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Monday, May 5, 2014

GotRadio Todays Country

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One, two, three trilobites. Trilobites, at this particular time, right at the beginning of the Cambrian, began to proliferate into all sorts of forms. These creatures, for the next million years, were probably the most advanced forms of life on this planet. To see how advanced the trilobites eventually became, I'm going to North Africa. In Morocco, on the southern flanks of the Atlas Mountains, the hills contain an amazing variety of them. They were only discovered a few years ago, but now the demand for them is so great that digging them out has become a major industry. These rocks, which were laid down about million years after the Burgess Shale, also contain trilobites. The trouble is, the rock is very hard and the trilobites are quite rare. But when these people find them, their specimens are absolutely extraordinary. Some species have features that are so delicate that it can take days, sometimes weeks, to fully prepare a specimen. Skilled technicians use dentists' drills to get down to the finest detail. Every particle of rock must be carefully removed, with enormous patience and absolute precision. The end results reveal that trilobites moulded their external skeletons into an almost unbelievable variety of shapes. And that enabled them to colonise a great variety of habitats, just as modern arthropods still do today. There were about , different trilobite species that we know of, and doubtless there are still many more to be discovered. Their hard exoskeletons not only ensured their abundance in the fossil record, they also tell us a lot about their owners' lives. Many of the trilobites that are found in these cliffs are curled up like this one. Sometimes even more tightly than this is, with their tail tucked underneath their heads. And it's clear that this was some kind of protective posture, just as it is for some kinds of woodlice that you find in the garden today. That protected them against their enemies.

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