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Yangtze Delta

The Yangtze Delta or Yangtze River Delta is a triangle-shaped megalopolis comprising the Wu Chinese-speaking areas of Shanghai, southern Jiangsu province and northern Zhejiang province. The area lies in the heart of the Jiangnan region, where Yangtze River drains into the East China Sea. Having a fertile soil, the Yangtze Delta abundantly produces grain, cotton and tea. In 2018, the Yangtze Delta had a GDP of US$2.2 trillion, about the same size as Italy. The urban build-up in the area has given rise to what may be the largest concentration of adjacent metropolitan areas in the world, it covers an area of 99,600 square kilometres and is home to over 115 million people as of 2013, of which an estimated 83 million is urban. If based on the greater Yangtze Delta zone, it has over 140 million people in this region. With about 1/10 of China's population and 1/5 of the country's GDP, the YRD is one of the fastest growing and richest regions in East Asia measured by purchasing power parity. Since the fourth century, when the national capital was moved to Jiankang at the start of the Eastern Jin dynasty, the Yangtze Delta has been a major cultural and political centre of China.

Hangzhou served as the Chinese capital during the Southern Song dynasty, Nanjing was the early capital of the Ming dynasty before the Yongle Emperor moved the capital to Beijing in 1421. Other key cities of the region in pre-modern times include Shaoxing; the ancient Suzhou was the capital of the Wu state, the ancient Shaoxing was the capital of the Yue state. Nanjing first served as a capital in the Three Kingdoms period as the capital of Eastern Wu. In these periods, there were several concomitant states or empires in China and each one had its own capital. Since the ninth century, the Yangtze Delta has been the most populous area in China, East Asia, one of the most densely populated areas of the world. During the mid to late period of the Tang dynasty, the region emerged as an economic centre, the Yangtze Delta became the most important agricultural, handicraft industrial and economic centre for the late Tang dynasty. In the Song dynasty during the Southern Song dynasty, with its capital situated in Lin'an, Lin'an became the biggest city in East Asia with a population more than 1.5 million, the economic status of the Yangtze Delta became more enhanced.

Ningbo became one of the two biggest seaports in East Asia along with Quanzhou. During the mid-late Ming dynasty, the first capitalism bud of the East Asia was born and developed in this area, although it was disrupted by the Manchu invasion and controlled and by the Confucian central government in Beijing, it continued its development throughout the rest of the Qing dynasty. During the Ming and Qing dynasties, the delta became a large economic centre for the country, played the most important role in agriculture and handicraft industry. During the Qianlong era of the Qing dynasty, Shanghai began developing and became the largest port in the Far East. From late 19th century to early 20th century, Shanghai was the biggest commercial centre in the Far East; the Yangtze Delta became the first industrialized area in China. After the Chinese economic reform program, which began in 1978, Shanghai again became the most important economic centre in mainland China, is emerging to become one of Asia's centres for commerce.

In modern times, the Yangtze Delta metropolitan region is centred at Shanghai, flanked by the major metropolitan areas of Hangzhou, Suzhou and Nanjing, home to nearly 105 million people. It is the centre of Chinese economic development, surpasses other concentrations of metropolitan areas in China in terms of economic growth and per capita income. In 1982, the Chinese government set up the Shanghai Economic Area. Besides Shanghai, four cities in Jiangsu and five cities in Zhejiang were included. In 1992, a 14-city cooperative joint meeting was launched. Besides the previous 10 cities, the members included Nanjing and Yangzhou in Jiangsu, Zhoushan in Zhejiang. In 1997, the regular joint meeting resulted in the establishment of the Yangtze Delta Economic Coordination Association, which included a new member Taizhou in Jiangsu in that year. In 2003, Taizhou in Zhejiang joined the association. In 2010, the association accepted six new members after a six-year observation and review, including Yancheng and Huai'an in Jiangsu and Quzhou in Zhejiang, Ma'anshan and Hefei in Anhui.

The total number of cities in the Yangtze Delta Economic Coordination Association is now 22. Some other cities that have been in consideration and in review include Wenzhou and Lishui in Zhejiang and Xuzhou in Jiangsu, Chuzhou, Tongling and Xuancheng in Anhui; the delta is one of the most densely populated regions on earth, includes one of the world's largest cities on its banks — Shanghai, with a density of 2,700 inhabitants per square kilometre. Because of the large population of the delta, factories and other cities upriver, the World Wide Fund for Nature says the Yangtze Delta is the biggest cause of marine pollution in the Pacific Ocean. Most of the people in this region speak Wu Chinese (sometimes called Shanghainese, although Shanghainese is one of

Smooth earth snake

The smooth earth snake is a species of nonvenomous natricine colubrid snake native to the eastern half of the United States. It is monotypic in the genus Virginia; the specific name or epithet, valeriae, is in honor of Valeria Biddle Blaney, who collected the first specimen in Kent County and was a first cousin of Spencer Fullerton Baird. The smooth earth snake is found from Iowa to New Jersey and Florida; the following is a description of the scalation of V. valeriae. Rostral nearly as deep as broad, visible from above. Dorsal scales in 15 or 17 rows. Anal divided. Ventrals 111-135; the following description of coloration of a live specimen uses Robert Ridgway's Color Standards and Color Nomenclature. Dorsally Virginia valeriae is benzo deep brownish drab, mars brown, or light brownish drab; the first row of dorsal scales is colored like the adjacent ventrals, which are light vinaceous-fawn, pale vinaceous-fawn, pale grayish vinaceous, or pale vinaceous-pink. The top of the head is hair like the dorsum, with many dark spots on the plates.

The upper labials are ecru-drab or lighter. There is a small black ring around the eye; the ventral surface of the head is white. Sometimes a faint median light line is present. There may be tiny black spots on the back and sides in the nominate race. Adults are 18–25 cm in total length; the smooth earth snake is a small, fossorial species which spends most of its time buried in loose soil or leaf litter. The smooth earth snake eats earthworms and soft-bodied arthropods. Given its lack of sufficient defense mechanisms against larger animals, the smooth earth snake is not aggressive towards humans and is harmless if encountered. While it does have teeth, the size of the mouth and teeth make any strikes against humans superficial at worst, it may defecate as a defense mechanism to make itself less palatable to would-be predators. If necessary, it can be relocated. Including the nominotypical subspecies, three subspecies of Virginia valeriae are recognized as being valid; these subspecies have been considered full species.

Virginia valeriae elegans Kennicott, 1859 – western earth snake, dorsal scales in 17 rows, southern Indiana through western Kentucky and Tennessee to the Gulf of Mexico, westward to eastern Kansas and central Texas. Virginia valeriae pulchra – mountain earth snake, dorsal scales weakly keeled, mountains of western Pennsylvania, adjacent northeastern West Virginia and western Maryland. Virginia valeriae valeriae Baird & Girard, 1853 – eastern earth snake, dorsal scales in 15 rows, New Jersey to Georgia and west through northern Alabama and southern Ohio. Nota bene: A trinomial authority in parentheses indicates that the subspecies was described in a genus other than Virginia. V. valeriae bears live young in August. Brood size is fewer than 10; the total length of a newborn is about 6 cm. Baird SF, Girard CF. Catalogue of North American Reptiles in the Museum of the Smithsonian Institution. Part I.—Serpents. Washington, District of Columbia: Smithsonian Institution. Xvi + 172 pp.. Behler JL, King FW.

The Audubon Society Field Guide to North American Reptiles and Amphibians. New York: Alfred A. Knopf. 743 pp. 657 color plates. ISBN 0-394-50824-6.. Conant R, Bridges W. What Snake Is That? A Field Guide to the Snakes of the United States East of the Rocky Mountains.. New York and London: D. Appleton-Century. Frontispiece map + viii + 163 pp. + Plates A-C, 1-32.. Goin CJ, Goin OB, Zug GR. Introduction to Herpetology, Third Edition. San Francisco: W. H. Freeman and Company. Xi + 378 pp. ISBN 0-7167-0020-4.. Kennicott R. "Notes on Coluber calligaster of Say, a description of new species of Serpents in the collection of the North Western University of Evanston, Ill." Proc. Acad. Nat. Sci. Philadelphia 11: 98-100.. McCoy CJ. Identification Guide to Pennsylvania Snakes.. Pittsburgh, Pennsylvania: Carnegie Museum of Natural History. 12 pp.. Morris PA. Boy's Book of Snakes: How to Recognize and Understand Them. A volume of the Humanizing Science Series, edited by Jacques Cattell. New York: Ronald Press. Viii + 185 pp.. 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.. Richmond ND. "The ground snake Haldea valeriae in Pennsylvania and West Virginia, with a description of a new subspecies". Annals of Carnegie Museum 33: 251-260.. Stejneger L, Barbour T. A Check List of North American Amphibians and Reptiles. Cambridge, Massachusetts: Harvard University Press. 125 pp.. Smooth Earth Snake, Reptiles and A

Pakicetidae

Pakicetidae is an extinct family of Archaeoceti that lived during the Early Eocene in Pakistan. Dehm & Oettingen-Spielberg 1958 described the first pakicetid, but at the time they did not recognize it as a cetacean, but identified it as a fish-eating mesonychid. Robert West was the first to identify pakicetids as cetaceans in 1980 and, after discovering a braincase, Phillip Gingerich and Donald Russell described the genus Pakicetus in 1981. During the following two decades, more research resulted in additional pakicetid cranial material and by 2001 postcranial material for the family had been described. Though all parts of pakicetid postcrania are known, no complete skeleton from a single individual has been recovered; the pakicetid goldmine is the "H-GSP Locality 62" site in the Kala Chitta Hills where fossils from all three genera have been found. However, this site is so littered with bones that identifying bones from a single individual is impossible, pakicetid skeletons are composites of bones from several individuals.

Pakicetids have been found in or near river deposits in northern Pakistan and northwestern India, a region, arid with only temporary streams when these animals lived there. No pakicetids have been found in marine deposits, they were terrestrial or freshwater animals, their long limbs and small hands and feet indicate they were poor swimmers. Their bones are heavy and compact and were used as ballast. Most pakicetids lived in or near bodies of freshwater and their diet could have included both land animals and aquatic organisms. During the Eocene, Pakistan was a coastal region of the Eurasian land mass and therefore an ideal habitat for the evolution, diversification of the Pakicetids. Pakicetid ears had an external auditory meatus and ear ossicles similar to those in living land mammals and most used normal land mammal hearing in air. In the pakicetid mandible, the mandibular foramen is small and comparable in size to those of extant land mammals and the acoustic mandibular fat pad characteristic of whales was not present.

The lateral wall of the mandible is relatively thick in pakicetids, further preventing sound transmission through the jaw. The tympanic bulla in pakicetid ears is similar to those in all cetaceans, with a thin lateral wall and thickened medial part known as the involucrum. However, in contrast to cetaceans, the tympanic bone makes contact with the periotic bone, attached to the skull leaving no space for isolating air sinuses preventing directional hearing in water. Pakicetids most used bone conduction for hearing in water. Interpretations of pakicetid habitat and locomotion behaviour varies considerably: In 2001, it was concluded by Thiwissen et al. that "pakicetids were terrestrial mammals, no more amphibious than a tapir." According to them, none of the aquatic adaptations found in the oldest obligate aquatic cetaceans and dorudontids, are present in pakicetids. Pakicetid cervical vertebrae are longer than in late Eocene whales, the thoracic vertebrae increase in size from the neck backwards, the lumbar and caudal vertebrae are longer than in modern cetaceans Motion in the spine of pakicetids was further reduced by the revolute zygapophyses like in stiff-backed runners such as mesonychians.

The sacral vertebrae are fused and the sacroiliac joints present like in land mammals and amphibious cetaceans. Furthermore, according to Thewissenet al. the pakicetid scapulae have large supraspinous fossae with small acromions, in contrast to other cetaceans. The deltopectoral crests are absent in the long and slender humeri like in cursorial animals but unlike other Eocene cetaceans. Pakicetid elbows are rigid hinge joints like in running mammals and the forearms are not flattened like in aquatic cetaceans. In the pakicetid pelvis, the innominates are large and the ischia are longer than the ilia; the pakicetid tibiae are long with a short tibial crest. Hindlimb features that all more reminiscent of jumping animals than swimming animals. Gingerich 2003 disagreed and got support from Madar 2007: postcranial morphology and microstructural features suggest that pakicetids were adapted to an aquatic lifestyle which included bottom wading and undulatory swimming, but not sustained running. Isotopic evidence indicate Pakicetids spent a considerable part of their life in freshwater and ate freshwater prey.

Family PakicetidaeIchthyolestes Ichtyolestes pinfoldi Nalacetus Nalacetus ratimitus Pakicetus Pakicetus attocki Pakicetus calcis Pakicetus chittas Archaeoceti Evolution of cetaceans