Evolution and systematics

First appearing in the fossil record in the early to middle Miocene, dasyurids were rare (only two species known) until the late Miocene, when they increased steadily in diversity to replace the thylacinids as the largest group of Australian carnivorous marsupials. Dasyurids comprise three extant subfamilies and one extinct subfamily (the earliest form), which was a sister group to the living subfamilies, and are most closely related to the thylacinids. Molecular data indicate that all four radiations of dasyurids took place in the late mid-Miocene, perhaps in response to climatic drying. Most of the species present in the Pleistocene were of living taxa, representatives of which occurred no earlier than the Pliocene. It is suggested that the dasyurids are highly specialized among dasyuromorphians in their morphology rather than primitive. The living fauna currently comprises 69 described species in seventeen genera (fifty-three restricted to Australia and islands, fourteen in New Guinea and islands). The number of species will almost certainly increase with taxonomic revisions, particularly with the recognition of morphologically cryptic but genetically distinct species. There is genetic and morphological differentiation at the subspecific level in some species.

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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