|
Ptyctodontids
The ptyctodontids ("folded-teeth") are placoderms of the order Ptyctodontida, containing the family Ptyctodontidae. With their big heads, big eyes, reduced armor and long bodies, the ptyctodontids bore a superficial resemblance to modern day chimaeras (Holocephali). Their armor was reduced to a pattern of small plates around the head and neck. Like the extinct and related acanthothoracids, and the living and unrelated holocephalians, most of the ptyctodontids are thought to have lived near the sea bottom and preyed on shellfish. On account of their radically reduced armor, some paleontologists have suggested that the Ptyctodontida were not actually placoderms, but actual holocephalians, some primitive group of elasmobranch fish, or even were the ancestors of the holocephalians, including the chimaeras. Thorough anatomical examinations of whole fossil specimens reveal that the profound similarities between these two groups are actually very superficial. The major differences b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhamphodopsis
''Rhamphodopsis'' is a genus of extinct ptyctodont placoderm from the Middle Devonian Old Red Sandstone of Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac .... Species There are two species of ''Rhamphodopsis'' recognized. ''R. thrieplandi'' This is the type species, and the smaller of the two described species, the adult total length being up to 7 centimeters. The median dorsal spine is shorter than the anterior lateral spines. ''R. trispinatus'' This is a much larger, more robust species, the adult total length being up to 12 centimeters. The main way to distinguish small individuals of ''R. trispinatus'' from individuals of ''R. thrieplandi'' is that the median dorsal and anterior lateral spines of ''R. trispinatus'' are both proportionally equal lengths and are propo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kimbryanodus
''Kimbryanodus'' is a genus of extinct ptyctodontid placoderm fish from the Frasnian of Australia.These placoderms can be told apart from others due to the large eyes, crushing tooth plates, long bodies, reduced armor, and a superficial resemblance to holocephalid fish. The group is so far the only Placoderms known with sexually dimorphic features. The fossils occur as small three dimensional isolated plates. Because of these new specimens the Ptyctodontid grouping got a taxonomic classification, it found that the genus ''Rhamphodopsis'' to be the most basal taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and .... They are divided by having the more basal taxa having a median dorsal spine, a simple spinal plate, and a simple V-shaped overlap of the anterior lateral and the anter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Austroptyctodus
''Austroptyctodus gardineri'' is a small ptyctodontid placoderm fish from the Upper Devonian Gogo Formation of Western Australia. First described by Miles & Young (1977) as a new species of the German genus '' Ctenurella''. Long (1997) redescribed the German material and found major differences in the skull roof pattern so assigned it to a new genus, ''Austroptyctodus''. This genus lacks spinal plates and has '' Ptyctodus''-like toothplates. The most significant discovery about ''Austroptyctodus'' is that one specimen depicts a female pregnant with 3 unborn embryos inside her, showing that like ''Materpiscis'', also from Gogo, this genus was a live bearer that reproduced through internal fertilization Internal fertilization is the union of an egg and sperm cell during sexual reproduction inside the female body. Internal fertilization, unlike its counterpart, external fertilization, brings more control to the female with reproduction. For inte .... Feeding habits ''Austro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placoderm
Placoderms (from Ancient Greek πλάξ [''plax'', ''plakos''] 'Plate (animal anatomy), plate' and δέρμα [''derma''] 'skin') are vertebrate animals of the class (biology), class Placodermi, an extinct group of prehistoric fish known from Paleozoic fossils during the Silurian and the Devonian geological period, periods. While their endoskeletons are mainly cartilaginous, their head and thorax were covered by articulated armour (zoology), armoured plates (hence the name), 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 Evolution, evolved from the first pair of gill arches), as well as the first vertebrates to have true tooth, teeth. They were also the first fish clade to develop pelvic fins, the second set of paired fins and the homology (biology), homologous precursor to hindlimbs in tetrapods. 380-million-year-old fossils of three other genera, ''Incisoscutum'', ''M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhynchodus
The ptyctodontids ("folded-teeth") are placoderms of the order Ptyctodontida, containing the family Ptyctodontidae. With their big heads, big eyes, reduced armor and long bodies, the ptyctodontids bore a superficial resemblance to modern day chimaeras (Holocephali). Their armor was reduced to a pattern of small plates around the head and neck. Like the extinct and related acanthothoracids, and the living and unrelated holocephalians, most of the ptyctodontids are thought to have lived near the sea bottom and preyed on shellfish. On account of their radically reduced armor, some paleontologists have suggested that the Ptyctodontida were not actually placoderms, but actual holocephalians, some primitive group of elasmobranch fish, or even were the ancestors of the holocephalians, including the chimaeras. Thorough anatomical examinations of whole fossil specimens reveal that the profound similarities between these two groups are actually very superficial. The major differences b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ptyctodus
''Ptyctodus'' is an extinct armour-plated fish of the late Devonian. ''Ptyctodus'' belongs to the family Ptyctodontidae and is of the class Placodermi. They share a close resemblance to modern day chimaeras (Holocephali). Fossils of this armour-plated fish have been found in locations such as in Russia, the Michigan Basis, and Arizona, United States. Description and paleobiology ''Ptyctodus'' species come in a variety of different sizes, measured data shows three specimens being 94 millimeters, 24 millimeters, 22 millimeters in length, 23 millimeters, 6 millimeters, 4 millimeter in height, and 18 millimeters, 7 millimeters, and 4 millimeters in thickness. Through time, an evolutionary morphological trait is that the species within Ptyctodontidae reduce the dermal armour. The dentition of the ''Ptyctodus'' has dental elements that are very similarly observed in ''chimaeroids''. Its dental plates are compressed into a thin cutting edge behind the symphysis and measure 3 inches ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Materpiscis
''Materpiscis'' (Latin for ''mother fish'') is a genus of ptyctodontid placoderm from the Late Devonian located at the Gogo Formation of Western Australia. Known from only one specimen, it is unique in having an unborn embryo present inside the mother, with remarkable preservation of a mineralised placental feeding structure (umbilical cord). This makes ''Materpiscis'' the oldest known vertebrate to show viviparity, or giving birth to live young. Discovery and naming The holotype was found in the Kimberley area of northern Western Australia by Lindsay Hatcher during the 2005 expedition to the Gogo led by John Long of Museum Victoria. Fossils from the Gogo Formation are preserved in limestone nodules, so dilute acetic acid is used to dissolve the surrounding limestone and reveal the fossil, often preserved in three dimensions with minimal distortion. The species was named ''Materpiscis attenboroughi'' in honour of David Attenborough who first drew attention to the significance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palaeomylus
''Palaeomylus'' (meaning 'ancient grinder') is an extinct Devonian ptychodontid placoderm fish. There are seven species accepted in this genus: Etymology The generic name is derived from Greek (''Palaeo'', meaning "ancient") and (''mylos'', meaning "grinder"). Not to be confused with the junior homonym ''Palaeomylus'' , which is an early diverging member of the mammal group Glires. Discovery ''P. greenei'', ''P. crassus'', and the type species ''P. frangens'' were originally classified as a species of ''Rhynchodus'', before being moved to a new genus, ''Palaeomylus'', in 1891. The first was found in Wisconsin, while the latter two species were found in Ohio. ''P. predator'' was found near Gerolstein Gerolstein () is a town in the Vulkaneifel district of Rhineland-Palatinate, Germany. Gerolstein is a local municipality of the ''Verbandsgemeinde Gerolstein''. It has been approved as a ''Luftkurort'' (spa town). History As early as the Stone ..., Germany. References ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Goniosteus
The ptyctodontids ("folded-teeth") are placoderms of the order Ptyctodontida, containing the family Ptyctodontidae. With their big heads, big eyes, reduced armor and long bodies, the ptyctodontids bore a superficial resemblance to modern day chimaeras (Holocephali). Their armor was reduced to a pattern of small plates around the head and neck. Like the extinct and related acanthothoracids, and the living and unrelated holocephalians, most of the ptyctodontids are thought to have lived near the sea bottom and preyed on shellfish. On account of their radically reduced armor, some paleontologists have suggested that the Ptyctodontida were not actually placoderms, but actual holocephalians, some primitive group of elasmobranch fish, or even were the ancestors of the holocephalians, including the chimaeras. Thorough anatomical examinations of whole fossil specimens reveal that the profound similarities between these two groups are actually very superficial. The major differences b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eczematolepis
''Eczematolepis'' is an extinct genus of ptyctodontidan from the Milwaukee Formation of Wisconsin Wisconsin ( ) is a U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest of the United States. It borders Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michig .... Three species are known: ''E. fragilis'', ''E. pustulosus'' and ''E. telleri''.''Eastman, C. R.'' 1898 B, p. 55, fig. 49. 1899 B, p. 283. It was originally classified as the genus ''Acantholepis'' but that name was preoccupied. References Ptyctodontids Givetian extinctions Placoderm genera Fossil taxa described in 1892 {{Placoderm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Destnoporella
The ptyctodontids ("folded-teeth") are placoderms of the order Ptyctodontida, containing the family Ptyctodontidae. With their big heads, big eyes, reduced armor and long bodies, the ptyctodontids bore a superficial resemblance to modern day chimaeras (Holocephali). Their armor was reduced to a pattern of small plates around the head and neck. Like the extinct and related acanthothoracids, and the living and unrelated holocephalians, most of the ptyctodontids are thought to have lived near the sea bottom and preyed on shellfish. On account of their radically reduced armor, some paleontologists have suggested that the Ptyctodontida were not actually placoderms, but actual holocephalians, some primitive group of elasmobranch fish, or even were the ancestors of the holocephalians, including the chimaeras. Thorough anatomical examinations of whole fossil specimens reveal that the profound similarities between these two groups are actually very superficial. The major differences b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ctenurella
''Ctenurella'' (from , 'comb' and , 'tail') is an extinct genus of ptyctodont placoderm from the Late Devonian of Germany. The first fossils were found in the Strunde valley in the Paffrather Kalkmulde. Description As with other ptyctodonts, the armor of ''Ctenurella'' was reduced to a few thin plates on the head and shoulder region. It was also relatively small for a placoderm, at just in length. ''Ctenurella'' had two dorsal fins and the rear of the body was relatively long and low. Most ptyctodonts are presumed to have fed on the ocean floor, but the well-developed fins of this genus indicate that it probably also swam in open waters. ''Ctenurella'' had a long, whip-like tail, large eyes, and robust upper and lower jaw tooth plates. Males also had hook-shaped sex organs, known as claspers. Since analogous features are also found in the unrelated living chimaeras, chimaeras and ptyctodonts are thought to be an example of convergent evolution. Etymology The specific name ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
