A report on QuadrupedalismWalking and Mammal

The zebra is a quadruped.
Computer simulation of a human walk cycle. In this model the head keeps the same level at all times, whereas the hip follows a sine curve.
The original synapsid skull structure contains one temporal opening behind the orbitals, in a fairly low position on the skull (lower right in this image). This opening might have assisted in containing the jaw muscles of these organisms which could have increased their biting strength.
Racewalkers at the World Cup Trials in 1987
Restoration of Juramaia sinensis, the oldest known Eutherian (160 M.Y.A.)
Nordic walkers
Fossil of Thrinaxodon at the National Museum of Natural History
Free heels are a defining characteristic of ski touring
Raccoon lungs being inflated manually
Human Walking Cycle
Mammal skin: 1 — hair, 2 — epidermis, 3 — sebaceous gland, 4 — Arrector pili muscle, 5 — dermis, 6 — hair follicle, 7 — sweat gland, 8 (not labeled, the bottom layer) — hypodermis, showing round adipocytes
Hiking with full packs.
Bovine kidney
Gauchetière Street, Montreal, Quebec, Canada
A diagram of ultrasonic signals emitted by a bat, and the echo from a nearby object
Two king penguins and one gentoo penguin walking on a beach on South Georgia, British overseas territory
Porcupines use their spines for defense.
The walk, a four-beat gait
A leopard's disruptively colored coat provides camouflage for this ambush predator.
An Asian elephant walking
Goat kids stay with their mother until they are weaned.
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Matschie's tree-kangaroo with young in pouch
Running gait. Photographs by Eadweard Muybridge, 1887.
Gibbons are very good brachiators because their elongated limbs enable them to easily swing and grasp on to branches.
Vervet monkeys use at least four distinct alarm calls for different predators.
A bonobo fishing for termites with a stick
Female elephants live in stable groups, along with their offspring.
Red kangaroos "boxing" for dominance
Upper Paleolithic cave painting of a variety of large mammals, Lascaux, c. 17,300 years old
Cattle have been kept for milk for thousands of years.
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Biodiversity of large mammal species per continent before and after humans arrived there
Sexual dimorphism in aurochs, the extinct wild ancestor of cattle.

Quadrupedalism is a form of terrestrial locomotion where a tetrapod (as well as mantises, who primarily walk in this way) animal uses all four limbs (legs) to bear weight, walk, and run.

- Quadrupedalism

Most quadrupeds are terrestrial vertebrates, including mammals and reptiles, though some are largely aquatic such as turtles, amphibians, and pinnipeds.

- Quadrupedalism

For quadrupedal species, there are numerous gaits which may be termed walking or running, and distinctions based upon the presence or absence of a suspended phase or the number of feet in contact any time do not yield mechanically correct classification.

- Walking

The basic body type is quadruped, and most mammals use their four extremities for terrestrial locomotion; but in some, the extremities are adapted for life at sea, in the air, in trees, underground, or on two legs.

- Mammal

Human walking has been found to be slightly more energy efficient than travel for a quadrupedal mammal of a similar size, like chimpanzees.

- Walking

For example, the main human gaits are bipedal walking and running, but they employ many other gaits occasionally, including a four-legged crawl in tight spaces.

- Mammal
The zebra is a quadruped.

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An example of terrestrial locomotion. A horse – an erect-stanced unguligrade quadruped – with a galloping gait. A 2006 animation of 1887 photos by Eadweard Muybridge

Terrestrial locomotion

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Terrestrial locomotion has evolved as animals adapted from aquatic to terrestrial environments.

Terrestrial locomotion has evolved as animals adapted from aquatic to terrestrial environments.

An example of terrestrial locomotion. A horse – an erect-stanced unguligrade quadruped – with a galloping gait. A 2006 animation of 1887 photos by Eadweard Muybridge
Hip joints and hindlimb postures.
The velvet worm (Onychophora)
A jumping kangaroo.
Helix pomatia crawling over razor blades. Terrestrial gastropods crawl on a layer of mucus. This adhesive locomotion allows them to crawl over sharp objects.
The pangolin Manis temminckii in defensive position.
Simulation of leg waves propagating forward.
Simulation of leg waves propagating backward.

There are also many gaits, ways of moving the legs to locomote, such as walking, running, or jumping.

Mammals and birds typically have a fully erect posture, though each evolved it independently.

With the exception of the birds, terrestrial vertebrate groups with legs are mostly quadrupedal – the mammals, reptiles, and the amphibians usually move on four legs.