In Neocene restoration of tropical forests stimulated intensive evolution of forest inhabitants and occurrence among them of specialized forms occupying strict ecological niche. One species of mammals living in forests of Meganesia reached an extreme degree of specialization to its way of life. This creature is the distant relative of marsupial mice passed to burrowing habit of life. Its specialization had gone very far; the result of it is a significant reduction of some parts of body. The name of animal means “almost legless caterpillar beast”. It lives in friable leaf litter of Meganesian forests, not being dug deeply in firm ground. In the body shape it has convergent similarity to wedgehead
(Herpethotalpa caeca), digging lizard of skink family living in the same places. The body of erucotherium is about 40 cm long at the maximal thickness up to 7 cm. It is cylindrical, truncated on the back end and wedge-shaped from head end. Wool is short, dense and velvety, of grey, brown or reddish color. On head there is a flat corneous plate of yellowish color is advanced; it serves for protection of skin at digging. Forepaws of erucotherium are strongly reduced. Bones are very short; ulna is reduced and radius is thickened. Hand bones fuse and lose mobility. Only humeral and wrist joints keep partial mobility. From outside from forward limbs two large claws (3-rd and 4-th fingers) located on small lumps protrude – it is an only seen part of forepaws. Claws serve for fastening in the ground and for pushes. Hinder legs are less reduced in comparison to front ones and keep the limited mobility. Two-toed foot with thin and mobile 2-nd and 3-rd toes and normally advanced ankle joint is visible outside. The role of these toes in life of erucotherium is great: they serve for clearing of pouch at females and for keeping of the female during the pairing at males. Strong flattened tail with the wide basis helps to push forward in the ground. The tip of tail is dulled and gristly – it serves as a support at burrowing in the ground. Tail vertebrae have wide and powerful lateral outgrowths. The chest of animal is motionless, ribs strongly fuse to backbone. The animal breathes exclusively with the help of diaphragm movements. The lumbar part of backbone is long and very flexible: animal can easily bite its own heel. Despite of deep specialization to underground habit of life erucotherium is not helpless if it should leave a usual inhabitancy. In case of need it is able to swim perfectly, waving the whole body as if a dolphin. With the help of sensitive bristles on muzzle it perceives the waves reflected from subjects, and can be guided in water and bypass large obstacles at least partly. Eyes of erucotherium are strongly reduced and hidden under skin. The skull of animal is strong and thicken; it serves for tunnel burrowing. It is flattened and has advanced cross crests for an attachment of the muscles raising head up. External ears are lack; the acoustic duct represents a small aperture. This animal perceives good the sounds getting in ear from the ground through bones of lower jaw. The similar mechanism of sound perception is characteristic for cetaceans, but in this case it was developed independently. This animal hears badly the sounds spreading in air. Erucotheres communicate to each other with the help of the odorous labels left in thickness of leaf layer. This mammal eats any animals living in leaf litter. In order to get food erucotherium developed long tongue which can be extended forward for length of head. Edges of tongue are covered with corneous combs, and its basis had shifted far back and is attached to sternum. Tongue serves for digging and capture of worms, insects and their larvae, and also helps to clean wool. Due to flexible backbone animal can lick wool on all parts of body. Erucotherium is reliably protected from enemies. In the basis of tail it has a pair of glands secreting badly smelling oily liquid. Defending against enemies, this animal can bite strongly. It has pointed teeth adapted to feeding on insects. Besides the saliva of erucotherium is toxic for small animals and in large predators it causes long weakness and pain if gets in open wounds. Seasonal prevalence in breeding of this species is not present. Male finds the female ready to breeding by smell, pairs with her keeping her by teeth and by hinder legs, and leaves female right after pairings. Pregnancy is short as at all marsupials – not longer than one week. The brooding pouch having two nipples is opened back and before birth of cubs the female clears it by toes. The female raises only two cubs two times per one year. During the cub birth she turns on back and cubs have an opportunity to creep into the pouch. Up to five cubs are born simultaneously, but only ones managed to reach nipples can survive. They develop in pouch till two months and then the female cares of them till about one month, feeding them up on caught insects. Young animals reach sexual maturity at the age of 8 – 9 months. Life expectancy does not exceed 8 years.