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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 intern ....Long, J.A., Trinajstic, K. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ctenurella
''Ctenurella'' (from el, κτείς , 'comb' and el, ουρά , '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. ... [...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] |
Gogo Formation
The Gogo Formation in the Kimberley region of Western Australia is a Lagerstätte that exhibits exceptional preservation of a Devonian reef community. The formation is named after Gogo Station, a cattle station where outcrops appear and fossils are often collected from, as is nearby Fossil Downs Station. History The reef, which now stands up abruptly in the western Australian desert (as the Windjana Limestone), was first identified in 1940 by paleontologist Curt Teichert, who discovered the first fossil fish from the region. Sedimentology Unweathered sections of the Gogo Formation are made of siltstone, shale and calcarenite with numerous limestone concretions. These concretions are resistant to weathering, producing extensive nodule fields on the ground in areas where the surrounding rock has eroded away. The Gogo sediments represent deep, hypoxic seafloor deposits in the vicinity of a large tropical reef composed primarily of algae and stromatoporoids during the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placoderms Of Australia
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 as tru ... [...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 Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located enti .... 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 * Wes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ptyctodontid
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] |
Australia
Australia, officially the Commonwealth of Australia, is a sovereign ''Sovereign'' is a title which can be applied to the highest leader in various categories. The word is borrowed from Old French , which is ultimately derived from the Latin , meaning 'above'. The roles of a sovereign vary from monarch, ruler or ... country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by area in Oceania and the world's sixth-largest country. Australia is the oldest, flattest, and driest inhabited continent, with the least fertile soils. It is a megadiverse country, and its size gives it a wide variety of landscapes and climates, with deserts in the centre, tropical Forests of Australia, rainforests in the north-east, and List of mountains in Australia, mountain ranges in the south-east. The ancestors of Aboriginal Australians began arriving from south east Asia approx ... [...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 in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viviparity
Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the mother. The term 'viviparity' and its adjective form 'viviparous' derive from the Latin ''vivus'' meaning "living" and ''pario'' meaning "give birth to". Reproductive mode Five modes of reproduction have been differentiated in animals based on relations between zygote and parents. The five include two nonviviparous modes: ovuliparity, with external fertilisation, and oviparity, with internal fertilisation. In the latter, the female lays zygotes as eggs with a large yolk; this occurs in all birds, most reptiles, and some fishes. These modes are distinguished from viviparity, which covers all the modes that result in live birth: *Histotrophic viviparity: the zygotes develop in the female's oviducts, but find their nutrients by oophagy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 internal fertilization to happen there needs to be a method for the male to introduce the sperm into the female's reproductive tract. Most taxa that reproduce by internal fertilization are gonochoric. In mammals, reptiles, and certain other groups of animals, this is done by copulation, an intromittent organ being introduced into the vagina or cloaca. In most birds, the cloacal kiss is used, the two animals pressing their cloacas together while transferring sperm. Salamanders, spiders, some insects and some molluscs undertake internal fertilization by transferring a spermatophore, a bundle of sperm, from the male to the female. Following fertilization, the embryos are laid as eggs in oviparous organisms, or continue to develop inside the reprod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kate Trinajstic
Professor Kate Trinajstic or Katherine M. Trinajstic is an Australian palaeontologist, evolutionary biologist, and winner of the Dorothy Hill Award. She is the Dean of Research, Faculty of Science and Engineering at Curtin University. Early life and career Trinajstic was awarded a Bachelor of Science, (Hons), in ecology and evolutionary biology, from Murdoch University in 1996. She then was awarded a PhD in palaeontology from the University of Western Australia, in 2000. She joined Curtin University in 2009 as a Curtin Research Fellow. In 2011 she was awarded an ARC QEII Fellowship, titled 'Fleshing out the fossil record', which was designed to investigate the development of early vertebrates, and the skeleton and specific musculature. She was both a Curtin Research Fellow, as well as an honorary Research Associate at the University of Western Australia. Her career has specialised in vertebrate palaeontology, and also how early vertebrate were able to evolve unique morphology, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
