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Thyestiida
Thyestiida is an order of bony-armored jawless fish in the extinct vertebrate class Osteostraci The class Osteostraci (meaning "bony shells") is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now North America, Europe and Russia from the Middle Silurian to Late Devonian. Anatomically speaking, ....The origin and early evolution of the Osteostraci (Vertebrata): A phylogeny for the Thyestiida. Robert S. Sansom, Journal of Systematic Palaeontology, Volume 6, Issue 3, 2008, pages 317-332, References External links Thyestiidaat fossilworks.org (retrieved 21 April 2016) Osteostraci Prehistoric jawless fish orders {{Paleo-jawless-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Auchenaspis
''Auchenaspis salteri'' is an extinct species of armored jawless fish of the order Thyestiida from the Late Silurian of England. In England, ''A. salteri'''s fossils are found in extreme abundance in the Lower Old Red Sandstone strata in Ledbury, Herefordshire. ''A. salteri'' strongly resembles the thyestiids ''Procephalaspis'' and ''Thyestes'', and within Thyestiida, it represents a transitional form between the primitive, superficially ''Cephalaspis''-like forms, such as ''Thyestes'', and the more specialized tremataspid thyestiids, like ''Tremataspis'', ''Dartmuthia ''Dartmuthia'' is an extinct genus of primitive jawless fish that lived in the Silurian period. Fossils of ''Dartmuthia'' have been found in Himmiste Quarry, on the island of Saaremaa in Estonia Estonia, formally the Republic of Estonia, ...'', or '' Dobraspis'', whose headshields tend to resemble hot buns or horseshoe crabs. References Osteostraci genera Silurian fish of Europe Fossils of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osteostraci
The class Osteostraci (meaning "bony shells") is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now North America, Europe and Russia from the Middle Silurian to Late Devonian. Anatomically speaking, the osteostracans, especially the Devonian species, were among the most advanced of all known agnathans. This is due to the development of paired fins, and their complicated cranial anatomy. The osteostracans were more similar to lampreys than to jawed vertebrates in possessing two pairs of semicircular canals in the inner ear, as opposed to the three pairs found in the inner ears of jawed vertebrates. They are thought to be the sister-group to pituriaspids, and together, these two taxa of jawless vertebrates are the sister-group of gnathostomes. Several synapomorphies support this hypothesis, such as the presence of: sclerotic ossicles, paired pectoral fins, a dermal skeleton with three layers (a basal layer of isopedin, a middle layer of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osteostraci Janvier
The class (biology), class Osteostraci (meaning "bony shells") is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now North America, Europe and Russia from the Wenlock epoch, Middle Silurian to Late Devonian. Anatomically speaking, the osteostracans, especially the Devonian species, were among the most advanced of all known Agnatha, agnathans. This is due to the development of paired fins, and their complicated cranial anatomy. The osteostracans were more similar to lampreys than to jawed vertebrates in possessing two pairs of semicircular canals in the inner ear, as opposed to the three pairs found in the inner ears of jawed vertebrates. They are thought to be the sister-group to Pituriaspida, pituriaspids, and together, these two taxa of jawless vertebrates are the sister-group of Gnathostomata, gnathostomes. Several synapomorphies support this hypothesis, such as the presence of: sclerotic ossicles, paired pectoral fins, a dermal skel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyestes (fish)
''Thyestes'' is an extinct genus of osteostracan agnathan vertebrate of Europe whose fossils are found in Middle to Late Ludlow-aged marine strata of Late Silurian Europe. Individuals of ''Thyestes'' superficially resembled ''Cephalaspis ''Cephalaspis'' (from el, κεφαλή , 'head' and el, ἀσπίς , 'shield') is a possibly monotypic genus of extinct osteostracan agnathan vertebrate. It was a trout-sized detritivorous fish that lived in the early Devonian. Description L ...'', but were more closely related to '' Auchenaspis'' and '' Tremataspis''. References Osteostraci genera Silurian fish of Europe {{silurian-animal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Procephalaspis
''Procephalaspis'' is an extinct genus of jawless fish Agnatha (, Ancient Greek 'without jaws') is an infraphylum of jawless fish in the phylum Chordata, subphylum Vertebrata, consisting of both present (cyclostomes) and extinct (conodonts and ostracoderms) species. Among recent animals, cyclostomes .... References * Telling the Evolutionary Time: Molecular Clocks and the Fossil Record (Systematics Association Special Volume) by Philip C J Donoghue and M. Paul Smith (page 227) Osteostraci genera Silurian jawless fish {{silurian-animal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
