63-551: The Sandhills , often written Sand Hills , is a region of mixed-grass prairie on grass-stabilized sand dunes in north-central Nebraska , covering just over one quarter of the state. The dunes were designated a National Natural Landmark in 1984. The boundaries of the Sandhills are variously defined by different organizations. Depending on the definition, the region's area can be as small as 19,600 mi (50,760 km) or as large as 23,600 mi (61,100 km). Dunes in
126-457: A Palmer Drought Index lower than -15, many times more severe than Texas during the Dust Bowl . The plant-anchored dunes of the Sandhills were long considered an irreclaimable desert. In the 1870s, cattlemen began to discover their potential as rangeland for Longhorn cattle . The fragility of the sandy soil makes the area unsuitable for cultivation of crops. Attempts at farming were made in
189-406: A vestigial coccyx . A dorsal nerve cord , which folds and fuses into a hollow neural tube during embryonic development and eventually gives rise to the brain and spinal cord , runs more dorsally to the axial endoskeleton (enclosed by protective skeletal extensions known as neural arches ), with a fore-end enlargement that is contained within a distinct skeletonized braincase (hence
252-426: A windbreak around homesteads and during early Arbor Day events during early settlement. Over time, the trees spread to replace large areas of grassland, leading to ecosystem collapse on ranchlands. The blowout penstemon ( Penstemon haydenii ) is an endangered species, found only in the Sandhills and in similar environments in central Wyoming . The blowout penstemon stabilizes the soil where wind erosion exposes
315-716: A 25-mile (40 km) stretch of the river. Fort Niobrara National Wildlife Refuge near Valentine covers 19,000 acres (77 km). Partnering in the effort to conserve the Sandhills are the Institute of Agriculture and Natural Resources, West Central Research and Extension Station, the Nature Conservancy of Nebraska, the Natural Resources Conservation Service, the Nebraska Natural Heritage Program,
378-409: A pair of secondary enlargements of the hindbrain become the cerebella , which modulate complex motor coordinations . The brain vesicles are usually bilaterally symmetrical , giving rise to the paired cerebral hemispheres in mammals . The resultant anatomy of a central nervous system arising from a single nerve cord dorsal to the gut tube , headed by a series of (typically paired) brain vesicles,
441-536: A special session to consider the issue." On November 3, 2015, the request for a Presidential Permit was denied. 42°08′N 102°11′W / 42.13°N 102.19°W / 42.13; -102.19 Mixed grass prairie Ecotone located between tall and shortgrass prairie [REDACTED] Mixed grass prairie around the Afterbay near Fort Smith, Montana [REDACTED] Mixed grass prairie in relation to
504-449: Is different from Wikidata Vertebrate Ossea Batsch, 1788 Vertebrates ( / ˈ v ɜːr t ə b r ɪ t s , - ˌ b r eɪ t s / ) are animals with a backbone or spine, consisting of vertebrae and intervertebral discs . The vertebrae are irregular bones , and the intervertebral discs are of fibrocartilage . The vertebral column surrounds and protects the spinal cord . The other feature unique to vertebrates
567-425: Is replaced by a segmented series of mineralized elements called vertebrae separated by fibrocartilaginous intervertebral discs , which are embryonic and evolutionary remnants of the notochord. Hagfish are the only extant vertebrate whose notochord persists and is not integrated/ replaced by the vertebral column. A few vertebrates have secondarily lost this feature and retain the notochord into adulthood, such as
630-526: Is strongly supported by two CSIs found in the proteins Rrp44 (associated with the exosome complex ) and serine palmitoyltransferase . These are exclusively shared by species from these two subphyla, but not cephalochordates . This indicates hat vertebrates are more closely related to tunicates than cephalochordates. The "Notochordata hypothesis" suggested that the Cephalochordata is the sister taxon to Craniata (Vertebrata). This group, called
693-446: Is the presence of neural crest cells, which are progenitor cells critical to coordinating the functions of cellular components. Neural crest cells migrate through the body from the dorsal nerve cord during development, initiate the formation of neuronal ganglia and various special sense organs. The peripheral nervous system forms when neural crest cells branch out laterally from the dorsal nerve cord and migrate together with
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#1732772486627756-423: Is the presence of a cranium , or skull. The vertebrates make up the subphylum Vertebrata with some 65,000 species in the phylum Chordata . The vertebrates include mammals , birds , amphibians , and various classes of reptiles and fish . Classes of fish include the jawless Agnatha , and the jawed Gnathostomata . The jawed fish include both the cartilaginous fish and the bony fish . Bony fish include
819-399: Is unique to vertebrates. This is in stark contrast to invertebrates with well-developed central nervous systems such as arthropods and cephalopods , which have an often ladder-like ventral nerve cord made of paired segmental ganglia on the opposite ( ventral ) side of the gut tube, with a split brain stem circumventing the foregut around each side to form a brain on the dorsal side of
882-468: The Great Plains Shortgrass prairie Mixed grass prairie Tallgrass prairie A mixed-grass prairie is an ecotone located between the tallgrass prairies and shortgrass prairies . The mixed-grass prairie is richer in botanical diversity than either the tall- or shortgrass prairie. The mixed-grass prairie occurs in the central plains portion of
945-986: The Great Plains , varying in width from central Texas in the United States up into southeastern Manitoba , Alberta and Saskatchewan in the northern mixed grasslands of Canada . See also [ edit ] American Prairie Nine Mile Prairie Buffalo Commons Oglala National Grassland Buffalo Gap National Grassland Texas blackland prairies Central Plains Biosphere Reserve Theodore Roosevelt National Park Missouri Coteau Valentine National Wildlife Refuge Drift Prairie Wichita Mountains Wildlife Refuge Nebraska Sand Hills Wind Cave National Park References [ edit ] ^ G. E. Wickens: Ecophysiology of economic plants in arid and semi-arid lands p.76 External links [ edit ] "Badlands Mixed-grass Prairies" . U.S. National Park Service ~ Prairie Ecology of
1008-474: The Izu–Ogasawara Trench at a depth of 8,336 metres (27,349 feet). Many fish varieties are the main predators in most of the world's freshwater and marine water bodies . The rest of the vertebrate species are tetrapods, a single lineage that includes amphibians (with roughly 7,000 species); mammals (with approximately 5,500 species); and reptiles and birds (with about 20,000 species divided evenly between
1071-633: The Jurassic . The Cenozoic world saw great diversification of bony fishes, amphibians, reptiles, birds and mammals. Over half of all living vertebrate species (about 32,000 species) are fish (non-tetrapod craniates), a diverse set of lineages that inhabit all the world's aquatic ecosystems, from the Tibetan stone loach ( Triplophysa stolickai ) in western Tibetan hot springs near Longmu Lake at an elevation of 5,200 metres (17,100 feet) to an unknown species of snailfish (genus Pseudoliparis ) in
1134-574: The Placodermi and the Acanthodii , both considered paraphyletic . Other ways of classifying the vertebrates have been devised, particularly with emphasis on the phylogeny of early amphibians and reptiles. An example based on Janvier (1981, 1997), Shu et al. (2003), and Benton (2004) is given here († = extinct ): While this traditional classification is orderly, most of the groups are paraphyletic , i.e. do not contain all descendants of
1197-469: The Placodermi , a group of armoured fish that dominated the entirety of that period since the late Silurian as well as the eurypterids , dominant animals of the preceding Silurian , and the anomalocarids . By the middle of the Devonian, several droughts, anoxic events and oceanic competition led a lineage of sarcopterygii to leave water, eventually establishing themselves as terrestrial tetrapods in
1260-637: The University of Nebraska , and the United States Fish and Wildlife Service . Turner Enterprises has acquired 445,000 acres (180,000 ha) of land in Nebraska. His extensive ranches for grazing cattle are known for their bison while focusing on sustainable practices such as rotational grazing of the grasslands . In 2021, Ted Turner announced that an 80,000-acre (32,000 ha) ranch he owns in western Nebraska would be turned over to
1323-494: The cephalochordates ), though it lacks eyes and other complex special sense organs comparable to those of vertebrates. Other chordates do not show any trends towards cephalization. The rostral end of the neural tube is expanded by a thickening of the walls and expansion of the central canal of spinal cord into three primary brain vesicles : the prosencephalon ( forebrain ), mesencephalon ( midbrain ) and rhombencephalon ( hindbrain ), which are further differentiated in
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#17327724866271386-565: The genetics of organisms. Phylogenetic classification is based solely on phylogeny . Evolutionary systematics gives an overview; phylogenetic systematics gives detail. The two systems are thus complementary rather than opposed. Conventional classification has extant vertebrates grouped into seven classes based on traditional interpretations of gross anatomical and physiological traits. The commonly held classification lists three classes of fish and four of tetrapods . In addition to these, there are two classes of extinct armoured fishes,
1449-466: The lobe-finned fish , which gave rise to the tetrapods , the animals with four limbs. Vertebrates make up less than five percent of all described animal species ; the rest are all invertebrates , that lack a backbone. The word 'vertebrate' derives from the Latin vertebratus ("jointed"), from vertebra meaning "joint", in turn from Latin vertere to turn. All vertebrates are built along
1512-444: The mesodermal somites to innervate the various different structures that develop in the body. The vertebrates are the only chordate group with neural cephalization , and their neural functions are centralized towards a series of enlarged clusters in the head , which give rise to a brain . A slight swelling of the anterior end of the nerve cord is found in invertebrate chordates such as lancelets (a sister subphylum known as
1575-520: The mouth . The higher functions of the vertebrate CNS are highly centralized towards the brain (particularly the forebrain), while the invertebrate CNS is significantly more decentralized with the segmental ganglia having substantial neural autonomy independent of the brain (which itself is a fused cluster of segmental ganglia from the rostral metameres ). Molecular markers known as conserved signature indels (CSIs) in protein sequences have been identified and provide distinguishing criteria for
1638-514: The pharynx . Research also suggests that the sixth branchial arch contributed to the formation of the vertebrate shoulder, which separated the head as a distinct part of the body. In amphibians and some primitive bony fishes, the larvae bear external gills , branching off from the gill arches. These are reduced in adulthood, their respiratory function taken over by the internal gills proper in fishes and by cutaneous respiration in most amphibians. While some amphibians such as axolotl retain
1701-456: The sturgeon . Most vertebrates are aquatic and carry out gas exchange via gills . The gills are carried right behind the head, bordering the posterior margins of a series of crescentic openings from the pharynx to the outside. Each gill is supported by a cartilaginous or bony gill arch , which develop embryonically from pharyngeal arches . Bony fish have three pairs of gill arches, cartilaginous fish have five to seven pairs, while
1764-444: The thyroid in most vertebrates. Vertebrates vary in body length ranging from the frog species Brachycephalus pulex , a Brazilian flea toad, with a minimum adult snout–vent length of 6.45 millimetres (0.254 in) to the blue whale , at up to 33 m (108 ft). With only one exception, the defining characteristic of all vertebrates is the vertebral column , in which the embryonic notochord found in all chordates
1827-440: The thyroid gland , the larynx , the columella (corresponding to the stapes in mammals ) and, in mammals, the malleus and incus . The central nervous system of vertebrates is based on the embryonic dorsal nerve cord (which then flattens into a neural plate before folding and fusing over into a hollow neural tube ) running along the dorsal aspect of the notochord . Of particular importance and unique to vertebrates
1890-495: The western meadowlark , the state bird of Nebraska. Valentine National Wildlife Refuge , located about 20 miles (32 km) south of Valentine, encompasses 71,516 acres (28,941 ha). Crescent Lake National Wildlife Refuge in the central Panhandle covers 45,849 acres (18,554 ha). The Nature conservancy 's Niobrara Valley Preserve in Cherry, Brown, and Keya Paha counties covers 60,000 acres (202 km) and includes
1953-575: The Badlands . U.S. Department of the Interior. "Central and Southern Mixed Grasslands" . Terrestrial Ecoregions - Temperate Grasslands, Savannas, and Shrublands . World Wildlife Fund (WWF). "Mixed-grass Prairie - Missouri Coteau" . North Dakota Game and Fish Department . State of North Dakota. "Sagebrush Steppe And Mixed Grass Prairie" . U.S. National Park Service - Bighorn Canyon National Recreation Area . U.S. Department of
Sandhills (Nebraska) - Misplaced Pages Continue
2016-713: The Cephalochordata. Amphioxiformes (lancelets) [REDACTED] Tunicata /Urochordata ( sea squirts , salps , larvaceans ) [REDACTED] Vertebrata [REDACTED] Vertebrates originated during the Cambrian explosion , which saw a rise in organism diversity. The earliest known vertebrates belongs to the Chengjiang biota and lived about 518 million years ago. These include Haikouichthys , Myllokunmingia , Zhongjianichthys , and probably Haikouella . Unlike
2079-533: The Great Plains. This is chiefly due to the lack of crop production: most of the Sandhills land has never been plowed. The Sandhills is classified as a semi-arid region, with average annual rainfall varying from 23 inches (580 mm) in the east to less than 17 inches (430 mm) of rain in the west. Temperatures range from lows of −30 °F (−34 °C) to highs of 105 °F (41 °C). Paleoclimate proxy data and computer simulations reveal that
2142-515: The Interior. "Wyoming Native Plants Program" . U.S. Bureau of Land Management ~ Wyoming . U.S. Department of the Interior. Retrieved from " https://en.wikipedia.org/w/index.php?title=Mixed_grass_prairie&oldid=1233079726 " Categories : Prairies Physiographic provinces Regions of the Western United States Hidden categories: Articles with short description Short description
2205-712: The Nebraska Sandhills likely had active sand dunes as recently as the Medieval Warm Period , when temperatures in the North Atlantic region were about 1 °C (1.8 °F) warmer than the current climate. Much of the area was a scrub desert , with desert-like conditions extending to several other states. Current global warming may make the grassland climate more unstable, giving way to desert given more fires, mild drought and erosion; UCAR simulations based on evapotranspiration support
2268-612: The Notochordata, was placed as sister group to the Tunicata (Urochordata). Studies since 2006 analyzing large sequencing datasets however strongly support Olfactores (tunicates + vertebrates) as a clade, and hence the placement of Cephalochordata as sister-group to Olfactores (known as the " Olfactores hypothesis "). The following cladogram summarizes the relationships between the Olfactores (vertebrates and tunicates) and
2331-468: The Ogallala Aquifer. Precipitation is insufficient to keep ponds and lakes permanent with the low humidity and high evaporation rates. The natural reservoirs are also primarily confined to a few regions of the Sandhills with the vast majority located in northern Garden County. The lakes and ponds are mainly sandy-bottomed and some contain many species of fish. Very few are used to water cattle as
2394-461: The Sand Hills (which includes a high concentration of wetlands of special concern, a sensitive ecosystem, and extensive areas of very shallow groundwater) and provided additional context and information about those characteristics. The concern about the proposed route's impact on the Sand Hills of Nebraska has increased significantly over time, and has resulted in the Nebraska legislature convening
2457-438: The Sandhills may exceed 330 ft (100 m) in height. The average elevation of the region gradually increases from about 1,800 ft (550 m) in the east to about 3,600 ft (1,100 m) in the west. The Sandhills sit atop the massive Ogallala Aquifer ; thus both temporary and permanent shallow lakes are common in low-lying valleys between the grass-stabilized dunes prevalent in the Sandhills. The eastern and central sections of
2520-401: The Sandhills. Most are native, with only 7% exotics — half the percentage of most other prairie systems. Most of the "exotics" are invasive species and considered noxious weeds and must be destroyed by landowners. One species threatening the ecosystem is the eastern redcedar . Native to the region but controlled by wildfires prior to European settlement, the trees were planted in great numbers as
2583-422: The alternative name for vertebrates, the craniates ). All vertebrate embryos develop transient pharyngeal arches , which in fish develop into the branchial arches that support the gills . Other vertebrate features are a jaw , hyoid and/or the middle ear ossicles . An iodine-concentrating organ called the endostyle , which functions as a filter feeding organ in aquatic animals has evolved into
Sandhills (Nebraska) - Misplaced Pages Continue
2646-404: The bare sand and creates a blowout, but is choked out when other species begin to recolonize. Grazing and land management practices used by Sandhills ranchers have reduced natural erosion, thus destroying some of the plant's habitat. Many of the plants of the Sandhills are sand-tolerant species from short-grass, mixed-grass, and tallgrass prairies; plants from all three of these can be found within
2709-477: The basic chordate body plan of five synapomorphies . These are a rigid axial skeleton that includes a vertebral column developed around an elastic notochord . The notochord becomes the intervertebral discs , and runs dorsally to the gut tube along the length of an animal, hence the common name of backbone. The axial endoskeleton typically continues beyond the anus / cloaca to form an elongated tail . Some vertebrates evolved to become tailless with only
2772-482: The biodiversity of the area. The Sandhills are home to 314 vertebrate species including mule deer, whitetail deer, jackrabbits, pronghorn antelope, elk, coyotes, red fox, Western meadowlarks (the Nebraska state bird), prairie dogs, bull snakes , prairie rattlesnakes , ringnecked pheasant , sharp-tailed grouse , badgers, ground squirrels, skunks, native bat species and many fish species. The Sandhills' thousands of ponds and lakes are spring-fed surface water areas of
2835-409: The class's common ancestor. For instance, descendants of the first reptiles include modern reptiles, mammals and birds; the agnathans have given rise to the jawed vertebrates ; the bony fishes have given rise to the land vertebrates ; the traditional " amphibians " have given rise to the reptiles (traditionally including the synapsids or mammal-like "reptiles"), which in turn have given rise to
2898-479: The concentration of concerns regarding the environmental sensitivities of the current proposed route through the Sand Hills area of Nebraska, the Department has determined it needs to undertake an in-depth assessment of potential alternative routes in Nebraska [...] The comments were consistent with the information in the final Environmental Impact Statement (EIS) about the unique combination of characteristics in
2961-456: The ecosystem. These plants have helped to stabilize the sand dunes, creating an ecosystem beneficial for other plants and animals. Better land management and grazing practices by the ranchers of the region have led to less erosion over time, which has kept the natural landscape of the area mostly intact. Many species of insect are found in the Sandhills, including dragonflies, grasshoppers and mosquitos. There are also many types of spiders. Due to
3024-415: The external gills into adulthood, the complex internal gill system as seen in fish apparently being irrevocably lost very early in the evolution of tetrapods , who evolved lungs (which are homologous to swim bladders ) to breathe air. While the more specialized terrestrial vertebrates lack gills, the gill arches form during fetal development , and form the basis of essential structures such as jaws ,
3087-599: The late Cambrian to the end of the Triassic. The first jawed vertebrates may have appeared in the late Ordovician (~445 mya) and became common in the Devonian period , often known as the "Age of Fishes". The two groups of bony fishes , the Actinopterygii and Sarcopterygii , evolved and became common. The Devonian also saw the demise of virtually all jawless fishes save for lampreys and hagfishes, as well as
3150-460: The mammals and birds. Most scientists working with vertebrates use a classification based purely on phylogeny , organized by their known evolutionary history and sometimes disregarding the conventional interpretations of their anatomy and physiology. In phylogenetics , the relationships between animals are illustrated as a hierarchy known as a phylogenetic tree . The cladogram below is based on studies compiled by Philippe Janvier and others for
3213-536: The newly created Turner Institute of Ecoagriculture. Turner and the institute publicly announced that the nonprofit would continue to pay property taxes on the land. A November 10, 2011 press release on the Keystone Pipeline Project Presidential Permit Review Process, announced that the U. S. State Department would assess TransCanada Keystone XL Project (Hardisty-Baker-Steele City) proposal. "[G]iven
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#17327724866273276-472: The other fauna that dominated the Cambrian, these groups had the basic vertebrate body plan: a notochord, rudimentary vertebrae, and a well-defined head and tail. All of these early vertebrates lacked jaws in the common sense and relied on filter feeding close to the seabed. A vertebrate group of uncertain phylogeny, small eel-like conodonts , are known from microfossils of their paired tooth segments from
3339-426: The primitive jawless fish have seven pairs. The ancestral vertebrates likely had more arches than seven, as some of their chordate relatives have more than 50 pairs of gill opens, although most, if not all, of these openings are actually involved in filter feeding rather than respiration . In jawed vertebrates , the first gill arch pair evolved into the jointed jaws and form an additional oral cavity ahead of
3402-535: The region are drained by tributaries of the Loup River and the Niobrara River , while the western section is largely composed of small interior drainage basins. The World Wide Fund for Nature (WWF) designated the Sandhills as an ecoregion , distinct from other grasslands of the Great Plains. According to their assessment, as much as 85% of the ecoregion is intact natural habitat, the highest level in
3465-402: The region continues to decline as older generations die out, younger generations move to the cities, and ranches are consolidated. A number of small towns remain in the region. The Sandhills contain a large array of plant and animal life. Minimal crop production has led to limited land fragmentation; the resulting extensive and continuous habitat for plant and animal species has largely preserved
3528-542: The region in the late 1870s and again around 1890. The 1904 Kinkaid Act allowed homesteaders to claim 640 acres (260 ha; 2.6 km) of land, rather than the 160 acres (65 ha; 0.65 km) allowed by the 1862 Homestead Act . Nearly nine million acres (36,000 km) were claimed by "Kinkaiders" between 1910 and 1917. Some of the Kinkaiders farmed the land, but these attempts generally failed. This included Nebraska's largest black settlement, DeWitty , which
3591-650: The succeeding Carboniferous . Amniotes branched from amphibious tetrapods early in the Carboniferous period. The synapsid amniotes were dominant during the late Paleozoic, the Permian , while diapsid amniotes became dominant during the Mesozoic . In the sea, the teleosts and sharks became dominant. Mesothermic synapsids called cynodonts gave rise to endothermic mammals and diapsids called dinosaurs eventually gave rise to endothermic birds , both in
3654-402: The two classes). Tetrapods comprise the dominant megafauna of most terrestrial environments and also include many partially or fully aquatic groups (e.g., sea snakes , penguins , cetaceans). There are several ways of classifying animals. Evolutionary systematics relies on anatomy , physiology and evolutionary history, which is determined through similarities in anatomy and, if possible,
3717-436: The various vertebrate groups. Two laterally placed retinas and optical nerves form around outgrowths from the midbrain, except in hagfish which may have secondarily lost the structures. The forebrain is more well-developed in most tetrapods and subdivided into the telencephalon and diencephalon , while the midbrain dominates in fish and some salamanders . In vertebrates with paired appendages, especially tetrapods,
3780-401: The vertebrate subphylum. Specifically, 5 CSIs in the following proteins: protein synthesis elongation factor-2 , eukaryotic translation initiation factor 3 , adenosine kinase and a protein related to ubiquitin carboxyl-terminal hydrolase are exclusively shared by all vertebrates and reliably distinguish them from all other animals. A specific relationship between vertebrates and tunicates
3843-569: The warm stagnant nature of both alkaline and freshwater lakes throughout the region, coupled with the wetland marsh areas, mosquito populations increase during the summer months. The Sandhills are part of the Central Flyway for many species of migratory birds, and the region's many bodies of water give them places to rest. The ponds and lakes of the region are lay-over points for migratory cranes (particularly Sandhill cranes ), geese, and many species of ducks. Species found year-round include
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#17327724866273906-484: The water is usually shallow, warm, brackish, turbid, saline, alkaline or conceals "quicksand" cattle would become stuck in. Windmills and solar-powered submersible electric pumps fed by the easily-accessible aquifer filling cement-bottom steel stock tanks up to 30 feet in diameter are used to supply livestock with cool, fresh water on a daily basis. Some lakes in the area are alkaline and support several species of phyllopod shrimp. 720 different species of plants are found in
3969-437: Was located in southeast Cherry County until the 1930s. Many of the largest ranches broke up about the same time due to regulations against fencing federal range lands. Some development of cropland agriculture in the modern era has occurred through the use of center-pivot irrigation systems. In the 21st century, the Sandhills are a productive cattle ranching area, supporting over 530,000 beef cattle. The human population of
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