Information om | Engelska ordet ACANTHODIANS

Exempel på hur man kan använda ACANTHODIANS i en mening

• They can be contrasted with the Chondrichthyes (cartilaginous fish) and the extinct placoderms and acanthodians, which have endoskeletons primarily composed of cartilage.
• The earliest known fossil vertebrates were heavily armored fish discovered in rocks from the Ordovician period about 485 to 444 Ma (megaannum, million years ago), with jawed vertebrates emerging in the following Silurian period (444 to 419 Ma) with the placoderms and acanthodians.
• Fish can be grouped into the more basal jawless fish and the more common jawed fish, the latter including all living cartilaginous and bony fish, as well as the extinct placoderms and acanthodians.
• The systematics of fossil and extant fishes has puzzled ichthyologists since the time of Louis Agassiz, who first grouped all Palaeozoic ray-finned fishes together with Chondrostei (sturgeons, paddlefishes), gars, lungfishes, and acanthodians in his Ganoidei.
• The list includes all commonly accepted genera, but also genera that are now considered invalid, doubtful (nomina dubia), or were not formally published (nomina nuda), as well as junior synonyms of more established names, and genera that are no longer considered acanthodians.
• The acanthodians, the class of fish that includes Ischnacanthus, are the subject of some dispute over their systematic position because they have features of both bony fish, the Osteichthyes, and cartilaginous fish, the Chondrichthyes.
• Remains of acanthodians, anaspids, heterostracans, osteostracans, thelodonts and bivalves have also been found in the same sediment layers.
• The palatoquadrate forms from splanchnocranium in various chordates including placoderms and acanthodians.
• Freshwater fish fossils are common, including remains of rhizodonts, putative "osteolepiforms", "palaeoniscoids", xenacanth sharks, petalodont-like chondrichthyans, gyracanthid acanthodians, and the lungfish Tranodis.
• Vertebrate fossils include fragmentary remains of actinistians (coelacanths) and actinopterygians (tentatively identified as belonging to Elonichthyidae), possible ichnofossils of acanthodians (Undichna insolentia), and numerous and well-preserved skulls and partial skeletons of mesosaurs (Stereosternum and Mesosaurus).
• primordialis forms a polytomy with arthrodires, ptyctodonts, and all advanced gnathostomes (namely bony fish, tetrapods, acanthodians, and chondrichthyes).
• A study of relationships and character distributions of early gnathostomes, including placoderms and acanthodians, is published by Brazeau and Friedman (2014).
• A description of the general anatomy, morphology and histology of dermal elements and the endoskeletal shoulder girdle of three Devonian (Eifelian-Givetian) species of acanthodians known from Scotland (Diplacanthus crassisimus, Diplacanthus tenuistriatus and Rhadinacanthus longispinus) is published by Burrow et al.
• His thesis on the scales of thelodonts and acanthodians was criticized and led to a restudy of the material by J.

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