The giant anteater known as the ant bear, is a large insectivorous mammal native to Central and South America. It is one of four living species of anteaters, the only extant member of the genus Myrmecophaga, is classified with sloths in the order Pilosa; this species is terrestrial, in contrast to other living anteaters and sloths, which are arboreal or semiarboreal. The giant anteater is the largest of its family, 182 to 217 cm in length, with weights of 33 to 41 kg for males and 27 to 39 kg for females, it is recognizable by its elongated snout, bushy tail, long fore claws, distinctively colored pelage. The giant anteater can be found including grassland and rainforest, it rests in more forested habitats. It feeds on ants and termites, using its fore claws to dig them up and its long, sticky tongue to collect them. Though giant anteaters live in overlapping home ranges, they are solitary except during mother-offspring relationships, aggressive interactions between males, when mating. Mother anteaters carry their offspring on their backs until weaning them.
The giant anteater is listed as Vulnerable by the International Union for Conservation of Nature. It has been extirpated from many parts including nearly all of Central America. Threats to its survival include habitat destruction and poaching for fur and bushmeat, although some anteaters inhabit protected areas. With its distinctive appearance and habits, the anteater has been featured in pre-Columbian myths and folktales, as well as modern popular culture; the giant anteater got its binomial name from Carl Linnaeus in 1758. Its generic name and specific name, are both Greek, meaning "anteater" and "three fingers", respectively. Myrmecophaga jubata was used as a synonym. Three subspecies have been tentatively proposed: M. t. tridactyla, M. t. centralis, M. t. artata. The giant anteater is grouped with the semiarboreal northern and southern tamanduas in the family Myrmecophagidae. Together with the family Cyclopedidae, whose only extant member is the arboreal silky anteater, the two families comprise the suborder Vermilingua.
Anteaters and sloths belong to order Pilosa and share superorder Xenarthra with the Cingulata. The two orders of Xenarthra split 66 million years ago during the Late Cretaceous epoch. Anteaters and sloths diverged between the Paleocene and Eocene epochs; the Cyclopes lineage emerged around 30 Mya in the Oligocene epoch, while the Myrmecophaga and Tamandua lineages split 10 Mya in the Late Miocene subepoch. During most of the Cenozoic era, anteaters were confined to South America, an island continent. Following the formation of the Isthmus of Panama about 3 Mya, anteaters of all three extant genera invaded Central America as part of the Great American Interchange; the fossil record for anteaters is sparse. Another member of the genus Myrmecophaga has been recovered from the Montehermosan Monte Hermoso Formation in Argentina and was described by Kraglievitch in 1934 as Nunezia caroloameghinoi, a preoccupied genus name by Nunezia Dyar 1928; the species was reclassified as Myrmecophaga caroloameghinoi by S. E. Hirschfeld in 1976.
Other known fossils include the Pliocene genus Palaeomyrmidon, a close relative to the silky anteater, the sister taxon to the clade that includes the giant anteater and the tamanduas from the Miocene, Neotamandua, a sister taxon to Myrmecophaga. Protamandua was larger than the silky anteater, but smaller than a tamandua, while Neotamandua was larger, falling somewhere between a tamandua and a giant anteater. Protamandua did not appear to have feet specialized for terrestrial or arboreal locomotion, but it may have had a prehensile tail. Neotamandua, though, is unlikely to have had a prehensile tail and its feet were intermediate in form between those of the tamanduas and the giant anteater; the species Neotamandua borealis was suggested to be an ancestor of the latter. The giant anteater is the most terrestrial of the living anteater species, its ancestors may have been adapted to arboreal life. Both the giant anteater and the southern tamandua are well represented in the fossil record of the late Pleistocene and early Holocene.
The giant anteater can be identified by its large size, elongated muzzle, long bushy tail. It has a total body length of 182 to 217 cm. Males weigh 33 to 41 kg and females weigh 27 to 39 kg, making the giant anteater the largest extant species in its suborder; the head of the giant anteater, at 30 cm long, is elongated when compared to other anteaters. Its tubular snout, which ends in its tiny mouth opening and nostrils, takes up most of its head, its eyes and ears are small. It has poor eyesight. Giant anteaters can live around 16 years in captivity. For an anteater, the neck is thick compared to the back of the head, a small hump can be found at the back of the neck; the coat is grey and salted with white. The forelimbs are white, with black bands around the wrists. Thick black bands with whit
Afrotheria is a clade of mammals, the living members of which belong to groups that are either living in Africa or of African origin: golden moles, elephant shrews, aardvarks, elephants, sea cows, several extinct clades. Most groups of afrotheres share little or no superficial resemblance, their similarities have only become known in recent times because of genetics and molecular studies. Many afrothere groups are found or in Africa, reflecting the fact that Africa was an island continent from the early Cenozoic until around 25 million years ago when the Tethys Sea shrank; because Africa was isolated by water, Laurasian groups of mammals such as insectivores, rabbits and large herbivores could not reach Africa for much of the early to mid Cenozoic. Instead, the niches occupied by those groups on the northern continents were filled by various groups of afrotheres via the process of convergent evolution; the small insectivorous afrotheres such as elephant shrews, golden moles, tenrecs filled the niches of insectivores, the hyraxes filled the roles of rodents and rabbits, the aardvarks filled the roles of various medium size ant-eating mammals found on other continents throughout the Cenozoic, proboscideans filled the roles of large herbivores such as hippos and rhinos.
The sirenians became aquatic and started spreading to other parts of the world by water, evolving convergently with the other groups of marine mammals. In addition to their similarity with Laurasian mammals in North America and Asia, many afrotheres exhibit convergent evolution with groups of mammals that evolved and lived in South America, an island continent for much of the Cenozoic; the common ancestry of these animals was not recognized until the late 1990s. The Paenungulata had been linked to other ungulates. Continuing work on the molecular and morphological diversity of afrotherian mammals has provided increasing support for their common ancestry; the afrotherian clade was proposed in 1998 based on analyses of DNA sequence data. However, previous studies had hinted at the close interrelationships among subsets of endemic African mammals; the core of the Afrotheria consists of the Paenungulata, i.e. elephants, sea cows, hyraxes, a group with a long history among comparative anatomists. Hence, while DNA sequence data have proven essential to infer the existence of the Afrotheria as a whole, while the Afroinsectiphilia were not recognized as part of Afrotheria without DNA data, some precedent is found in the comparative anatomical literature for the idea that at least part of this group forms a clade.
The Paleocene genus Ocepeia, the most completely-known Paleocene African mammal and the oldest afrotherian known from a complete skull, shares similarities with both Paenungulata and Afroinsectiphilia, may help to characterize the ancestral body type of afrotherians. Since the 1990s, increasing molecular and anatomical data have been applied to the classification of animals. Both types of data support the idea that afrotherian mammals are descended from a single common ancestor to the exclusion of other mammals. On the anatomical side, features shared by most, if not all, afrotheres include high vertebral counts, aspects of placental membrane formation, the shape of the ankle bones, the late eruption of the permanent dentition; the snout is unusually mobile in several Afrotherian species. Studies of genomic data, including millions of aligned nucleotides sampled for a growing number of placental mammals support Afrotheria as a clade. Additionally, there might be some dental synapomorphies uniting afroinsectiphilians, if not afrotheres as a whole: p4 talonid and trigonid of similar breadth, a prominent p4 hypoconid, presence of a P4 metacone and absence of parastyles on M1–2.
Afrotheria is now recognized as one of the three major groups within the Eutheria. Relations within the three cohorts, Xenarthra and the identity of the placental root, remain somewhat controversial. Afrotheria as a clade has been discussed without a Linnaean rank, but has been assigned the rank of cohort and superorder. One reconstruction, which applies the molecular clock, proposes that the oldest split occurred between Afrotheria and the other three some 105 million years ago in the mid-Cretaceous, when the African continent was separated from other major land masses; this idea is consistent with the fossil record of Xenarthra, restricted to South America. However, Afrotheria itself does not have a fossil record restricted to Africa, appears in fact to have evolved in the continent's isolation. More recent, genomic-scale phylogenies favor the hypothesis that Afrotheria and Xenarthra comprise sister taxa at the base of the placental mammal radiation, suggesting an ancient Gondwanan clade of placental mammalsRelations between the various afrotherian orders are still being studied.
On the basis of molecular studies and manatees appear to be related, elephant shrews and aardvarks. These findings are compatible with the work of earlier anatomists. Many extant members of Afrotheria appe
Xenarthra (Latin, from Ancient Greek ξένος + ἄρθρον is a superorder of placental mammals found in the Americas. It consists of anteaters, tree sloths, armadillos. Xenarthrans originated in South America during the Paleocene about 59 million years ago, they evolved and diversified extensively in South America during the continent's long period of isolation in the early to mid Cenozoic Era. They spread to the Antilles by the early Miocene and, starting about 3 Mya, spread to Central and North America as part of the Great American Interchange. Nearly all of the abundant megafaunal xenarthrans, such as ground sloths and pampatheres, became extinct at the end of the Pleistocene. Xenarthrans share several characteristics not present in other placental mammals, are considered to be among the most primitive order of placental mammals; the name Xenarthra, which means "strange joints", was chosen because their vertebral joints have extra articulations unlike other mammals. This trait is referred to as "xenarthry".
Unlike other mammals, the ischium and sacrum are fused. The males have internal testicles, which are located between the rectum. Xenarthrans have been determined to have single-color vision. Furthermore, xenarthrans have the lowest metabolic rates among the therians, they seem to lack a functional pineal gland. Xenarthrans were classified alongside the pangolins and aardvarks in the order Edentata. Subsequently, Edentata was found to be a polyphyletic grouping whose New World and Old World taxa are unrelated, it was split up to reflect their true phylogeny. Aardvarks and pangolins are now placed in individual orders, the new order Xenarthra was erected to group the remaining families; the name Xenarthra means "strange joints", was chosen because their vertebral joints have extra articulations and are unlike those of any other mammals. The morphology of xenarthrans suggests that the anteaters and sloths are more related to each other than either is to the armadillos. Since its conception, Xenarthra has come to be considered to be of a higher rank than'order'.
Whatever the rank, Xenarthra is now considered to be divided into two orders: Cingulata, which contains the armadillos. Xenarthra may be most related to either Afrotheria, Boreoeutheria, or Epitheria. In other words, it may be nested within Eutheria or it may be the basal extant group. A comprehensive phylogeny by Goloboff et al. includes xenarthrans as a sister clade of Euarchontoglires within Boreoeutheria. Below is a recent simplified phylogeny of the xenarthran families based on Slater et al. and Delsuc et al.. The dagger symbol, "†", denotes extinct groups. XENARTHRA Order Cingulata Family Chlamyphoridae: armadillos and glyptodonts Greater fairy armadillo, Calyptophractus retusus Pink fairy armadillo, Chlamyphorus truncatus Northern naked-tailed armadillo, Cabassous centralis Chacoan naked-tailed armadillo, Cabassous chacoensis Southern naked-tailed armadillo, Cabassous unicinctus Greater naked-tailed armadillo, Cabassous tatouay Screaming hairy armadillo, Chaetophractus vellerosus Big hairy armadillo, Chaetophractus villosus Andean hairy armadillo, Chaetophractus nationi Six-banded armadillo or yellow armadillo, Euphractus sexcinctus Giant armadillo, Priodontes maximus Southern three-banded armadillo, Tolypeutes matacus Brazilian three-banded armadillo, Tolypeutes tricinctus Pichi or dwarf armadillo, Zaedyus pichiy Subfamily †Glyptodontinae: glyptodonts Family Dasypodidae: long-nosed armadillos Nine-banded armadillo or long-nosed armadillo, Dasypus novemcinctus Seven-banded armadillo, Dasypus septemcinctus Southern long-nosed armadillo, Dasypus hybridus Llanos long-nosed armadillo, Dasypus sabanicola Great long-nosed armadillo, Dasypus kappleri Hairy long-nosed armadillo, Dasypus pilosus Yepes's mulita, Dasypus yepesi Family †Pampatheriidae: pampatheres Order Pilosa Suborder Folivora: sloths Family Bradypodidae: three-toed sloths Pygmy three-toed sloth, Bradypus pygmaeus Brown-throated three-toed sloth, Bradypus variegatus Pale-throated three-toed sloth, Bradypus tridactylus Maned three-toed sloth, Bradypus torquatus Family Megalonychidae: two-toed sloths and extinct megalonychid ground sloths Hoffman's two-toed sloth, Choloepus hoffmanni Linnaeus's two-toed sloth or southern two-toed sloth, Choloepus didactylus Family †Megatheriidae: megatheriid ground sloths Family †Mylodontidae: mylodontid ground sloths Family †Nothrotheriidae: nothrotheriid ground sloths and aquatic sloths Suborder Vermilingua: anteaters Family Cyclopedidae: silky anteaters Silky anteater, Cyclopes didactylus Family Myrmecophagidae: anteaters Giant anteater, Myrmecophaga tridactyla Northern tamandua, Tamandua mexicana Southern tamandua, Tamandua tetradactyla Xenarthrans share several characteristics not present in other placental mammals, are considered to be among the most primitive order of placental mammals.
The name Xenarthra, which means "strange joints", was chosen because their vertebral joints have extra articulations unlike other mammals. This trait is referred to as "xenarthry". Unlike other mammals, the ischium and sacrum are fused; the males have internal testicles, which are located between the bladder and the rectum
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
In cladistics, a monophyletic group, or clade, is a group of organisms that consists of all the descendants of a common ancestor. Monophyletic groups are characterised by shared derived characteristics, which distinguish organisms in the clade from other organisms; the arrangement of the members of a monophyletic group is called a monophyly. Monophyly is contrasted with polyphyly as shown in the second diagram. A paraphyletic group consists of all of the descendants of a common ancestor minus one or more monophyletic groups. A polyphyletic group is characterized by convergent habits of scientific interest; the features by which a polyphyletic group is differentiated from others are not inherited from a common ancestor. These definitions have taken some time to be accepted; when the cladistics school of thought became mainstream in the 1960s, several alternative definitions were in use. Indeed, taxonomists sometimes used terms without defining them, leading to confusion in the early literature, a confusion which persists.
The first diagram shows a phylogenetic tree with two monophyletic groups. The several groups and subgroups are situated as branches of the tree to indicate ordered lineal relationships between all the organisms shown. Further, any group may be considered a taxon by modern systematics, depending upon the selection of its members in relation to their common ancestor; the term monophyly, or monophyletic, derives from the two Ancient Greek words μόνος, meaning "alone, unique", φῦλον, meaning "genus, species", refers to the fact that a monophyletic group includes organisms consisting of all the descendants of a unique common ancestor. Conversely, the term polyphyly, or polyphyletic, builds on the ancient greek prefix πολύς, meaning "many, a lot of", refers to the fact that a polyphyletic group includes organisms arising from multiple ancestral sources. By comparison, the term paraphyly, or paraphyletic, uses the ancient greek prefix παρά, meaning "beside, near", refers to the situation in which one or several monophyletic subgroups are left apart from all other descendants of a unique common ancestor.
That is, a paraphyletic group is nearly monophyletic, hence the prefix pará. On the broadest scale, definitions fall into two groups. Willi Hennig defined monophyly as groups based on synapomorphy; some authors have sought to define monophyly to include paraphyly as any two or more groups sharing a common ancestor. However, this broader definition encompasses both monophyletic and paraphyletic groups as defined above. Therefore, most scientists today restrict the term "monophyletic" to refer to groups consisting of all the descendants of one common ancestor. However, when considering taxonomic groups such as genera and species, the most appropriate nature of their common ancestor is unclear. Assuming that it would be one individual or mating pair is unrealistic for sexually reproducing species, which are by definition interbreeding populations. Monophyly and associated terms are restricted to discussions of taxa, are not accurate when used to describe what Hennig called tokogenetic relationships—now referred to as genealogies.
Some argue that using a broader definition, such as a species and all its descendants, does not work to define a genus. The loose definition fails to recognize the relations of all organisms. According to D. M. Stamos, a satisfactory cladistic definition of a species or genus is impossible because many species may form by "budding" from an existing species, leaving the parent species paraphyletic. Clade Crown group Glossary of scientific naming Monotypic taxon Paraphyly Polyphyly Abbey, Darren. "Graphical explanation of basic phylogenetic terms". University of California, Berkeley. Retrieved 15 January 2010. Carr, Steven M.. "Concepts of monophyly, polyphyly & paraphyly". Memorial University. Retrieved 15 January 2010. Hyvönen, Jaako. "Monophyly, compromise". University of Helsinki. Retrieved 15 January 2010
The Cyclopedidae is a family of anteaters that includes the silky anteater and its extinct relative, Palaeomyrmidon