57-511: Taeniolabidoidea is a group of extinct mammals known whose fossils can be found in North America and Asia . They were the largest members of the extinct order Multituberculata , as well as the largest non-therian mammals. Lambdopsalis even provides direct fossil evidence of mammalian fur in a fairly good state of preservation for a 60-million-year-old animal. Some of these animals were large for their time; Taeniolabis taoensis
114-576: A similar aquatic lifestyle. Hippopotamuses appeared in the late Miocene and occupied Africa and Asia—they never got to the Americas. The camels ( Tylopoda ) were, during large parts of the Cenozoic , limited to North America; early forms like Cainotheriidae occupied Europe. Among the North American camels were groups like the stocky, short-legged Merycoidodontidae . They first appeared in
171-477: A simple stomach that digests food. Thus, they were grouped together as non-ruminants (Porcine). All other even-toed ungulates have molars with a selenodont construction (crescent-shaped cusps) and have the ability to ruminate , which requires regurgitating food and re-chewing it. Differences in stomach construction indicated that rumination evolved independently between tylopods and ruminants ; therefore, tylopods were excluded from Ruminantia . The taxonomy that
228-474: A slim build, lanky legs, and a long tail. Their hind legs were much longer than their front legs. The early to middle Eocene saw the emergence of the ancestors of most of today's mammals. Two formerly widespread, but now extinct, families of even-toed ungulates were Entelodontidae and Anthracotheriidae . Entelodonts existed from the middle Eocene to the early Miocene in Eurasia and North America. They had
285-473: A stocky body with short legs and a massive head, which was characterized by two humps on the lower jaw bone. Anthracotheres had a large, porcine ( pig -like) build, with short legs and an elongated muzzle . This group appeared in the middle Eocene up until the Pliocene , and spread throughout Eurasia, Africa, and North America. Anthracotheres are thought to be the ancestors of hippos, and, likewise, probably led
342-424: A very flexible body, contributing to their speed by increasing their stride length. Many even-toed ungulates have a relatively large head. The skull is elongated and rather narrow; the frontal bone is enlarged near the back and displaces the parietal bone , which forms only part of the side of the cranium (especially in ruminants). Four families of even-toed ungulates have cranial appendages. These Pecora (with
399-475: Is more adapted to a squeezing mastication , which is characteristic of omnivores . Camels and ruminants have fewer teeth; there is often a yawning diastema , a designated gap in the teeth where the molars are aligned for crushing plant matter. The incisors are often reduced in ruminants, and are completely absent in the upper jaw . The canines are enlarged and tusk-like in the Suina, and are used for digging in
456-572: Is primarily driven by human poaching and habitat destruction , primarily deforestation . Over 70% of mammal species are in the orders Rodentia , Chiroptera , and Eulipotyphla . Mammal classification has been through several revisions since Carl Linnaeus initially defined the class, and at present , no classification system is universally accepted. McKenna & Bell (1997) and Wilson & Reeder (2005) provide useful recent compendiums. Simpson (1945) provides systematics of mammal origins and relationships that had been taught universally until
513-426: Is the viviparous placental mammals , so named for the temporary organ ( placenta ) used by offspring to draw nutrition from the mother during gestation . Most mammals are intelligent , with some possessing large brains, self-awareness , and tool use . Mammals can communicate and vocalize in several ways, including the production of ultrasound , scent marking , alarm signals , singing , echolocation ; and, in
570-460: Is the largest known multituberculate and though smaller, Yubaatar is the largest known Mesozoic Asian multituberculate. T. taoensis averaged a body mass of 22.7 kilograms (50 lb). The group was initially established as a suborder , before being assigned the rank of a superfamily by McKenna and Bell in 1997. Two families are recognised: the primarily North American Taeniolabididae , composed of Taeniolabis and Kimbetopsalis , and
627-708: Is therefore focused on anthracotheres (family Anthracotheriidae); one dating from the Eocene to Miocene was declared to be "hippo-like" upon discovery in the 19th century. A study from 2005 showed that the anthracotheres and hippopotamuses had very similar skulls , but differed in the adaptations of their teeth. It was nevertheless believed that cetaceans and anthracothereres descended from a common ancestor, and that hippopotamuses developed from anthracotheres. A study published in 2015 confirmed this, but also revealed that hippopotamuses were derived from older anthracotherians. The newly introduced genus Epirigenys from Eastern Africa
SECTION 10
#1732766098200684-525: Is thus the sister group of hippos. Linnaeus postulated a close relationship between camels and ruminants as early as the mid-1700s. Henri de Blainville recognized the similar anatomy of the limbs of pigs and hippos, and British zoologist Richard Owen coined the term "even-toed ungulates" and the scientific name "Artiodactyla" in 1848. Internal morphology (mainly the stomach and the molars) were used for classification. Suines (including pigs ) and hippopotamuses have molars with well-developed roots and
741-473: The Cretaceous . The relationships between these three lineages is contentious, and all three possible hypotheses have been proposed with respect to which group is basal . These hypotheses are Atlantogenata (basal Boreoeutheria), Epitheria (basal Xenarthra) and Exafroplacentalia (basal Afrotheria). Boreoeutheria in turn contains two major lineages— Euarchontoglires and Laurasiatheria . Estimates for
798-564: The International Union for Conservation of Nature (IUCN) completed a five-year Global Mammal Assessment for its IUCN Red List , which counted 5,488 species. According to research published in the Journal of Mammalogy in 2018, the number of recognized mammal species is 6,495, including 96 recently extinct. The word " mammal " is modern, from the scientific name Mammalia coined by Carl Linnaeus in 1758, derived from
855-556: The Latin mamma ("teat, pap"). In an influential 1988 paper, Timothy Rowe defined Mammalia phylogenetically as the crown group of mammals, the clade consisting of the most recent common ancestor of living monotremes ( echidnas and platypuses ) and therian mammals ( marsupials and placentals ) and all descendants of that ancestor. Since this ancestor lived in the Jurassic period, Rowe's definition excludes all animals from
912-694: The Old World , exist today only in the Americas . South America was settled by even-toed ungulates only in the Pliocene, after the land bridge at the Isthmus of Panama formed some three million years ago. With only the peccaries, lamoids (or llamas ), and various species of capreoline deer , South America has comparatively fewer artiodactyl families than other continents, except Australia, which has no native species. The classification of artiodactyls
969-606: The biological classification scheme used, are the primates : apes , monkeys , and lemurs ; the Cetartiodactyla : whales and even-toed ungulates ; and the Carnivora which includes cats , dogs , weasels , bears , seals , and allies. According to Mammal Species of the World , 5,416 species were identified in 2006. These were grouped into 1,229 genera , 153 families and 29 orders. In 2008,
1026-406: The dominant terrestrial animal group from 66 million years ago to the present. The basic mammalian body type is quadrupedal , with most mammals using four limbs for terrestrial locomotion ; but in some, the limbs are adapted for life at sea , in the air , in trees or underground . The bipeds have adapted to move using only the two lower limbs, while the rear limbs of cetaceans and
1083-507: The hind legs have a reduction in the number of toes to three. The central axis of the leg is between the third and fourth toe. The first toe is missing in modern artiodactyls, and can only be found in now-extinct genera. The second and fifth toes are adapted differently between species: When camels have only two toes present, the claws are transformed into nails (while both are made of keratin , claws are curved and pointed while nails are flat and dull). These claws consist of three parts:
1140-537: The order Artiodactyla ( / ˌ ɑːr t i oʊ ˈ d æ k t ɪ l ə / AR -tee-oh- DAK -tih-lə , from Ancient Greek ἄρτιος , ártios 'even' and δάκτυλος , dáktylos 'finger, toe'). Typically, they are ungulates which bear weight equally on two (an even number) of their five toes (the third and fourth, often in the form of a hoof ). The other three toes are either present, absent, vestigial , or pointing posteriorly. By contrast, most perissodactyls bear weight on an odd number of
1197-428: The rodents , bats , and Eulipotyphla (including hedgehogs , moles and shrews ). The next three are the primates (including humans , monkeys and lemurs ), the even-toed ungulates (including pigs , camels , and whales ), and the Carnivora (including cats , dogs , and seals ). Mammals are the only living members of Synapsida ; this clade , together with Sauropsida (reptiles and birds), constitutes
SECTION 20
#17327660982001254-412: The ruminants as the sister group of cetaceans. Subsequent studies established the close relationship between hippopotamuses and cetaceans; these studies were based on casein genes , SINEs , fibrinogen sequences, cytochrome and rRNA sequences, IRBP (and vWF ) gene sequences, adrenergic receptors , and apolipoproteins . In 2001, the fossil limbs of a Pakicetus (amphibioid cetacean
1311-439: The sea cows are mere internal vestiges . Mammals range in size from the 30–40 millimetres (1.2–1.6 in) bumblebee bat to the 30 metres (98 ft) blue whale —possibly the largest animal to have ever lived. Maximum lifespan varies from two years for the shrew to 211 years for the bowhead whale . All modern mammals give birth to live young, except the five species of monotremes , which lay eggs. The most species-rich group
1368-490: The taxon (apomorphies) include: "snout short and wide with anterior part of zygomatic arches directed transversely, resulting in a square-like shape of the skull (shared with Kogaionidae ); frontals small, pointed posteriorly, almost or completely excluded from the orbital rim". Mammals A mammal (from Latin mamma 'breast') is a vertebrate animal of the class Mammalia ( / m ə ˈ m eɪ l i . ə / ). Mammals are characterized by
1425-492: The case of humans, complex language . Mammals can organize themselves into fission–fusion societies , harems , and hierarchies —but can also be solitary and territorial . Most mammals are polygynous , but some can be monogamous or polyandrous . Domestication of many types of mammals by humans played a major role in the Neolithic Revolution , and resulted in farming replacing hunting and gathering as
1482-469: The clade is otherwise only clearly represented in Paleocene strata . Members of this group have dental formulas of 2.0.1.2 1.0.1.2 or 2.0.2.2 1.0.1.2 . Russell notes that the taeniolabidoids had ever-growing, self-sharpening incisors, much like modern rodents , and the premolars that are usually characteristic of multituberculates are sometimes lost in this family. Derived characteristics of
1539-812: The clade originating with the last common ancestor of Sinoconodon and living mammals. The earliest-known synapsid satisfying Kemp's definitions is Tikitherium , dated 225 Ma , so the appearance of mammals in this broader sense can be given this Late Triassic date. However, this animal may have actually evolved during the Neogene. As of the early 21st century, molecular studies based on DNA analysis have suggested new relationships among mammal families. Most of these findings have been independently validated by retrotransposon presence/absence data . Classification systems based on molecular studies reveal three major groups or lineages of placental mammals— Afrotheria , Xenarthra and Boreoeutheria —which diverged in
1596-444: The closest thing to an official classification of mammals, despite its known issues. Most mammals, including the six most species-rich orders , belong to the placental group. The three largest orders in numbers of species are Rodentia : mice , rats , porcupines , beavers , capybaras , and other gnawing mammals; Chiroptera : bats; and Eulipotyphla : shrews , moles , and solenodons . The next three biggest orders, depending on
1653-1397: The divergence times between these three placental groups range from 105 to 120 million years ago, depending on the type of DNA used (such as nuclear or mitochondrial ) and varying interpretations of paleogeographic data. Monotremata Marsupialia Xenarthra Afrotheria Glires Euarchonta [REDACTED] Eulipotyphla Chiroptera Pholidota Carnivora [REDACTED] Perissodactyla [REDACTED] Artiodactyla [REDACTED] Monotremata [REDACTED] Paucituberculata [REDACTED] Didelphimorphia [REDACTED] Microbiotheria Notoryctemorphia [REDACTED] Peramelemorphia [REDACTED] Dasyuromorphia [REDACTED] Diprotodontia [REDACTED] Cingulata [REDACTED] Pilosa [REDACTED] Hyracoidea [REDACTED] Sirenia [REDACTED] Proboscidea [REDACTED] Tubulidentata [REDACTED] Macroscelidea [REDACTED] Afrosoricida [REDACTED] Eulipotyphla [REDACTED] Chiroptera [REDACTED] Pholidota [REDACTED] Carnivora [REDACTED] Perissodactyla [REDACTED] Artiodactyla [REDACTED] Scandentia [REDACTED] Lagomorpha [REDACTED] Artiodactyl Cetartiodactyla Montgelard et al. 1997 Artiodactyls are placental mammals belonging to
1710-585: The earlier Triassic , despite the fact that Triassic fossils in the Haramiyida have been referred to the Mammalia since the mid-19th century. If Mammalia is considered as the crown group, its origin can be roughly dated as the first known appearance of animals more closely related to some extant mammals than to others. Ambondro is more closely related to monotremes than to therian mammals while Amphilestes and Amphitherium are more closely related to
1767-462: The early Eocene (about 53 million years ago). Since these findings almost simultaneously appeared in Europe , Asia , and North America , it is very difficult to accurately determine the origin of artiodactyls. The fossils are classified as belonging to the family Diacodexeidae ; their best-known and best-preserved member is Diacodexis . These were small animals, some as small as a hare , with
Taeniolabidoidea - Misplaced Pages Continue
1824-609: The early Cenozoic ( Paleocene and Eocene ), which had hooves instead of claws on their feet. Their molars were adapted to a carnivorous diet, resembling the teeth in modern toothed whales , and, unlike other mammals, had a uniform construction. The suspected relations can be shown as follows: Artiodactyla [REDACTED] Mesonychia † [REDACTED] Cetacea [REDACTED] Molecular findings and morphological indications suggest that artiodactyls, as traditionally defined, are paraphyletic with respect to cetaceans. Cetaceans are deeply nested within
1881-451: The end of the 20th century. However, since 1945, a large amount of new and more detailed information has gradually been found: The paleontological record has been recalibrated, and the intervening years have seen much debate and progress concerning the theoretical underpinnings of systematization itself, partly through the new concept of cladistics . Though fieldwork and lab work progressively outdated Simpson's classification, it remains
1938-419: The exception of the musk deer ), have one of four types of cranial appendages: true horns, antlers , ossicones , or pronghorns . True horns have a bone core that is covered in a permanent sheath of keratin, and are found only in the bovids . Antlers are bony structures that are shed and replaced each year; they are found in deer (members of the family Cervidae ). They grow from a permanent outgrowth of
1995-555: The exclusively Asian Lambdopsalidae , composed of Lambdopsalis , Sphenopsalis and Prionessus , with Valenopsalis being a basal form outside of either clade. Some of the fossils are well-preserved. Though the possible taeniolabidoid Bubodens is known from the Lancian Late Cretaceous deposits of South Dakota , and Yubaatar is known from Late Cretaceous deposits in the Henan Province ,
2052-456: The five toes. Another difference between the two orders is that many artiodactyls (except for Suina ) digest plant cellulose in one or more stomach chambers rather than in their intestine (as perissodactyls do). Molecular biology, along with new fossil discoveries, has found that cetaceans ( whales , dolphins , and porpoises ) fall within this taxonomic branch, being most closely related to hippopotamuses . Some modern taxonomists thus apply
2109-1021: The former; the two groups together form a monophyletic taxon, for which the name Cetartiodactyla is sometimes used. Modern nomenclature divides Artiodactyla (or Cetartiodactyla) in four subordinate taxa: camelids (Tylopoda), pigs and peccaries (Suina), ruminants (Ruminantia), and hippos plus cetaceans (Whippomorpha). The presumed lineages within Artiodactyla can be represented in the following cladogram : Tylopoda (camels) [REDACTED] Suina (pigs) [REDACTED] Tragulidae (mouse deer) [REDACTED] Pecora (horn bearers) [REDACTED] Hippopotamidae (hippopotamuses) [REDACTED] Cetacea (whales) [REDACTED] The four summarized Artiodactyla taxa are divided into ten extant families: Although deer, musk deer, and pronghorns have traditionally been summarized as cervids (Cervioidea), molecular studies provide different—and inconsistent—results, so
2166-674: The frontal bone called the pedicle and can be branched, as in the white-tailed deer ( Odocoileus virginianus ), or palmate , as in the moose ( Alces alces ). Ossicones are permanent bone structures that fuse to the frontal or parietal bones during an animal's life and are found only in the Giraffidae . Pronghorns , while similar to horns in that they have keratinous sheaths covering permanent bone cores, are deciduous. All these cranial appendages can serve for posturing, battling for mating privilege, and for defense. In almost all cases, they are sexually dimorphic, and are often found only on
2223-401: The ground and for defense. In ruminants, the males' upper canines are enlarged and used as a weapon in certain species (mouse deer, musk deer, water deer ); species with frontal weapons are usually missing the upper canines. The lower canines of ruminants resemble the incisors, so that these animals have eight uniform teeth in the frontal part of the lower jaw . The molars of porcine have only
2280-613: The larger Amniota clade. Early synapsids are referred to as " pelycosaurs ." The more advanced therapsids became dominant during the Guadalupian . Mammals originated from cynodonts , an advanced group of therapsids, during the Late Triassic to Early Jurassic . Mammals achieved their modern diversity in the Paleogene and Neogene periods of the Cenozoic era, after the extinction of non-avian dinosaurs , and have been
2337-601: The late Eocene and developed a great diversity of species in North America. Only in the late Miocene or early Pliocene did they migrate from North America into Eurasia. The North American varieties became extinct around 10,000 years ago. Suina (including pigs ) have been around since the Eocene. In the late Eocene or the Oligocene , two families stayed in Eurasia and Africa; the peccaries , which became extinct in
Taeniolabidoidea - Misplaced Pages Continue
2394-407: The limbs are predominantly localized, which ensures that artiodactyls often have very slender legs. A clavicle is never present, and the scapula is very agile and swings back and forth for added mobility when running. The special construction of the legs causes the legs to be unable to rotate, which allows for greater stability when running at high speeds. In addition, many smaller artiodactyls have
2451-634: The males are consistently larger and heavier than the females. In deer, only the males boast antlers, and the horns of bovines are usually small or not present in females. Male Indian antelopes have a much darker coat than females. Almost all even-toed ungulates have fur, with the exception being the nearly hairless hippopotamus. Fur varies in length and coloration depending on the habitat. Species in cooler regions can shed their coat. Camouflaged coats come in colors of yellow, gray, brown, or black tones. Even-toed ungulates bear their name because they have an even number of toes (two or four)—in some peccaries,
2508-463: The males. One exception is the species Rangifer tarandus , known as reindeer in Europe or caribou in North America, where both sexes can grow antlers yearly, though the females' antlers are typically smaller and not always present. There are two trends in terms of teeth within Artiodactyla. The Suina and hippopotamuses have a relatively large number of teeth (with some pigs having 44); their dentition
2565-421: The mouse deer, often reaches a body length of only 45 centimeters (18 in) and a weight of 1.5 kilograms (3.3 lb). The largest member, the hippopotamus, can grow up to 5 meters (16 ft) in length and weigh 4.5 metric tons (5 short tons), and the giraffe can grow to be 5.5 meters (18 ft) tall and 4.7 meters (15 ft) in body length. All even-toed ungulates display some form of sexual dimorphism :
2622-948: The name Cetartiodactyla ( / s ɪ ˌ t ɑːr t i oʊ ˈ d æ k t ɪ l ə / ) to this group, while others opt to include cetaceans within the existing name of Artiodactyla. Some researchers use " even-toed ungulates " to exclude cetaceans and only include terrestrial artiodactyls, making the term paraphyletic in nature. The roughly 270 land-based even-toed ungulate species include pigs , peccaries , hippopotamuses , antelopes , deer , giraffes , camels , llamas , alpacas , sheep , goats and cattle . Many are herbivores, but suids are omnivorous, whereas cetaceans are entirely carnivorous. Artiodactyls are also known by many extinct groups such as anoplotheres , cainotheriids , merycoidodonts , entelodonts , anthracotheres , basilosaurids , and palaeomerycids . Many artiodactyls are of great dietary, economic, and cultural importance to humans. The oldest fossils of even-toed ungulates date back to
2679-442: The plate (top and sides), the sole (bottom), and the bale (rear). In general, the claws of the forelegs are wider and blunter than those of the hind legs, and they are farther apart. Aside from camels, all even-toed ungulates put just the tip of the foremost phalanx on the ground. In even-toed ungulates, the bones of the stylopodium (upper arm or thigh bone) and zygopodiums (tibia and fibula) are usually elongated. The muscles of
2736-555: The presence of milk -producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair , and three middle ear bones . These characteristics distinguish them from reptiles and birds , from which their ancestors diverged in the Carboniferous Period over 300 million years ago. Around 6,400 extant species of mammals have been described and divided into 27 orders . The largest orders of mammals, by number of species , are
2793-716: The primary source of food for humans. This led to a major restructuring of human societies from nomadic to sedentary, with more co-operation among larger and larger groups, and ultimately the development of the first civilizations . Domesticated mammals provided, and continue to provide, power for transport and agriculture, as well as food ( meat and dairy products ), fur , and leather . Mammals are also hunted and raced for sport, kept as pets and working animals of various types, and are used as model organisms in science. Mammals have been depicted in art since Paleolithic times, and appear in literature, film, mythology, and religion. Decline in numbers and extinction of many mammals
2850-413: The question of phylogenetic systematics of infraorder Pecora (the horned ruminants) for the time being, cannot be answered. Artiodactyls are generally quadrupeds . Two major body types are known: suinids and hippopotamuses are characterized by a stocky body, short legs, and a large head; camels and ruminants, though, have a more slender build and lanky legs. Size varies considerably; the smallest member,
2907-472: The sequence with that of other living beings—the more similar they are, the more closely they are related. Comparison of even-toed ungulate and cetaceans genetic material has shown that the closest living relatives of whales and hippopotamuses is the paraphyletic group Artiodactyla. Dan Graur and Desmond Higgins were among the first to come to this conclusion, and included a paper published in 1994. However, they did not recognize hippopotamuses and classified
SECTION 50
#17327660982002964-668: The size of a wolf) and Ichthyolestes (an early whale the size of a fox) were found in Pakistan. They were both archaeocetes ("ancient whales") from about 48 million years ago (in the Eocene). These findings showed that archaeocetes were more terrestrial than previously thought, and that the special construction of the talus (ankle bone) with a double-rolled joint surface, previously thought to be unique to even-toed ungulates, were also in early cetaceans. The mesonychians , another type of ungulate, did not show this special construction of
3021-521: The talus, and thus was concluded to not have the same ancestors as cetaceans. The oldest cetaceans date back to the early Eocene (53 million years ago), whereas the oldest known hippopotamus dates back only to the Miocene (15 million years ago). The hippopotamids are descended from the anthracotheres, a family of semiaquatic and terrestrial artiodactyls that appeared in the late Eocene, and are thought to have resembled small- or narrow-headed hippos. Research
3078-548: The therians; as fossils of all three genera are dated about 167 million years ago in the Middle Jurassic , this is a reasonable estimate for the appearance of the crown group. T. S. Kemp has provided a more traditional definition: " Synapsids that possess a dentary – squamosal jaw articulation and occlusion between upper and lower molars with a transverse component to the movement" or, equivalently in Kemp's view,
3135-479: The traditional order Artiodactyla and infraorder Cetacea are sometimes subsumed into the more inclusive Cetartiodactyla taxon. An alternative approach is to include both land-dwelling even-toed ungulates and ocean-dwelling cetaceans in a revised Artiodactyla taxon. In the 1990s, biological systematics used not only morphology and fossils to classify organisms, but also molecular biology . Molecular biology involves sequencing an organism's DNA and RNA and comparing
3192-426: Was hotly debated because ocean-dwelling cetaceans evolved from land-dwelling even-toed ungulates. Some semiaquatic even-toed ungulates ( hippopotamuses ) are more closely related to ocean-dwelling cetaceans than to other even-toed ungulates. Phylogenetic classification only recognizes monophyletic taxa; that is, groups that descend from a common ancestor and include all of its descendants. To address this problem,
3249-621: Was widely accepted by the end of the 20th century was: Suidae [REDACTED] Hippopotamidae [REDACTED] Tylopoda [REDACTED] Tragulidae [REDACTED] Pecora [REDACTED] Modern cetaceans are highly adapted sea creatures which, morphologically, have little in common with land mammals; they are similar to other marine mammals , such as seals and sea cows , due to convergent evolution . However, they evolved from originally terrestrial mammals. The most likely ancestors were long thought to be mesonychians—large, carnivorous animals from
#199800