The Cenozoic Era meaning "new life", is the current and most recent of the three Phanerozoic geological eras, following the Mesozoic Era and extending from 66 million years ago to the present day. The Cenozoic is known as the Age of Mammals, because the extinction of many groups allowed mammals to diversify so that large mammals dominated it; the continents moved into their current positions during this era. Early in the Cenozoic, following the K-Pg extinction event, most of the fauna was small, included small mammals, birds and amphibians. From a geological perspective, it did not take long for mammals and birds to diversify in the absence of the large reptiles that had dominated during the Mesozoic. A group of avians known as the "terror birds" grew larger than the average human and were formidable predators. Mammals came to occupy every available niche, some grew large, attaining sizes not seen in most of today's mammals; the Earth's climate had begun a drying and cooling trend, culminating in the glaciations of the Pleistocene Epoch, offset by the Paleocene-Eocene Thermal Maximum.
Cenozoic, meaning "new life," is derived from Greek καινός kainós "new," and ζωή zōḗ "life." The era is known as the Cænozoic, Caenozoic, or Cainozoic. The name "Cenozoic" was proposed in 1840 by the British geologist John Phillips; the Cenozoic is divided into three periods: the Paleogene and Quaternary. The Quaternary Period was recognized by the International Commission on Stratigraphy in June 2009, the former term, Tertiary Period, became disused in 2004 due to the need to divide the Cenozoic into periods more like those of the earlier Paleozoic and Mesozoic eras; the common use of epochs during the Cenozoic helps paleontologists better organize and group the many significant events that occurred during this comparatively short interval of time. Knowledge of this era is more detailed than any other era because of the young, well-preserved rocks associated with it; the Paleogene spans from the extinction of non-avian dinosaurs, 66 million years ago, to the dawn of the Neogene, 23.03 million years ago.
It features three epochs: the Paleocene and Oligocene. The Paleocene epoch lasted from 66 million to 56 million years ago. Modern placental mammals originated during this time; the Paleocene is a transitional point between the devastation, the K-T extinction, to the rich jungle environment, the Early Eocene. The Early Paleocene saw the recovery of the earth; the continents began to take their modern shape, but all the continents and the subcontinent of India were separated from each other. Afro-Eurasia was separated by the Tethys Sea, the Americas were separated by the strait of Panama, as the isthmus had not yet formed; this epoch featured a general warming trend, with jungles reaching the poles. The oceans were dominated by sharks. Archaic mammals filled the world such as creodonts; the Eocene Epoch ranged from 56 million years to 33.9 million years ago. In the Early-Eocene, species living in dense forest were unable to evolve into larger forms, as in the Paleocene. There was nothing over the weight of 10 kilograms.
Among them were early primates and horses along with many other early forms of mammals. At the top of the food chains were huge birds, such as Paracrax; the temperature was 30 degrees Celsius with little temperature gradient from pole to pole. In the Mid-Eocene, the Circumpolar-Antarctic current between Australia and Antarctica formed; this disrupted ocean currents worldwide and as a result caused a global cooling effect, shrinking the jungles. This allowed mammals to grow to mammoth proportions, such as whales which, by that time, had become fully aquatic. Mammals like Andrewsarchus were at the top of the food-chain; the Late Eocene saw the rebirth of seasons, which caused the expansion of savanna-like areas, along with the evolution of grass. The end of the Eocene was marked by the Eocene-Oligocene extinction event, the European face of, known as the Grande Coupure; the Oligocene Epoch spans from 33.9 million to 23.03 million years ago. The Oligocene featured the expansion of grass which had led to many new species to evolve, including the first elephants, dogs and many other species still prevalent today.
Many other species of plants evolved in this period too. A cooling period featuring seasonal rains was still in effect. Mammals still continued to grow larger; the Neogene spans from 23.03 million to 2.58 million years ago. It features 2 epochs: the Miocene, the Pliocene; the Miocene epoch spans from 23.03 to 5.333 million years ago and is a period in which grass spread further, dominating a large portion of the world, at the expense of forests. Kelp forests evolved, encouraging the evolution such as sea otters. During this time, perissodactyla thrived, evolved into many different varieties. Apes evolved into 30 species; the Tethys Sea closed with the creation of the Arabian Peninsula, leaving only remnants as the Black, Red and Caspian Seas. This increased aridity. Many new plants evolved: 95% of modern seed plants evolved in the mid-Miocene; the Pliocene epoch lasted from 5.333 to 2.58 million years ago. The Pliocene featured dramatic climactic changes, which led to modern species and plants; the Mediterranean Sea dried up for several million years (because the ice ages reduced sea levels, disconnecting the Atlantic from
Flotsam, jetsam, lagan, and derelict
In maritime law, jetsam and derelict are specific kinds of shipwreck. The words have specific nautical meanings, with legal consequences in the law of admiralty and marine salvage. A shipwreck is defined as the remains of a ship, wrecked—a destroyed ship at sea, whether it be sunken or floating on the surface of the water. A wreck is categorized as property belonging to no apparent owner, that either sinks to the seabed, or floats on the surface of the water, whether it be intentionally cast overboard, or as the result of an accident; the term encompasses the hull of the vessel and its fixtures, as well as any other form of object on board, such as cargo and stores, personal effects of the crew and passengers. This encompasses the narrower definition of salvage, that is, property, recovered from a wreckage, or the recovery of the ship itself. There are a number of factors that contribute to the formation of a shipwreck, that can be divided into physical and cultural processes. A site can be affected by physical processes, occurring processes, such as the corrosion caused by salinity and ocean currents, or the growth of native and foreign marine organisms.
It can be affected by cultural processes, that is, by human interactions, such as adding or removing materials from the site of the wreck. Any archaeological activity, such as excavation, may be considered invasive and tampering. In terms of maritime law, different meanings are attributed to the terms, based on what the jurisdiction is, as well as the context. For example, a distinction is made between goods that wash ashore, from those that are for some reason not salvageable and/or lost at sea. Ownership of a wreck is a controversial issue, as there are no clear lines within which it is defined, it may be acquired through various means. There is a distinction to be made between the ownership of the hull itself and the cargo it contains, as the hull may be abandoned intentionally, whereas the cargo may be out of necessity. In these parameters, abandonment of the ship by its passengers constitutes as a loss of possession, but to abandon the claim on the title itself, intention to relinquish it is required.
This affects wrecks by limiting that, considered "abandoned". A ship is defined as "abandoned" if there is no hope of recovery, known as Sine spe recuperandi, this fact must be proven by the salvaging party, it must occur on navigable waters. The term "salvage" is used to indicate a salvage operation, as well as the subsequent awarded compensation, it is considered a voluntary service rendered in cases such as danger to the wreck, or the surrounding navigable waters. In terms of compensation, it is seen as being awarded to anyone who voluntarily assisted in the recuperation of the wreck, whether it be saved from upcoming danger, or from loss; the Law of Salvage finds its origins in the Roman practice of negotiorum gestio, which dictated that one who preserved or improved upon the property of another, was owed compensation from the owner if the service was not requested by the latter. The law did not apply to maritime regulations, but were the basis for following ordinances, such as the Marine Ordinance of Trani, which stated that a "finder" was to be rewarded, whether the owner claimed the goods or not.
The laws have evolved since negotiorum gestio, today, in the United States, a salvor who voluntarily brings the goods back into port may lay claim to them, or deliver them to a marshal, in return for a reward. Known as "flotsan", the term "flotsam" refers to a sunken vessel whose goods float to the surface of the sea, or any floating cargo, cast overboard. In terms of maritime law, the definition of flotsam pertains to goods that are floating on the surface of the water as the result of a wreck or an accident; as there is no clear way of defining ownership, one who discovers flotsam is allowed to claim it, unless someone claims ownership to the items in question. When the source is known, as with the up to 270 cargo containers lost by the MSC ZOE in heavy seas in December 2018 off the German island of Borkum, as a practical matter the lost goods found on the Dutch coast was considered to be flotsam; the term "jetsam" designates any cargo, intentionally discarded from a ship or wreckage. Jetsam floats, although floating is not part of the etymological meaning.
"jettisoning" connotes the action of throwing goods overboard to lighten the load of the ship if it is in danger of being sunk. Per maritime law, one who discovers these artifacts is required to return them to their rightful owner only in the case that the latter makes a abiding claim. Although, according to the National Oceanic and Atmospheric Administration "flotsam may be claimed by the original owner, whereas jetsam may be claimed as property of whoever discovers it". Called "ligan", the term refers to goods that are cast overboard and are heavy enough to sink to the ocean floor, but are tied or otherwise linked to a floating marker, such as a buoy or cork, so that they can be found again by whoever marked the item. Lagan can refer to large objects that are trapped within the sinking vessel. According to maritime law, a buoy, or otherwise floating object, constitutes as sufficient grounds in laying claim to an artifact. In other words, when faced with a lagan, one is required to return the artifact to its rightful owner.
"Derelict" can refer to goods that have sunk to the ocean floor, relinquished willingly or forcefully by its owner, thus abandoned, but which no one has any hope of reclaiming
The gastropod shell is part of the body of a gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, dehydration, but serves for muscle attachment and calcium storage; some gastropods appear shell-less but may have a remnant within the mantle, or the shell is reduced such that the body cannot be retracted within. Some snails possess an operculum that seals the opening of the shell, known as the aperture, which provides further protection; the study of mollusc shells is known as conchology. The biological study of gastropods, other molluscs in general, is malacology. Shell morphology terms vary by species group. An excellent source for terminology of the gastropod shell is "How to Know the Eastern Land Snails" by John B. Burch now available at the Hathi Trust Digital Library; the gastropod shell has three major layers secreted by the mantle. The calcareous central layer, tracum, is made of calcium carbonate precipitated into an organic matrix known as conchiolin.
The outermost layer is the periostracum, resistant to abrasion and provides most shell coloration. The body of the snail contacts the innermost smooth layer that may be composed of mother-of-pearl or shell nacre, a dense horizontally packed form of conchiolin, layered upon the periostracum as the snail grows. Gastropod shell morphology is quite constant among individuals of a species. Controlling variables are: The rate of growth per revolution around the coiling axis. High rates give wide-mouthed forms such as the abalone, low rates give coiled forms such as Turritella or some of the Planorbidae; the shape of the generating curve equivalent to the shape of the aperture. It may be round, for instance in the turban shell, elongate as in the cone shell or have an irregular shape with a siphonal canal extension, as in the Murex; the rate of translation of the generating curve along the axis of coiling, controlling how high-spired the resulting shell becomes. This may range from a flat planispiral shell, to nearly the diameter of the aperture.
Irregularities or "sculpturing" such as ribs, spines and varices made by the snail changing the shape of the generating curve during the course of growth, for instance in the many species of Murex. Ontologic growth changes as the animal reaches adulthood. Good examples are the inward-coiled lip of the cowry; some of these factors can be modelled mathematically and programs exist to generate realistic images. Early work by David Raup on the analog computer revealed many possible combinations that were never adopted by any actual gastropod; some shell shapes are found more in certain environments, though there are many exceptions. Wave-washed high-energy environments, such as the rocky intertidal zone, are inhabited by snails whose shells have a wide aperture, a low surface area, a high growth rate per revolution. High-spired and sculptured forms become more common in quiet water environments; the shell of burrowing forms, such as the olive and Terebra, are smooth and lack elaborate sculpture, in order to decrease resistance when moving through sand.
On land, high-spired forms are associated with vertical surfaces, whereas flat-shelled snails tend to live on the ground. A few gastropods, for instance the Vermetidae, cement the shell to, grow along, solid surfaces such as rocks, or other shells. Most gastropod shells are spirally coiled; the majority of gastropod species have dextral shells, but a small minority of species and genera are always sinistral, a few species show a mixture of dextral and sinistral individuals. There occur aberrantly sinistral forms of dextral species and some of these are sought by shell collectors. If a coiled gastropod shell is held with the spire pointing upwards and the aperture more or less facing the observer, a dextral shell will have the aperture on the right-hand side, a sinistral shell will have the aperture on the left-hand side; this chirality of gastropods is sometimes overlooked when photographs of coiled gastropods are "flipped" by a non-expert prior to being used in a publication. This image "flipping" results in a normal dextral gastropod appearing to be a rare or abnormal sinistral one.
Sinistrality arose independently 19 times among marine gastropods since the start of the Cenozoic. This left-handedness seems to be more common in land pulmonates, but still the dextral living species in gastropods seem to account for 99% of the total number. The chirality in gastropods appears in the gene NODAL is involved. A more recent study correlates the asymmetric coiling of the shell by the left-right asymmetric expression of the decapentaplegic gene in the mantle. In a few cases, both left- and right-handed coiling are found in the same population. Sinistral mutants of dextral species and dextral mutants of sinistral species are rare but well documented occurrences among land snails in general. Populations or species with mixed coiling are much rarer, and, so far as is known, are confined, with one exception, to a few genera of arboreal tropical snails. Besides Amphidromus, the Cuban Liguus vittatus, Haitian Liguus virgineus, some Hawaiian Partulina and many Hawaiian Achatinella, as well as several species of Pacific islands Partula, are known to have mixed dextral-sinistral populations.
A possible exception may concern some of the European clausiliids of the subfamily Alopiinae. They are ob
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres and have complex interactions with each other and their environments, forming intricate food webs. The category includes humans, but in colloquial use the term animal refers only to non-human animals; the study of non-human animals is known as zoology. Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan; the Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes and molluscs—and the deuterostomes, containing the echinoderms and chordates.
Life forms interpreted. Many modern animal phyla became established in the fossil record as marine species during the Cambrian explosion which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified. Aristotle divided animals into those with those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between animal taxa. Humans make use of many other animal species for food, including meat and eggs. Dogs have been used in hunting, while many aquatic animals are hunted for sport.
Non-human animals have appeared in art from the earliest times and are featured in mythology and religion. The word "animal" comes from the Latin animalis, having soul or living being; the biological definition includes all members of the kingdom Animalia. In colloquial usage, as a consequence of anthropocentrism, the term animal is sometimes used nonscientifically to refer only to non-human animals. Animals have several characteristics. Animals are eukaryotic and multicellular, unlike bacteria, which are prokaryotic, unlike protists, which are eukaryotic but unicellular. Unlike plants and algae, which produce their own nutrients animals are heterotrophic, feeding on organic material and digesting it internally. With few exceptions, animals breathe oxygen and respire aerobically. All animals are motile during at least part of their life cycle, but some animals, such as sponges, corals and barnacles become sessile; the blastula is a stage in embryonic development, unique to most animals, allowing cells to be differentiated into specialised tissues and organs.
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible; this may be calcified, forming structures such as shells and spicules. In contrast, the cells of other multicellular organisms are held in place by cell walls, so develop by progressive growth. Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, desmosomes. With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues; these include muscles, which enable locomotion, nerve tissues, which transmit signals and coordinate the body. There is an internal digestive chamber with either one opening or two openings. Nearly all animals make use of some form of sexual reproduction, they produce haploid gametes by meiosis.
These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement, it first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm develops between them; these germ layers differentiate to form tissues and organs. Repeated instances of mating with a close relative during sexual reproduction leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. In some species, such as the splendid fairywren, females benefit by mating with multiple males, thus producing more offspring of higher genetic quality; some animals are capable of asexual reproduction, which results
The lentil is an edible legume. It is a bushy annual plant known for its lens-shaped seeds, it is about 40 cm tall, the seeds grow in pods with two seeds in each. In cuisines of the Indian subcontinent, split lentils are known as dal. Eaten with rice or rotis, the lentil is a dietary staple throughout the Indian subcontinent; as a food crop, the majority of world production comes from Canada and Australia. The cultivated lentil Lens culinaris was derived from its wild subspecies L. culinaris subsp. Orientalis, although other species may have contributed some genes, according to Jonathan Sauer Unlike their wild ancestors, domesticated lentil crops have indehiscent pods and nondormant seeds. Lentils are the oldest pulse crop known, among the earliest crops domesticated in the Old World, having been found as carbonized remains alongside human habitations dating to 11,000 BC in Greece; the lentil is indigenous to Central Asia. Many different names in different parts of the world are used for the crop lentil.
The first use of the word lens to designate a specific genus was in the 16th century by the botanist Tournefort. The genus Lens is part of the subfamily Faboideae, contained in the flowering plant family Fabaceae or known as legume or bean family, of the order Fabales in the kingdom Plantae. Lens is a small genus which consists of six related wild taxa. Among the different taxa of wild lentils, L. orientalis is considered to be the progenitor of the cultivated lentil and is now classified as L. culinaris subsp. Orientalis. Therefore, the genus Lens comprises seven taxa in six species: Lens culinaris subsp. Culinaris Lens odemensis Lens ervoides Lens nigricans Lens lamottei Lens tomentosus Lentil is hypogeal, which means the cotyledons of the germinating seed stay in the ground and inside the seed coat. Therefore, it is less vulnerable to wind erosion, or insect attack; the plant is a diploid, bushy herb of erect, semierect, or spreading and compact growth and varies from 30 to 50 cm in height.
It has many hairy branches and its stem is slender and angular. The rachis bears 10 to 15 leaflets in five to eight pairs; the leaves are alternate, of oblong-linear and obtuse shape and from yellowish green to dark bluish green in colour. In general, the upper leaves are converted into tendrils. If stipules are present, they are small; the flowers, one to four in number, are small, pink, pale purple, or pale blue in colour. They arise from the axils of the leaves, on a slender footstalk as long as the leaves; the pods are oblong inflated, about 1.5 cm long. Each of them contains two seeds, about 0.5 cm in diameter, in the characteristic lens shape. The seeds can be mottled and speckled; the several cultivated varieties of lentil differ in size and colour of the leaves and seeds. Lentils are self-pollinating; the flowering begins from the lowermost buds and moves upward, so-called acropetal flowering. About two weeks are needed. At the end of the second day and on the third day after the opening of the flowers, they close and the colour begins to fade.
After three to four days, the setting of the pods takes place. Brewer's: a large brown lentil, considered the "regular" lentil in the United States Beluga, bead-like, lens-shaped, dicotilidon spherical, named for resemblance to beluga caviar Brown/Spanish pardina French green Puy lentils, Lens esculenta puyensis, Protected Designation of Origin name Yellow/tan lentils Red Chief Eston Green Richlea Laird Masoor Petite crimson/red Macachiados In 2016, global production of lentils was 6.3 million tonnes, led by Canada with 51% and India with 17% of the world total. Saskatchewan is the most productive growing region in Canada. For 2016, Statistics Canada reported a national production yield of 3.2 million tonnes from 5,700,000 acres harvested. The Palouse region of eastern Washington and the Idaho panhandle, with its commercial center at Pullman, constitutes the most important lentil-producing region in the United States. Montana and North Dakota are significant lentil growers. Lentils can grow on various soil types, from sand to clay loam, growing best in deep sandy loam soils with moderate fertility.
A soil pH around 7 would be the best. Lentils do not tolerate flooding or water-logged conditions. Lentils increase the yield of succeeding cereal crops. Biological nitrogen fixation or other rotational effects could be the reason for higher yields after lentils; the conditions under which lentils are grown differ across different growing regions. In the temperate climates lentils are planted in the winter and spring under low temperatures and vegetative growth occurs in spring and the summer. Rainfall during this time is not limited. In the subtropics, lentils are planted under high temperatures at the end of the rainy season, vegetative growth occurs on the residual soil moisture in the summer season. Rainfall during this time is limited. In West A
The Carboniferous is a geologic period and system that spans 60 million years from the end of the Devonian Period 358.9 million years ago, to the beginning of the Permian Period, 298.9 Mya. The name Carboniferous means "coal-bearing" and derives from the Latin words carbō and ferō, was coined by geologists William Conybeare and William Phillips in 1822. Based on a study of the British rock succession, it was the first of the modern'system' names to be employed, reflects the fact that many coal beds were formed globally during that time; the Carboniferous is treated in North America as two geological periods, the earlier Mississippian and the Pennsylvanian. Terrestrial animal life was well established by the Carboniferous period. Amphibians were the dominant land vertebrates, of which one branch would evolve into amniotes, the first terrestrial vertebrates. Arthropods were very common, many were much larger than those of today. Vast swaths of forest covered the land, which would be laid down and become the coal beds characteristic of the Carboniferous stratigraphy evident today.
The atmospheric content of oxygen reached its highest levels in geological history during the period, 35% compared with 21% today, allowing terrestrial invertebrates to evolve to great size. The half of the period experienced glaciations, low sea level, mountain building as the continents collided to form Pangaea. A minor marine and terrestrial extinction event, the Carboniferous rainforest collapse, occurred at the end of the period, caused by climate change. In the United States the Carboniferous is broken into Mississippian and Pennsylvanian subperiods; the Mississippian is about twice as long as the Pennsylvanian, but due to the large thickness of coal-bearing deposits with Pennsylvanian ages in Europe and North America, the two subperiods were long thought to have been more or less equal in duration. In Europe the Lower Carboniferous sub-system is known as the Dinantian, comprising the Tournaisian and Visean Series, dated at 362.5-332.9 Ma, the Upper Carboniferous sub-system is known as the Silesian, comprising the Namurian and Stephanian Series, dated at 332.9-298.9 Ma.
The Silesian is contemporaneous with the late Mississippian Serpukhovian plus the Pennsylvanian. In Britain the Dinantian is traditionally known as the Carboniferous Limestone, the Namurian as the Millstone Grit, the Westphalian as the Coal Measures and Pennant Sandstone; the International Commission on Stratigraphy faunal stages from youngest to oldest, together with some of their regional subdivisions, are: A global drop in sea level at the end of the Devonian reversed early in the Carboniferous. There was a drop in south polar temperatures; these conditions had little effect in the deep tropics, where lush swamps to become coal, flourished to within 30 degrees of the northernmost glaciers. Mid-Carboniferous, a drop in sea level precipitated a major marine extinction, one that hit crinoids and ammonites hard; this sea level drop and the associated unconformity in North America separate the Mississippian subperiod from the Pennsylvanian subperiod. This happened about 323 million years ago, at the onset of the Permo-Carboniferous Glaciation.
The Carboniferous was a time of active mountain-building as the supercontinent Pangaea came together. The southern continents remained tied together in the supercontinent Gondwana, which collided with North America–Europe along the present line of eastern North America; this continental collision resulted in the Hercynian orogeny in Europe, the Alleghenian orogeny in North America. In the same time frame, much of present eastern Eurasian plate welded itself to Europe along the line of the Ural Mountains. Most of the Mesozoic supercontinent of Pangea was now assembled, although North China, South China continents were still separated from Laurasia; the Late Carboniferous Pangaea was shaped like an "O." There were two major oceans in the Carboniferous—Panthalassa and Paleo-Tethys, inside the "O" in the Carboniferous Pangaea. Other minor oceans were shrinking and closed - Rheic Ocean, the small, shallow Ural Ocean and Proto-Tethys Ocean. Average global temperatures in the Early Carboniferous Period were high: 20 °C.
However, cooling during the Middle Carboniferous reduced average global temperatures to about 12 °C. Lack of growth rings of fossilized trees suggest a lack of seasons of a tropical climate. Glaciations in Gondwana, triggered by Gondwana's southward movement, continued into the Permian and because of the lack of clear markers and breaks, the deposits of this glacial period are referred to as Permo-Carboniferous in age; the cooling and drying of the climate led to the Carboniferous Rainforest Collapse during the late Carboniferous. Tropical rainforests fragmented and were devastated by climate change. Carboniferous rocks in Europe and eastern North America consist of a repeated sequence of limestone, sandstone and coal beds. In North America, the early Carboniferous is marine
The Jurassic period was a geologic period and system that spanned 56 million years from the end of the Triassic Period 201.3 million years ago to the beginning of the Cretaceous Period 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era known as the Age of Reptiles; the start of the period was marked by the major Triassic–Jurassic extinction event. Two other extinction events occurred during the period: the Pliensbachian-Toarcian extinction in the Early Jurassic, the Tithonian event at the end; the Jurassic period is divided into three epochs: Early and Late. In stratigraphy, the Jurassic is divided into the Lower Jurassic, Middle Jurassic, Upper Jurassic series of rock formations; the Jurassic is named after the Jura Mountains within the European Alps, where limestone strata from the period were first identified. By the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses: Laurasia to the north, Gondwana to the south; this created more coastlines and shifted the continental climate from dry to humid, many of the arid deserts of the Triassic were replaced by lush rainforests.
On land, the fauna transitioned from the Triassic fauna, dominated by both dinosauromorph and crocodylomorph archosaurs, to one dominated by dinosaurs alone. The first birds appeared during the Jurassic, having evolved from a branch of theropod dinosaurs. Other major events include the appearance of the earliest lizards, the evolution of therian mammals, including primitive placentals. Crocodilians made the transition from a terrestrial to an aquatic mode of life; the oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, while pterosaurs were the dominant flying vertebrates. The chronostratigraphic term "Jurassic" is directly linked to the Jura Mountains, a mountain range following the course of the France–Switzerland border. During a tour of the region in 1795, Alexander von Humboldt recognized the limestone dominated mountain range of the Jura Mountains as a separate formation that had not been included in the established stratigraphic system defined by Abraham Gottlob Werner, he named it "Jura-Kalkstein" in 1799.
The name "Jura" is derived from the Celtic root *jor via Gaulish *iuris "wooded mountain", borrowed into Latin as a place name, evolved into Juria and Jura. The Jurassic period is divided into three epochs: Early and Late. In stratigraphy, the Jurassic is divided into the Lower Jurassic, Middle Jurassic, Upper Jurassic series of rock formations known as Lias and Malm in Europe; the separation of the term Jurassic into three sections originated with Leopold von Buch. The faunal stages from youngest to oldest are: During the early Jurassic period, the supercontinent Pangaea broke up into the northern supercontinent Laurasia and the southern supercontinent Gondwana; the Jurassic North Atlantic Ocean was narrow, while the South Atlantic did not open until the following Cretaceous period, when Gondwana itself rifted apart. The Tethys Sea closed, the Neotethys basin appeared. Climates were warm, with no evidence of a glacier having appeared; as in the Triassic, there was no land over either pole, no extensive ice caps existed.
The Jurassic geological record is good in western Europe, where extensive marine sequences indicate a time when much of that future landmass was submerged under shallow tropical seas. In contrast, the North American Jurassic record is the poorest of the Mesozoic, with few outcrops at the surface. Though the epicontinental Sundance Sea left marine deposits in parts of the northern plains of the United States and Canada during the late Jurassic, most exposed sediments from this period are continental, such as the alluvial deposits of the Morrison Formation; the Jurassic was a time of calcite sea geochemistry in which low-magnesium calcite was the primary inorganic marine precipitate of calcium carbonate. Carbonate hardgrounds were thus common, along with calcitic ooids, calcitic cements, invertebrate faunas with dominantly calcitic skeletons; the first of several massive batholiths were emplaced in the northern American cordillera beginning in the mid-Jurassic, marking the Nevadan orogeny. Important Jurassic exposures are found in Russia, South America, Japan and the United Kingdom.
In Africa, Early Jurassic strata are distributed in a similar fashion to Late Triassic beds, with more common outcrops in the south and less common fossil beds which are predominated by tracks to the north. As the Jurassic proceeded and more iconic groups of dinosaurs like sauropods and ornithopods proliferated in Africa. Middle Jurassic strata are neither well studied in Africa. Late Jurassic strata are poorly represented apart from the spectacular Tendaguru fauna in Tanzania; the Late Jurassic life of Tendaguru is similar to that found in western North America's Morrison Formation. During the Jurassic period, the primary vertebrates living in the sea were marine reptiles; the latter include ichthyosaurs, which were at the peak of their diversity, plesiosaurs and marine crocodiles of the families Teleosauridae and Metriorhynchidae. Numerous turtles could be found in rivers. In the invertebrate world, several new groups appeared, including rudists (a reef-formi