what is burgess shale? what is the significance of this discovery to evolutionary biology
The Burgess Shale Formation, located in the Canadian Rockies of British Columbia, is one of the world's most celebrated fossil fields,[2] and the best of its kind.[3] It is famous for the exceptional preservation of the soft parts of its fossils. At 505 million years (Middle Cambrian) old[4] it is one of the earliest fossil beds containing the imprints of soft-parts.
The rock unit is a black shale, and crops out at a number of localities near the town of Field in Yoho National Park.
The Burgess Shale was discovered by palaeontologist Charles Walcott in 1909, towards the end of the season's fieldwork.[5] He returned in 1910 with his sons, daughter, and wife, establishing a quarry on the flanks of Fossil Ridge. The significance of soft-bodied preservation, and the range of organisms he recognised as new to science, led him to return to the quarry almost every year until 1924.
From Wikipedia, the free encyclopedia
The Burgess Shale is a fossil-bearing deposit located in the Canadian Rockies of British Columbia. It is renowned for its exceptionally preserved fossils from the Middle Cambrian period, around 508 million years ago. The significance of the Burgess Shale lies in the astonishing diversity and preservation of ancient marine organisms it contains.
To fully understand the significance of the Burgess Shale to evolutionary biology, it is essential to explain how the fossils were discovered and their impact on our understanding of the history of life.
1. Discovery: The Burgess Shale fossils were first discovered in 1909 by Charles Doolittle Walcott, a paleontologist and Secretary of the Smithsonian Institution. Over several years, Walcott collected thousands of fossils from the site.
2. Exceptional Preservation: What makes the Burgess Shale fossils so remarkable is their exceptional preservation. The soft-tissue structures of many organisms are preserved in intricate detail. Typically, fossils only preserve hard parts, such as shells or bones, but the Burgess Shale captures the delicate soft tissues, providing significant insights into the complexity of ancient life.
3. Biodiversity and Novel Morphologies: The Burgess Shale fossils represent a remarkable snapshot of the Cambrian explosion, a period of rapid evolutionary diversification. The fauna discovered at the site reveals a staggering diversity of previously unknown organisms, many of which have no modern descendants and possess unique anatomical features. These fossils challenge earlier assumptions about the evolution of life during the Cambrian period and the origins of major animal groups.
4. Understanding Ancient Ecosystems: The Burgess Shale provides crucial information about early marine ecosystems. The fossils reveal predator-prey relationships, symbiotic associations, and the ecological strategies employed by ancient organisms. This knowledge helps us build a more comprehensive understanding of the dynamics and interactions of ancient ecosystems.
5. Origins of Complex Animal Life: One of the most significant contributions of the Burgess Shale is shedding light on the origins of complex animal life. The fossils provide evidence that many complex body plans and adaptations seen in modern animals had already emerged in the Cambrian period. This challenges previous assumptions that complex life forms evolved gradually over an extended period.
In summary, the Burgess Shale fossils are of immense significance to evolutionary biology due to their exceptional preservation, revealing unique and diverse ancient organisms, providing insights into ancient ecosystems, and challenging previous notions about the origins of complex animal life.