17. Morphology and Physiology of the Metatheria
FAUNA of AUSTRALIA 17. MORPHOLOGY AND PHYSIOLOGY OF THE METATHERIA T.J. DAWSON, E. FINCH, L. FREEDMAN, I.D. HUME, MARILYN B. RENFREE & P.D. TEMPLE-SMITH 1 17. MORPHOLOGY AND PHYSIOLOGY OF THE METATHERIA 2 17. MORPHOLOGY AND PHYSIOLOGY OF THE METATHERIA EXTERNAL CHARACTERISTICS The Metatheria, comprising a single order, Marsupialia, is a large and diverse group of animals and exhibits a considerable range of variation in external features. The variation found is intimately related to the animals' habits and, in most instances, parallels that are found in the Eutheria. Useful general references to external characteristics include Pocock (1921), Jones (1923a, 1924), Grassé (1955), Frith & Calaby (1969), Ride (1970) and Strahan (1983). Body form In size, the marsupials range upwards from the Long-tailed Planigale, Planigale ingrami, a small, mouse-like animal weighing only around 4.2 g, with a head- body length of 59 mm and a tail 55 mm long. At the other extreme, there are large kangaroos, such as the Red Kangaroo, Macropus rufus, in which the males may weigh as much as 85 kg and attain a head-body length of 1400 mm and a tail of 1000 mm. Body shape also varies greatly. The primarily carnivorous marsupials, the dasyurids (for example, antechinuses, dunnarts, quolls, planigales and others), are small to medium sized quadrupeds with subequal limbs. The tail is relatively slender and generally about half the length of the body. The omnivorous peramelids show increased development of the hind limbs in keeping with their rapid bounding locomotion. Saltatory or hopping forms (for example kangaroos and wallabies), carry the hind limb specialisation to an extreme, with a concomitant reduction of the forelimbs (Fig.
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