Evolution and systematics

The family Ornithorhynchidae includes just one modern species, the duck-billed platypus. No subspecies or races are known to occur. Several extinct ornithorhynchid species have been described, mainly from fossils found in Australia. At least one type of ancient platypus is also known to have lived in the Patagonian region of South America some 61-63 million years ago (mya), when South America was still physically joined to Australia as part of the giant southern supercontinent, Gond-wana. The nearest living relatives are the echidnas (family Tachyglossidae). Based on genetic evidence, it is believed that the platypus and echidna lines have been evolving separately since the late Cretaceous or early Tertiary periods, 63-78 mya.

The taxonomy of this species is Ornithorynchus anatinus (Shaw, 1799), New Holland (Sydney), New South Wales, Australia.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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