X is for XENARTHRA

The superorder Xenathra is a group of placental mammals (infraclass Eutheria), extant today only in the Americas and represented by the anteaters, tree sloths and armadillos.  The origins of the order can be traced as far back as the Paleogene (about 60-65 Ma, shortly after the Mesozoic) in South America.  Xenarthrans developed and diversified extensively in South America during its long period of isolation.  They invaded the Antilles by the early Miocene and, starting about nine million years ago, they spread to Central and North America as part of the Great American Interchange.  Nearly all of the formerly abundant megafaunal xenarthrans, such as ground sloths, glyptodonts and pampatheres, west extinct at the end of the Pleistocene.

Xenarthrans share several characteristics that are not present in other placental mammals.  The name Xenarthra, which means "strange joints", was chosen because their vertebral joints have extra articulations and are unlike those of any other mammals - a character referred to as "xenarthry" - and ischiosacral fusion.  The males have internal testicles, which are located between the bladder and the rectum.  Also, xenarthrans have the lowest metabolic rate among the therians.

One member of this order is the GIANT ANTEATER (Myrmecophaga tridactyla) which can be found in large parts of southern Central America and the northern and central parts of South America.  Populations are densest in the tropical forests, grasslands, and highlands where ants are most abundant.  Its coat is brown with a large black and white stripe on the shoulder and it a long snout and a large, bushy tail.  It has small ears and eyes, which contributes to the streamlined appearance of its head.  The giant anteater has a long, thin tongue that it uses to extract ants from their mounds.  It also has one of the lowest body temperatures of any known kind of mammal (91F).

It eats carpenter ants and other large ants are also its primary food.  They usually ignore termites. army ants, and other species of ants with large jaws.  Ants are carefully removed from the colony when the anteater inserts its long tongue covered with sticky saliva in the mound where it will dine for about one minute before moving on to another mound.  A keen sense of smell is critical for this anteater as it is used to locate colonies located in the anteater's territory.  They also have a keen sense of hearing that is used to warn the anteater of approaching predators, i.e. pumas and jaguars.

These giant anteaters are solitary animals that usually only pair up for a brief period of the time during the mating season.  After about 140 days of gestation, the mother gives birth to a single offspring.  The newborn crawls onto the back of the mother.  The baby suckles for about 6 months and will not feed independently until it is about two years old.
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This next animal is a creature that has always fascinated me over the years and I was pleased to learn more about them and share the information with you.

Another member of this order is the THREE-TOED SLOTH (Bradypus variegatus).  The sloth is the world's slowest mammal, so sedentary that algae grows on its furry coat.  The plant gives it a greenish tint that is useful camouflage in the trees of its Central and South American rain forest home.

Sloths are identified by the number of long, prominent claws that they have on each front foot. There are both two-toed and three-toed sloths.  All of them are built for life in the treetops.  They spend nearly all of their time aloft, hanging from branches with a powerful grip aided by their long claws.  (Dead sloths have been known to retain their grip and remain suspended from a branch). Sloths even sleep in trees, and they sleep a lot - some 15 to 20 hours each and every day.  Even when awake they often remain motionless.  At night they eat leaves, shoots, and fruit from the trees and get almost all of their water from juice plants.

Sloths mate and give birth while hanging in the trees.  Three-toed sloths are often seen clinging to their mothers - they travel by hanging on to them for the first nine months of their lives.

On land sloths' weak hind legs provide no power and their long claws are a hindrance.  They must dig into the earth with their front claws and use their strong front legs to pull themselves along, dragging their bellies across the ground.  If caught on land, these animals have no chance to evade predators, such as big cats, and must try to defend themselves by clawing and biting.  Though they couldn't be clumsier on land, sloths are surprisingly good swimmers.  They sometimes fall directly from rain forest trees into rivers and stroke efficiently with their long arms.

The three-toed sloth emits a long, high-pitched call that echoes through the forests as "ahh-eeee" and because of this cry these sloths are sometimes called 'ais' (pronounced "eyes").  These animals also have an advantage that few other mammals possess:  they have extra neck vertebrae that allows them to turn their heads some 270 degrees.

I think these days I am a little sloth-like....I move very slowly and sometimes remain quite motionless even when awake!!!!
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The third member of this order is the ARMADILLO (of the family Dasypodidae) which is native to both North America and South America, although only one species is found in the United States.  The average armadillo measures around 75cm in length, including the tail, but the giant armadillo can grow to more than 1.5m long and the miniature pink fairy armadillo (the smallest species) only gets to around 10cm in length.  There are around 20 species of armadillo still existent on the American continent with nine-banded armadillo being the only species outside of the South American tropics.

The armadillo has a hard outer shell and can curl up into a ball leaving no soft body parts exposed to danger (a bit like a woodlouse).  The armadillo also has long claws which it uses for digging burrows and hunting for insects in the earth.  Despite its odd shape, most armadillos can also reach a top speed of nearly 30 mph so can easily outrun most jungle predators.  The primary predators of the armadillo are bears, wolves, wildcats and cougars.  It has poor vision which makes it somewhat vulnerable in its jungle environment.  The armour is formed by plates of bone covered in relatively small overlapping scales.  the scales are known are scutes and these scutes are made up of bone covered with horn.

The armadillo has additional armour that covers the top of its head, the upper parts of the limbs and tail. The underside of the body has no armour, and is simply covered with soft skin and fur, hence its strategy of curling into a ball leaving only the armoured plates exposed.

The armadillo is generally an insectivore, meaning that the diet is primarily comprised of insects.  They also snack on other things including worms, spiders, snakes and frogs although the exact diet of the armadillo is very much dependent on the area which it inhabits.

Female armadillos give birth to around four young which are born after a gestation period of 3-4 months.  After birth, baby armadillos remain in the burrow for a few months, only feeding on their mother's milk.  Then then begin to forage with the mother, eventually leaving after six months to a year.  Some species of armadillo are known to reproduce every year so a single female can produce up to 5 young over the couse of her life.

This is the dainty fairy armadillo (the smallest of the armadillos) (Chlamyphorus truncatus).  Isn't it just so cute?