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Polarornis
''Polarornis'' is a genus of prehistoric bird, possibly an anserimorph. It contains a single species ''Polarornis gregorii'', known from incomplete remains of one individual found on Seymour Island, Antarctica, in rocks which are dated to the Late Cretaceous (López de Bertodano Formation, about 66 Ma). The discovery of ''Polarornis gregorii'' was first announced by Sankar Chatterjee in 1989, but he did not describe and officially name the species until 2002.Chatterjee, S. (2002). "The morphology and systematics of ''Polarornis'', a Cretaceous loon (Aves: Gaviidae) from Antarctica." Pp. 125-155 in Zhou and Zhang (eds), ''Proceedings of the 5th Symposium of the Society of Avian Paleontology and Evolution, Beijing, 1–4 June 2000''. Beijing: Science Press. The name ''Polarornis'' had been announced unofficially several years prior to its official publication, in Chatterjee's 1997 book ''The Rise of Birds''.Chatterjee, S. (1997). ''The Rise of Birds''. Baltimore: Johns Hopkins U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maastrichtian
The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from . The Maastrichtian was preceded by the Campanian and succeeded by the Danian (part of the Paleogene and Paleocene). The Cretaceous–Paleogene extinction event (formerly known as the Cretaceous–Tertiary extinction event) occurred at the end of this age. In this mass extinction, many commonly recognized groups such as non-avian dinosaurs, plesiosaurs and mosasaurs, as well as many other lesser-known groups, died out. The cause of the extinction is most commonly linked to an asteroid about wide colliding with Earth, ending the Cretaceous. Stratigraphic definitions Definition The Maastrichtian was introduced into scientific literature by Belgian geologist André Hubert Dumont in 1849, after studying rock strata of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australornis
''Australornis'' (Latin: "southern bird") is a genus of extinct seabird discovered in New Zealand. It lived in the Paleocene epoch, 60.5 to 61.6 million years ago (Ma). The type species name originates from ''australis'', Latin for "southern", and ''ornis'', the Greek word for "bird", and ''lovei'' commemorates Leigh Love, an amateur paleontologist who discovered it. ''Australornis'' is one of the oldest flying seabirds. It is also the first non- sphenisciform (penguins and allies) bird fossil discovered from New Zealand for that age. The fossil originates from an era just after the Cretaceous–Paleogene extinction event 66 million years ago. The features of the bird indicate that it does not belong to any of the extant bird families, but to a precursor group or clade which is extinct; hence it is a find of global significance with regard to the evolution of birds. Though the fossil evidence is incomplete to substantiate phylogeny, ''Australornis'' contributes to the emergi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolution (journal)
''Evolution: International Journal of Organic Evolution'', is a monthly scientific journal that publishes significant new results of empirical or theoretical investigations concerning facts, processes, mechanics, or concepts of evolutionary phenomena and events. ''Evolution'' is published by the Society for the Study of Evolution. Its current editor-in-chief is Tracey Chapman. Former editors-in-chief The journal was founded soon after the Second World War. Its first editor was the evolutionary geneticist Ernst Mayr Ernst Walter Mayr (; 5 July 1904 – 3 February 2005) was one of the 20th century's leading evolutionary biologists. He was also a renowned taxonomist, tropical explorer, ornithologist, philosopher of biology, and historian of science. His w .... * Ruth Geyer Shaw, July 2013 – 2017 * Daphne Fairbairn, 2010- June 2013 References External linksOfficial website Evolutionary biology journals Publications established in 1947 Academic journals published b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Polar Region Of The Cretaceous
The South Polar region of the Cretaceous comprised the continent of East Gondwana–modern day Australia and Antarctica–a product of the break-up of Gondwana in the Cretaceous Period. The southern region, during this time, was much warmer than it is today, ranging from perhaps in the latest Cretaceous Maastrichtian in what is now southeastern Australia. This prevented permanent ice sheets from developing and fostered polar forests, which were largely dominated by conifers, cycads, and ferns, and relied on a temperate climate and heavy rainfall. Major fossil-bearing geological formations that record this area are: the Santa Marta and Sobral Formations of Seymour Island off the Antarctic Peninsula; the Snow Hill Island, Lopez de Bertodano, and the Hidden Lake Formations on James Ross Island also off the Antarctic Peninsula; and the Eumeralla and Wonthaggi Formations in Australia. The South Polar region housed many endemic species, including several relict forms that had gon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Fossiliferous Stratigraphic Units In Antarctica
This is a list of fossiliferous stratigraphic units in Antarctica. __NOTOC__ List of fossiliferous stratigraphic units See also * Geology of Antarctica * List of fossiliferous stratigraphic units in Namibia * List of fossiliferous stratigraphic units in South Africa * List of fossiliferous stratigraphic units in the Falkland Islands References Further reading * G. Arratia, R. Scasso, and W. Kiessling. 2004. Late Jurassic fishes from Longing Gap, Antarctic Peninsula. Journal of Vertebrate Paleontology 24(1):41-55 * A. C. Ashworth and G. Kuschel. 2003. Fossil weevils (Coleoptera: Curculionidae) from latitude 85 ˚S Antarctica. Palaeogeography, Palaeoclimatology, Palaeoecology 191:191-202 * R. A. Askin. 1990. Cryptogam spores from the upper Campanian and Maastrichtian of Seymour Island, Antarctica. Micropaleontology (36)141-156 * R. A. Askin. 1989. Endemism and heterochrony in the Late Cretaceous (Campanian) to Paleocene palynofloras of Seymour Island, Antarctica: im ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of Antarctica
The geology of Antarctica covers the geological development of the continent through the Archean, Proterozoic and Phanerozoic eons. The geological study of Antarctica has been greatly hindered by the fact that nearly all of the continent is continuously covered with a thick layer of ice. However, techniques such as remote sensing have begun to reveal the structures beneath the ice. Geologically, West Antarctica closely resembles the Andes of South America. The Antarctic Peninsula was formed by uplift and metamorphism of sea-bed sediments during the late Paleozoic and the early Mesozoic eras. This sediment uplift was accompanied by igneous intrusions and volcanism. The most common rocks in West Antarctica are andesite and rhyolite volcanics formed during the Jurassic Period. There is also evidence of volcanic activity, even after the ice sheet had formed, in Marie Byrd Land and Alexander Island. The only anomalous area of West Antarctica is the Ellsworth Mountains region, whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Penguin
Penguins ( order Sphenisciformes , family Spheniscidae ) are a group of aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: only one species, the Galápagos penguin, is found north of the Equator. Highly adapted for life in the water, penguins have countershaded dark and white plumage and flippers for swimming. Most penguins feed on krill, fish, squid and other forms of sea life which they catch with their bills and swallow it whole while swimming. A penguin has a spiny tongue and powerful jaws to grip slippery prey. They spend roughly half of their lives on land and the other half in the sea. The largest living species is the emperor penguin (''Aptenodytes forsteri''): on average, adults are about tall and weigh . The smallest penguin species is the little blue penguin (''Eudyptula minor''), also known as the fairy penguin, which stands around tall and weighs . Today, larger penguins generally inhabit colder regions, and smaller penguins in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Texas Tech University
Texas Tech University (Texas Tech, Tech, or TTU) is a public research university in Lubbock, Texas. Established on , and called Texas Technological College until 1969, it is the main institution of the five-institution Texas Tech University System. The university's student enrollment is the sixth-largest in Texas as of the Fall 2020 semester. As of fall 2020, there were 40,322 students (33,269 undergraduate and 7,053 graduate) enrolled at Texas Tech. With over 25% of its undergraduate student population identifying as Hispanic, Texas Tech University is a designated Hispanic-serving institution (HSI). The university offers degrees in more than 150 courses of study through 13 colleges and hosts 60 research centers and institutes. Texas Tech University has awarded over 200,000 degrees since 1927, including over 40,000 graduate and professional degrees. Texas Tech is classified among "R1: Doctoral Universities – Very high research activity." Research projects in the areas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Femur
The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with the tibia (shinbone) and patella (kneecap), forming the knee joint. By most measures the two (left and right) femurs are the strongest bones of the body, and in humans, the largest and thickest. Structure The femur is the only bone in the upper leg. The two femurs converge medially toward the knees, where they articulate with the proximal ends of the tibiae. The angle of convergence of the femora is a major factor in determining the femoral-tibial angle. Human females have thicker pelvic bones, causing their femora to converge more than in males. In the condition ''genu valgum'' (knock knee) the femurs converge so much that the knees touch one another. The opposite extreme is ''genu varum'' (bow-leggedness). In the general pop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northern Hemisphere
The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's North Pole. Owing to Earth's axial tilt of 23.439281°, winter Winter is the coldest season of the year in Polar regions of Earth, polar and temperate climates. It occurs after autumn and before spring (season), spring. The tilt of Axial tilt#Earth, Earth's axis causes seasons; winter occurs when a Hemi ... in the Northern Hemisphere lasts from the December solstice (typically December 21 UTC) to the March equinox (typically March 20 UTC), while summer lasts from the June solstice through to the September equinox (typically on 23 September UTC). The dates vary each year due to the difference between the calendar year and the Year#Astronomical years, astronomical year. Within the Northern Hemisphere, oceanic currents can change the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hesperornithes
Hesperornithes is an extinct and highly specialized group of aquatic avialans closely related to the ancestors of modern birds. They inhabited both marine and freshwater habitats in the Northern Hemisphere, and include genera such as ''Hesperornis'', ''Parahesperornis'', ''Baptornis'', ''Enaliornis'', and ''Potamornis'', all strong-swimming, predatory divers. Many of the species most specialized for swimming were completely flightless. The largest known hesperornithean, '' Canadaga arctica'', may have reached a maximum adult length of . Hesperornitheans were the only Mesozoic avialans to colonize the oceans. They were wiped out in the Cretaceous–Paleogene extinction event, along with enantiornitheans and all other non-avian dinosaurs, and many other diverse plant and animal groups. Anatomy and ecology Most of what is known about this group rests on analyses of single species, as few provide sufficiently complete fossils for analysis. Although some of the smaller and more basa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Invertebrates
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate subphylum Vertebrata. Familiar examples of invertebrates include arthropods, mollusks, annelids, echinoderms and cnidarians. The majority of animal species are invertebrates; one estimate puts the figure at 97%. Many invertebrate taxa have a greater number and variety of species than the entire subphylum of Vertebrata. Invertebrates vary widely in size, from 50 μm (0.002 in) rotifers to the 9–10 m (30–33 ft) colossal squid. Some so-called invertebrates, such as the Tunicata and Cephalochordata, are more closely related to vertebrates than to other invertebrates. This makes the invertebrates paraphyletic, so the term has little meaning in taxonomy. Etymology The word "invertebrate" comes from the Latin word ''verteb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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