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Burgess Shale
Burgess Shale A rock formation in the western Canadian Rockies containing a wealth of fossilized invertebrates of the early Cambrian Period that were buried by an underwater avalanche of fine silt, preserving many details of their soft parts and providing valuable information about the evolution of early life.
[After nearby Mount Burgess.]Burgess Shale n 1. (Placename) a bed of Cambrian sedimentary rock in the Rocky Mountains in British Columbia containing many unique invertebrate fossils 2. (Geological Science) a bed of Cambrian sedimentary rock in the Rocky Mountains in British Columbia containing many unique invertebrate fossils [named after the Burgess Pass, where the bed is exposed]Bur·gess Shale (bûr′jĭs) A rock formation in the western Canadian Rockies that contains numerous fossilized invertebrates from the early Cambrian Period.Did You Know? Early animals on the Earth included many oddities. These animals had bizarre combinations of legs, spines, segments, and heads found in no animals since, as if Nature were trying out different models to see what might work best. Many of these animals became extinct and left no descendants. Others may have evolved into groups that are well known today. We know a lot about these bizarre life forms thanks to the Burgess Shale, a 540-million-year-old formation of black shale in the Rocky Mountains of British Columbia. Unlike most rocks in which fossils are preserved, the Burgess Shale preserved the soft parts of organisms that normally would have rotted away (by reacting with oxygen) before the animals became fossils. This happened because the animals were killed instantly by a mudslide deep in the ocean, where there is very little oxygen. After the mud buried the animals, it hardened into shale. Thanks to this, we know a lot about the period of early animal evolution known as the Cambrian Explosion.Burgess Shale
Burgess Shale a bed of Cambrian sedimentary rock in the Rocky Mountains in British Columbia containing many unique invertebrate fossils Burgess Shale[¦bər·jəs ′shāl] (geology) A fossil deposit in the Canadian Rockies, British Columbia, consisting of a diverse fauna that accumulated in a clay and silt sequence during the Cambrian. Burgess shale
Burgess shale 500 million year-old fossil-bearing strata discovered in the Canadian Rockies by the American palaeontologist Charles Walcott. The fossils are extremely well preserved and many have no relationships with present day organisms. Collectively, the fossils show an explosion of early life in which the variety of body forms exceeds that of the whole of the present day animal kingdom. Most are now extinct but others have close relationships with organisms which gave rise to present day forms. |