|
Gannanoolithus
''Gannanoolithus'' (meaning " Gannan stone egg") is an oogenus of dinosaur eggs likely laid by a dromaeosaurid theropod. It contains a single oospecies, ''G. yingliangi'', known from the Late Cretaceous (Maastrichtian) Lianhe Formation of Jiangxi Province, China. Etymology The generic name, ''Gannanoolithus'', combines "Gannan", an alternate name of Ganzhou City where the fossils were found, with the suffix "‑oolithus", meaning "stone egg". The specific name, ''yingliangi'', honors the Yingliang Stone Natural History Museum, where the fossils are housed. The authors also used the binomial variation "''Ganzhouoolithus yingliangensis''" in a figure in their publication. Description The ''Gannanoolithus'' holotype specimen, YLSNHM 01579, consists of a clutch of eight eggs. Specimens CUGW EH067-1 (a single egg) and EH067-2 (a pair of eggs) were also referred to the oogenus. All of the known fossil eggs have been found in layers of the Lianhe Formation in the Shahe Indust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2024 In Archosaur Paleontology
This article records new taxa of every kind of fossil archosaur that are scheduled to be Species description, described during 2024, as well as other significant discoveries and events related to the paleontology of archosaurs published in 2024. Pseudosuchians New pseudosuchian taxa General pseudosuchian research * Evidence of the impact of function on the evolution of the lower jaw morphology in crocodile-line archosaurs is presented by Rawson ''et al.'' (2024). * A review of studies on the thermometabolism of crocodile-line archosaurs from the preceding 20 years is published by Faure-Brac (2024). * Sennikov (2024) interprets Ornithosuchidae, ornithosuchids as macrophagous predators with specialized jaw apparatus, and notes analogs between them and saber-toothed therapsids (including mammals). * A study on the locomotion of ''Riojasuchus, Riojasuchus tenuisceps'' is published by von Baczko ''et al.'' (2024), who reconstruct ''R. tenuisceps'' as having an erect posture ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the Latin word for the white limestone known as chalk. The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period. Climate During the Late Cretaceous, the climate was warmer than present, although throughout the period a cooling trend is evident. The tropics became restricted to equatorial regions and northern latitudes experienced markedly more seasonal climatic conditions. Geography Due to plate tectonics, the Americas were gradually moving westward, causing the Atlantic Ocean to expand. The Western Interior Seaway divided North America into eastern and western halves; Appalachia and Laramidia. India maintained a northward course towards Asia. In the Southern Hemisphere, Aus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clutch
A clutch is a mechanical device that allows an output shaft to be disconnected from a rotating input shaft. The clutch's input shaft is typically attached to a motor, while the clutch's output shaft is connected to the mechanism that does the work. In a motor vehicle, the clutch acts as a mechanical linkage between the engine and transmission. By disengaging the clutch, the engine speed (RPM) is no longer determined by the speed of the driven wheels. Another example of clutch usage is in electric drills. The clutch's input shaft is driven by a motor and the output shaft is connected to the drill bit (via several intermediate components). The clutch allows the drill bit to either spin at the same speed as the motor (clutch engaged), spin at a lower speed than the motor (clutch slipping) or remain stationary while the motor is spinning (clutch disengaged). Types Dry clutch A ''dry clutch'' uses dry friction to transfer power from the input shaft to the output shaft, f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elongatoolithidae
Elongatoolithidae is an oofamily of fossil eggs, representing the eggs of oviraptorosaurs (with the exception of the Bird, avian ''Ornitholithus''). They are known for their highly elongated shape. Elongatoolithids have been found in Europe, Asia, and both North and South America.Simon, D. J. (2014).Giant Dinosaur (theropod) Eggs of the Oogenus Macroelongatoolithus (Elongatoolithidae) from Southeastern Idaho: Taxonomic, Paleobiogeographic, and Reproductive Implications. (Doctoral dissertation, Montana State University, Bozeman). Distribution Elongatoolithids have a very broad distribution. They have been found across Asia and the US, as well as in Spain, France, and Argentina, with ages ranging from lower Cretaceous to the Paleocene. Description Elongatoolithids are, as their name suggests, highly elongated eggs; they are at least twice as long as they are wide. They vary widely in size, ranging from the 7 cm long ''Elongatoolithus chichengshanensis'' to the gigantic 60 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sister Taxon
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and taxon B are sister groups to each other. Taxa A and B, together with any other extant or extinct descendants of their most recent common ancestor (MRCA), form a monophyletic group, the clade AB. Clade AB and taxon C are also sister groups. Taxa A, B, and C, together with all other descendants of their MRCA form the clade ABC. The whole clade ABC is itself a subtree of a larger tree which offers yet more sister group relationships, both among the leaves and among larger, more deeply rooted clades. The tree structure shown connects through its root to the rest of the universal tree of life. In cladistic standards, taxa A, B, and C may represent specimens, species, genera, or any other taxonomic units. If A and B are at the same taxonomic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polytomy
An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tree that contains any multifurcations can be described as a multifurcating tree. Soft polytomies vs. hard polytomies Two types of polytomies are recognized, soft and hard polytomies. Soft polytomies are the result of insufficient phylogenetic information: though the lineages diverged at different times – meaning that some of these lineages are closer relatives than others, and the available data does not allow recognition of this. Most polytomies are soft, meaning that they would be resolved into a typical tree of dichotomies if better data were available. In contrast, a hard polytomy represents a true divergence event of three or more lineages. Applications Interpretations for a polytomy depend on the individuals that are represented ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylogenetic Analyses
In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as Computational phylogenetics, phylogenetic inference. It infers the relationship among organisms based on empirical data and observed heritable traits of DNA sequences, protein amino acid sequences, and Morphology (biology), morphology. The results are a phylogenetic tree—a diagram depicting the hypothesis, hypothetical relationships among the organisms, reflecting their inferred evolutionary history. The tips of a phylogenetic tree represent the observed entities, which can be living Taxon, taxa or fossils. A phylogenetic diagram can be rooted or unrooted. A rooted tree diagram indicates the hypothetical common ancestor of the taxa represented on the tree. An unrooted tree diagram (a network) makes no assumption about directionality of character state transformation, and does not show the origin or "root" of the taxa in questi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oviraptorosaurs
Oviraptorosaurs ("egg thief lizards") are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot-like skulls, with or without bony crests atop the head. They ranged in size from '' Caudipteryx'', which was the size of a turkey, to the 8-meter-long, 1.4-ton ''Gigantoraptor''. The group (along with all maniraptoran dinosaurs) is close to the ancestry of birds. Some researchers such as Maryanska ''et al'' (2002) and Osmólska ''et al.'' (2004) have proposed that they may represent primitive flightless birds.Osmólska, Halszka, Currie, Philip J., Brasbold, Rinchen (2004) "The Dinosauria" Weishampel, Dodson, Osmólska. "Chapter 8 Oviraptorosauria" University of California Press. The most complete oviraptorosaur specimens have been found in Asia. The North American oviraptorosaur record is sparse.Varricchio, D. J. 2001. Late Cretaceous oviraptorosaur (Theropo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Troodontids
Troodontidae is a clade of bird-like theropod dinosaurs from the Late Jurassic to Late Cretaceous. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinosaurian lineages. More recent fossil discoveries of complete and articulated specimens (including specimens which preserve feathers, eggs, embryos, and complete juveniles), have helped to increase understanding about this group. Anatomical studies, particularly studies of the most primitive troodontids, like '' Sinovenator'', demonstrate striking anatomical similarities with ''Archaeopteryx'' and primitive dromaeosaurids, and demonstrate that they are relatives comprising a clade called Paraves. Evolution The oldest definitive troodontid known is '' Hesperornithoides'' from the Late Jurassic of Wyoming. The slightly older '' Koparion'' of Utah is only represented by a single tooth, and small maniraptoran teeth from the Middle Jurassic o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galliforms
Galliformes is an order of heavy-bodied ground-feeding birds that includes turkey (bird), turkeys, chickens, Old World quail, quail, and other landfowl. Gallinaceous birds, as they are called, are important in their ecosystems as seed dispersers and predators, and are often reared by humans for their meat and eggs, or hunted as game birds. The order contains about 290 species, inhabiting every continent except Antarctica, and divided into five Family (biology), families: Phasianidae (including chicken, quail, partridges, pheasants, turkeys, peafowl (peacocks) and grouse), Odontophoridae (New World quail), Numididae (guinea fowl), Cracidae (including chachalacas and curassows), and Megapodiidae (incubator birds like malleefowl and Brushturkey, brush-turkeys). They adapt to most environments except for innermost deserts and perpetual ice. Many gallinaceous species are skilled runners and escape predators by running rather than flying. Males of most species are more colorful ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crocodilians
Crocodilia () is an order of semiaquatic, predatory reptiles that are known as crocodilians. They first appeared during the Late Cretaceous and are the closest living relatives of birds. Crocodilians are a type of crocodylomorph pseudosuchian, a subset of archosaurs that appeared about 235 million years ago and were the only survivors of the Triassic–Jurassic extinction event. While other crocodylomorph groups further survived the Cretaceous–Paleogene extinction event, notably sebecosuchians, only the crocodilians have survived into the Quaternary. The order includes the true crocodiles (family Crocodylidae), the alligators and caimans (family Alligatoridae), and the gharial and false gharial (family Gavialidae). Although the term "crocodiles" is sometimes used to refer to all of these families, the term "crocodilians" is less ambiguous. Extant crocodilians have flat heads with long snouts and tails that are compressed on the sides, with their eyes, ears, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neontology
Neontology is a part of biology that, in contrast to paleontology, studies and deals with living (or, more generally, '' recent'') organisms. It is the study of extant taxa (singular: extant taxon): taxa (such as species, genera and families) with members still alive, as opposed to (all) being extinct. For example: * The Indian elephant (''Elephas maximus'') is an extant species, and the woolly mammoth (''Mammuthus primigenius'') is an extinct species. * The moose (''Alces alces'') is an extant species, and the Irish elk (''Megaloceros giganteus'') is an extinct species. * In the group of molluscs known as the cephalopods, there were approximately 600 extant species and 7,500 extinct species. A taxon can be classified as extinct if it is broadly agreed or certified that no members of the group are still alive. Conversely, an extinct taxon can be reclassified as extant if there are new discoveries of living species (" Lazarus species"), or if previously known extant species ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
