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Figure 2.3 The medusoid phase of a living aequorian hydroid. Diameter approximately 1 cm. compaction, would have been greater. In chapter 5 we see how recognition of the convex-side-down aspect of Ediacaran medusoids was the precursor to Garden of Ediacara theory, the concept that these medu-soids were actually bowl-shaped solar collectors. Many Ediacaran medusoids are three-dimensional fossils filled with fine sediment. The Mexican specimen (figure 2.1) is one of these, as is the Irish find....

Corumbella

Corumbella holds the record for the toughest integument of an Ediacaran (except the mineralized cloudinids, to be discussed in chapter 6). Described in 1982, Corumbella werneri (figure 2.25) forms deep impressions, showing a central ridge and perpendicular ridgelets.76 It may be a frond fossil with a particularly heavy integument. Its description inspired me to suggest Corumbella as a link between the Ediacaran frond fossils and an enigmatic group of Paleozoic organisms known as conularids.77...

Mystery Fossil

Your whole creation is never silent and never ceases to praise you. The spirit of every man utters its praises in words directed to you animals and material bodies praise you through the mouth of those who meditate upon them, so that our soul may rise out of its weariness toward you, supporting itself upon the things which you created, and then passing on to you yourself who made them marvelously. At the dawn of European civilization, with the Greek philosophers, there were two clear tendencies...

The Nama Group

Outrageous hypotheses arouse interest, invite attack, and thus serve useful fermentative purposes in the advancement of geology. In spring 1993 I received an invitation from Professor Adolf Seilacher (figure 4.1) to join his field party for an expedition to Namibia. Seilacher2 had just been awarded the prestigious Crafoord Prize by the Swedish National Academy of Sciences and was wasting no time in putting the prize money to good use. I was honored by his invitation and hastened, on April 18,...

Dorion Sagan

Virtually as soon as earth's crust cools enough to be hospitable to life, we find evidence of life on its surface. But we are latecomers, and just as we must be familiar with the beginning of a mystery novel to understand its end, we must scrutinize the often ignored early phase of evolution. Mark McMenamin's allusively named Garden of Ediacara hones in on some of the key events and players in life's early phase a time for the biosphere that, like the first three years of a human life, is not...

Arkarua adami

Arkarua adami (figure 2.27), also described by Jim Gehling,79 is a globular fossil with five rays on its surface and an outer flange with radial markings. Based on its putative similarities to an ancient type of discoid echino-derm,80 Arkarua adami is presented by Gehling as the oldest known fossil echinoderm. Arkarua s similarities to echinoderms of later times may prove superficial, however. Consider the similarities between the radially marked flange in Arkarua adami and (with apologies for...

The Garden of Ediacara

Copyright 1998 Columbia University Press All rights reserved Library of Congress Cataloging-in-Publication Data McMenamin, Mark A. The garden of Ediacara discovering the first complex life Mark A. S. McMenamin. p. cm. Includes bibliographical references and index. Casebound editions of Columbia University Press books are printed on permanent and durable acid-free paper. Printed in the United States of America c 10 9 8 7 6 5 4 3 2 1 p 10 9 8 7 6 5 4 3 2 1 Some images in the original version of...

Dickinsonia

The best-known Ediacaran fossil, Dickinsonia, promises to provide a tremendous amount of information concerning the paleobiology of these organisms. If only we knew what it was. Dickinsonia has the distinction of being the only fossil to be described as a jellyfish, a coral, a sea anemone, an annelid worm,58 a polychaete worm, an arthropod, a bacterium, a protozoan, a member of a new phylum, a member of a new kingdom, and even an alien creature from outer space. In 1992 Rudolf Raff asked seven...

Nung Animus

A few Aloe dichotoma were seen scattered on hills across the road. We saw more hills reminiscent of Joshua Tree National Monument. Could a variant of the Joshua tree principle apply to landscape recognition Do similar landscapes evoke uncannily similar vegetation The South Atlantic was beginning, as we proceeded, to fill the low spots in the western horizon like a rising tide. We passed a battered and stripped small blue station wagon to the right. Sand dunes were beginning to drape the hills...