1.3 White-beaked DolphinLagenorhynchus albirostris.- 4.1.4 Pilot WhaleGlobicephala melas.- 4.1.5 Common PorpoisePhocoena phocoena 28.- 4.1.6 NarwhalMonodon monoceros 29.- 4.1.7 Sperm WhalePhyseter catodon 31.- 4.2 Mysticeti.- 4.2.1 Fin WhaleBalaenoptera physalus.- 4.2.2 Minke Whale Balaenoptera acutorostrata.- 4.2.3 Humpback WhaleMegaptera novaeangliae.- 5 Metamorphosis and Translocation of the Nasal Structures.- 5.1 Stages Around 40 mm in Size.- 5.2 Stages Around 80 mm in Size.- 5.3 Stages Around 150 mm in Size.- 5.4 Course of the Most Important Transformations.- 6 Comparison of the Embryonic Nasal Structures.- 6.1 The Median Structures.- 6.1.1 Septum nasi.- 6.1.2 Spina mesethmoidalis.- 6.2 The Posterior Side Wall Structures.- 6.2.1 Tectum nasi.- 6.2.2 Lamina cribrosa.- 6.2.3 Paries nasi.- 6.2.4 Commissura orbitonasalis.- 6.2.5 Cupula nasi anterior.- 6.2.6 Maxilloturbinale.- 6.2.7 The Nasal Cavity.- 6.2.8 Processus paraseptalis posterior.- 6.3 The Anterior Side Wall Structures.- 6.3.1 Lamina transversalis anterior.- 6.3.2 Processus lateralis ventralis.- 6.3.3 Cartilago paraseptalis.- 6.3.4 Cartilago ductus nasopalatini.- 7 The Nasal Structures of Adult Cetacea.- 7.1 The Ethmoid Complex.- 7.2 Cartilaginous Rostrum.- 7.3 Cartilages of the Nostril.- 7.4 Nasal Roof Cartilage in the Sperm WhalePhyseter catodon.- 7.5 Pararostral Bones, or the so-called Meckelian Ossicles.- 8 Evolutional and Functional Relationships.- 8.1 Position of the Nostrils and the Mode of Surfacing in Cetaceans.- 8.2 Position of the Nostrils and the Mode of Surfacing in Ichthyosaurs.- 8.3 Position of the Nostrils and the Modell9 of Surfacing in Sirenians.- 9 The Systematics of Cetacea According to the Morphogeny of Their Nasal Skull.- 9.1 On the Phylogenetic Origin of Cetacea.- 9.2 The Present Results and Their Significance for the Systematics of Cetacea.- 9.3 Other Recent Criteria for the Systematics of Cetacea.- 10 Summary.- References.