On American Devonian
نویسندگان
چکیده
منابع مشابه
A Reappraisal of the North American Species of the Siluro-devonian Trilobite Genus Scotiella
The type material of Scotiella Delo 1935 is redescribed and the generic diagnosis emended to include trilobites in which the anterior and median lateral glabellar furrows are both strongly and poorly defined. The genus now embraces the species Scotiella logani (Hall 1860), S. conservatrix (McLearn 1924) new combination, S. minor (M'Coy 1851), S. samsonowiczi Tomczykowa 1962b and S. opatowiensis...
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Among the oldest convincing fossils of early vascular land plants are those of the Division Rhyniophyta. The members of this division consist of: (1) simple axes with cuticle, stomates, epidermis, cortex and a terete (circular) centrarch xylem (xylem development occurs from the center of the stem to the periphery), without well-developed appendages or roots; (2) simple, isotomous branching syst...
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The Rhipidistia (Osteichthyes, Crossopterygii) comprise three superfamilies of Paleozoic fossil fishes, the Holoptychoidea, Osteolepoidea and Rhizodontoidea. Of these the members of the Holoptychoidea (families Holoptychidae and Porolepidae) are by far the least well known, and consequently there exists a considerable gap in our knowledge of the evolution of the Rhipidistia as a whole. The aim ...
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To test the extent of herbivory in early terrestrial ecosystems, we examined compression-impression specimens of the late Middle Devonian liverwort Metzgeriothallus sharonae, from the Catskill Delta deposit of eastern New York state. Shale fragments of field-collected specimens were processed by applying liquid nitrocellulose on exposed surfaces. After drying, the film coatings were lifted off ...
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The rarity of Devonian tetrapods and the absence of tetrapods during the first 14 million years of the Mississippian (Romer’s Gap) have inspired hypotheses of fish-tetrapod evolutionary transition as an escape from difficult habitats such as deserts or stagnant waters. These hypotheses and Romer’s Gap are tested here using depth to calcic horizon in paleosols of the northern Appalachians as a p...
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ژورنال
عنوان ژورنال: American Journal of Science
سال: 1863
ISSN: 0002-9599
DOI: 10.2475/ajs.s2-35.105.309