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Pseudopetalichthyida
Pseudopetalichthyida is an extinct order of lightly armored placoderms known only from rare fossils in Lower Devonian strata in Hunsrück, Germany. Like ''Stensioella heintzi'', and the Rhenanida, the Pseudopetalichthids had armor made up of a mosaic of tubercles. Like ''Stensioella heintzi'', the Pseudopetalichthids' placement within Placodermi is suspect. However, due to a gross lack of whole, uncrushed, articulated specimens, there are no other groups that the Pseudopetalichthids could be, for a lack of a better word, pigeonholed into. On the other hand, according to anatomical studies done on the crushed specimens that have been found, those experts who do regard the Pseudopetalichthyida as placoderms consider them to be a group more advanced than the Ptyctodonts. And as such, pro-placoderm experts consider Pseudopetalichthyida to be the sister group of the Arthrodires + Phyllolepida + Antiarchi trichotomy and the Acanthothoraci + Rhenanida dichotomy. The best known s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placodermi
Placodermi (from Greek πλάξ 'plate' and δέρμα 'skin', literally 'Plate (animal anatomy), plate-skinned') is a Class (biology), 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 scale (zoology), scaled or naked, depending on the species. Placoderms were among the first jawed fish; their Fish jaw, jaws likely evolved from the first of their gill arches. Placoderms are thought to be paraphyly, paraphyletic, consisting of several distinct Outgroup (cladistics), outgroups or sister taxon, 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. Plac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudopetalichthys
''Pseudopetalichthys problematica'' is a lightly armored pseudopetalichthyid placoderm from the Hunsrückschiefer Lagerstätte of Early Devonian Germany. The holotype and only known specimen is an articulated, but incomplete individual consisting of a large, mostly intact, plate-covered head, the bases of the pectoral fins, and most of the vertebral column, with a total length of . The specimen superficially resembles ''Stensioella'', though the structures of the mouth, and orbits (the orbits being unknown in ''Stensioella''), and placement of the gill rakers all differ. Some experts suggest that ''P. problematica'' and the related ''Paraplesiobatis'' are the same species, suggesting that the differences between them are merely due to different circumstances of taphonomy, but this hypothesis can not be tested until more specimens are found. The holotype was originally held in the Schlosspark Museum in Bad Kreuznach, but was then lost at an unknown date. References External ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudopetalicthys Problematica
''Pseudopetalichthys problematica'' is a lightly armored pseudopetalichthyid placoderm from the Hunsrückschiefer Lagerstätte of Early Devonian Germany. The holotype and only known specimen is an articulated, but incomplete individual consisting of a large, mostly intact, plate-covered head, the bases of the pectoral fins, and most of the vertebral column, with a total length of . The specimen superficially resembles ''Stensioella'', though the structures of the mouth, and orbits (the orbits being unknown in ''Stensioella''), and placement of the gill rakers all differ. Some experts suggest that ''P. problematica'' and the related ''Paraplesiobatis'' are the same species, suggesting that the differences between them are merely due to different circumstances of taphonomy, but this hypothesis can not be tested until more specimens are found. The holotype was originally held in the Schlosspark Museum in Bad Kreuznach, but was then lost at an unknown date. References External ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraplesiobatis
''Paraplesiobatis heinrichsi'' is a lightly armored Pseudopetalichthyida, pseudopetalichthyid placoderm from the Hunsrück Slate, Hunsrückschiefer Lagerstätte of Early Devonian Germany. The Type specimen, type and only known specimen is an articulated, but very incomplete individual consisting of a large, incomplete, plate-covered head, and some of the vertebral column, with a total length of 10 centimeters. The specimen strongly resembles ''Pseudopetalichthys'' to the point that many experts suggest they may be of the same genus or species, though because the only specimens of both genera are so poorly preserved, talk of Synonymy (biology), synonymizing the two can not begin (let alone continue) until more, better preserved specimens are found. References External links ''Pseudopetalichthys'' at the Paleobiology Database Pseudopetalichthyida Placoderms of Europe {{placoderm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nessariostoma
''Nessariostoma granulosum'' is a lightly armored Pseudopetalichthyida, pseudopetalichthyid placoderm from the Hunsrück Slate, Hunsrückschiefer Lagerstätte of Early Devonian Germany. The Type specimen, type and only known specimen is an articulated, but very incomplete individual, deformed and elongated, consisting of a large, incomplete, tubercle-covered head, a long, beak-like Rostrum (anatomy), rostrum, and some of the Trunk (anatomy), trunk, with a total length of 18 centimeters. ''N. granulosum'' was once placed in Stensioellida, though most other experts regard it at as a pseudopetalichthyid: Denison 1978 regards it as a placoderm ''incertae sedis'' because the specimen is deformed and so poorly preserved so as to stymie proper attempts at classification. References External links ''Pseudopetalichthys'' at the Paleobiology Database Pseudopetalichthyida Fossils of Germany {{placoderm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nessariostoma Granulosum
''Nessariostoma granulosum'' is a lightly armored Pseudopetalichthyida, pseudopetalichthyid placoderm from the Hunsrück Slate, Hunsrückschiefer Lagerstätte of Early Devonian Germany. The Type specimen, type and only known specimen is an articulated, but very incomplete individual, deformed and elongated, consisting of a large, incomplete, tubercle-covered head, a long, beak-like Rostrum (anatomy), rostrum, and some of the Trunk (anatomy), trunk, with a total length of 18 centimeters. ''N. granulosum'' was once placed in Stensioellida, though most other experts regard it at as a pseudopetalichthyid: Denison 1978 regards it as a placoderm ''incertae sedis'' because the specimen is deformed and so poorly preserved so as to stymie proper attempts at classification. References External links ''Pseudopetalichthys'' at the Paleobiology Database Pseudopetalichthyida Fossils of Germany {{placoderm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraplesiobatis Heinrichsi
''Paraplesiobatis heinrichsi'' is a lightly armored Pseudopetalichthyida, pseudopetalichthyid placoderm from the Hunsrück Slate, Hunsrückschiefer Lagerstätte of Early Devonian Germany. The Type specimen, type and only known specimen is an articulated, but very incomplete individual consisting of a large, incomplete, plate-covered head, and some of the vertebral column, with a total length of 10 centimeters. The specimen strongly resembles ''Pseudopetalichthys'' to the point that many experts suggest they may be of the same genus or species, though because the only specimens of both genera are so poorly preserved, talk of Synonymy (biology), synonymizing the two can not begin (let alone continue) until more, better preserved specimens are found. References External links ''Pseudopetalichthys'' at the Paleobiology Database Pseudopetalichthyida Placoderms of Europe {{placoderm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acanthothoraci
Acanthothoraci (''spine chests'') is an extinct group of chimaera-like placoderms who were closely related to the rhenanid placoderms. Superficially, the acanthoracids resembled scaly chimaeras, or (relatively) heavily armored ptyctodonts. They were distinguished from chimaeras by the presence of large scales and plates, a pair of large spines that emanate from their chests (thus, the order's name), tooth-like beak plates, and the typical bone-enhanced placoderm eyeball. They were distinguished from other placoderms due to differences in the anatomy of their skulls, and due to patterns on the skull plates and thoracic plates that are unique to this order. Fossil record Fossils of the Acanthothoracids are found in various deposits from the Lower Devonian throughout the world. Fossils of the Palaeacanthaspids are found in Eurasia and Canada, while the Weejasperaspids have only been found in the Taemas Wee Jasper reef, in Southeastern Australia. Ecology From what can be inferr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hunsrück
The Hunsrück () is a long, triangular, pronounced upland in Rhineland-Palatinate, Germany. It is bounded by the valleys of the Moselle-Saar (north-to-west), the Nahe (south), and the Rhine (east). It is continued by the Taunus mountains, past the Rhine and by the Eifel past the Moselle. To the south of the Nahe is a lower, hilly country forming the near bulk of the Palatinate region and all of the, smaller, Saarland. Below its north-east corner is Koblenz. As the Hunsrück proceeds east it acquires north-south width and three notable gaps in its southern ridges. In this zone are multi-branch headwaters including the Simmerbach ending at Simmertal on the southern edge. This interior is therefore rarely higher than above sea level. Peaks and escarpments are principally: the (Black Forest) Hochwald, the Idar Forest, the Soonwald, and the Bingen Forest. The highest mountain is the Erbeskopf (816 m; 2,677 ft), towards the region's south-west. Notable towns are Simmern, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinction
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" (typically in the fossil record) after a period of apparent absence. More than 99% of all species that ever lived on Earth, amounting to over five billion species, are estimated to have died out. It is estimated that there are currently around 8.7 million species of eukaryote globally, and possibly many times more if microorganisms, like bacteria, are included. Notable extinct animal species include non-avian dinosaurs, saber-toothed cats, dodos, m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chordata
A chordate () is an animal of the phylum Chordata (). All chordates possess, at some point during their larval or adult stages, five synapomorphies, or primary physical characteristics, that distinguish them from all the other taxa. These five synapomorphies include a notochord, dorsal hollow nerve cord, endostyle or thyroid, pharyngeal slits, and a post-anal tail. The name “chordate” comes from the first of these synapomorphies, the notochord, which plays a significant role in chordate structure and movement. Chordates are also Bilateral symmetry, bilaterally symmetric, have a coelom, possess a circulatory system, and exhibit Metameric, metameric segmentation. In addition to the morphological characteristics used to define chordates, analysis of genome sequences has identified two conserved signature indels (CSIs) in their proteins: cyclophilin-like protein and mitochondrial inner membrane protease ATP23, which are exclusively shared by all vertebrates, tunicates and cep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinction
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" (typically in the fossil record) after a period of apparent absence. More than 99% of all species that ever lived on Earth, amounting to over five billion species, are estimated to have died out. It is estimated that there are currently around 8.7 million species of eukaryote globally, and possibly many times more if microorganisms, like bacteria, are included. Notable extinct animal species include non-avian dinosaurs, saber-toothed cats, dodos, m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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