The Cambrian is a geologic period of the Paleozoic Era, spanning approximately 539–485 million years ago, characterized by a major diversification of multicellular life known as the Cambrian explosion. It follows the Ediacaran Period and precedes the Ordovician. Stratigraphically, its base is defined by the first appearance datum of complex trace fossils such as Treptichnus pedum, and it is subdivided into series and stages based on biostratigraphic markers, particularly trilobites and small shelly fossils. The Cambrian is critical for calibrating early Phanerozoic evolutionary, paleoenvironmental, and tectonic reconstructions.
Extant and ancient cephalopods—including octopuses, squids, extinct ammonites, cuttlefish and nautiluses—have all had to solve the problem of buoyancy, whether they have hard external shells or not.
Evolution
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An international study led by researchers from the University of Tartu shows that approximately 470 million years ago, a significant ecological change took place in the world's oceans: For the first time, the interiors of ...
Ecology
Jul 22, 2026
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How life started on our own planet may not seem as interesting as finding evidence of life on Mars or the icy moons Europa or Enceladus. But the search for the first eukaryotes on Earth remains as important to astrobiology ...
Cell & Microbiology
Jul 20, 2026
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The earliest evidence of spiders' fangs has been identified in a 518-million-year-old fossil by scientists at the University of Leicester and Yunnan University.
Evolution
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The way that Earth's first animals reproduced held back life's diversity for millions of years, until stress and competition led to the development of sexual reproduction, which in turn accelerated the pace of evolution.
Evolution
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Bryozoans are tiny, filter-feeding colonial invertebrates that thrive in the world's oceans today, yet for decades their origins presented a puzzling gap in the fossil record. While nearly every other major animal group made ...
Evolution
Jun 3, 2026
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Tracks left by some of the earliest complex animals are giving new insights into how they experienced the world. New research reveals how these creatures started to understand their surroundings, paving the way for animal ...
Evolution
Jun 2, 2026
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New research published in BMC Biology helps to fill in questions about the so-called "Furongian gap" from about 497 million to 485 million years ago, when paleontologists previously thought there were far fewer fossils than ...
Evolution
May 28, 2026
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From butterflies to blue whales, corals and worms, Earth is home to an incredible diversity of animals. How all of these animals evolved from earlier, simpler ancestors is one of the most exciting stories in the history book ...
Evolution
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More than 500 million years ago, during what is known as the Cambrian period, the seas and oceans on Earth were filled with a myriad of marine animals, many of which have now become extinct. This evolutionary burst in new ...
