Hoyal Cuthill, Jennifer F. Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom.
- Body plan modeling
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Enigmatic fossil macroorganisms, assigned to the taxon Rangeomorpha, that possessed a characteristic frond. To Charles Darwin, writing in 1859, and even to paleontologists in the early twentieth century, the evolutionary origins of macroorganisms (organisms large enough to be seen with the naked eye) remained a mystery. Rocks of Cambrian age, laid down 541 to 485 million years ago (MYA), were known to preserve fossils of recognizable marine animals (such as worms, arthropods, and cnidarians). However, no fossils of animals themselves, or their close relatives, were known from the Precambrian Era (4600–541 MYA), although tantalizing trace fossils of possible burrows and trails had been found. See also: Cambrian; Fossil; Geologic time scale; Paleontology; Phylogeny; Precambrian; Trace fossils
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