A fossil is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, petrified wood, coal, DNA remnants; the totality of fossils is known as the fossil record. Paleontology is the study of fossils: their age, method of formation, evolutionary significance. Specimens are considered to be fossils if they are over 10,000 years old; the oldest fossils are around 3.48 billion years old to 4.1 billion years old. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils; the development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absolute ages of rocks and the fossils they host. There are many processes that lead to fossilization, including permineralization and molds, authigenic mineralization and recrystallization, adpression and bioimmuration.
Fossils vary in size from one-micrometre bacteria to dinosaurs and trees, many meters long and weighing many tons. A fossil preserves only a portion of the deceased organism that portion, mineralized during life, such as the bones and teeth of vertebrates, or the chitinous or calcareous exoskeletons of invertebrates. Fossils may consist of the marks left behind by the organism while it was alive, such as animal tracks or feces; these types of fossil are called trace ichnofossils, as opposed to body fossils. Some fossils are called chemofossils or biosignatures; the process of fossilization varies according to external conditions. Permineralization is a process of fossilization; the empty spaces within an organism become filled with mineral-rich groundwater. Minerals precipitate from the groundwater; this process can occur in small spaces, such as within the cell wall of a plant cell. Small scale permineralization can produce detailed fossils. For permineralization to occur, the organism must become covered by sediment soon after death, otherwise decay commences.
The degree to which the remains are decayed when covered determines the details of the fossil. Some fossils consist only of skeletal teeth; this is a form of diagenesis. In some cases, the original remains of the organism dissolve or are otherwise destroyed; the remaining organism-shaped hole in the rock is called an external mold. If this hole is filled with other minerals, it is a cast. An endocast, or internal mold, is formed when sediments or minerals fill the internal cavity of an organism, such as the inside of a bivalve or snail or the hollow of a skull; this is a special form of mold formation. If the chemistry is right, the organism can act as a nucleus for the precipitation of minerals such as siderite, resulting in a nodule forming around it. If this happens before significant decay to the organic tissue fine three-dimensional morphological detail can be preserved. Nodules from the Carboniferous Mazon Creek fossil beds of Illinois, USA, are among the best documented examples of such mineralization.
Replacement occurs. In some cases mineral replacement of the original shell occurs so and at such fine scales that microstructural features are preserved despite the total loss of original material. A shell is said to be recrystallized when the original skeletal compounds are still present but in a different crystal form, as from aragonite to calcite. Compression fossils, such as those of fossil ferns, are the result of chemical reduction of the complex organic molecules composing the organism's tissues. In this case the fossil consists of original material, albeit in a geochemically altered state; this chemical change is an expression of diagenesis. What remains is a carbonaceous film known as a phytoleim, in which case the fossil is known as a compression. However, the phytoleim is lost and all that remains is an impression of the organism in the rock—an impression fossil. In many cases, however and impressions occur together. For instance, when the rock is broken open, the phytoleim will be attached to one part, whereas the counterpart will just be an impression.
For this reason, one term covers the two modes of preservation: adpression. Because of their antiquity, an unexpected exception to the alteration of an organism's tissues by chemical reduction of the complex organic molecules during fossilization has been the discovery of soft tissue in dinosaur fossils, including blood vessels, the isolation of proteins and evidence for DNA fragments. In 2014, Mary Schweitzer and her colleagues reported the presence of iron particles associated with soft tissues recovered from dinosaur fossils. Based on various experiments that studied the interaction of iron in haemoglobin with blood vessel tissue they proposed that solution hypoxia coupled with iron chelation enhances the stability and preservation of soft tissue and provides the basis for an explanation for the unforeseen preservation of fossil soft tissues. However, a older study based on eight taxa ranging in time from the Devonian to the Jurassic found that reasonably well-preserved fibrils that represent collagen were preser
Guineafowl are birds of the family Numididae in the order Galliformes. They rank among the oldest of the gallinaceous birds. Phylogenetically, they branch off from the core Galliformes after the Cracidae and before the Odontophoridae. An Eocene fossil lineage, has been associated with guineafowl. Telecrex inhabited Mongolia, may have given rise to the oldest of the true Phasianids such as Ithaginis and Crossoptilon, which evolved into high-altitude montane-adapted species with the rise of the Tibetan Plateau. While modern guineafowl species are endemic to Africa, the helmeted guineafowl has been introduced elsewhere; this is a list of guineafowl species, presented in taxonomic order. Genus Agelastes White-breasted guineafowl, Agelastes meleagrides Black guineafowl, Agelastes niger Genus Numida Helmeted guineafowl, Numida meleagris Genus Guttera Plumed guineafowl, Guttera plumifera Crested guineafowl, Guttera pucherani Western crested guineafowl, Guttera verreauxi Eastern or Kenya crested guineafowl, Guttera pucherani Southern crested guineafowl, Guttera edouardi Genus Acryllium Vulturine guineafowl, Acryllium vulturinum Living Galliformes based on the work by John Boyd.
The insect- and seed-eating, ground-nesting birds of this family resemble partridges, but with featherless heads, though both members of the genus Guttera have a distinctive black crest, the vulturine guineafowl has a downy brown patch on the nape. Most species of guineafowl have a dark grey or blackish plumage with dense white spots, but both members of the genus Agelastes lack the spots. While several species are well known, the plumed guineafowl and the two members of the genus Agelastes remain poorly known; these large birds measure from 40–71 cm in length, weigh 700–1600 grams or 1.5-3.5 pounds. Guinea hens weigh more than guinea cocks because of the larger reproductive organs in the female compared to the male guinea fowl; the presence of larger egg clusters in the dual purpose guinea hens may be a factor that contributes to the higher body weight of the guinea hens. The species for which information is known are monogamous, mating for life, or are serially monogamous. All guineafowl are social, live in small groups or large flocks.
Though they are monogamous, species of the least-derived genera Guttera and Acryllium tend toward social polyandry, a trait shared with other primitive galliformes like roul roul, Congo peafowl. Guineafowl travel behind herd animals and beneath monkey troops where they forage within manure and on items that have fallen to the understory from the canopy. Guineafowl play a pivotal role in the control of ticks, locusts and other invertebrates, they pluck maggots from carcasses and manure. Wild guineafowl are strong fliers, their breast muscles are dark, enabling them to sustain themselves in flight for considerable distances if hard-pressed. Grass and bush fires are a constant threat to these galliformes and flight is the most effective escape; some species of guineafowl, like the vulturine, may go without drinking water for extended periods, instead sourcing their moisture from their food. Young guineafowl are sensitive to weather, in particular cold temperatures; each gender has a different call which can be used to differentiate between male.
Guineafowl species are found across sub-Saharan Africa, some in the entire range, others more localized, such as the plumed guineafowl in west-central Africa and the vulturine guineafowl in north-east Africa. They live in semi-open habitats such as savanna or semideserts, while some, such as the black guineafowl inhabit forests; some perch high on treetops. The helmeted guinea fowl has been introduced in East Africa, the West Indies, the United States and India, where it is raised as food or pets. Guineafowl meat has a gamey flavour, it has marginally more protein than chicken or turkey half the fat of chicken and fewer calories per gram. Their eggs are richer than those of chickens. Madge and McGowan, Pheasants and Grouse. ISBN 0-7136-3966-0 Martínez, I.. "Family Numididae", p. 554–570 in. Handbook of the Birds of the World, Vol. 2. New World Vultures to Guineafowl. Lynx Edicions, Barcelona. ISBN 84-87334-15-6 Guineafowl videos on the Internet Bird Collection SPPA article on Guinea Fowl Early Birds: Guinea Fowl by Dennis Headley
The black guineafowl is a member of the guineafowl bird family. It occurs in humid forests in Central Africa, where it is heard, but seen, it is a medium-sized black bird with upper neck. Little is known of its behaviour; the head and upper neck of an adult black guineafowl are unfeathered. A crest of short downy feathers is on the forehead and crown, the throat and lower neck have a scattering of downy feathers; the body and tail feathers are black with some paler speckled markings on the belly. Males have one to three spurs on their legs, while females either have a single short spur. Juveniles are similar, but have buff tips to the feathers on their upper parts, a speckled breast, white belly; the beak is greenish grey and the legs greyish brown. Males are slightly larger than females and measure about 42 cm in length, weighing about 700 g; the call is a monotonous high-pitched "kwee" repeated at the rate of two to three notes per second. The alarm call is an shriller sound repeated more rapidly.
The black guineafowl has been little studied. It is found in pairs or small groups, is a shy, elusive bird of the forest floor, it occurs in primary and secondary growth woodland, favouring parts with thick undergrowth, but sometimes venturing out onto adjacent cultivated lands. It feeds on invertebrates such as ants, termites and beetles, small frogs, seeds and shoots; the nesting habits of this species are not known, but the eggs are pale reddish-brown, sometimes shaded with yellow or purple. It may breed in the dry season or at any time of year; the black guineafowl is native to West Central Africa south of the Sahara. Its range includes Nigeria, Equatorial Guinea, Angola, the Central African Republic, the Republic of the Congo, the Democratic Republic of the Congo; the extent of its range is estimated to be 764,000 km2. It is found on the forest floor in primary and secondary tropical rainforest with thick undergrowth, in nearby cultivated croplands. Black guineafowl are resistant to various diseases that affect poultry, including Ehrlichia ruminantium, which causes heartwater, but the mechanism for this resistance is not known to researchers.
The black guineafowl's genome includes a toll-like receptor which plays an important role in the bird's immune system. This gene includes 2,115 nucleotides, encoding 705 amino acids. TLR1 is associated with infections caused by bacteria in both humans and mice, this gene is of interest to researchers because genetic variation in it is associated with increased Gram-positive bacterial infections, organ failure, death; the population trend for the black guineafowl seems to be downward, because it is hunted for food unsustainably, may suffer from degradation of its habitat. However, it is quite common within its range and the IUCN lists it as being of least concern in its Red List of Threatened Species, as the rate of decline does not seem to justify the bird being placed in a more vulnerable category
Galliformes is an order of heavy-bodied ground-feeding birds that includes turkey, chicken, New World quail and Old World quail, partridge, francolin and the Cracidae. The name derives from "gallus", Latin for "cock" or "rooster". Common names are gamefowl or gamebirds, gallinaceous birds, or galliforms. "Wildfowl" or just "fowl" are often used for the Galliformes, but these terms refer to waterfowl, to other hunted birds. This group has about 290 species, one or more of which are found in every part of the world's continents, they are rarer on islands, in contrast to the related waterfowl, are absent from oceanic islands—unless introduced there by humans. Several species have been domesticated during their extensive relationships with humans; this order contains five families: Phasianidae, Numididae and Megapodiidae. They are important as seed dispersers and predators in the ecosystems they inhabit, are reared as game birds by humans for their meat and eggs and for recreational hunting. Many gallinaceous species are skilled runners and escape predators by running rather than flying.
Males of most species are more colorful than the females. Males have elaborate courtship behaviors that include strutting, fluffing of tail or head feathers, vocal sounds, they are nonmigratory. The living Galliformes were once divided into seven or more families. Despite their distinctive appearance and turkeys do not warrant separation as families due to their recent origin from partridge- or pheasant-like birds; the turkeys became larger after their ancestors colonized temperate and subtropical North America, where pheasant-sized competitors were absent. The ancestors of grouse, adapted to harsh climates and could thereby colonize subarctic regions; the Phasianidae are expanded in current taxonomy to include the former Tetraonidae and Meleagrididae as subfamilies. The Anseriformes and the Galliformes together make up the Galloanserae, they are basal among the living neognathous birds, follow the Paleognathae in modern bird classification systems. This was first proposed in the Sibley-Ahlquist taxonomy and has been the one major change of that proposed scheme, universally adopted.
However, the Galliformes as they were traditionally delimited are called Gallomorphae in the Sibley-Ahlquist taxonomy, which splits the Cracidae and Megapodiidae as an order "Craciformes". This is not a natural group, but rather an erroneous result of the now-obsolete phenetic methodology employed in the Sibley-Ahlquist taxonomy. Phenetic studies do not distinguish between plesiomorphic and apomorphic characters, which leads to basal lineages appearing as monophyletic groups; the buttonquails and the hoatzin were placed in the Galliformes, too. The former are now known to be shorebirds adapted to an inland lifestyle, whereas the mesites are closely related to pigeons and doves; the relationships of the hoatzin are obscure, it is treated as a monotypic order Opisthocomiformes to signify this. Galliform-like birds were one of the main survivors of the K-T Event that killed off the rest of the dinosaurs, they were a niche group that were toothless and ground-dwelling, unlike the dominant birds of the era called the enantiornithes, which had teeth and dominated the trees and skies.
Fossils of these galliform-like birds originate in the Late Cretaceous, most notably those of Austinornis lentus. Its partial left tarsometatarsus was found in the Austin Chalk near Fort McKinney, dating to about 85 million years ago; this bird was quite closely related to Galliformes, but whether it was a part of these or belongs elsewhere in the little-known galliform branch of Galloanserae is not clear. However, in 2004, Clarke classified it as a member of the larger group Pangalliformes, more related to chickens than to ducks, but not a member of the crown group that includes all modern galliformes. Another specimen, PVPH 237, from the Late Cretaceous Portezuelo Formation in the Sierra de Portezuelo has been suggested to be an early galliform relative; this is a partial coracoid of a neornithine bird, which in its general shape and the wide and deep attachment for the muscle joining the coracoid and the humerus bone resembles the more basal lineages of galliforms. It is believed that an asteroid impact killed off all dinosaurs, including the dominant birds, during the K-T event, destroying all creatures that lived in trees and on open ground.
While the more successful enantiornithes were wiped out, the ancestors of galliformes were small and lived in the ground or water. This protected them from the destruction. Additional galliform-like pangalliformes are represented by extinct families from the Paleogene, namely the Gallinuloididae and Quercymegapodiidae. In the early Cenozoic, some additional birds may or may not be early Galliformes, though if they are, they are unlikely to belong to extant families: †Argillipes †Coturnipes †Paleophasianus †Percolinus †Amitabha (Bridger middle Eocene
The crested partridge known as the crested wood partridge, roul-roul, red-crowned wood partridge, green wood quail or green wood partridge is a gamebird in the pheasant family Phasianidae of the order Galliformes, gallinaceous birds. It is the only member of the genus Rollulus; this small partridge is a resident breeder in lowland rainforests in south Burma, south Thailand, Malaysia and Borneo. Its nest is a ground scrape lined with leaves, concealed under a heap of leaf litter. Five or six white eggs are incubated for 18 days. Unusually for a galliform species, the young are fed bill-to-bill by both parents instead of pecking from the ground, although precocial, they roost in the nest while small. Crested partridge is a rotund short-tailed bird, 25 cm in length, with the male marginally larger than the female. Both sexes have a scarlet patch of bare skin around the eye and red legs without hind toe; the male is metallic green above with a brownish wing panel. The head is adorned with a white forehead spot and black frontal bristles.
The female has pea-green body plumage apart from the brown wing coverts. She has a slate-grey head with the bristles but no crest; the bill is all-dark. Young birds are duller versions of the adult of the same sex; the song is a mournful whistled si-ul. The crested partridge is seen singly or in pairs as it uses its feet to probe the forest floor for fruit and invertebrates; when disturbed, it prefers to run but if necessary it flies a short distance on its rounded wings. There is some concern about the effect of habitat destruction on this bird with regard to logging. However, it seems to be somewhat more adaptable than other southeast Asian pheasants; the crested wood partridge is evaluated as Near Threatened on the IUCN Red List of Threatened Species. It is listed on Appendix III of CITES. Pheasants and Grouse by Madge and McGowan, ISBN 0-7136-3966-0 ARKive - images and movies of the Crested Wood Partridge BirdLife Species Factsheet Red Data Book
The Tibetan Plateau known in China as the Qinghai–Tibet Plateau or the Qing–Zang Plateau or Himalayan Plateau, is a vast elevated plateau in Central Asia and East Asia, covering most of the Tibet Autonomous Region and Qinghai in western China, as well as Ladakh and Lahaul & Spiti in India. It stretches 1,000 kilometres north to south and 2,500 kilometres east to west. With an average elevation exceeding 4,500 metres, the Tibetan Plateau is sometimes called "the Roof of the World" because it stands over 3 miles above sea level and is surrounded by imposing mountain ranges that harbor the world's two highest summits, Mount Everest and K2, is the world's highest and largest plateau, with an area of 2,500,000 square kilometres. Sometimes termed the Third Pole, the Tibetan Plateau contains the headwaters of the drainage basins of most of the streams in surrounding regions, its tens of thousands of glaciers and other geographical and ecological features serve as a "water tower" storing water and maintaining flow.
The impact of global warming on the Tibetan Plateau is of intense scientific interest. The Tibetan Plateau is surrounded by the massive mountain ranges of High-mountain Asia; the plateau is bordered to the south by the inner Himalayan range, to the north by the Kunlun Mountains, which separate it from the Tarim Basin, to the northeast by the Qilian Mountains, which separate the plateau from the Hexi Corridor and Gobi Desert. To the east and southeast the plateau gives way to the forested gorge and ridge geography of the mountainous headwaters of the Salween and Yangtze rivers in northwest Yunnan and western Sichuan. In the west the curve of the rugged Karakoram range of northern Kashmir embraces the plateau; the Indus River originates in the western Tibetan Plateau in the vicinity of Lake Manasarovar. The Tibetan Plateau is bounded in the north by a broad escarpment where the altitude drops from around 5,000 metres to 1,500 metres over a horizontal distance of less than 150 kilometres. Along the escarpment is a range of mountains.
In the west the Kunlun Mountains separate the plateau from the Tarim Basin. About halfway across the Tarim the bounding range becomes the Altyn-Tagh and the Kunluns, by convention, continue somewhat to the south. In the'V' formed by this split is the western part of the Qaidam Basin; the Altyn-Tagh ends near the Dangjin pass on the Dunhuang-Golmud road. To the west are short ranges called the Danghe, Yema and Tulai Nanshans; the easternmost range is the Qilian Mountains. The line of mountains continues east of the plateau as the Qinling, which separates the Ordos Plateau from Sichuan. North of the mountains runs the Gansu or Hexi Corridor, the main silk-road route from China proper to the West; the plateau is a high-altitude arid steppe interspersed with mountain ranges and large brackish lakes. Annual precipitation ranges from 100 to 300 millimetres and falls as hail; the southern and eastern edges of the steppe have grasslands which can sustainably support populations of nomadic herdsmen, although frost occurs for six months of the year.
Permafrost occurs over extensive parts of the plateau. Proceeding to the north and northwest, the plateau becomes progressively higher and drier, until reaching the remote Changtang region in the northwestern part of the plateau. Here the average altitude exceeds 5,000 metres and winter temperatures can drop to −40 °C; as a result of this inhospitable environment, the Changthang region is the least populous region in Asia, the third least populous area in the world after Antarctica and northern Greenland. The geological history of the Tibetan Plateau is related to that of the Himalayas; the Himalayas are among the youngest mountain ranges on the planet and consist of uplifted sedimentary and metamorphic rock. Their formation is a result of a continental collision or orogeny along the convergent boundary between the Indo-Australian Plate and the Eurasian Plate; the collision began in the Upper Cretaceous period about 70 million years ago, when the north-moving Indo-Australian Plate, moving at about 15 cm per year, collided with the Eurasian Plate.
About 50 million years ago, this fast moving Indo-Australian plate had closed the Tethys Ocean, the existence of, determined by sedimentary rocks settled on the ocean floor, the volcanoes that fringed its edges. Since these sediments were light, they crumpled into mountain ranges rather than sinking to the floor; the Indo-Australian plate continues to be driven horizontally below the Tibetan Plateau, which forces the plateau to move upwards. Much of the Tibetan Plateau is of low relief; the cause of this is debated among geologists. Some argue that the Tibetan Plateau is an uplifted peneplain formed at low altitude, while others argue that the low relief stems from erosion and infill of topographic depressions that occurred at high elevations; the Tibetan Plateau supports a variety of most of them classified as montane grasslands. While parts of the plateau feature an alpine tundra-like environment, other areas feature monsoon-influenced shrublands and forests. Species diversity is reduced on the plateau due to the elevation and low precipitation.
The Tibetan Plateau hosts the Tibetan wolf, species of snow leopard, wild yak, wild donkey, vultures, hawk
The Congo peafowl, known as the African peafowl or mbulu by the Bakôngo, is a species of peafowl native to the Congo Basin. It is one of three extant species of peafowl, the other two being the Indian peafowl and the green peafowl, it was only recorded as a species in 1936 by Dr. James Chapin after his failed search for the elusive okapi. Dr. Chapin noticed that the native Congolese headdresses contained long reddish-brown feathers that he couldn't identify with any known species of bird. Chapin visited the Royal Museum of Central Africa and saw two stuffed specimens with similar feathers labeled as the'Indian peacock' which he discovered to be the Congo peacock, a different species. In 1955 Chapin managed to find seven specimens of the species; the Congo peacock has physical characteristics of both the peafowl and the guineafowl, which may indicate that the Congo peacock is a link between the two families. The male of this species is a large bird of up to 64–70 cm in length. Though much less impressive than its Asiatic cousins, the male's feathers are deep blue with a metallic green and violet tinge.
It has bare red neck skin, grey feet, a black tail with fourteen tail feathers. Its crown is adorned with vertical white elongated hair-like feathers; the female measures up to 60–63 centimetres in length and is a chestnut brown bird with a black abdomen, metallic green back, a short chestnut brown crest. Both sexes resemble immature Asian peafowl, with early stuffed birds being erroneously classified as such before they were designated as members of a unique species. Like members of the genus Pavo, the Congo peafowl are omnivores with a diet consisting of fruits and insects. In Salonga National Park, its diet is taxonomically narrower in secondary forest than in primary forest; the male has a similar display to that of other species of peafowl, though the Congo peacock fans its tail feathers while other peacocks fan their upper tail covert feathers. The Congo peafowl is monogamous; the peacock of the species has a high-pitched "gowe" calling noise while the peahen emits a low "gowah". They have loud duets consisting of "rro-ho-ho-o-a" from both sexes.
The Congo peafowl inhabits and is endemic to the Central Congolian lowland forests of the Democratic Republic of the Congo where it has been designated the national bird. It occurs in both secondary forest in Salonga National Park. Secondary signs of its presence like droppings and feathers were more encountered in regenerating secondary forest than in primary forest. In secondary forest, its droppings were found close to watercourses, where trees were smaller and plant diversity lower than in primary forest. In the 1990s, it was recorded in Maiko National Park, foremost in low hills and ridges between watersheds; the Congo peafowl is threatened by habitat loss caused by shifting cultivation and logging. The Congo peafowl is listed as Vulnerable on the IUCN Red List; as of 2013 the wild population was estimated at between 9,000 adult individuals. Given its use of regenerating forest in Salonga National Park, secondary forests might be an important habitat to include in a conservation strategy.
Captive breeding programs were intiated at Salonga National Park. Green peafowl Indian peafowl Images and movies of the Congo Peacock — ARKive BirdLife Species Factsheet Congo Peacock —gbwf.org Kimball, R. T, Braun, E. L. and J. D. Ligon. "Resolution of the phylogenetic position of the Congo Peafowl, Afropavo congensis: a biogeographic and evolutionary enigma". Proc. R. Soc. Lond. B 264:1517–1523