The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States, the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone and limestone and is light gray, greenish gray, or red. Most of the fossils occur in the green siltstone beds and lower sandstones, relics of the rivers and floodplains of the Jurassic period, it is centered in Wyoming and Colorado, with outcrops in Montana, North Dakota, South Dakota, Kansas, the panhandles of Oklahoma and Texas, New Mexico, Arizona and Idaho. Equivalent rocks under different names are found in Canada, it covers an area of 1.5 million square kilometers, although only a tiny fraction is exposed and accessible to geologists and paleontologists. Over 75% is still buried under the prairie to the east, much of its western paleogeographic extent was eroded during exhumation of the Rocky Mountains, it was named after Morrison, where the first fossils in the formation were discovered by Arthur Lakes in 1877.
That same year, it became the center of the Bone Wars, a fossil-collecting rivalry between early paleontologists Othniel Charles Marsh and Edward Drinker Cope. In Colorado, New Mexico, Utah, the Morrison Formation was a major source of uranium ore. According to radiometric dating, the Morrison Formation dates from 156.3 ± 2 million years old at its base, to 146.8 ± 1 million years old at the top, which places it in the earliest Kimmeridgian, early Tithonian stages of the late Jurassic. This is similar in age to the Solnhofen Limestone Formation in Germany and the Tendaguru Formation in Tanzania; the age and much of the fauna is similar to the Lourinhã Formation in Portugal. Throughout the western United States, it variously overlies the Middle Jurassic Summerville, Bell Ranch and Stump Formations. At the time, the supercontinent of Laurasia had split into the continents of North America and Eurasia, although they were still connected by land bridges. North America was passing through the subtropical regions.
The Morrison Basin, which stretched from New Mexico in the south to Alberta and Saskatchewan in the north, was formed during the Nevadan orogeny, a precursor event to orogenic episodes that created the Rocky Mountains started pushing up to the west. The deposits from their east-facing drainage basins, carried by streams and rivers from the Elko Highlands and deposited in swampy lowlands, river channels and floodplains, became the Morrison Formation. In the north, the Sundance Sea, an extension of the Arctic Ocean, stretched through Canada down to the United States. Coal is found in the Morrison Formation of Montana, which means that the northern part of the formation, along the shores of the sea, was wet and swampy, with more vegetation. Aeolian, or wind-deposited sandstones, are found in the southwestern part, which indicates it was much more arid—a desert, with sand dunes. In the Colorado Plateau region, the Morrison Formation is further broken into four sub-divisions, or members. From the oldest to the most recent, they are: Windy Hill Member: The oldest member.
At the time, the Morrison basin was characterized by shallow marine and tidal flat deposition along the southern shore of the Sundance Sea. Tidwell Member: The Sundance Sea receded to Wyoming during this member and was replaced by lakes and mudflats. Salt Wash Member: The first purely terrestrial member; the basin was a semi-arid alluvial plain, with seasonal mudflats. Brushy Basin Member: Much finer-grained than the Salt Wash Member, the Brushy Basin Member is dominated by mudstone rich in volcanic ash. Rivers flowed from the west into a basin that contained a giant, saline alkaline lake called Lake T'oo'dichi' and extensive wetlands that were located just west of the modern Uncompahgre Plateau. Deposition in the Morrison Formation ended about 147 Ma; the latest Morrison strata are followed by a thirty-million-year gap in the geologic record. The overlying units are the Lower Cretaceous Cedar Mountain, Burro Canyon and Cloverly Formations. Though many of the Morrison Formation fossils are fragmentary, they are sufficient to provide a good picture of the flora and fauna in the Morrison Basin during the Kimmeridgian.
Overall, the climate was dry, similar to a savanna but, since there were no angiosperms, the flora was quite different. Conifers, the dominant plants of the time, were to be found with ginkgos, tree ferns, horsetail rushes. Much of the fossilized vegetation was riparian. Insects were similar to modern species, with termites building 30-meter-tall nests. Along the rivers, there were fish, salamanders, crocodiles, pterosaurs, crayfish and mammaliforms; the dinosaurs were most riparian, as well. Hundreds of dinosaur fossils have been discovered, such as Allosaurus, Ornitholestes, several stegosaurs comprising at least two species of Stegosaurus and the older Hesperosaurus, the early ankylosaurs and Gargoyleosaurus, most notably a broad range of sauropods. Since at least some of these species are known to have nested in the area, there are indications that it was a good environment for dinosaurs and not just home to migratory, seasonal populations. Sauropods that have been discovered include Diplodocus, Brachiosaurus
The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago, to the beginning of the Devonian Period, 419.2 Mya. The Silurian is the shortest period of the Paleozoic Era; as with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by several million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when 60% of marine species were wiped out. A significant evolutionary milestone during the Silurian was the diversification of jawed fish and bony fish. Multi-cellular life began to appear on land in the form of small, bryophyte-like and vascular plants that grew beside lakes and coastlines, terrestrial arthropods are first found on land during the Silurian. However, terrestrial life would not diversify and affect the landscape until the Devonian; the Silurian system was first identified by British geologist Roderick Murchison, examining fossil-bearing sedimentary rock strata in south Wales in the early 1830s.
He named the sequences for a Celtic tribe of Wales, the Silures, inspired by his friend Adam Sedgwick, who had named the period of his study the Cambrian, from the Latin name for Wales. This naming does not indicate any correlation between the occurrence of the Silurian rocks and the land inhabited by the Silures. In 1835 the two men presented a joint paper, under the title On the Silurian and Cambrian Systems, Exhibiting the Order in which the Older Sedimentary Strata Succeed each other in England and Wales, the germ of the modern geological time scale; as it was first identified, the "Silurian" series when traced farther afield came to overlap Sedgwick's "Cambrian" sequence, provoking furious disagreements that ended the friendship. Charles Lapworth resolved the conflict by defining a new Ordovician system including the contested beds. An early alternative name for the Silurian was "Gotlandian" after the strata of the Baltic island of Gotland; the French geologist Joachim Barrande, building on Murchison's work, used the term Silurian in a more comprehensive sense than was justified by subsequent knowledge.
He divided the Silurian rocks of Bohemia into eight stages. His interpretation was questioned in 1854 by Edward Forbes, the stages of Barrande, F, G and H, have since been shown to be Devonian. Despite these modifications in the original groupings of the strata, it is recognized that Barrande established Bohemia as a classic ground for the study of the earliest fossils; the Llandovery Epoch lasted from 443.8 ± 1.5 to 433.4 ± 2.8 mya, is subdivided into three stages: the Rhuddanian, lasting until 440.8 million years ago, the Aeronian, lasting to 438.5 million years ago, the Telychian. The epoch is named for the town of Llandovery in Wales; the Wenlock, which lasted from 433.4 ± 1.5 to 427.4 ± 2.8 mya, is subdivided into the Sheinwoodian and Homerian ages. It is named after Wenlock Edge in England. During the Wenlock, the oldest-known tracheophytes of the genus Cooksonia, appear; the complexity of later Gondwana plants like Baragwanathia, which resembled a modern clubmoss, indicates a much longer history for vascular plants, extending into the early Silurian or Ordovician.
The first terrestrial animals appear in the Wenlock, represented by air-breathing millipedes from Scotland. The Ludlow, lasting from 427.4 ± 1.5 to 423 ± 2.8 mya, comprises the Gorstian stage, lasting until 425.6 million years ago, the Ludfordian stage. It is named for the town of Ludlow in England; the Přídolí, lasting from 423 ± 1.5 to 419.2 ± 2.8 mya, is the final and shortest epoch of the Silurian. It is named after one locality at the Homolka a Přídolí nature reserve near the Prague suburb Slivenec in the Czech Republic. Přídolí is the old name of a cadastral field area. In North America a different suite of regional stages is sometimes used: Cayugan Lockportian Tonawandan Ontarian Alexandrian In Estonia the following suite of regional stages is used: Ohessaare stage Kaugatuma stage Kuressaare stage Paadla stage Rootsiküla stage Jaagarahu stage Jaani stage Adavere stage Raikküla stage Juuru stage With the supercontinent Gondwana covering the equator and much of the southern hemisphere, a large ocean occupied most of the northern half of the globe.
The high sea levels of the Silurian and the flat land resulted in a number of island chains, thus a rich diversity of environmental settings. During the Silurian, Gondwana continued a slow southward drift to high southern latitudes, but there is evidence that the Silurian icecaps were less extensive than those of the late-Ordovician glaciation; the southern continents remained united during this period. The melting of icecaps and glaciers contributed to a rise in sea level, recognizable from the fact that Silurian sediments overlie eroded Ordovician sediments, forming an unconformity; the continents of Avalonia and Laurentia drifted together near the equator, starting the formation of a second supercontinent known as Euramerica. When the proto-Europe coll
Binomial nomenclature called binominal nomenclature or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomen, binominal name or a scientific name; the first part of the name – the generic name – identifies the genus to which the species belongs, while the second part – the specific name or specific epithet – identifies the species within the genus. For example, humans belong within this genus to the species Homo sapiens. Tyrannosaurus rex is the most known binomial; the formal introduction of this system of naming species is credited to Carl Linnaeus beginning with his work Species Plantarum in 1753. But Gaspard Bauhin, in as early as 1623, had introduced in his book Pinax theatri botanici many names of genera that were adopted by Linnaeus; the application of binomial nomenclature is now governed by various internationally agreed codes of rules, of which the two most important are the International Code of Zoological Nomenclature for animals and the International Code of Nomenclature for algae and plants.
Although the general principles underlying binomial nomenclature are common to these two codes, there are some differences, both in the terminology they use and in their precise rules. In modern usage, the first letter of the first part of the name, the genus, is always capitalized in writing, while that of the second part is not when derived from a proper noun such as the name of a person or place. Both parts are italicized when a binomial name occurs in normal text, thus the binomial name of the annual phlox is now written as Phlox drummondii. In scientific works, the authority for a binomial name is given, at least when it is first mentioned, the date of publication may be specified. In zoology "Patella vulgata Linnaeus, 1758"; the name "Linnaeus" tells the reader who it was that first published a description and name for this species of limpet. "Passer domesticus". The original name given by Linnaeus was Fringilla domestica; the ICZN does not require that the name of the person who changed the genus be given, nor the date on which the change was made, although nomenclatorial catalogs include such information.
In botany "Amaranthus retroflexus L." – "L." is the standard abbreviation used in botany for "Linnaeus". "Hyacinthoides italica Rothm. – Linnaeus first named this bluebell species Scilla italica. The name is composed of two word-forming elements: "bi", a Latin prefix for two, "-nomial", relating to a term or terms; the word "binomium" was used in Medieval Latin to mean a two-term expression in mathematics. Prior to the adoption of the modern binomial system of naming species, a scientific name consisted of a generic name combined with a specific name, from one to several words long. Together they formed a system of polynomial nomenclature; these names had two separate functions. First, to designate or label the species, second, to be a diagnosis or description. In a simple genus, containing only two species, it was easy to tell them apart with a one-word genus and a one-word specific name; such "polynomial names" may sometimes look like binomials, but are different. For example, Gerard's herbal describes various kinds of spiderwort: "The first is called Phalangium ramosum, Branched Spiderwort.
The other... is aptly termed Phalangium Ephemerum Virginianum, Soon-Fading Spiderwort of Virginia". The Latin phrases are short descriptions, rather than identifying labels; the Bauhins, in particular Caspar Bauhin, took some important steps towards the binomial system, by pruning the Latin descriptions, in many cases to two words. The adoption by biologists of a system of binomial nomenclature is due to Swedish botanist and physician Carl von Linné, more known by his Latinized name Carl Linnaeus, it was in his 1753 Species Plantarum that he first began using a one-word "trivial name" together with a generic name in a system of binomial nomenclature. This trivial name is what is now known as specific name; the Bauhins' genus names were retained in many of these, but the descriptive part was reduced to a single word. Linnaeus's trivial names introduced an important new idea, namely that the function of a name could be to give a species a unique label; this meant. Thus Gerard's Phalangium ephemerum virginianum became Tradescantia virgi
The Precambrian is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic eon, named after Cambria, the Latinised name for Wales, where rocks from this age were first studied; the Precambrian accounts for 88% of the Earth's geologic time. The Precambrian is an informal unit of geologic time, subdivided into three eons of the geologic time scale, it spans from the formation of Earth about 4.6 billion years ago to the beginning of the Cambrian Period, about 541 million years ago, when hard-shelled creatures first appeared in abundance. Little is known about the Precambrian, despite it making up seven-eighths of the Earth's history, what is known has been discovered from the 1960s onwards; the Precambrian fossil record is poorer than that of the succeeding Phanerozoic, fossils from the Precambrian are of limited biostratigraphic use. This is because many Precambrian rocks have been metamorphosed, obscuring their origins, while others have been destroyed by erosion, or remain buried beneath Phanerozoic strata.
It is thought that the Earth coalesced from material in orbit around the Sun at 4,543 Ma, may have been struck by a large planetesimal shortly after it formed, splitting off material that formed the Moon. A stable crust was in place by 4,433 Ma, since zircon crystals from Western Australia have been dated at 4,404 ± 8 Ma; the term "Precambrian" is recognized by the International Commission on Stratigraphy as the only "supereon" in geologic time. "Precambrian" is still used by geologists and paleontologists for general discussions not requiring the more specific eon names. As of 2010, the United States Geological Survey considers the term informal, lacking a stratigraphic rank. A specific date for the origin of life has not been determined. Carbon found in 3.8 billion-year-old rocks from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have been found in Western Australia. Probable fossils 100 million years older have been found in the same area.
However, there is evidence. There is a solid record of bacterial life throughout the remainder of the Precambrian. Excluding a few contested reports of much older forms from North America and India, the first complex multicellular life forms seem to have appeared at 1500 Ma, in the Mesoproterozoic era of the Proterozoic eon. Fossil evidence from the Ediacaran period of such complex life comes from the Lantian formation, at least 580 million years ago. A diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma; these are referred to as Vendian biota. Hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic eon. By the middle of the following Cambrian period, a diverse fauna is recorded in the Burgess Shale, including some which may represent stem groups of modern taxa; the increase in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life. While land seems to have been devoid of plants and animals and other microbes formed prokaryotic mats that covered terrestrial areas.
Tracks from an animal with leg like appendages have been found in what was mud 551 million years ago. Evidence of the details of plate motions and other tectonic activity in the Precambrian has been poorly preserved, it is believed that small proto-continents existed prior to 4280 Ma, that most of the Earth's landmasses collected into a single supercontinent around 1130 Ma. The supercontinent, known as Rodinia, broke up around 750 Ma. A number of glacial periods have been identified going as far back as the Huronian epoch 2400–2100 Ma. One of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a "Snowball Earth"; the atmosphere of the early Earth is not well understood. Most geologists believe it was composed of nitrogen, carbon dioxide, other inert gases, was lacking in free oxygen. There is, evidence that an oxygen-rich atmosphere existed since the early Archean. At present, it is still believed that molecular oxygen was not a significant fraction of Earth's atmosphere until after photosynthetic life forms evolved and began to produce it in large quantities as a byproduct of their metabolism.
This radical shift from a chemically inert to an oxidizing atmosphere caused an ecological crisis, sometimes called the oxygen catastrophe. At first, oxygen would have combined with other elements in Earth's crust iron, removing it from the atmosphere. After the supply of oxidizable surfaces ran out, oxygen would have begun to accumulate in the atmosphere, the modern high-oxygen atmosphere would have developed. Evidence for this lies in older rocks that contain massive banded iron formations that were laid down as iron oxides. A terminology has evolved covering the early years of the Earth's existence, as radiometric dating has allowed real dates to be assigned to specific formations and features; the Precambrian is divided into
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
Lourinhã is a municipality in the District of Lisbon, in subregion Oeste in Portugal. The population in 2011 was 25,735, in an area of 147.17 km². The seat of the municipality is the town of Lourinhã, with a population of 8,800 inhabitants; the present Mayor is João Duarte, elected by the Socialist Party. The name Lourinhã originated in the period of Roman domination, when a villa was located in the area; the origin of the medieval village is linked to Jordan, a French knight who took part in the successful Siege of Lisbon in 1147. King Afonso Henriques granted Jordan the region of Lourinhã as fief and allowed him to grant a foral to its settlers in 1160; the name Lourinhã may be related to the origin of its feudal lord, since Jordan was from the Loire region in France. The rights of Lourinhã were confirmed by letters of King Sancho I in 1218 and again by Afonso III in 1258; the parish of Lourinhã became one of the richest of the Lisbon Diocese, as reflected by its main church, a fine example of 14th-century Portuguese Gothic architecture.
The Gothic works of the main church were sponsored by Lourenço Vicente, a Lourinhã-born Archbishop of Braga who received the village as a donation of King John I in 1384. In the 16th century, the Franciscan monastery of Santo António and a Misericórdia Church and Charity were founded in Lourinhã; the Misericórdia, a religious charity, now houses a museum with outstanding Renaissance paintings. The most important paintings are by the hand of a mysterious early 16th-century painter, dubbed the Master of Lourinhã. Starting at the end of the 19th century, the infrastructure of the municipality was modernised with roads, canalised water and electric light, as well as improvements in the educational system; the economy depended on agriculture and fishing. Tourism is an important source of revenue, due to the municipality's extensive, picturesque beaches and, more by the paleontological remains, which include fossilised bones, footprints and embryos from Jurassic dinosaurs. Many of which can be seen nowadays at the local museum, Museu da Lourinhã.
Lourinhã, is one of the few brandy-making areas, besides Cognac and Jerez, that have received appellation status. Administratively, the municipality is divided into 8 civil parishes: Lourinhã e Atalaia Miragaia e Marteleira Moita dos Ferreiros Reguengo Grande Ribamar Santa Bárbara São Bartolomeu dos Galegos e Moledo Vimeiro Lourinhã has 12 km of coastline with several popular beaches. Praia de Areal Praia da Areia Branca Praia do Caniçal Praia de Paimogo Praia de Vale Frades Praia de Porto das Barcas Praia da Peralta The area of Lourinhã is known by the Late Jurassic findings of dinosaurs and other fossils, give the name for Lourinhã Formation; the Museu da Lourinhã holds the main dinosaur collection. Nadrupe, a village situated in the parish of Lourinhã Municipality official website
Eusauropoda is a derived clade of sauropod dinosaurs. Eusauropods represent the node-based group that includes all descendant sauropods starting with the basal eusauropods of Shunosaurus, Barapasaurus, Amygdalodon, but excluding Vulcanodon and Rhoetosaurus; the Eusauropoda was coined in 1995 by Paul Upchurch to create a monophyletic new taxonomic group that would include all sauropods, except for the vulcanodontids. Eusauropoda are herbivorous and have long necks, they have been found in South America, North America, China and Africa. The temporal range of Eusauropoda ranges from the early Jurassic to the Latest Cretaceous periods; the most basal forms of eusauropods are not well known and because the cranial material for the Vulcanodon is not available, the distribution of some of these shared derived traits that distinguish Eusauropoda is still clear. Eusauropods are long-necked herbivorous, obligate quadrupedals, they have a specialized set of skeletal adaptions due to their large size, are graviportal.
Yates and Upchurch described eusauropod evolution as moving towards a “bulk-browsing mode of feeding”. They describe the development of lateral plates on the alveolar margins of tooth-bearing bones; these plates can be used to strip foliage, the eusauropod's “U-shaped” jaws create a wide bite, their loss of “fleshy cheeks” increased the gape. The crowns of eusauropod teeth have “wrinkled enamel textures”, but it is unclear what this meant for their feeding habits; the skull length of the basal eusauropod, Patagosaurus is about 60 centimetres. One of the most basal eusauropods, has two characteristic features of the eusauropod elongated neck: the incorporation of the equivalent of the first dorsal vertebra into the cervical region of the spine, the addition of two cervical vertebra in the middle of the cervical vertebrae. Other synapomorphies of Eusauropoda includes a retracted position of the external nares. Unlike prosauropods and theropods, which have a snout with smooth, unprotruding alveolar and subnarial regions, eusauropods have snouts with “stepped anterior margins”.
Further distinguishing features of eusauropods include the absence of the contact between the squamosal and the quadratojugal, the absence of the anterior process of the prefrontal, a distally elongated anterior ramus of the quadratojugal. Separating the anteroventral process of the nasal from the posterolateral process of the premaxilla, eusauropods have a long maxilla that forms the posteroventral margin of the external naris. Eusauporoda are hypothesized to have a semi-digitigrade foot posturem demonstrated by footprint evidence. Paleontologist Jeffrey Wilson explains that eusauropods differ from theropods and prosauropods that have digitigrade pes where their heel and metatarsals are lifted off of the ground. Eusauropods show asymmetry in their metatarsal shaft diameters where metatarsal I is broader than the others, suggesting that their weight was assumed by their inner feet. According to Steven Salisbury and Jay Nair, basal eusauropods retain four pedal unguals but reduce their phalangeal number in their fourth digit to three units.
The metatarsus in eusauropods is less than a quarter of their tibial length, unlike sauropod outgroups that have long hindlimbs and metatarsus that are half of their tibial length. Eusauropods are found on all major continents, except Antarctica, with diplocodoids being widespread in the Northern Hemisphere, titanosaurs being found in Southern Hemisphere. However, basal eusauropods that do not fall into either group are well represented. Early eusauropods such as Volkeimeria and Amygdalodon, more derived eusauropods such as Patagosaurus have been found in South America. Volkeimeria is classified as a basal eusauropod, though in 2004 Paul Upchurch was suspicious of its placement, because of its “opisthoceolous cervical centra, the absence of a femoral anterior trochanter, laterally projecting cnemial crest of the tibia”, instead thought it may be a generic sauropod. African eusauropods may include Spinophorosaurus, from Niger, although that taxon may instead be closer to Vulcanodon and outside Eusauropoda.
Atlasaurus was found in Morocco, Jobaria was found in Niger. However, both genera have been found as possible Macronarians, but Atlasaurus was found to be a turiasaurian, Jobaria a eusauropod, by a phylogenetic analysis of Xing in 2012. In Europe, the clade Turiasauria has been found in France and England, with multiple genera from the same locality in Spain. Cetiosaurus skeletons have been found in England, along with the eusauropod genera Cardiodon and Oplosaurus, known only from teeth; the family Mamenchisauridae is found widespread throughout Asia. A majority of the genera are found in China, although a possible specimen of Mamenchisaurus has been found in Thailand. In China, the basal eusauropod Nebulasaurus taito was found to be a sister taxon to Spinophorosaurus, more derived than Mamenchisauridae, but less derived than Patagosaurus, the genus Shunosaurus is one of the most basal eusauropods; the genus Barapasaurus has been found in India, may represent a cetiosaurid, a basal eusauropod, or a genus outside Eusauropoda.
The data around sauropods evolution, as Novas points out, is based on a few formations in the Northern Hemisphere. However, other beds in places such as Tanzania the Canadon Asfalto and Canadon Calcereo formations reveal a more diverse and widespread peleobiology of eusauropods in the Late Jurassic period; the following cladogram demonstrates hypothesized relationships within the Eusauropoda