Gaining Ground: The Origin and Evolution of Tetrapods

Gaining Ground: The Origin and Evolution of Tetrapods

Gaining Ground: The Origin and Evolution of Tetrapods

Gaining Ground: The Origin and Evolution of Tetrapods

Synopsis

Around 370 million years ago, a distant relative of a modern lungfish began a most extraordinary adventure--emerging from the water and laying claim to the land. Over the next 70 million years, this tentative beachhead had developed into a worldwide colonization by ever-increasing varieties of four-limbed creatures known as tetrapods, the ancestors of all vertebrate life on land. This new edition of Jennifer A. Clack's groundbreaking book tells the complex story of their emergence and evolution. Beginning with their closest relatives, the lobe-fin fishes such as lungfishes and coelacanths, Clack defines what a tetrapod is, describes their anatomy, and explains how they are related to other vertebrates. She looks at the Devonian environment in which they evolved, describes the known and newly discovered species, and explores the order and timing of anatomical changes that occurred during the fish-to-tetrapod transition.

Excerpt

Since the first edition of Gaining Ground was completed, much has happened in the field of early tetrapod paleontology and in the wider world that has affected not only the ideas and conclusions presented in the first edition, but also what paleontologists are able to do with material, the techniques that they use, and how easily and quickly things can be done.

One of the most significant events worldwide has been the global spread of the Internet, which has not only allowed discoveries to be published more quickly, but has enabled rapid searches for material and references. the ease and speed of access to references by electronic means and Internet search have improved enormously, allowing information and citations to be readily found at the touch of a button. It’s hard to remember that in the late 1990s and the first couple of years of the 21st century, when the first edition was written, online connections were often slow and limited. Today, the ease and availability of electronic techniques has greatly affected many aspects of producing and delivering a wide range of scientific output. I personally have been most affected by my familiarity with software packages such as Photoshop, which permits manipulation of scanned images to produce diagrams. Some of the diagrams in the first edition were admittedly clumsy, and I hope that readers will find these improved in the second. Digital photography, of course, is another boon.

Technological advances have affected many areas of study, and paleontology is no exception here. One of the techniques that has improved in availability, cost, and degree of resolution is that of X-ray computed tomography (CT), or micro-CT scanning. This is becoming the technique of choice for examining new aspects of fossil material previously inaccessible. Software programs build the serial sections produced by scans into three-dimensional images that can be easily manipulated and dissected. These have become more sophisticated but at the same time more amenable to being run on a moderately powerful desktop computer, as well as becoming more intuitive to use. Such advances have allowed new questions to be framed and answered. One stage up from micro-CT scanning with X-rays is the use of a synchrotron. This allows minute examination of tissue structure inside fossil material, from which, for example, threedimensional images of growth patterns of bone can be built. For really high-resolution scanning to get these results, at present, the limitation of this technique is the small size of sample that can be examined at any one time. Larger specimens can be scanned at lower resolution, often higher than with micro-CT machines, but results still depend on the geological makeup of the material.

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.