Fringe-toed lizards are lizards of the genus Uma in the family Phrynosomatidae, native to deserts of North America. They are adapted for life in sandy deserts with fringe-like scales on their hind toes hence their common name. Lizards of the genus Uma have a tan coloration that helps them to blend in with the sand; the dorsal surface has a velvety texture with intricate markings. In addition, they have prominent elongated scales which form a fringe on the sides of their hind toes; these fringes aid with traction and speed, help the lizard avoid sinking into loose, sandy dunes. Fringe-toed lizards possess upper jaws which overlap the lower ones, preventing the intrusion of sand particles, nostrils that can be closed at will. Flaps close against the ear openings when moving through sand, the upper and lower eyelids have interlocking scales that prevent sand from getting into the eyes. Fringe-toed lizards range throughout southeast California and southwest Arizona, extend into northwest Sonora and northeast Baja California.
Lizards of the genus Uma are found in low desert areas having loose sand. Fringe-toed lizards eat insects, including ants, beetles and caterpillars. Flower buds, stems and seeds of plants are eaten. Lizards of the genus Uma bury themselves underground in the winter, they sleep in their burrows, use their burrows for protection from predators and extreme temperatures. Coachella Valley fringe-toed lizard, Uma inornata Cope, 1895 Colorado Desert fringe-toed lizard, Uma notata Baird, 1858 Mojave fringe-toed lizard, Uma scoparia Cope, 1894 Yuman Desert fringe-toed lizard, Uma cowlesi Heifetz, 1941 Mexican fringe-toed lizard, Uma paraphygas K. L. Williams, Chrapliwy & H. M. Smith, 1959 Coahuila fringe-toed lizard, Uma exsul Schmidt & Bogert, 1947 Meroles, a genus of African lizards with morphological and ecological similarities Xerocoles, animals adapted to desert environments
Spiny lizards is the common name for the genus Sceloporus in the family Phrynosomatidae. This genus includes some of the most seen lizards in the United States; the 106 species in the genus Sceloporus are organized into 21 species groups. However, their relationships to each other are under review. Listed below are species of Sceloporus: Nota bene: A binomial authority in parentheses indicates that the species was described in a genus other than Sceloporus. Moloch horridus, an unrelated Australian lizard, sometimes referred to as "spiny lizard" Video of Sceloporus jarrovii in Arizona Data related to Sceloporus at Wikispecies Media related to Sceloporus at Wikimedia Commons Boulenger GA. Catalogue of the Lizards in the British Museum. Second Edition. Volume II. Iguanidæ... London: Trustees of the British Museum.. Xiii + 497 pp. + Plates I-XXIV.. Goin, Coleman J.. Introduction to Herpetology, Third Edition. San Francisco: W. H. Freeman. Xi + 378 pp. ISBN 0-7167-0020-4.. Powell R, Conant R, Collins JT. Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America, Fourth Edition.
Boston and New York: Houghton Mifflin Harcourt. Xiv + 494 pp. 207 Figures. ISBN 978-0-544-12997-9.. Smith, Hobart M.. New York: Golden Press. 240 pp. ISBN 0-307-13666-3, ISBN 0-307-47009-1.. Wiegmann AF Jr. "Beyträge zur Amphibienkunde ". Isis von Oken 21: 364-383
Among animals, viviparity is development of the embryo inside the body of the parent leading to live birth, as opposed to reproduction by laying eggs that complete their incubation outside the parental body. Viviparity and the adjective viviparous derive from Latin vivus and parire. Five modes of reproduction have been differentiated in animals based on relations between zygote and parents; the five include two nonviviparous modes: ovuliparity, with external fertilisation, oviparity, with internal fertilisation. In the latter, the female lays zygotes as eggs with a large yolk; these modes are distinguished from viviparity, which covers all the modes that result in live birth: Histotrophic viviparity: the zygotes develop in the female's oviducts, but find their nutriments by oophagy or adelphophagy. Hemotrophic viviparity: nutrients are provided by the female through some form of placenta. In the frog Gastrotheca ovifera, embryos are fed by the mother through specialized gills; the skink Pseudemoia entrecasteauxii and most mammals exhibit a hemotrophic viviparity.
Placental viviparity is arguably the most developed form of viviparity. Placental mammals, including humans, are the best-known example, but adaptations in some other animals have incorporated this principle or close analogies. Other examples include some species of scorpions and cockroaches, certain genera of sharks and snakes, velvet worms. Ovoviviparity, a less developed form of viviparity, occurs in most vipers, in most live-bearing bony fishes. However, the term is poorly and inconsistently defined, may be obsolete. At least some transport of nutrients from mother to embryo appears to be common to all viviparous species, but those with developed placentas such as found in the Theria, some skinks, some fish can rely on the placenta for transfer of all necessary nutrients to the offspring and for removal of all the metabolic wastes as well once it has been established during the early phases of a pregnancy. In such species, there is direct, intimate contact between maternal and embryonic tissue, though there is a placental barrier to control or prevent uncontrolled exchange and the transfer of pathogens.
In at least one species of skink in the large genus Trachylepis, placental transport accounts for nearly all of the provisioning of nutrients to the embryos before birth. In the uterus, the eggs are small, about 1mm in diameter, with little yolk and thin shells; the shell membrane is transient. The embryo produces invasive chorionic tissues that grow between the cells of the uterine lining till they can absorb nutrients from maternal blood vessels; as it penetrates the lining, the embryonic tissue grows aggressively till it forms sheets of tissue beneath the uterine epithelium. They strip it away and replace it, making direct contact with maternal capillaries. In several respects, the phenomenon is of considerable importance in theoretical zoology; the authors remark that such an endotheliochorial placenta is fundamentally different from that of any known viviparous reptile. There is no relationship between sex-determining mechanisms and whether a species bears live young or lays eggs. Temperature-dependent sex determination, which cannot function in an aquatic environment, is seen only in terrestrial viviparous reptiles.
Therefore, marine viviparous species, including sea snakes and, it now appears, the mosasaurs and plesiosaurs of the Cretaceous, use genotypic sex determination, much as birds and mammals do. Genotypic sex determination is found in most reptiles, including many viviparous ones, whilst temperature dependent sex determination is found in some viviparous species, such as the montane water skink. In general and matrotrophy are believed to have evolved from an ancestral condition of oviparity and lecithotrophy. One traditional hypothesis concerning the sequence of evolutionary steps leading to viviparity is a linear model. According to such a model, provided that fertilization was internal, the egg might have been retained for progressively longer periods in the reproductive tract of the mother. Through continued generations of egg retention, viviparous lecithotrophy may have developed; the next evolutionary development would be incipient matrotrophy, in which yolk supplies are reduced and are supplemented with nutrients from the mother's reproductive tract.
In many ways, depending on the ecology and life strategy of the species, viviparity may be more strenuous and more physically and energetically taxing on the mother than oviparity. However, its numerous evolutionary origins imply that in some scenarios there must be worthwhile benefits to viviparous modes of reproduction. There is no one mode of reproduction, universally superior in selective terms, but in many circumstances viviparity of various forms offers good protection from parasites and predators and permits flexibility in dealing with problems of reliability and economy in adverse circumstances. Variations on the theme in biology are enormous, ranging from trophic eggs to
Canada is a country in the northern part of North America. Its ten provinces and three territories extend from the Atlantic to the Pacific and northward into the Arctic Ocean, covering 9.98 million square kilometres, making it the world's second-largest country by total area. Canada's southern border with the United States is the world's longest bi-national land border, its capital is Ottawa, its three largest metropolitan areas are Toronto and Vancouver. As a whole, Canada is sparsely populated, the majority of its land area being dominated by forest and tundra, its population is urbanized, with over 80 percent of its inhabitants concentrated in large and medium-sized cities, many near the southern border. Canada's climate varies across its vast area, ranging from arctic weather in the north, to hot summers in the southern regions, with four distinct seasons. Various indigenous peoples have inhabited what is now Canada for thousands of years prior to European colonization. Beginning in the 16th century and French expeditions explored, settled, along the Atlantic coast.
As a consequence of various armed conflicts, France ceded nearly all of its colonies in North America in 1763. In 1867, with the union of three British North American colonies through Confederation, Canada was formed as a federal dominion of four provinces; this began an accretion of provinces and territories and a process of increasing autonomy from the United Kingdom. This widening autonomy was highlighted by the Statute of Westminster of 1931 and culminated in the Canada Act of 1982, which severed the vestiges of legal dependence on the British parliament. Canada is a parliamentary democracy and a constitutional monarchy in the Westminster tradition, with Elizabeth II as its queen and a prime minister who serves as the chair of the federal cabinet and head of government; the country is a realm within the Commonwealth of Nations, a member of the Francophonie and bilingual at the federal level. It ranks among the highest in international measurements of government transparency, civil liberties, quality of life, economic freedom, education.
It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many other countries. Canada's long and complex relationship with the United States has had a significant impact on its economy and culture. A developed country, Canada has the sixteenth-highest nominal per capita income globally as well as the twelfth-highest ranking in the Human Development Index, its advanced economy is the tenth-largest in the world, relying chiefly upon its abundant natural resources and well-developed international trade networks. Canada is part of several major international and intergovernmental institutions or groupings including the United Nations, the North Atlantic Treaty Organization, the G7, the Group of Ten, the G20, the North American Free Trade Agreement and the Asia-Pacific Economic Cooperation forum. While a variety of theories have been postulated for the etymological origins of Canada, the name is now accepted as coming from the St. Lawrence Iroquoian word kanata, meaning "village" or "settlement".
In 1535, indigenous inhabitants of the present-day Quebec City region used the word to direct French explorer Jacques Cartier to the village of Stadacona. Cartier used the word Canada to refer not only to that particular village but to the entire area subject to Donnacona. From the 16th to the early 18th century "Canada" referred to the part of New France that lay along the Saint Lawrence River. In 1791, the area became two British colonies called Upper Canada and Lower Canada collectively named the Canadas. Upon Confederation in 1867, Canada was adopted as the legal name for the new country at the London Conference, the word Dominion was conferred as the country's title. By the 1950s, the term Dominion of Canada was no longer used by the United Kingdom, which considered Canada a "Realm of the Commonwealth"; the government of Louis St. Laurent ended the practice of using'Dominion' in the Statutes of Canada in 1951. In 1982, the passage of the Canada Act, bringing the Constitution of Canada under Canadian control, referred only to Canada, that year the name of the national holiday was changed from Dominion Day to Canada Day.
The term Dominion was used to distinguish the federal government from the provinces, though after the Second World War the term federal had replaced dominion. Indigenous peoples in present-day Canada include the First Nations, Métis, the last being a mixed-blood people who originated in the mid-17th century when First Nations and Inuit people married European settlers; the term "Aboriginal" as a collective noun is a specific term of art used in some legal documents, including the Constitution Act 1982. The first inhabitants of North America are hypothesized to have migrated from Siberia by way of the Bering land bridge and arrived at least 14,000 years ago; the Paleo-Indian archeological sites at Old Crow Flats and Bluefish Caves are two of the oldest sites of human habitation in Canada. The characteristics of Canadian indigenous societies included permanent settlements, complex societal hierarchies, trading networks; some of these cultures had collapsed by the time European explorers arrived in the late 15th and early 16th centuries and have only been discovered through archeological investigations.
The indigenous population at the time of the first European settlements is estimated to have been between 200,000
Franz Hermann Troschel
Franz Hermann Troschel was a German zoologist born in Spandau. He studied mathematics and natural history at the University of Berlin, beginning in 1840 was an assistant to Martin Lichtenstein at the Natural History Museum of Berlin. In 1849 he became a professor of zoology and natural history at the University of Bonn. In 1851 he became a member of the Academy of Sciences Leopoldina. Troschel is remembered for the identification and classification of species in the fields of malacology and herpetology. A few of the species that contain his name are Troschel's sea star, Troschel's parrotfish, Troschel's murex and the freshwater snail Bithynia troschelii. System der Asteriden. Braunschweig: Friedrich Vieweg und Sohn. 1842. Über die Bedeutsamkeit des naturgeschichtlichen Unterrichts. Berlin 1845. Horae ichthyologicae. Berlin 1845–49, 3 volumes. Handbuch der Zoologie, third to seventh edition, Berlin 1848/1853/1859/1864/1871. Digital 6th edition by the University and State Library Düsseldorf Troschel F. H. 1856–1879.
Das Gebiß der Schnecken zur Begründung einer natürlichen Klassifikation. Berlin 1856–1879, two volumes. Volume 1 and volume 2 were published in parts: 1856. Volume 1, part 1: 1–72, plates 1–4. 1857. 1: 73–112, plates 5–8. 1858. 1: 113–152, plates 9–12. 1861. 1: 153–196, plates 13–16. 1863. 1: i–viii, 197–252, plates 17–20. 1865. 2: 1–48, plates 1–4. 1867. 2: 49–96, plates 5–8. 1869. 2: 97–132, plates 9–12. 1875. 2: 133–180, plates 13–16. 1878. 2: 181–216, plates 17–20. 1879. 2: 217–246, plates 21–24. Two last parts 2 and 2 were continued by Johannes Thiele and published in 1891 and 1893. Troschel was the editor of Archiv für Naturgeschichte from volume 15 to 48, Nicolaische Verlagsbuchhandlung; this article is based on a translation of an equivalent article at the German Wikipedia. H. von Dechen, 1883. Zur Erinnerung an Dr. Franz Hermann Troschel. Works by or about Franz Hermann Troschel at Internet Archive
A forest is a large area dominated by trees. Hundreds of more precise definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing and ecological function. According to the used Food and Agriculture Organization definition, forests covered 4 billion hectares or 30 percent of the world's land area in 2006. Forests are the dominant terrestrial ecosystem of Earth, are distributed around the globe. Forests account for 75% of the gross primary production of the Earth's biosphere, contain 80% of the Earth's plant biomass. Net primary production is estimated at 21.9 gigatonnes carbon per year for tropical forests, 8.1 for temperate forests, 2.6 for boreal forests. Forests at different latitudes and elevations form distinctly different ecozones: boreal forests near the poles, tropical forests near the equator and temperate forests at mid-latitudes. Higher elevation areas tend to support forests similar to those at higher latitudes, amount of precipitation affects forest composition.
Human society and forests influence each other in both negative ways. Forests serve as tourist attractions. Forests can affect people's health. Human activities, including harvesting forest resources, can negatively affect forest ecosystems. Although forest is a term of common parlance, there is no universally recognised precise definition, with more than 800 definitions of forest used around the world. Although a forest is defined by the presence of trees, under many definitions an area lacking trees may still be considered a forest if it grew trees in the past, will grow trees in the future, or was designated as a forest regardless of vegetation type. There are three broad categories of forest definitions in use: administrative, land use, land cover. Administrative definitions are based upon the legal designations of land, bear little relationship to the vegetation growing on the land: land, designated as a forest is defined as a forest if no trees are growing on it. Land use definitions are based upon the primary purpose.
For example, a forest may be defined as any land, used for production of timber. Under such a land use definition, cleared roads or infrastructure within an area used for forestry, or areas within the region that have been cleared by harvesting, disease or fire are still considered forests if they contain no trees. Land cover definitions define forests based upon the type and density of vegetation growing on the land; such definitions define a forest as an area growing trees above some threshold. These thresholds are the number of trees per area, the area of ground under the tree canopy or the section of land, occupied by the cross-section of tree trunks. Under such land cover definitions, an area of land can only be known as forest if it is growing trees. Areas that fail to meet the land cover definition may be still included under while immature trees are establishing if they are expected to meet the definition at maturity. Under land use definitions, there is considerable variation on where the cutoff points are between a forest and savanna.
Under some definitions, forests require high levels of tree canopy cover, from 60% to 100%, excluding savannas and woodlands in which trees have a lower canopy cover. Other definitions consider savannas to be a type of forest, include all areas with tree canopies over 10%; some areas covered in trees are defined as agricultural areas, e.g. Norway spruce plantations in Austrian forest law when the trees are being grown as Christmas trees and below a certain height; the word forest comes from Middle English, from Old French forest "forest, vast expanse covered by trees". A borrowing of the Medieval Latin word foresta "open wood", foresta was first used by Carolingian scribes in the Capitularies of Charlemagne to refer to the king's royal hunting grounds; the term was not endemic to Romance languages. The exact origin of Medieval Latin foresta is obscure; some authorities claim the word derives from the Late Latin phrase forestam silvam, meaning "the outer wood". Frankish *forhist is attested by Old High German forst "forest", Middle Low German vorst "forest", Old English fyrhþ "forest, game preserve, hunting ground", Old Norse fýri "coniferous forest", all of which derive from Proto-Germanic *furhísa-, *furhíþija- "a fir-wood, coniferous forest", from Proto-Indo-European *perkwu- "a coniferous or mountain forest, wooded height".
Uses of the word "forest" in English to denote any uninhabited area of non-enclosure are now considered archaic. The word was introduced by the Norman rulers of England as a legal term denoting an uncultivated area set aside for hunting by feudal nobility; these hunting forests were not neces
Spencer Fullerton Baird
Spencer Fullerton Baird was an American naturalist, ichthyologist and museum curator. Baird was the first curator to be named at the Smithsonian Institution, he would serve as assistant Secretary of the Smithsonian from 1850 to 1878, as Secretary from 1878 until 1887. He was dedicated to expanding the natural history collections of the Smithsonian which he increased from 6,000 specimens in 1850 to over 2 million by the time of his death, he published over 1,000 works during his lifetime. Spencer Fullerton Baird was born in Reading, Pennsylvania in 1823, he became a self-trained naturalist as a young man, learning about the field from his brother, a birder, the likes of John James Audubon, who instructed Baird on how to draw scientific illustrations of birds. His father was a big influence on Baird's interest in nature, taking Baird on walks and gardening with him, he died of cholera. As a young boy he attended Nottingham Academy in Port Deposit and public school in Carlisle, Pennsylvania. Baird attended Dickinson College and earned his bachelor's and master's degrees, finishing the former in 1840.
After graduation he moved to New York City with an interest in studying medicine at the Columbia University College of Physicians and Surgeons. He returned to Carlisle two years later, he taught natural history at Dickinson starting in 1845. While at Dickinson, he did research, participated in collecting trips, did specimen exchanges with other naturalists, traveled frequently, he married Mary Helen Churchill in 1846. In 1848, their daughter, Lucy Hunter Baird, was born, he was awarded a grant, in 1848, from the Smithsonian Institution to explore bone caves and the natural history of southeastern Pennsylvania. In 1849 he was given $75 by the Smithsonian Institution to collect and transport specimens for them, it was during this time. The two would become close colleagues. Throughout the 1840s Baird traveled extensively throughout the northeastern and central United States. Traveling by foot, Baird hiked more than 2,100 miles in 1842 alone. In 1850, Baird became the first curator at the Smithsonian Institution and the Permanent Secretary for the American Association for the Advancement of Science, the latter which he served for three years.
Upon his arrival in Washington, he brought two railroad box cars worth of his personal collection. Baird would create a museum program for the Smithstonian, requesting that the organization focus on natural history in the United States, his program allowed him to create a network of collectors through an exchange system. He would ask that members of the Army and Navy collect rare animals and plant specimens from west of the Mississippi River and the Gulf of Mexico. In order to balance the collection, Baird sent duplicate specimens to other museums around the country exchanging the duplicates for specimens the Smithsonian needed. During the 1850s he described over 50 new species of reptiles, some by himself, others with his student Charles Frédéric Girard, their 1853 catalog of the Smithsonian's snake collection is a benchmark work in North American herpetology. Baird was a mentor to herpetologist Robert Kennicott who died prematurely, at which point Baird left the field of herpetology to focus on larger projects.
He became the Assistant Secretary, serving under Joseph Henry. As Assistant, Baird would help develop a publication and journal exchange, that provided scientists around the world with publications they would have a hard time accessing, he supported the work of Robert Kennicott, Henry Ulke and Henry Bryant. Between his start as Assistant Secretary and 1855, he worked with Joseph Henry to provide scientific equipment and needs to the United States and Mexican Boundary Survey, he received his Ph. D. in physical science in 1856 from Dickinson College. In 1857 and 1852 he acquired the collection of the National Institute for the Promotion of Science. However, the objects wouldn't join the permanent collection of the Smithsonian until 1858. Baird would attend the funeral of Abraham Lincoln alongside Joseph Henry. In 1870, Baird was vacationing in Woods Hole, where he developed an interest in maritime research, he would go on to lead expeditions in New England. On February 25, 1871, Ulysses S. Grant appointed Baird as the first Commissioner of Fish and Fisheries for the United States Fish Commission.
He would serve in this position until his death. With Baird as Commissioner, the commission sought opportunities to restock rivers with salmon and lakes with other food fish and the depletion of food fish in coastal waters. Baird reported. Individuals with access to shoreline property used weirs, or nets, to capture large amounts of fish on the coast, which threatened the supply of fish on the coast. Baird used the U. S. Fish Commission to limit human impact through a compromise by prohibiting the capture of fish in traps from 6pm on Fridays until 6pm on Mondays; the Albatross research vessel would be launched during his tenure, in 1882. He was active in developing fishing and fishery policies for the United States, was instrumental in making Wood's Hole the research venue it is today. Baird became the manager of the United States National Museum in 1872. Baird told George Perkins Marsh that he sought to be the director of the National Museum and that he had intentions to expand on the collections within the museum en masse.
He was the primary writer of A History of North American Birds, published in 1874 and continues to be an important publication in