Placental Mammals, SPI-WHA
Placental mammal, (infraclass Eutheria), any member of the mammalian group characterized by the presence of a placenta, which facilitates exchange of nutrients and wastes between the blood of the mother and that of the fetus. The placentals include all living mammals except marsupials and monotremes. Although some authorities consider the marsupials (cohort Marsupialia) to be placental mammals, these animals have a less-developed, less-efficient type of placenta that limits the gestation period. The true placenta of the placentals allows for a longer developmental period within the protection of the womb, a factor considered to have contributed to the evolutionary success of the group. Fossil evidence shows that the first placental mammals evolved between about 163 million and 157 million years ago during the Jurassic Period (201.3 million to about 145 million years ago).
Placental Mammals Encyclopedia Articles By Title
spitz, any of a group of northern dogs—such as the Akita, Pomeranian, and Samoyed—characterized by a wolflike or......
sporting dog, dog that scents and either points, flushes, or retrieves birds and other game on land and in water.......
spring hare, (Pedetes capensis), a bipedal grazing rodent indigenous to Africa. About the size of a rabbit, the......
springbok, (Antidorcas marsupialis), graceful, strikingly marked antelope of the gazelle tribe, Antilopini (family......
springer spaniel, either of two ancient breeds of sporting dogs used to flush game from cover and to retrieve it.......
squirrel, (family Sciuridae), generally, any of the 50 genera and 268 species of rodents whose common name is derived......
squirrel monkey, (genus Saimiri), most abundant primate of riverside forests in the Guianas and the Amazon River......
Staffordshire Bull Terrier, breed of terrier developed in 19th-century England for fighting other dogs in pits.......
Standardbred, breed of horse developed in the United States in the 19th century and used primarily for harness......
steer, young neutered male cattle primarily raised for beef. In the terminology used to describe the sex and age......
Steinheim skull, human fossil remnant found in 1933 along the Murr River about 20 km (12 miles) north of Stuttgart,......
Suffolk, smallest draft-horse breed, which originated in Suffolk, Eng. Descended from the medieval “great horse,”......
Suffolk, breed of medium-wool, dark-faced, hornless sheep developed in England during the years 1800 to 1850 by......
suid, any member of the family Suidae, hoofed mammals, order Artiodactyla, including the wild and domestic pigs.......
Sumatran rhinoceros, (Dicerorhinus sumatrensis), one of three Asian species of rhinoceroses and the smallest living......
sun bear, (Helarctos malayanus), the smallest bear in the world, found in Southeast Asian forests. It weighs only......
suslik, any of the 13 species of Eurasian ground squirrels belonging to the genus...
Sussex spaniel, breed of sporting dog developed in Great Britain in the late 18th century; like other land spaniels,......
swamp monkey, (Allenopithecus nigroviridis), small heavily built primate of the Congo River basin. It is dark olive......
tabby, type of dark-striped coat colouring found in both wild and domestic cats. One of the most common coat colours,......
taeniodont, any member of an extinct suborder (Taeniodonta) of mammals that lived in North America throughout the......
tahr, (genus Hemitragus), any of three wary and sure-footed wild goatlike mammals of the family Bovidae (order......
takin, (Budorcas taxicolor), heavily built, hoofed mammal of Southeast Asia, belonging to the family Bovidae (order......
talapoin, (genus Miopithecus), either of two small species of monkeys found in swamp forests on each side of the......
tamarau, (species Anoa mindorensis), small species of buffalo...
tamarin, any marmoset species belonging to the genus Saguinus or...
tapir, (genus Tapirus), any of five species of hoofed mammals, the only extant members of the family Tapiridae......
tarpan, European wild horse that survived in small herds in remote parts of central Europe during the Middle Ages......
tarsier, (family Tarsiidae), any of about 13 species of small leaping primates found only on various islands of......
tayra, (Eira barbara), weasel-like mammal of tropical forests from southern Mexico through South America to northern......
teacup dog, unofficial name for any of several breeds of dogs that are bred to be less than 4 to 6 pounds (1.8–2.7......
teledu, species of badger (q.v.) found in Southeast...
Tennessee walking horse, breed of horse that derives its name from the state of Tennessee and from its distinctive......
tenrec, (family Tenrecidae), any of 29 species of shrewlike and hedgehoglike mammals. Most are endemic to Madagascar......
terrier, any of a diverse group of dog breeds of various sizes—from the diminutive Yorkshire Terrier to the large......
Naked mole rats (Heterocephalus glaber) are unlikely to win any beauty contests in the animal world, but they have......
Thoroughbred, breed of horse developed in England for racing and jumping (see photograph). The origin of the Thoroughbred......
Tibetan terrier, breed of nonsporting dog that originated in Tibet to aid shepherds. It was believed to bring luck......
tiger, (Panthera tigris), largest member of the cat family (Felidae), rivaled only by the lion (Panthera leo) in......
tigon, offspring of a tiger and a lioness. The tigon, or tiglon, is a zoo-bred hybrid, as is the liger, the product......
titanothere, any member of an extinct group of large-hoofed mammals that originated in Asia or North America during......
titi, (genus Callicebus), any of about 20 species of small arboreal monkeys that have long furred tails and are......
Toggenburg, breed of dairy goat originating in the Toggenburg valley of Switzerland. The oldest breed of dairy......
toothed whale, (suborder Odontoceti), any of the odontocete cetaceans, including the oceanic dolphins, river dolphins,......
topi, (Damaliscus lunatus), one of Africa’s most common and most widespread antelopes. It is a member of the tribe......
Toxodon, extinct genus of mammals of the late Pliocene and the Pleistocene Epoch (about 3.6 million to 11,700 years......
toy dog, Any of several breeds of dogs that were bred to be small, portable, good-natured companions. Toy dogs......
tree shrew, (order Scandentia), any of 17 Southeast Asian species of small mammals resembling squirrels and “true”......
tuco-tuco, (genus Ctenomys), South American burrowing rodents similar to the North American pocket gopher in both......
Turkish Angora cat, Breed of longhaired domestic cat that probably arose from a domesticated cat of Tatars who......
Turkish Van cat, breed of semilonghaired domestic cat distinguished mainly by its unusual colour pattern: white,......
tylopod, any of the pad-footed, even-toed, hoofed mammals of the suborder Tylopoda (order Artiodactyla). This group......
uakari, (genus Cacajao), any of several types of short-tailed South American monkeys with shaggy fur, humanlike......
Uintatherium, extinct genus of large, hoofed mammals found as fossils in North America and Asia in terrestrial......
ungulate, any hoofed mammal. Although the term may be used to refer to any member of the grandorder Ungulata, which......
urial, (Ovis orientalis), medium-size, rather stout-bodied wild sheep, distributed from northwest India and Ladakh......
vampire bat, (family Desmodontidae), any of three species of blood-eating bats, native to the New World tropics......
vaquita, (Phocoena sinus), species of nonmigratory marine mammal known for being the smallest member of the porpoise......
vervet, (genus Chlorocebus), any of six known species of widely distributed semiarboreal African monkeys. Vervet......
vesper bat, (family Vespertilionidae), large family of bats numbering more than 400 species. They are found worldwide......
vicuña, (Vicugna vicugna), smallest member of the camel family, Camelidae (order Artiodactyla). The vicuña is closely......
While Vikings don’t exactly have a reputation for being cuddly, their travel companions do. Hoping to shed some......
viscacha, any of four species of slender yet fairly large South American rodents similar to chinchillas. They have......
viverrid, (family Viverridae), any of 35 species of small Old World mammals including civets, genets, and linsangs.......
Vizsla, breed of sporting dog whose ancestors were probably brought to Hungary by the Magyars more than a thousand......
vole, any of numerous species of small-bodied mouselike rodents of the Northern Hemisphere that are classified,......
Wagyu, slow-growing Japanese cattle breed prized for its tender, flavorful, and highly marbled meat. Evidence suggests......
walrus, (Odobenus rosmarus), huge, seal-like mammal found in Arctic seas. There are two subspecies: the Atlantic......
warthog, (Phacochoerus aethiopicus), member of the pig family, Suidae (order Artiodactyla), found in open and lightly......
The city of Chicago is known for many things: the Great Chicago Fire of 1871, 1930s gangster Al Capone, the Democratic......
water buffalo, (Bubalus bubalis), either of two forms, wild and domestic, of Asian mammal similar to the ox. There......
water rat, any of 18 species of amphibious carnivorous rodents. They exhibit many adaptations associated with hunting......
water shrew, any of 12 species of amphibious shrews that have a broad, fleshy muzzle, large chest, and long hind......
waterbuck, antelope species of the genus Kobus...
weasel, any of various small carnivores with very elongated slender bodies. Most live in the Northern Hemisphere......
Weddell seal, (Leptonychotes weddellii), nonmigratory earless seal (family Phocidae) found around the South Pole,......
Weimaraner, sporting dog breed developed in the early 19th century by German nobles of the court of Weimar. First......
Welsh Corgi, either of two breeds (Pembroke Welsh Corgi and Cardigan Welsh Corgi) of affectionate dogs developed......
Welsh pony, breed of small horse popular as a child’s or an adult’s mount. A hardy breed that developed in the......
Welsh terrier, breed of terrier native to Wales, where it has been used as a hunter of foxes, otters, and badgers.......
West Highland white terrier, a short-legged dog standing 10 to 11 inches (25 to 28 cm) tall and weighing 13 to......
whale, any of the larger species of aquatic mammals belonging to the order Cetacea. The term whale can be used......
Elephants use their trunks as multifunctional appendages for a variety of tasks essential to their survival and......
Wolves hold a unique place in nature and in the human psyche. The precursor to “man’s best friend” but also evil......
Cheetahs are carnivores, which means that their diet consists primarily of meat. They hunt a variety of animals,......
Giraffes, as browsers, primarily feed on new, tender shoots and leaves of trees, with a particular fondness for......
Rabbits are herbivores and primarily consume a diet rich in plant material, such as grasses and forbs (herbs other......
Squirrels’ diets vary based on their species and habitat. The most commonly recognized squirrel, the bushy-tailed......
Whales have a diverse diet that varies significantly between species, primarily depending on whether they are baleen......
A variety of theories have been proposed for the specific function of the narwhal’s long, straight tusk, but first......
There are several dogs that are closely associated with dingoes, including the rare Carolina Dog and the wild New......
All dogs are close relatives of wolves—after all, domestic dogs (Canis lupus familiaris) descend from gray wolves......
An American Bully is a type of dog created to incorporate the physical traits of the American Pit Bull Terrier......
A mature female elephant is called a cow. Cows are fundamental to elephant herds. As seen in most mammals, the......
In English, a female yak is called a cow. This designation aligns with the common practice of using cow for mature......
A group of cows is called a herd. This is the standard term used universally in both common speech and scientific......
Unsettling photographs of wild cottontail rabbits near Fort Collins, Colorado, sporting hornlike or tentacle-like......
The most obvious difference between wolves and coyotes is in their size and build. Most wolves, in particular the......
The largest animal on Earth is the blue whale (Balaenoptera musculus). It is also the largest animal to have ever......
The sperm whale is the loudest animal on Earth. These majestic creatures can produce sounds that reach an astonishing......