Chordate Zoology - textbook - Y. V. Tsaryk - 2013

Chapter 5. SUPERCLASS TETRAPODS (LAND VERTEBRATES) TETRAPODA, seu QUADRIPEDA.

ANAMNIOTES (ANAMNIA) AND AMNIOTES (AMNIOTA)

5.4. CLASS MAMMALS, or BEASTS, MAMMALIA, seu THERIA

5.4.4. Systematics and Characteristics of Representatives of the Main Orders of the Class Mammalia

5.4.4.1. Subclass Prototheria, or Cloacal Mammals, Prototheria

The most primitive of modern mammals, distributed in Australia, New Guinea, and Tasmania.

5.4.4.1.1. Order Monotremes Monotremata

A single order, Monotremes Monotremata. The order contains two families.

Family Tachyglossidae (echidnas). The body is covered with spines up to 6 cm long; the snout is elongated, pointed, and ends in a beak covered with a horny sheath. The body length is up to 40 cm. The legs are equipped with strong claws. They feed on small animals. The female lays 1-2 eggs, which she incubates in a leathery pouch that forms on her abdomen before egg-laying. The newborn offspring, 1.5–2.0 cm long, leaves the pouch after 42-56 days. There are four species: three long-beaked echidnas (New Guinea) and one short-beaked echidna (Australia, New Guinea, Tasmania).

Family Ornithorhynchidae (platypuses) includes a single species, Ornithorhynchus anatinus (Fig. 5.74, 1), which lives in Australia and Tasmania. It is a semi-aquatic animal whose body is covered with a dense fur coat that is almost waterproof. The snout ends in a wide, "duck-like" bill covered with a horny sheath, which the animal uses to strain

Water and mud in search of worms, insects and their larvae, crustaceans, and Mollusks. The feet have webbed toes. One to three eggs are laid in a specially dug burrow, where the young are hatched. During the incubation period (up to ten days), the female blocks the entrance to the nesting chamber with a soil plug.

According to modern Taxonomy, the aforementioned families are classified into separate orders: the order Tachyglossa (echidnas) and the order Platypoda (platypuses).