Cambrian Explosion
- 演化之聲
- Mar 14
- 4 min read
In the history of animal evolution, the Cambrian Explosion stands as one of the most important and fascinating episodes. Its recognition arose from early studies of stratigraphic fossils. Researchers were struck by the observation that Cambrian rock layers suddenly contained an abundant and diverse array of animal fossils. Compared with the strata from the preceding period, this represented a dramatic transformation and marked the beginning of the Phanerozoic Eon. As early as the eighteenth century, the paleontologist William Buckland had already commented on this phenomenon, and Charles Darwin himself referred to it in On the Origin of Species, expressing his puzzlement over the seemingly abrupt expansion of animal diversity during this time.
Fossils from the early Cambrian show that animals had already developed increasingly refined anatomical features. Symmetry, appendages, and internal organs became more clearly differentiated, and many organisms began to resemble the general body plans seen in modern animals. In some lineages body size also increased, and ecosystems gradually became more complex. Burrowing animals capable of penetrating sediments began to appear, reshaping the structure of marine substrates. At the same time, organisms with hard tissues such as skeletons and shells became more common, greatly improving the likelihood that their remains would be preserved in the fossil record. Trace fossils likewise reveal a growing diversity of animal activities and behaviors preserved in ancient sediments. Many modern animal phyla may trace their origins to this interval, and numerous Cambrian organisms can be placed within groups related to living animals, sometimes as early members of their evolutionary stem lineages.
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