Theropoda or theropods are a dinosaur suborder, characterized by hollow bones and three-toed limbs. They are classed as a group of saurischian dinosaurs, although a 2017 paper has instead placed them in the proposed clade Ornithoscelida as the closest relatives of the Ornithischia. Theropods were ancestrally carnivorous, although a number of theropod groups evolved to become herbivores, omnivores and insectivores. Theropods first appeared during the Carnian age of the late Triassic period 231.4 million years ago and included the sole large terrestrial carnivores from the Early Jurassic until at least the close of the Cretaceous, about 66 Ma. In the Jurassic, birds evolved from small specialized coelurosaurian theropods, are today represented by about 10,500 living species. Theropods exhibit a wide range of diets, from insectivores to carnivores. Strict carnivory has always been considered the ancestral diet for theropods as a group, a wider variety of diets was considered a characteristic exclusive to the avian theropods.
However, discoveries in the late 20th and early 21st centuries showed that a variety of diets existed in more basal lineages. All early finds of theropod fossils showed them to be carnivorous. Fossilized specimens of early theropods known to scientists in the 19th and early 20th centuries all possessed sharp teeth with serrated edges for cutting flesh, some specimens showed direct evidence of predatory behavior. For example, a Compsognathus longipes fossil was found with a lizard in its stomach, a Velociraptor mongoliensis specimen was found locked in combat with a Protoceratops andrewsi; the first confirmed non-carnivorous fossil theropods found were the therizinosaurs known as segnosaurs. First thought to be prosauropods, these enigmatic dinosaurs were proven to be specialized, herbivorous theropods. Therizinosaurs possessed large abdomens for processing plant food, small heads with beaks and leaf-shaped teeth. Further study of maniraptoran theropods and their relationships showed that therizinosaurs were not the only early members of this group to abandon carnivory.
Several other lineages of early maniraptors show adaptations for an omnivorous diet, including seed-eating and insect-eating. Oviraptorosaurs and advanced troodontids were omnivorous as well, some early theropods appear to have specialized in catching fish. Diet is deduced by the tooth morphology, tooth marks on bones of the prey, gut contents; some theropods, such as Baryonyx, Lourinhanosaurus and birds, are known to use gastroliths, or gizzard-stones. The majority of theropod teeth are blade-like, with serration on the edges, called ziphodont. Others are phyllodont depending on the shape of the tooth or denticles; the morphology of the teeth is distinct enough to tell the major families apart, which indicate different diet strategies. An investigation in July 2015 discovered that what appeared to be "cracks" in their teeth were folds that helped to prevent tooth breakage by strengthening individual serrations as they attacked their prey; the folds helped the teeth stay in place longer as theropods evolved into larger sizes and had more force in their bite.
Mesozoic theropods were very diverse in terms of skin texture and covering. Feathers or feather-like structures are attested in most lineages of theropods.. However, outside the coelurosaurs, feathers may have been confined to the young, smaller species, or limited parts of the animal. Many larger theropods had skin covered in bumpy scales. In some species, these osteoderms; this type of skin is best known in the ceratosaur Carnotaurus, preserved with extensive skin impressions. The coelurosaur lineages most distant from birds had feathers that were short and composed of simple branching filaments. Simple filaments are seen in therizinosaurs, which possessed large, stiffened "quill"-like feathers. More feathered theropods, such as dromaeosaurs retain scales only on the feet; some species may have mixed feathers elsewhere on the body as well. Scansoriopteryx preserved scales near the underside of the tail, Juravenator may have been predominantly scaly with some simple filaments interspersed. On the other hand, some theropods were covered with feathers, such as the troodontid Anchiornis, which had feathers on the feet and toes.
Tyrannosaurus was for many decades the largest known best-known to the general public. Since its discovery, however, a number of other giant carnivorous dinosaurs have been described, including Spinosaurus, Carcharodontosaurus, Giganotosaurus; the original Spinosaurus specimens support the idea that Spinosaurus is longer than Tyrannosaurus, showing that Spinosaurus was 3 meters longer than Tyrannosaurus though Tyrannosaurus could still be taller than Spinosaurus. There is still no clear explanation for why these animals grew so much larger than the land predators that came before and after them; the largest extant theropod is the common ostrich, up to 2.74 m tall and weighing between 63.5 and 145.15 kg. The smallest non-avialan theropod known from adult specimens is the troodontid Anchiornis huxleyi, at 110 grams in weight and 34 centimeters in length; when modern birds are included, the bee hummingbird Mellisuga helenae is sm
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
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 Cretaceous is a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago to the beginning of the Paleogene Period 66 mya. It is the last period of the Mesozoic Era, the longest period of the Phanerozoic Eon; the Cretaceous Period is abbreviated K, for its German translation Kreide. The Cretaceous was a period with a warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas; these oceans and seas were populated with now-extinct marine reptiles and rudists, while dinosaurs continued to dominate on land. During this time, new groups of mammals and birds, as well as flowering plants, appeared; the Cretaceous ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs and large marine reptiles died out. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary, a geologic signature associated with the mass extinction which lies between the Mesozoic and Cenozoic eras.
The Cretaceous as a separate period was first defined by Belgian geologist Jean d'Omalius d'Halloy in 1822, using strata in the Paris Basin and named for the extensive beds of chalk, found in the upper Cretaceous of Western Europe. The name Cretaceous was derived from Latin creta; the Cretaceous is divided into Early and Late Cretaceous epochs, or Lower and Upper Cretaceous series. In older literature the Cretaceous is sometimes divided into three series: Neocomian and Senonian. A subdivision in eleven stages, all originating from European stratigraphy, is now used worldwide. In many parts of the world, alternative local subdivisions are still in use; as with other older geologic periods, the rock beds of the Cretaceous are well identified but the exact age of the system's base is uncertain by a few million years. No great extinction or burst of diversity separates the Cretaceous from the Jurassic. However, the top of the system is defined, being placed at an iridium-rich layer found worldwide, believed to be associated with the Chicxulub impact crater, with its boundaries circumscribing parts of the Yucatán Peninsula and into the Gulf of Mexico.
This layer has been dated at 66.043 Ma. A 140 Ma age for the Jurassic-Cretaceous boundary instead of the accepted 145 Ma was proposed in 2014 based on a stratigraphic study of Vaca Muerta Formation in Neuquén Basin, Argentina. Víctor Ramos, one of the authors of the study proposing the 140 Ma boundary age sees the study as a "first step" toward formally changing the age in the International Union of Geological Sciences. From youngest to oldest, the subdivisions of the Cretaceous period are: Late Cretaceous Maastrichtian – Campanian – Santonian – Coniacian – Turonian – Cenomanian – Early Cretaceous Albian – Aptian – Barremian – Hauterivian – Valanginian – Berriasian – The high sea level and warm climate of the Cretaceous meant large areas of the continents were covered by warm, shallow seas, providing habitat for many marine organisms; the Cretaceous was named for the extensive chalk deposits of this age in Europe, but in many parts of the world, the deposits from the Cretaceous are of marine limestone, a rock type, formed under warm, shallow marine circumstances.
Due to the high sea level, there was extensive space for such sedimentation. Because of the young age and great thickness of the system, Cretaceous rocks are evident in many areas worldwide. Chalk is a rock type characteristic for the Cretaceous, it consists of coccoliths, microscopically small calcite skeletons of coccolithophores, a type of algae that prospered in the Cretaceous seas. In northwestern Europe, chalk deposits from the Upper Cretaceous are characteristic for the Chalk Group, which forms the white cliffs of Dover on the south coast of England and similar cliffs on the French Normandian coast; the group is found in England, northern France, the low countries, northern Germany, Denmark and in the subsurface of the southern part of the North Sea. Chalk is not consolidated and the Chalk Group still consists of loose sediments in many places; the group has other limestones and arenites. Among the fossils it contains are sea urchins, belemnites and sea reptiles such as Mosasaurus. In southern Europe, the Cretaceous is a marine system consisting of competent limestone beds or incompetent marls.
Because the Alpine mountain chains did not yet exist in the Cretaceous, these deposits formed on the southern edge of the European continental shelf, at the margin of the Tethys Ocean. Stagnation of deep sea currents in middle Cretaceous times caused anoxic conditions in the sea water leaving the deposited organic matter undecomposed. Half the worlds petroleum reserves were laid down at this time in the anoxic conditions of what would become the Persian Gulf and the Gulf of Mexico. In many places around the world, dark anoxic shales were formed during this interval; these shales are an important source rock for oil and gas, for example in the subsurface of the North Sea. During th
The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy. In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous series. Campanian spans the time from 83.6 to 72.1 million years ago. It is preceded by the Santonian and it is followed by the Maastrichtian; the Campanian was an age. The morphology of some of these areas has been preserved: it is an unconformity beneath a cover of marine sedimentary rocks; the Campanian was introduced in scientific literature by Henri Coquand in 1857. It is named after the French village of Champagne in the département Charente-Maritime; the original type locality was an outcrop near the village of Aubeterre-sur-Dronne in the same region. Due to changes of the stratigraphic definitions, this section is now part of the Maastrichtian stage; the base of the Campanian stage is defined as a place in the stratigraphic column where the extinction of crinoid species Marsupites testudinarius is located.
The top of the Campanian stage is defined as the place in the stratigraphic column where the ammonite Pachydiscus neubergicus first appears. The Campanian can be subdivided into Lower and Upper subages. In the Tethys domain, the Campanian encompasses six ammonite biozones, they are, from young to old: zone of Nostoceras hyatti zone of Didymoceras chayennense zone of Bostrychoceras polyplocum zone of Hoplitoplacenticeras marroti/Hoplitoplacenticeras vari zone of Delawarella delawarensis zone of Placenticeras bidorsatum During the Campanian age, a radiation among dinosaur species occurred. In North America, for example, the number of known dinosaur genera rises from 4 at the base of the Campanian to 48 in the upper part; this development is sometimes referred to as the "Campanian Explosion". However, it is not yet clear if the event is artificial, i.e. the low number of genera in the lower Campanian can be caused by a lower preservation chance for fossils in deposits of that age. The warm climates and large continental area covered in shallow sea during the Campanian favoured the dinosaurs.
In the following Maastrichtian stage, the number of North American dinosaur genera found is 30% less than in the upper Campanian. Animals that lived in the Campanian include: David J. Varrichio observes that during the late Campanian Alberta and Montana had similar theropods despite significant differences in the types of herbivorous dinosaur faunas. Gradstein, F. M.. G. & Smith, A. G.. Varricchio, D. J. 2001. Late Cretaceous oviraptorosaur dinosaurs from Montana. Pp. 42–57 in D. H. Tanke and K. Carpenter, Mesozoic Vertebrate Life. Indiana University Press, Indiana. Weishampel, D. B.. M.. A.. M. P. & Noto, C. N.. B.. GeoWhen Database - Campanian Late Cretaceous timescale, at the website of the subcommission for stratigraphic information of the ICS Stratigraphic chart of the Late Cretaceous, at the website of Norges Network of offshore records of geology and stratigraphy Campanian Microfossils: 75+ images of Foraminifera
Isisaurus is a genus of dinosaur from the Late Cretaceous Period. Isisaurus was a sauropod. There are two types of sauropod skulls from Maastrichtian India. While Jainosaurus had a broad and flat cranium, the skull of Isisaurus was compact. Additionally, the angle between the occipital bone and occipital condyle is different in the two taxa. In the specimen from Dongargaon it is equal to 120°; the cranium of Isisaurus resembles in that matter the skulls of Diplodocus and Apatosaurus, but the bone modifications are different. The type specimen of Isisaurus colberti, ISI R 335/1-65, was described and named as Titanosaurus colberti by Sohan Lal Jain and Saswati Bandyopadhyay in 1997, the specific name honouring Edwin Harris Colbert, but was placed in its own genus, by Wilson and Upchurch, in 2003, it had a short, vertically directed neck and long forelimbs, making it different from other sauropods. The humerus is 148 centimetres long. Based on this specimen, Isisaurus would have grown to about 18 meters in length and weighed about 14,000 kg.
Isisaurus is known from much better remains than most titanosaurs. Most of its postcranial skeleton is known; the skeletal material Jain and Bandyopadhyay found between 1984 and 1986 was "in associated and articulated condition. The site locality is Dongargaon Hill, in a Maastrichtian crevasse splay claystone in the Lameta Formation of India. Dongargaon Hill is located near Warora, in Chandrapur District, Maharashtra. Fungus in coprolites believed to have been voided by Isisaurus indicate that it ate leaves from several species of tree, since these fungi are known to be pathogens which infect tree leaves. Isisaurus lived in the area belonging nowadays to India during the Maastrichtian, its remains are the most complete among the Cretaceous dinosaurs known from that region. Khosla et al. listed the following Indian sauropods: Titanosaurus indicus Titanosaurus balnfordi Titanosaurus rahiolensis Jainosaurus septentrionalis. Wilson et al. listed only two Indian titanosaurs and its distant relative, Jainosaurus.
Isisaurus and Jainosaurus lived sympatrically in the area of nowadays middle and western India, Isisaurus being present in the area of western Pakistan
Saltasaurus is a genus of titanosaurid sauropod dinosaur of the Late Cretaceous Period of Argentina. Small among sauropods, though still heavy by the standards of modern creatures, Saltasaurus was characterized by a short neck and stubby limbs, it was the first genus of sauropod known to possess armour of bony plates embedded in its skin. Such small bony plates, called osteoderms, have since been found on other titanosaurids; the fossils of Saltasaurus were excavated by José Fernando Bonaparte, Martín Vince and Juan C. Leal between 1975 and 1977 at the Estancia "El Brete"; the find. Saltasaurus was named and described by Bonaparte and Jaime E. Powell in 1980; the type species is Saltasaurus loricatus. Its generic name is derived from Salta Province, the region of north-west Argentina where the first fossils were recovered; the specific name means "protected by small armoured plates" in Latin. The holotype, PVL 4017-92, was found in a layer of the Lecho Formation dating from the early Maastrichtian stage of the Upper Cretaceous period, about seventy million years old.
It consists of a sacrum connected to two ilia. Under the inventory number PVL 4017 over two hundred additional fossils have been catalogued; these include rear skull elements, vertebrae of the neck, back and tail, parts of the shoulder girdle and the pelvis, limb bones — plus various pieces of armour. These bones represent a minimum of two adults and three juveniles or subadults; the only recognised species of Saltasaurus is S. loricatus. A S. robustus and a S. australis have been suggested but these are now considered to belong to a separate genus, Neuquensaurus. Earlier, armour plates from the area had been named as Loricosaurus by Friedrich von Huene who assumed them to be from an armoured ankylosaurian, it has been suggested. Saltasaurus is small compared to most other members of the Sauropoda. Powell estimated the adult length at six metres. In 2010, Gregory S. Paul estimated the maximum length at the weight at 2.5 tonnes. However, Donald Henderson in 2013 estimated the animal at 12.8 metres in length and 6.87 tonnes in weight.
The teeth of Saltasaurus were cylindrical, with spatulate points. Saltasaurus had a short neck with shortened neck vertebrae; the vertebrae from the middle part of its tail had elongated centra. Saltasaurus had vertebral lateral fossae, that resembled shallow depressions. Fossae that resemble shallow depressions are known from Malawisaurus, Alamosaurus and Gondwanatitan. Venenosaurus had depression-like fossae, but its pleurocoels penetrated deeper into the vertebrae, were divided into two chambers, extend farther into the vertebral columns. In Saltasaurus, the vertebral bone was cancellous and there were larger air chambers present as well; the limbs were short and stubby with short hands and feet. Saltasaurus had more robust radii than Venenosaurus; the belly was wide. The osteoderms came in two types. There were larger oval plates with a length of up to twelve centimetres; these were keeled or spiked and were ordered in longitudinal rows along the back. The second type consists of small ossicles, rounded or pentagonal, about seven millimetres in diameter, that formed a continuous armour between the plates.
A study in 2010 concluded that the larger plates had cancellous bone but that the ossicles had a denser bone tissue. Like all sauropods, Saltasaurus was herbivorous; because of its barrel-like rump, shaped like a hippopotamus, Powell suggested that Saltasaurus was aquatic. Despite its small stature, Saltasaurus was still graviportal like other sauropods, meaning it could not run because its hindlimbs had to be held straight at the load-bearing phase of their walking cycle. Powell assumed adult individuals were protected against predators by their body armour, while juveniles were protected by the herd as a whole. In the Cretaceous Period, sauropods in North America were no longer the dominant group of herbivorous dinosaurs, with the ornithopod and ceratopsian dinosaurs, such as Edmontosaurus and Triceratops, becoming the most abundant. However, on other landmasses such as South America and Africa sauropods, in particular the titanosaurs continued to be the dominant herbivores. Saltasaurus was one such titanosaur sauropod, lived around 70 million years ago.
When it was first discovered, in 1975, it forced palaeontologists to reconsider some assumptions about sauropods as Saltasaurus possessed crocodile-like armour 10 to 12 centimetres in diameter. It had been assumed that size alone was sufficient defence for the massive sauropods. Since palaeontologists have investigated the possibility that other sauropods may have had armour. A new discovery, from another formation, may shed light on the nesting habits of Saltasaurus. A large titanosaurid nesting ground was discovered in Patagonia, Argentina. Several hundred female saltasaurines dug holes with their back feet, laid eggs in clutches averaging around 25 eggs each, buried the nests under dirt and vegetation; the small eggs, about 11–12 cm in diameter, contained fossilised embryos, complete with skin impressions showing a mosaic armour of small bead-like scales. The armour pattern resembled that of Saltasaurus. Coria, R. A. and Chiappe, L. M. 2007. Embryonic Skin From Late Cretaceous Sauropods of Auca Mahuevo, Argent