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Ptomacanthus
''Ptomacanthus'' (meaning ''thorny corpse'') is an extinction, extinct genus of Acanthodii, spiny shark, an early relative of living Chondrichthyes, cartilaginous fishes (sharks, rays, and chimaeras). Location found ''Ptomacanthus'' is known mainly from the Old Red Sandstone of the United Kingdom. The most completely known species, ''P. anglicus'' is known from several articulated fossils from Wayne Herbert Quarry, Herefordshire, United Kingdom. Two indeterminate species are known from shoulder-girdles recovered from Castle Mattock Quarry, Herefordshire and Zaleszychi, Ukraine. Description The only species known in any detail, ''P. anglicus'' was a fish about 25 cm long. Like other acanthodians it had small, shark like scales, and a suite of fin-spines in front of its dorsal, pectoral, and pelvic fins. Paleobiology ''P. anglicus'' is important to our understanding of early vertebrate evolution as it preserves part of the Neurocranium, braincase, a scientifically inform ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, where rocks from this period were first studied. The first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. The arthropod groups of myriapods, arachnids and hexapods also became well-established early in this period, after starting their expansion to land at least from the Ordovician period. Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the Age of Fishes. The placoderms began domina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
