Large ground birds like ostriches are fast runners. Animals can be classified by their mode of locomotion. Their legs also include metatarsals or metacarpals which are similar to the bones that form the arch of the foot and the palm in humans.
The foot posture is positioned in a way that the heel plays a part in supporting the body weight when walking, running or standing. Centigrade animals include humans while unguligrades consist of horses, donkeys, and cattle.
Examples of semi- digitigrade include elephants, Barbara, pigs, and hippos in that they walk, stand, or run with an elevated heel that does not come into contact with the substrate. The cat tribe has the intermediate form because their three lower tiers of the feet rest on the ground as they run, stand, or jump.
Large ground birds such as ostriches can use their kick to lethal effect for primary defense. Bipedal Digitigrades, however, are not very stable, and it is easier to knock them over compared to plantigrades and unguligrades.
This is due to the smaller surface area in touch with the ground, and they have a lower load bearing capacity for this reason. Add: Legs, Feet, and Curatorial Locomotion The and each consist of a series of bones, meeting the trunk of the body at the pectoral (forelimb) or pelvic (hind limb) girdle.
The pectoral girdle of most mammals consists of a shoulder blade (scapula) and in many, a clavicle. Honorees are an exception; their pectoral girdles include several of these primitive elements.
The clavicle, if it is present, runs from the region of the articulation between scapula and forelimb to the anterior part of the sternum. The pelvic girdle of mammals is made up of three bones, the ilium, schism, and pubis.
The forelimb itself consists of a humerus (which meets the scapula), paired radius and ulna, a set of carpals and metacarpals, and (primitively) five digits, each made up of several phalanges. The bones of the hind limb are the femur (articulates with the acetabulum of the pelvis), the tibia and fibula, the tarsals and metatarsals, and (primitively) five digits, each made up of 2 or more several phalanges.
Tarsal and carpal bones are referred to collectively as pedals, and metacarpals and metatarsals are metapodials. The calcaneus is a large tarsal bone that extends behind the ankle, forming the heel.
It provides an important lever arm for muscles that move the hind foot. The straggles is another important bone of the tarsus; it lies between calcaneus and tibia.
These structures are derived from the skin and are composed of the protein keratin, not bone. Claws are composed of a dorsal plate, called the fungus, and a ventral subunit.
A nail is similarly constructed except that the fungus is more or less flat, not folding over the subunit. Hooves are also derived from claws; in a hoof, the fungus completely surrounds the subunit, which remains exposed only at the tip of the digit.
Censorial animals are climbers; in the extreme, they are arboreal, spending most of their lives in the trees. A full cycle of motion of a running or walking mammal is called a stride.
Others move rapidly by having a very fast stride rate; these would include, for example, shrews and voles. Species are those that place the full length of their foot, including pedals and metapodials, on the ground during each stride.
Species walk with most of the length of their digits, but not the soles of their feet, in contact with the ground. A second way of increasing stride length, often found in unguligrade species, is to lengthen limb elements.
Among perissodactyls, rhinos and tapirs have three or four toes, but the center one (3) is enlarged and bears much of the weight (a condition termed metabolic). In horses, the 3rd metaphorical is very long, similar in length to the other main limb elements.
The other toes are lost or reduced to the point of being slivers of bones that fuse with the 3rd. Among the much more diverse artiodactyls, pigs, peccaries and hippos have moderately long metapodials, which are unused.
In camels, the third and fourth metapodials are very long and fused for most of their length, although the distal ends remain separate. Fusion is complete in bodies and corvids, and the resulting bone is called a . Other digits are much reduced or lost.
The second and third digits are fused for most of their length (syndactylous), except the claws, which remain separate and are used for grooming. In these species, the 3 central metatarsals are not only elongated but fused, forming a distinctive cannon bone.
Yet another means of lengthening the stride is to increase the distance traveled by the animal when its feet are off of the ground. This is determined by the animal's gait, or the sequence and manner by which it moves its feet when running.
Weakly curatorial animals generally keep at least one foot on the ground most of the time; highly developed cursors have extended unsupported periods; and the feet of ricochet animals may be off the ground for more than half of the stride (85% for the springs, Predates ! Hildebrand's (1974) excellent and thorough discussion of the biomechanics of motion by mammals should be consulted for more a more detailed treatment of the subject.
We might also expect that bony processes to which major limb muscles attach (such as the olecranal process of the ulna) might be longer in animals requiring more power, as this would increase the mechanical advantage of the muscle as it contracts. Bullet fired from a stationary rifle moves at the velocity imparted by the shell.
The effort required to move a limb is a function of its mass and the distance of its center of gravity from the joint. The ulna of cursors typically is reduced or fused to the radius, and the fibula to the tibia.
The number of digits is also reduced, concentrating the weight on one or two and decreasing the mass of the foot (this also this moves the center of gravity of the limb closer to the body). Phil Myers (author); Barbara Person (artist); Cecilia Morgan (annotated photographs).
In mammal: Locomotion …of curatorial species may be digitigrade (the complete digits contacting the ground, as in dogs) or unguligrade (only tips of digits contacting the ground, as in horses). In advanced groups limb movement is forward and backward in a single plane.
Group of animals that use the tips of their toes or hooves to walk on For elephants and relatives, sometimes called ungulates or subungulates, see Paenungulata.
Ungulates (pronounced UNG-gy-layts) are members of a diverse clade of primarily large mammals with hooves. These include odd-toed ungulates such as horses, rhinoceroses and tapirs, and even-toed ungulates such as cattle, pigs, giraffes, camels, sheep, deer, and hippopotamuses.
Most terrestrial ungulates use the tips of their toes, usually hoofed, to sustain their whole body weight while moving. As a descriptive term, “ungulate” normally excludes cetaceans (whales, dolphins, porpoises), as they do not possess most of the typical morphological characteristics of ungulates, but recent discoveries indicate that they were descended from early artiodactyls.
Ungulates are typically herbivorous and many employs specialized gut bacteria to allow them to digest cellulose. In 2009 morphological and molecular work found that aardvarks, hoaxes, sea cows, and elephants were more closely related to each other and to songs, genres, and golden moles than to the perissodactyls and artiodactyls, and form the clade Afrotheria.
Elephants, sea cows, and hoaxes were grouped together in the clade Paenungulata, while the aardvark has been considered as either a close relative to them or a close relative to songs in the clade Afroinsectiphilia. There is now some dispute whether this smaller Ungulate is a sadistic (evolution-based) group, or merely a phonetic group (form taxon) or folk taxon (similar, but not necessarily related).
Some studies have indeed found the Estonian ungulates and Patagonian ungulates to form a monophyletic lineage, closely related to either the Feral (the carnivorous and the pangolins) in the clade Fereuungulata or to the bats. Below is a simplified taxonomy (assuming that ungulates do indeed form a natural grouping) with the extant families, in order of the relationships.
See each family for the relationships of the species as well as the controversies in their respective article. Below is the consensus of the phylogeny of the ungulate families.
Cladogram showing relationships within Ungulate Perissodactyla and Artiodactyla include the majority of large land mammals. These two groups first appeared during the late Paleocene, rapidly spreading to a wide variety of species on numerous continents, and have developed in parallel since that time.
Some scientists believed that modern ungulates were descended from an evolutionary grade of mammals known as the condylarths ; the earliest known member of the group was the tiny Protungulatum, an ungulate that co-existed with the last of non-avian dinosaurs 66 million years ago; however, many authorities do not consider it a true placental, let alone an ungulate. The enigmatic dinoceratans were among the first large herbivorous mammals, although their exact relationship with other mammals is still debated with one of the theories being that they might just be distant relatives to living ungulates; the most recent study recovers them as within the true ungulate assemblage, closest to Carolina.
In Australia, the marsupial Carpus also developed hooves similar to those of artiodactyls, an example of convergent evolution. The thick dermal armor of the Rhinoceros evolved at the same time as shearing tusks Perissodactyls were said to have evolved from the Phenacodontidae, small, sheep-sized animals that were already showing signs of anatomical features that their descendants would inherit (the reduction of digit I and V for example).
By the start of the Eocene, 55 million years ago (MYA), they had diversified and spread out to occupy several continents. Horses and tapirs both evolved in North America; rhinoceroses appear to have developed in Asia from tapir-like animals and then colonized the Americas during the middle Eocene (about 45 MYA).
Of the approximately 15 families, only three survive (McKenna and Bell, 1997; Hooker, 2005). These families were very diverse in form and size; they included the enormous brontosaurs and the bizarre chalicotheres.
The desmostylians were large amphibious quadrupeds with massive limbs and a short tail. They grew to 1.8 meters (6 ft) in length and were thought to have weighed more than 200 kilograms (440 lb).
Their fossils were known from the northern Pacific Rim, from southern Japan through Russia, the Aleutian Islands and the Pacific coast of North America to the southern tip of Baja California. Their dental and skeletal form suggests desmostylians were aquatic herbivores dependent on littoral habitats.
The South American meridiungulates contain the somewhat tapir-like protheses and astrapotheres, the metabolic litters and the diverse notoungulates. Some paleontologists have even challenged the monopoly of Meridiungulata by suggesting that the protheses may be more closely related to other mammals, such as Embrithopoda (an African order that were related to elephants) than to other South American ungulates.
A recent study based on bone collagen has found that at least litters and the notoungulates were closely related to the perissodactyls. The oldest known fossils assigned to Equine date from the early Eocene, 54 million years ago.
They had been assigned to the genus Hyracotherium, but the type species of that genus is now considered not a member of this family, but the other species have been split off into different genera. They were herbivorous browsers on relatively soft plants, and already adapted for running.
The complexity of their brains suggest that they already were alert and intelligent animals. Later species reduced the number of toes, and developed teeth more suited for grinding up grasses and other tough plant food.
Rhinocerotoids diverged from other perissodactyls by the early Eocene. Fossils of Hyrachyus exists found in North America date to this period.
Three families, sometimes grouped together as the super family Rhinocerotoidea, evolved in the late Eocene: Hyracodontidae, Amynodontidae and Rhinocerotidae, thus creating an explosion of diversity unmatched for a while until environmental changes drastically eliminated several species. The first tapir ids, such as Heptagon, appeared in the early Eocene.
They appeared very similar to modern forms, but were about half the size, and lacked the proboscis. By the Miocene, such genera as Rotavirus were almost indistinguishable from the extant species.
Asian and American tapirs were believed to have diverged around 20 to 30 million years ago; and tapirs migrated from North America to South America around 3 million years ago, as part of the Great American Interchange. Perissodactyls were the dominant group of large terrestrial browsers right through the Oligocene.
However, the rise of grasses in the Miocene (about 20 MYA) saw a major change: the artiodactyl species with their more complex stomachs were better able to adapt to a coarse, low-nutrition diet, and soon rose to prominence. Nevertheless, many perissodactyl species survived and prospered until the late Pleistocene (about 10,000 years ago) when they faced the pressure of human hunting and habitat change.
The artiodactyls were thought to have evolved from a small group of condylarths, Arctocyonidae, which were unspecialized, superficially raccoon-like to bear-like omnivores from the Early Paleocene (about 65 to 60 million years ago). They had relatively short limbs lacking specializations associated with their relatives (e.g. reduced side digits, fused bones, and hooves), and long, heavy tails.
Their primitive anatomy makes it unlikely that they were able to run down prey, but with their powerful proportions, claws, and long canines, they may have been able to overpower smaller animals in surprise attacks. Evidently these mammals soon evolved into two separate lineages: the mesonychians and the artiodactyls.
Mesonychians were depicted as “wolves on hooves” and were the first major mammalian predators, appearing in the Paleocene. Early mesonychids had five digits on their feet, which probably rested flat on the ground during walking (centigrade locomotion), but later mesonychids had four digits that ended in tiny hooves on all of their toes and were increasingly well adapted to running.
Like running members of the even-toed ungulates, mesonychids (Achaean, for example) walked on their digits (digitigrade locomotion). Mesonychians fared very poorly at the close of the Eocene epoch, with only one genus, Congolese, surviving into the Early Oligocene epoch, as the climate changed and fierce competition arose from the better adapted credits.
The first artiodactyls looked like today's chevrons or pigs: small, short-legged creatures that ate leaves and the soft parts of plants. Nevertheless, artiodactyls were far from dominant at that time: the perissodactyls were much more successful and far more numerous.
Artiodactyls survived in niche roles, usually occupying marginal habitats, and it is presumably at that time that they developed their complex digestive systems, which allowed them to survive on lower-grade food. These animals had unusual triangular teeth very similar to those of primitive cetaceans.
This is why scientists long believed that cetaceans evolved from a form of mesonychid. Today, many scientists believe cetaceans evolved from the same stock that gave rise to hippopotamuses.
This hypothesized ancestral group likely split into two branches around 54 million years ago. One branch would evolve into cetaceans, possibly beginning about 52 million years ago with the proto-whale Pakicetus and other early cetacean ancestors collectively known as Archaeoceti, which eventually underwent aquatic adaptation into the completely aquatic cetaceans.
The other branch became the anthracotheres, a large family of four-legged beasts, the earliest of whom in the late Eocene would have resembled skinny hippopotamuses with comparatively small and narrow heads. All branches of the anthracotheres, except that which evolved into Hippopotamidae, became extinct during the Pliocene without leaving any descendants.
Consequentially, new theories in cetacean evolution hypothesize that whales and their ancestors escaped predation, not competition, by slowly adapting to the ocean. Ungulates were in high diversity in response to sexual selection and ecological events; the majority of ungulates lack a collar bone.
Terrestrial ungulates were for the most part herbivores, with some of them being grazers. However, there were exceptions to this as pigs, peccaries, hippos and cookers were known to have an omnivorous diet.
Some cetaceans were the only modern ungulates that were carnivores; baleen whales consume tiny animals in relation to their body size, such as small species of fish and krill ; toothed whales, depending on the species, can consume a wide range of species: squid, fish, sharks, and other species of mammals such as seals and other whales. In terms of ecosystem ungulates have colonized all corners of the planet, from mountains to the ocean depths ; grasslands to deserts and some have been domesticated by humans.
Ungulates have developed specialized adaptations, especially in the areas of cranial appendages, dentition, and leg morphology including the modification of the straggles (one of the ankle bones at the end of the lower leg) with a short, robust head. Cloven hooves of Roe Deer (Capreolus), with dew castle hoof is the tip of a toe of an ungulate mammal, strengthened by a thick horny (keratin) covering.
The hoof consists of a hard or rubbery sole, and a hard wall formed by a thick nail rolled around the tip of the toe. The weight of the animal is normally borne by both the sole and the edge of the hoof wall.
Hooves grow continuously, and were constantly worn down by use. In most modern ungulates, the radius and ulna were fused along the length of the forelimb; early ungulates, such as the arctocyonids, did not share this unique skeletal structure.
The fusion of the radius and ulna prevents an ungulate from rotating its forelimb. While the two orders of ungulates colloquial names were based on the number of toes of their members (“odd-toed” for the perissodactyls and “even-toed” for the terrestrial artiodactyls), it is not an accurate reason they were grouped.
Tapirs have four toes in the front, yet they were members of the “odd-toed” order; peccaries and modern cetaceans were members of the “even-toed” order, yet peccaries have three toes in the front and whales were an extreme example as they have flippers instead of hooves. Scientists had classified them according to the distribution of their weight to their toes.
Perissodactyls have a metabolic foot meaning that the weight is distributed on the third toe on all legs thanks to the plane symmetry of their feet. There has been reduction of toes from the common ancestor, with the classic example being horses with their single hooves.
In consequence, there was an alternative name for the perissodactyls the nearly obsolete Estonia. Terrestrial artiodactyls have a parabolic foot meaning that the weight is distributed on the third and the fourth toe on all legs.
The majority of these mammals have cloven hooves, with two smaller ones known as the dewclaws that were located further up on the leg. The earliest cetaceans (the archdioceses), also have this characteristic in the addition of also having both an straggles and cuboid bone in the ankle, which were further diagnostic traits of artiodactyls.
In modern cetaceans, the front limbs have become pectoral fins and the hind parts were internal and reduced. Occasionally, the genes that code for longer extremities cause a modern cetacean to develop miniature legs (known as atavism).
The main method of moving is an up-and-down motion with the tail fin, called the fluke, which is used for propulsion, while the pectoral fins together with the entire tail section provide directional control. All modern cetaceans still retain their digits despite the external appearance suggesting otherwise.
Most ungulates have developed reduced canine teeth and specialized molars, including abundant (low, rounded cusps) and hypsodont (high crowned) teeth. The development of hypsodonty has been of particular interest as this adaptation was strongly associated with the spread of grasslands during the Miocene about 25 million years.
As forest biomes declined, grasslands spread, opening new niches for mammals. Many ungulates switched from browsing diets to grazing diets, and possibly driven by abrasive silica in grass, hypsodonty became common.
However, recent evidence ties the evolution of hypsodonty to open, gritty habitats and not the grass itself. Some ungulates completely lack upper incisors and instead have a dental pad to assist in browsing.
It can be found in camels, ruminants, and some toothed whales; modern baleen whales were remarkable in that they have baleen instead to filter out the krill from the water. On the other spectrum teeth have been evolved as weapons or sexual display seen in pigs and peccaries, some species of deer, musk deer, hippopotamuses, beaked whales and the Narwhal, with its long canine tooth.
Cranial appendages Velvet covers a growing antler and provides it with blood, supplying oxygen and nutrients. Ungulates evolved a variety of cranial appendages that today can be found in corvids (except musk deer). In oxen and antelope, the size and shape of the horns vary greatly, but the basic structure is always a pair of simple bony protrusions without branches, often having a spiral, twisted or fluted form, each covered in a permanent sheath of keratin.
The unique horn structure is the only unambiguous morphological feature of bodies that distinguishes them from other pecans. Male horn development has been linked to sexual selection, while the presence of horns in females is likely due to natural selection.
The horns of female bodies were thought to have evolved for defense against predators or to express territoriality, as nonterritorial females, which were able to use cry psis for predator defense, often do not have horns. The horns rest on the nasal ridge of the animals' skull.
Nevertheless, fertile does from other species of deer have the capacity to produce antlers on occasion, usually due to increased testosterone levels. Each antler grows from an attachment point on the skull called a pedicle.
Antlers were considered one of the most exaggerated cases of male secondary sexual traits in the animal kingdom, and grow faster than any other mammal bone. Growth occurs at the tip, and is initially cartilage, which is mineralized to become bone.
In most cases, the bone at the base is destroyed by osteoclasts and the antlers fall off at some point. As a result of their fast growth rate, antlers were considered a handicap since there is an incredible nutritional demand on deer to re-grow antlers annually, and thus can be honest signals of metabolic efficiency and food gathering capability.
Ossicles were horn -like (or antler -like) protuberances that can be found on the heads of giraffes and male okapis today. They were similar to the horns of antelopes and cattle, save that they were derived from ossified cartilage, and that the ossicles remain covered in skin and fur, rather than horn.
Each “horn” of the pronghorn is composed of a slender, laterally flattened blade of bone that grows from the frontal bones of the skull, forming a permanent core. As in the Giraffe, skin covers the bony cores, but in the pronghorn it develops into a gelatinous sheath which is shed and regrown on an annual basis.
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