Adaptation for flight in bats

Bats, and an uneasy creeping in one's scalp As the bats swoop overhead! Flying madly. Pipistrello! Black piper on an infinitesimal pipe. Little lumps that fly in air and have voices indefinite, wildly vindictive; Wings like bits of umbrella. Bats!

The poet, D. H. Lawrence, seemed to find bats disgusting, but these creatures of the night are the only mammals to have evolved powered flight. Occupying the nocturnal flier niche has been extremely successful—so successful that one out of every four mammal species is a bat.

Three vertebrate taxa have evolved lineages capable of powered flight: the pterosaurs (Reptilia), birds (Aves), and bats (Mammalia). In all three cases, the forelimbs of these vertebrates were modified over time to form wings. This is an example of convergence, the independent evolution of a common structure that performs a similar function among unrelated species. The pterosaurs, the only reptiles to evolve true flight, were the first vertebrates to develop powered flight. Pterosaurs (order Pterosauria) appeared about 225 million years ago and lasted about 130 million years until they became extinct at the end of the Mesozoic era. The most diverse lineage of flying vertebrates is the birds (class Aves), which underwent extremely rapid evolution during the Cretaceous period, approximately 150 million years ago (mya). Bats (order Chiroptera) appear to be the most recent flying lineage among vertebrates, although precisely how recent is uncertain because only a few examples are represented in the fossil record. The oldest unquestioned fossil bat dates back to the early Eocene (about 50 mya) and is already a well-developed bat. Fossils from the early Paleocene (65-60 mya) attributable to bats consist mainly of teeth and jaws. They are often disputed as belonging to the order Primates.

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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