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Earliest fossil finds_

Fossils are very common in certain kinds of rocks, and they are often attractive and beautiful objects. It is probable that people picked up fossils long ago, and perhaps even wondered why shells of sea creatures are now found high in the mountains, or how a perfectly preserved fish specimen came to lie buried deep within layers of rock. Prehistoric peoples picked up fossils and used them as ornaments, presumably with little understanding of their meaning.

Some early speculations about fossils by the classical authors seem now very sensible to modern observers. Early Greeks such as Xenophanes (576-480 bce) and Herodotus (484-426 bce) recognized that some fossils were marine organisms, and that these

Box 1.2 Bringing the sabertooths to life

Everyone's image of dinosaurs and ancient life changed in 1993. Steven Spielberg's film Jurassic Park was the first to use the new techniques of computer-generated imagery (CGI) to produce realistic animations. Older dinosaur films had used clay models or lizards with cardboard crests stuck on their backs. These looked pretty terrible and could never be taken seriously by paleontologists. Up to 1993, dinosaurs had been reconstructed seriously only as two-dimensional paintings and three-dimensional museum models. CGI made those superlative color images move.

Following the huge success of Jurassic Park, Tim Haines at the BBC in London decided to try to use the new CGI techniques to produce a documentary series about dinosaurs. Year by year, desktop computers were becoming more powerful, and the CGI software was becoming more sophisticated. What had once cost millions of dollars now cost only thousands. This resulted in the series Walking with Dinosaurs, first shown in 1999 and 2000.

Following the success of that series, Haines and the team moved into production of the follow-up, Walking with Beasts, shown first in 2001. There were six programs, each with six or seven key beasts. Each of these animals was studied in depth by consultant paleontologists and artists, and a carefully measured clay model (maquette) was made. This was the basis for the animation. The maquette was laser scanned, and turned into a virtual "stick model" that could be moved in the computer to simulate running, walking, jumping and other actions.

While the models were being developed, BBC film crews went round the world to film the background scenery. Places were chosen that had the right topography, climatic feel and plants. Where ancient mammals splashed through water, or grabbed a branch, the action (splashing, movement of the branch) had to be filmed. Then the animated beasts were married with the scenery in the studios of Framestore, the CGI company. This is hard to do, because shadowing and reflections had to be added, so the animals interacted with the backgrounds. If they run through a forest, they have to disappear behind trees and bushes, and their muscles have to move beneath their skin (Fig. 1.5); all this can be semiautomated through the CGI software.

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Figure 1.5 The sabertooth Smilodon as seen in Walking with Beasts (2001). The animals were reconstructed from excellent skeletons preserved at Rancho La Brea in Los Angeles, and the hair and behavior were based on studies of the fossils and comparisons with modern large cats. (Courtesy of Tim Haines, image © BBC 2001.)

Figure 1.5 The sabertooth Smilodon as seen in Walking with Beasts (2001). The animals were reconstructed from excellent skeletons preserved at Rancho La Brea in Los Angeles, and the hair and behavior were based on studies of the fossils and comparisons with modern large cats. (Courtesy of Tim Haines, image © BBC 2001.)

CGI effects are commonplace now in films, advertizing and educational applications. From a start in about 1990, the industry now employs thousands of people, and many of them work full-time on making paleontological reconstructions for the leading TV companies and museums. Find out more about CGI at http://www.blackwellpublishing.com/paleobiology/.

provided evidence for earlier positions of the oceans. Other classical and medieval authors, however, had a different view.

Fossils as magical stones_

In Roman and medieval times, fossils were often interpreted as mystical or magical objects. Fossil sharks' teeth were known as glossopetrae ("tongue stones"), in reference to their supposed resemblance to tongues, and many people believed they were the petrified tongues of snakes. This interpretation led to the belief that the glossopetrae could be used as protection against snakebites and other poisons. The teeth were worn as amulets to ward off danger, and they were even dipped into drinks in order to neutralize any poison that might have been placed there.

Most fossils were recognized as looking like the remains of plants or animals, but they were said to have been produced by a "plastic force" (vis plastica) that operated within the Earth. Numerous authors in the 16th and 17th centuries wrote books presenting this interpretation. For example, the Englishman Robert Plot (1640-1696) argued that ammonites (see pp. 344-51) were formed "by two salts shooting different ways, which by thwarting one another make a helical figure". These interpretations seem ridiculous now, but there was a serious problem in explaining how such specimens came to lie far from the sea, why they were often different from living animals,

Figure 1.6 Lying stones: two of the remarkable "fossils" described by Professor Beringer of Wurzburg in 1726: he believed these specimens represented real animals of ancient times that had crystallized into the rocks by the action of sunlight.

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