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McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
An order of Granuloreticulosia in the class Rhizopodea. Foraminiferans are dominantly marine protozoa (single-celled animals), with a secreted or agglutinated shell, or test, enclosing the continually changing ameboid body that characterizes this and other orders of the superclass Sarcodina. Their unique combination of long geologic history, ubiquitous geographic distribution, and exceptional diversity of test composition, form, and structure make the foraminiferans the most useful of all marine fossils for stratigraphic correlation, geologic age dating of sediments, and paleoecologic interpretation. Although small in size, commonly less than 0.04 in. (1 mm), with a range between 20 micrometers and 4.8 in. (12 cm), foraminiferans may be abundant, more than 2600 living specimens having been recorded on 1.5 in.<sup>2</sup> (10 cm<sup>2</sup>) of sea floor. Their tests accumulated in great numbers and are recoverable from small quantities of sediment, rock outcroppings, well cores or cuttings, or ocean dredging and submarine coring.
Industry:Science
An order of gymnosperms in the class Ginkgoopsida (Pinophyta) with only one extant species, <i>Ginkgo biloba</i> (the maidenhair tree). Leaves identified as <i>Ginkgo</i> appeared first in the Upper Triassic, but <i>Ginkgo</i>-like leaves have been discovered as early as the Permian. During the Jurassic and Cretaceous periods, <i>Ginkgo</i> was a large taxon containing many species and having a circumpolar distribution in the Northern Hemisphere. The group diminished in size during the Early Cretaceous and into the Tertiary periods. It is probable that <i>Ginkgo</i>, considered sacred by the Chinese, would have become extinct had it not been cultivated in Chinese temple gardens, where the ginkgos became magnificent, old specimens several hundred feet tall.
Industry:Science
An order of herbivorous aquatic placental mammals, commonly known as sea cows, that includes the living manatees and dugongs and the recently exterminated Steller's sea cow. The order has an extensive fossil record dating from the early Eocene Epoch, some 50 million years ago.
Industry:Science
An order of herbivorous, odd-toed, hoofed mammals, including the living horses, zebras, asses, tapirs, rhinoceroses, and their extinct relatives. They are defined by a number of unique specializations, but the most diagnostic feature is their feet. Most perissodactyls have either one or three toes on each foot, and the axis of symmetry of the foot runs through the middle digit. The woodchucklike hyraxes, or conies, are apparently closely related to perissodactyls, although there is still some question about the relationships.
Industry:Science
An order of inarticulated brachiopods consisting of a group of sessile, suspension-feeding, marine, benthic, epifaunal bivalves, with representatives occurring throughout the Phanerozoic Era (from the Early Cambrian to the present). Extant members of this group originated in the Ordovician Period, when the order achieved maximum diversity.
Industry:Science
An order of inarticulated brachiopods consisting of an exclusively marine group of lophophorate animals (i.e., animals with a tentacular food-gathering, respiratory, and protective organ): sessile benthic suspension-feeders possessing a chitino-phosphatic shell. Representatives occur throughout the Phanerozoic Era (from the Early Cambrian to the present). Three superfamilies are recognized: Linguloidea, with the family Lingulidae, extends from the Middle Ordovician to the present; Discinoidea, with the family Discinidae, extends from the Early Ordovician to the present; and Acrotheloidea, known from the Early Cambrian to the Early Ordovician.
Industry:Science
An order of insects commonly known as fleas. These insects are bloodsucking ectoparasites of animals and humans and may transmit serious diseases.
Industry:Science
An order of invertebrate crustaceans related to crabs, shrimps, and lobsters, all members of the class Malacostraca. The closest relatives of Isopoda are the amphipods, mysids (opposum shrimps), cumaceans, and tanaids, all of which are placed in the superorder Peracarida. Isopods are generally small but very common, highly diversified, and occurring in marine, freshwater, and terrestrial habitats. Sow bugs, pill bugs, and woodlice, as well as their marine relatives (such as gribbles and sea slaters), belong to this group.
Industry:Science
An order of irregular echinoids in the superorder Neognathostomata resembling clypeasteroids but lacking the accessory ambulacral pores characteristic of that group. Oligopygoids have well-developed petals, and there are characteristic small demiplates present below the petals. These demiplates are wedge-shaped and usually do not reach the inner surface of the test. Each has a simple ambulacral pore. The apical disk is monobasal and the mouth oval and usually deeply sunken. Oligopygoids have a lantern, which closely resembles that of clypeasteroids, and their lantern muscle-attachment structures are a mixture of ambulacral and interambulacral processes.
Industry:Science
An order of jellyfish of the class Hydrozoa of the phylum Cnidaria. These jellyfish are of moderate size. They differ from other hydrozoan jellyfish in having balancing organs which develop partly from the digestive epithelium and in having only a small polyp stage or none at all. Many authorities now recognize three distinct orders of trachylines, Limnomedusae, Trachymedusae, and Narcomedusae, and in this case the older term Trachylina is abandoned.
Industry:Science
