Paleontological studies on the placodermi and chondrichthyan remains from Japan

1. 日本placodermi化石的分类、形态学和组织学研究：在日本中部阜县Kmitakara-mura的虎地组（下泥盆世）发现的真皮甲被形态学和组织学研究描述为Romundina sp.， acantho胸i的脊柱板（Okura and Goto, 1992）。2 .对中生代弹性鳃目牙齿的研究：中三叠统Hybodus sp.、上三叠统Acrodus sp.和日本下侏罗统Asteracanthus sp.的牙齿进行了描述（Goto et al., 1991）。软骨鱼形态和结构的进化研究：对化石和现存软骨鱼牙齿的形态和组织学进行了研究。可以认为，软骨鱼的牙齿结构并不取决于它们的进化水平，而是适应它们的饮食习惯的结果（Goto, 1991）。日本古生代和中生代早期鱼类区系：根据现有资料，将日本古生代和中生代早期鱼类化石划分为22属31种，即：下泥盆纪板皮目1种，二叠纪-侏罗纪板鳃目15种，二叠纪蜗齿目2种，瓣齿目11种，三叠纪骨鱼目2种（Goto, 1992）。脊椎动物骨骼组织的起源和进化：原始agnathians的皮肤盔甲（外骨骼）是作为一种从血液中去除多余钙的机制而形成的，它转变为陆地脊椎动物身体的有组织的功能支持（内骨骼）（Goto, 1991; 1992）。

1. Taxonomical, morphological and histological studies on the placodermi remains from Japan : The dermal armours which were discovered from the Hukuji Formation (Lower Devonian) in Hukuji, Kmitakara-mura, Gifu Prefecture, central Japan were described as spinal plates of Romundina sp., Acanthothoraci by the morphological and histological studies (Okura and Goto, 1992).2. Studies on the teeth of Mesozoic elasmobranchii : Tooth of Hybodus sp. from the Middle Triassic, Acrodus sp. from the Upper Triassic and Asteracanthus sp. from the Lower Jurassic of Japan were described (Goto et al., 1991).3. Evolutionary study on the form and structure of chondrichthyes : The morpology and histology of teeth in fossil and extant chondrichthyes were investigated. It can be considered that the tooth structure of Chondrichthyes is not dependent on their evolutionary level, but the result of an adaptation to their food habits (Goto, 1991).4. Palaeozoic and Early Mesozoic fish fauna in Japan : Based on the present data, the fossil fishes of the Palaeozoic and Early Mesozoic of Japan are classified into twenty-two genera and thirty-one species, that is, one species of placodermi (Lower Devonian), fifteen species of elasmobranchs (Permian-Jurassic), two species of cochliodonts (Permian), eleven species of petalodonts and two species of osteichthyes (Triassic) (Goto, 1992).5. Origin and evolution of skeletal tissues in vertebrates : The dermal armor (exoskeleton) of primitive agnathians which was formed as a mechanism for removing excess calcium from the blood changed to an organized functional support (endoskeleton) for the body of terrestrial vertebrates (Goto, 1991 ; 1992).