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Jagorina
''Jagorina pandora'' is a rhenanid placoderm of Upper Frasnian Germany. As with other rhenanids, it was a flattened, skate-like fish protected in an armor made up of unfused tubercles, and preyed on other, smaller fish by ambushing them from the sea bottom. Although ''J. pandora'' is known primarily from bone fragments and an intact skull, it is the second most studied rhenanid, after ''Gemuendina stuertzi ''Gemuendina stuertzi'' (named for Gemünden from where it was discovered) is a placoderm of the order Rhenanida, of the seas of Early Devonian Germany. In life, ''Gemuendina'' resembled a scaly ray with an upturned head, or a large-finned s ...''. It is from ''Jagorina'' that the details of the skull anatomy of rhenanids are known. Although scientists know of the overall anatomy and bodyplan of rhenanids because of ''G. stuertzi'', very little information has been gleaned from the skulls of ''G. stuertzi'', as all of the specimens of that species have been greatly f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhenanida
Rhenanida ("Rhine (fish)") is an Order (biology), order of scaly placoderms. Unlike most other placoderms, the rhenanids' armor was made up of a mosaic of unfused scales and tubercles. The patterns and components of this "mosaic" correspond to the plates of armor in other, more advanced placoderms, suggesting that the ancestral placoderm had armor made of unfused components, as well. All rhenanids were flattened, Batoidea, ray-like, bottom-dwelling predators that lived in marine environments. Evolution The rhenanids were once presumed to be the most primitive, or at least the closest to the ancestral placoderm, as their armor was made up of a mosaic of tubercles, as opposed to the solidified plates of "advanced" placoderms, such as antiarchs and arthrodires. Through comparing the skull anatomies of ''Jagorina pandora'' with those of antiarchs, the rhenanids are considered to be the sister group of the antiarchs (together with their respective Acanthothoracid relatives). Presen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhenanid
Rhenanida ("Rhine (fish)") is an order of scaly placoderms. Unlike most other placoderms, the rhenanids' armor was made up of a mosaic of unfused scales and tubercles. The patterns and components of this "mosaic" correspond to the plates of armor in other, more advanced placoderms, suggesting that the ancestral placoderm had armor made of unfused components, as well. All rhenanids were flattened, ray-like, bottom-dwelling predators that lived in marine environments. Evolution The rhenanids were once presumed to be the most primitive, or at least the closest to the ancestral placoderm, as their armor was made up of a mosaic of tubercles, as opposed to the solidified plates of "advanced" placoderms, such as antiarchs and arthrodires. Through comparing the skull anatomies of ''Jagorina pandora'' with those of antiarchs, the rhenanids are considered to be the sister group of the antiarchs (together with their respective Acanthothoracid relatives). Presence in the fossil record ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frasnian
The Frasnian is one of two faunal stages in the Late Devonian Period. It lasted from million years ago to million years ago. It was preceded by the Givetian Stage and followed by the Famennian Stage. Major reef-building was under way during the Frasnian Stage, particularly in western Canada and Australia. On land, the first forests were taking shape. In North America, the Antler orogeny peaked, which were contemporary with the Bretonic phase of the Variscan orogeny in Europe. The Frasnian coincides with the second half of the "charcoal gap" in the fossil record, a time when atmospheric oxygen levels were below 13 percent, the minimum necessary to sustain wildfires. North American subdivisions of the Frasnian include * West Falls Group * Sonyea Group * Genesee Group Name and definition The Frasnian Stage was proposed in 1879 by French geologist Jules Gosselet Jules-Auguste Gosselet (19 April 1832 – 20 March 1916) was a French geologist born in Cambrai, France. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germany
Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated between the Baltic and North seas to the north, and the Alps to the south; it covers an area of , with a population of almost 84 million within its 16 constituent states. Germany borders Denmark to the north, Poland and the Czech Republic to the east, Austria and Switzerland to the south, and France, Luxembourg, Belgium, and the Netherlands to the west. The nation's capital and most populous city is Berlin and its financial centre is Frankfurt; the largest urban area is the Ruhr. Various Germanic tribes have inhabited the northern parts of modern Germany since classical antiquity. A region named Germania was documented before AD 100. In 962, the Kingdom of Germany formed the bulk of the Holy Roman Empire. During the 16th ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skate (fish)
Skates are cartilaginous fish belonging to the family Rajidae in the superorder Batoidea of rays. More than 150 species have been described, in 17 genera.LAST, P.R. & SÉRET, B. & STEHMANN, M.F.W. & WEIGMANN, S. (2016) Skates, Family Rajidae. In: Last, P.R., White, W.T., Carvalho, M.R. de, Séret, B., Stehmann, M.F.W & Naylor, G.J.P (Eds.) Rays of the World. CSIRO Publishing, Melbourne: 204–363 Softnose skates and pygmy skates were previously treated as subfamilies of Rajidae (Arhynchobatinae and Gurgesiellinae), but are now considered as distinct families. Alternatively, the name "skate" is used to refer to the entire order of Rajiformes (families Anacanthobatidae, Arhynchobatidae, Gurgesiellidae and Rajidae). Members of Rajidae are distinguished by a stiff snout and a rostrum that is not reduced. Taxonomy and systematics Evolution Skates belong to the ancient lineage of cartilaginous fishes. Fossil denticles (tooth-like scales in the skin) resembling those of today's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gemuendina Stuertzi
''Gemuendina stuertzi'' (named for Gemünden from where it was discovered) is a placoderm of the order Rhenanida, of the seas of Early Devonian Germany. In life, ''Gemuendina'' resembled a scaly ray with an upturned head, or a large-finned stargazer. ''G. stuertzi'' is often invoked as an example of convergent evolution- with its flat body and huge, wing-like pectoral fins it has a strong, albeit superficial similarity to rays. Unlike rays, however, both ''Gemuendina''`s eyes and nostrils were placed atop the head, facing upward. Furthermore, ''G. stuertzis upturned mouth would have enabled it to suction prey that swam overhead, rather than swallow sediment or suction prey out of the substrate like modern rays. Unlike most other placoderm orders, such as the Antiarchs, or the Arthrodires, ''Gemuendina'' and its four other known relatives (or seven, if the three species of the ichthyolith genus '' Ohioaspis'' are confirmed to be rhenanids) had armor made up of a mosaic of u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placoderms Of Europe
Placodermi (from Greek πλάξ 'plate' and δέρμα 'skin', literally 'plate-skinned') is a class of armoured prehistoric fish, known from fossils, which lived from the Silurian to the end of the Devonian period. Their head and thorax were covered by articulated armoured plates and the rest of the body was scaled or naked, depending on the species. Placoderms were among the first jawed fish; their jaws likely evolved from the first of their gill arches. Placoderms are thought to be paraphyletic, consisting of several distinct outgroups or sister taxa to all living jawed vertebrates, which originated among their ranks. In contrast, one 2016 analysis concluded that placodermi are likely monophyletic, though these analyses have been further dismissed with more transitional taxa between placoderms and modern gnathosthomes, solidifying their paraphyletic status. Placoderms were also the first fish to develop pelvic fins, the precursor to hindlimbs in tetrapods, as well a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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