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Evolution ran wild 500 million years ago in the friendly waters of the Grand Canyon, study suggests

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Original Story by CNN
July 24, 2025
Evolution ran wild 500 million years ago in the friendly waters of the Grand Canyon, study suggests

Context:

Paleontologists have uncovered remarkable fossils in the Grand Canyon that provide new insights into the emergence of complex life approximately 500 million years ago. The findings reveal that the Grand Canyon was once a 'Goldilocks zone,' offering optimal conditions for life to flourish during the Cambrian explosion, a period when most animal body types appeared in a short timeframe. The team discovered well-preserved internal fragments of soft-bodied mollusks, crustaceans, and priapulids, or penis worms, which allow for a detailed study of their morphology and lifestyle. These discoveries highlight the diverse evolutionary innovations of Cambrian animals in response to the rich, oxygenated environment, which enabled them to develop unique adaptations for survival. The study draws parallels between economic investment strategies and evolutionary risk-taking in times of abundance versus scarcity, illustrating how favorable conditions allowed for greater evolutionary experimentation.

Dive Deeper:

  • The Grand Canyon was once a warm, shallow sea teeming with life, located closer to the equator during the Cambrian period, which provided ideal conditions for an evolutionary explosion of diverse animal body types.

  • Paleontologists discovered fossils of soft-bodied species, including mollusks, crustaceans, and priapulids, within the canyon's sedimentary rock layers, offering new insights into the morphology and lifestyles of Cambrian animals.

  • The Cambrian explosion, a pivotal evolutionary event, is believed to have been driven by increasing oxygen levels in Earth's atmosphere, which allowed animals to metabolize food more efficiently and engage in predatory behavior, spurring an evolutionary 'arms race.'

  • The Grand Canyon's ecosystem, with its optimal depth and oxygen-rich environment, allowed sunlight to reach photosynthesizing plants on the seafloor, supporting a complex food web and enabling animals to develop novel feeding strategies.

  • Among the unusual findings were extinct penis worms, with mouths that turned inside out and were lined with hairy teeth, and crustaceans with fine-haired limbs used for capturing and grinding food, showcasing the innovative adaptations of Cambrian fauna.

  • The study highlights the evolutionary parallels with economic theories, where abundant resources allow for risk-taking and innovation, while scarcity leads to conservative strategies, illustrating how favorable conditions facilitated evolutionary experimentation in the Cambrian era.

  • This research contrasts with fossil finds from harsher environments, such as Canada's Burgess Shale and China's Maotianshan Shales, emphasizing the unique evolutionary pressures and opportunities presented by the Grand Canyon's Cambrian ecosystem.

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