Paleontological studies on the placodermi and chondrichthyan remains from Japan

1.日本安慰剂化石的分类、形态和组织学研究：1.日本中部岐阜县克米塔卡拉村村胡库寺组(下泥盆统)发现的真皮盔甲被描述为Romundina sp.，Acanthothoraci的脊板(Okura和Goto，1992)。中生代棘鳃亚纲的牙齿研究：Hybodus sp.产于中三叠世，Acrodus sp.取自上三叠统星形藻Asteracantus sp.3.描述了日本下侏罗世的化石(Goto等人，1991)。软骨动物形态和结构的进化研究：对化石和现存软骨动物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，而是它们对食物习性适应的结果(Goto，1991)。日本古生代和早中生代鱼类动物群：根据现有资料，将日本古生代和早中生代的鱼类化石划分为22属31种，即安氏鱼类1种(下泥盆统)，棘鳃类15种(二叠纪-侏罗纪)，腔齿类2种(二叠纪)，瓣齿类11种，骨鱼2种(三叠纪)(Goto，1992)。脊椎动物骨骼组织的起源和进化：原始无脊椎动物的皮甲(外骨骼)作为一种从血液中清除多余钙的机制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).