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Geikia
''Geikia'' is an extinct genus of dicynodont therapsids from the late Permian. The abundance and diversity of dicynodonts during this period, combined with incomplete or inadequately prepared specimens, have led to challenges in determining relationships within this taxon. Only two species, ''Geikia locusticeps'' and ''Geikia elginensis'' have been assigned to this genus. While this is the currently accepted classification, fossil record limitations have led to repeated debate on the genus assignments of these species. Description A high level of skull specialization was significant in the classification of ''Geikia''. Maisch and Gebauer considered the squared off anterior snout tip and reduced exposure of squamosal in occiput to be characteristics exclusively expressed in ''Geikia''. Prior to their analysis, Rowe described the generic diagnosis of Geikia as “dicynodonts having no tusk or postcanine teeth; highly vaulted palate; anterior palatal ridges of premaxilla reduced or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geikia And Sclerosaurus
''Geikia'' is an extinct genus of dicynodont therapsids from the late Permian. The abundance and diversity of dicynodonts during this period, combined with incomplete or inadequately prepared specimens, have led to challenges in determining relationships within this taxon. Only two species, ''Geikia locusticeps'' and ''Geikia elginensis'' have been assigned to this genus. While this is the currently accepted classification, fossil record limitations have led to repeated debate on the genus assignments of these species. Description A high level of skull specialization was significant in the classification of ''Geikia''. Maisch and Gebauer considered the squared off anterior snout tip and reduced exposure of squamosal in occiput to be characteristics exclusively expressed in ''Geikia''. Prior to their analysis, Rowe described the generic diagnosis of Geikia as “dicynodonts having no tusk or postcanine teeth; highly vaulted palate; anterior palatal ridges of premaxilla reduced or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geikiidae
Geikiidae is a family of Late Permian dicynodonts. Fossils are known from Scotland, South Africa, and Tanzania. The family was first named by Franz Nopcsa in 1923, although Friedrich von Huene's 1948 description of the family brought it into common usage. Von Huene established Geikiidae as a monotypic family for ''Geikia'', then known from Scotland. He distinguished ''Geikia'' from all other dicynodonts because it lacked a preparietal bone. The outlines on the bones of the skull roof could not be seen however, meaning that this characteristic was uncertain in geikiids. Geikiids were originally classified as close relatives of ''Dicynodon'' and ''Lystrosaurus ''Lystrosaurus'' (; 'shovel lizard'; proper Greek is λίστρον ''lístron'' ‘tool for leveling or smoothing, shovel, spade, hoe’) is an extinct genus of herbivorous dicynodont therapsids from the late Permian and Early Triassic epochs (a ...'', but the characters that linked these dicynodonts are also seen in many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelanomodon Tuberosus Skull
''Pelanomodon'' is an extinct genus of dicynodont therapsids that lived in the Late Permian period. Fossil evidence of this genus is principally found in the Karoo Basin of South Africa, in the ''Dicynodon'' Assemblage Zone.Kammerer, C. F., K. D. Angielczyk, and Jörg Fröbisch. 2015. Redescription of the geikiid Pelanomodon (Therapsida, Dicynodontia), with a reconsideration of ‘Propelanomodon’. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2015.1030408. http://www.tandfonline.com/doi/full/10.1080/02724634.2015.1030408 Lack of fossil record after the Late Permian epoch suggests that ''Pelanomodon'' fell victim to the Permian-Triassic extinction event. The name ''Pelanomodon'' can be broken up into three parts; “pelos” meaning mud, “anomo” meaning irregular and “odon” meaning tooth. Together, this suggests ''Pelanomodon'' to be a mud dwelling anomodont (a group of therapsids that are characterized by their lack of teeth). The Karoo Basin during this pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elgin Reptiles
Elgin Reptiles is the name given to the Permian and Triassic fossils found in the sandstone deposits in and around the town of Elgin, in Moray, Scotland. They are of historical and scientific importance, and many of the specimens are housed in the Elgin Museum, and some in the Hunterian in Glasgow, and the National Museum of Scotland in Edinburgh. The Elgin Reptiles include the dinosauriform ''Saltopus elginensis'', the dicynodont '' Gordonia'', and the pareiasaur ''Elginia''. There are also many footprints and tail-drags associated with the same Permian and Triassic sandstone deposits. History The sandstone in the Elgin area was originally quarried for building materials. The quarries were where the first reptile fossils were found, and they have continued to yield fossils to this day. The first Elgin Reptile was discovered in 1844, but because it was only a few scales scientists of the time believed it was an Old Red Sandstone fish fossil, which were relatively well-known from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dicynodont
Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivorous animals with a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typically toothless beak, unique amongst all synapsids. Dicynodonts first appeared in Southern Pangaea during the mid-Permian, ca. 270–260 million years ago, and became globally distributed and the dominant herbivorous animals in the Late Permian, ca. 260–252 Mya. They were devastated by the end-Permian Extinction that wiped out most other therapsids ca. 252 Mya. They rebounded during the Triassic but died out towards the end of that period. They were the most successful and diverse of the non-mammalian therapsids, with over 70 genera known, varying from rat-sized burrowers to elephant-sized browsers. Characteristics The dicynodont skull is highly specialised, light but strong, with the synapsid temporal openings at the rear of the skull ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelanomodon
''Pelanomodon'' is an extinct genus of dicynodont therapsids that lived in the Late Permian period. Fossil evidence of this genus is principally found in the Karoo Basin of South Africa, in the ''Dicynodon'' Assemblage Zone.Kammerer, C. F., K. D. Angielczyk, and Jörg Fröbisch. 2015. Redescription of the geikiid Pelanomodon (Therapsida, Dicynodontia), with a reconsideration of ‘Propelanomodon’. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2015.1030408. http://www.tandfonline.com/doi/full/10.1080/02724634.2015.1030408 Lack of fossil record after the Late Permian epoch suggests that ''Pelanomodon'' fell victim to the Permian-Triassic extinction event. The name ''Pelanomodon'' can be broken up into three parts; “pelos” meaning mud, “anomo” meaning irregular and “odon” meaning tooth. Together, this suggests ''Pelanomodon'' to be a mud dwelling anomodont (a group of therapsids that are characterized by their lack of teeth). The Karoo Basin during this pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dicynodon
''Dicynodon'' ("two dog-teeth") is a genus of dicynodont therapsid that flourished during the Upper Permian period. Like all dicynodonts, it was herbivorous animal. This reptile was toothless, except for prominent tusks, hence the name. It probably cropped vegetation with a horny beak, much like a tortoise, while the tusks may have been used for digging up roots and tubers. Many species of ''Dicynodon'' have been named, and the genus is considered a wastebasket taxon. A 2011 study of the genus found most of the species to represent a paraphyletic grouping, with the only valid members of ''Dicynodon'' being ''D. lacerticeps'' and ''D. huenei''. A 2019 study named a new species ''D. angielczyki'', but simultaneously transferred ''D. huenei'' to the genus ''Daptocephalus''. Description ''Dicynodon'' was a medium-sized and advanced member of the Dicynodont group. It had an average length of , although size differed among species. Its fossil remains have been found in sediments of l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Usili Formation
The Usili Formation is a Late Permian geologic formation in Tanzania. It preserves fossils of many terrestrial vertebrates from the Permian, including temnospondyls, pareiasaurs, therapsids and the archosauromorph ''Aenigmastropheus''. History of study One of the first to study rocks of the Usili Formation was British geologist G. M. Stockley. In 1932, Stockley explored the geology of the Ruhuhu Basin in Tanzania. He called a series of layers dating from the Late Carboniferous to the Middle Triassic of the Songea Series and divided it into eight units labelled K1-K8. Stockley was also the first to describe fossils from these rocks, naming an older layer the "Lower Bone Bed" and a younger layer the "Upper Bone Bed". In 1957, paleontologist Alan J. Charig described many more fossils from the upper bone beds in his Ph.D. thesis for the University of Cambridge.Charig, A. J. (1957). New Triassic archosaurs from Tanganyika, including ''Mandasuchus'' and ''Teleocrater'': Dissertati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cutties Hillock Sandstone
The Hopeman Sandstone Formation is a geologic formation in Scotland. It preserves fossil footprints and body fossils from the Guadalupian Epoch in the Late Permian, to the Early Triassic,Walker, AD. 1973. The age of Cuttie's Hillock Sandstone (Perm-Triassic) of the Elgin Area. Scottish Journal of Geology 9:177-183. It preserves fossils and fossil footprints from various extinct animals such as pareiasaurs and dicynodonts, which are collectively often referred to as the Elgin Reptiles. The formation, named for the village of Hopeman, lies unconformably over the Devonian Upper Old Red Sandstone, and it underlies the waterlain sandstones of the Burghead Sandstone Formation. It represents a windswept dune landscape. The Hopeman Sandstones were previously referred to as the Cutties Hillock Sandstone, Quarry Wood Sandstones, Sandstones of Hopeman, and Hopeman-Cummingstown Sandstone, but these names have since been superseded. Lithology The Hopeman Sandstone Formation is predomina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ontogeny
Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the study of the entirety of an organism's lifespan. Ontogeny is the developmental history of an organism within its own lifetime, as distinct from phylogeny, which refers to the evolutionary history of a species. Another way to think of ontogeny is that it is the process of an organism going through all of the developmental stages over its lifetime. The developmental history includes all the developmental events that occur during the existence of an organism, beginning with the changes in the egg at the time of fertilization and events from the time of birth or hatching and afterward (i.e., growth, remolding of body shape, development of secondary sexual characteristics, etc.). While developmental (i.e., ontogenetic) processes can influence sub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incertae Sedis
' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty at specific taxonomic levels is indicated by ' (of uncertain family), ' (of uncertain suborder), ' (of uncertain order) and similar terms. Examples *The fossil plant '' Paradinandra suecica'' could not be assigned to any family, but was placed ''incertae sedis'' within the order Ericales when described in 2001. * The fossil ''Gluteus minimus'', described in 1975, could not be assigned to any known animal phylum. The genus is therefore ''incertae sedis'' within the kingdom Animalia. * While it was unclear to which order the New World vultures (family Cathartidae) should be assigned, they were placed in Aves ''incertae sedis''. It was later agreed to place them in a separate order, Cathartiformes. * Bocage's longbill, ''Motacilla bocagii' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plesiomorphy
In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, and synapomorphy, all mean a trait shared between species because they share an ancestral species. Apomorphic and synapomorphic characteristics convey much information about evolutionary clades and can be used to define taxa. However, plesiomorphic and symplesiomorphic characteristics cannot. The term ''symplesiomorphy'' was introduced in 1950 by German entomologist Willi Hennig. Examples A backbone is a plesiomorphic trait shared by birds and mammals, and does not help in placing an animal in one or the other of these two clades. Birds and mammals share this trait because both clades are descended from the same far distant ancestor. Other clades, e.g. snakes, lizards, turtles, fish, frogs, all have backbones and none are either birds n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
