Results 161 to 170 of about 1,690 (206)

A review of placoderm scales, and their significance in placoderm phylogeny

Journal of Vertebrate Paleontology, 1999
An historical review of the literature relating to placoderm scales preserved in association with articulated dermal plates, or as isolated units in microvertebrate assemblages, is followed by a discussion of their relevance in phylogenetic analyses of the Placodermi.
Burrow, C. J., Turner, S.
openaire   +2 more sources

XV.—The Paired Fins of Placoderms

Transactions of the Royal Society of Edinburgh, 1947
Within the last twenty years our knowledge of the structure and distribution of the armoured Placodermi (including Arthrodira, Ptyctodonta, Phyllolepida, Macropetalichthyida, Rhenanida, and Antiarcha) has increased tremendously. The writer is engaged on a morphogenetic analysis of the group, early publication of which is uncertain.
T. S. Westoll
semanticscholar   +2 more sources

PART I: PAIRED FINS AND GIRDLES IN OSTRACODERMS, PLACODERMS, AND OTHER PRIMITIVE FISHES

Annals of the New York Academy of Sciences, 1941
W. K. Gregory, H. C. Raven
exaly   +2 more sources

A Silurian maxillate placoderm illuminates jaw evolution

Science, 2016
Jaws from the jawless Until a fossil called Entelognathus was found to contain a tripartite jaw a few years ago, it was believed that the skeletons of early osteichthyans (bony fish), the ancestors of all vertebrates, were derived independently of those of the earlier placoderms (so-called jawless fish). Zhu et al.
Min, Zhu, Per E, Ahlberg, Zhaohui, Pan, Youan, Zhu, Tuo, Qiao, Wenjin, Zhao, Liantao, Jia, Jing, Lu   +7 more
openaire   +2 more sources

Histologic Studies of Ostracoderms, Placoderms and Fossil Elasmobranchs

Zoologica Scripta, 1980
An account is given of the structure and growth of certain ptyctodontid tooth plates, especially those of Ctenurella gladbachensis, based on study by light microscopy and the SEM. These tooth plates consist of a framework of acellular bone tissue and an interior hard tissue referred to as pleromin.
Tor Ørvig
semanticscholar   +3 more sources

Phenotypic plasticity, polymorphism and phylogeny within placoderms

Acta Zoologica, 2009
AbstractIntraspecies variation, polymorphism and asymmetric traits are observed within two families of Arthrodira, the Incisoscutidae and Camuropiscidae, from the Gogo Formation in northern Western Australia. Individual plates of the head and trunk shield show considerable variation between individuals.
K. Trinajstic, K. Dennis-Bryan
semanticscholar   +2 more sources

Placoderm fishes, pharyngeal denticles, and the vertebrate dentition

Journal of Morphology, 2003
AbstractThe correlation of the origin of teeth with jaws in vertebrate history has recently been challenged with an alternative to the canonical view of teeth deriving from separate skin denticles. This alternative proposes that organized denticle whorls on the pharyngeal (gill) arches in the fossil jawless fish Loganellia are precursors to tooth ...
Johanson, Z, Smith, M M
openaire   +3 more sources

Further consideration of placoderm evolution

Journal of Vertebrate Paleontology, 1983
ABSTRACT The flight performances of Pteranodon ingens and Nyctosaurus gracilis from the Upper Cretaceous of Kansas were modeled using data from a Sailvane hang-glider which has an airfoil similar to that of a pterosaur. The aerodynamics of large pterosaurs were mainly dictated by three parameters: low wing loadings, wings with high aspect ratios, and ...
openaire   +1 more source

Ventral Thoracic Neuromast Lines of Placoderm Fishes

Nature, 1965
IN the past forty years, following Stenso's1 pioneer work on the arthrodire Macropetalichthys, much information has come to light in support of the view that the Palaeozoic placoderms and the still surviving elasmo-branchs and holocephalians are more closely related to each other than to any other group of fishes2.
exaly   +2 more sources

TERMINOLOGY OF PALEOZOIC PLACODERM FISHES (ANTIARCHI) EXOSKELETAL ELEMENTS

THE LIFE OF THE EARTH, 2021
The terminology and morphology of plates of the posterior part of the antiarch head shield (Placodermi, Antiarchi) are discussed. The terms «zatilochnaya» and «bokovaya (kraevaya) zatilochnaya» was previously accepted in antiarch skulls and are suggested for use in Russian-language literature.
openaire   +1 more source