Archives par mot-clé : Cambrian

Scientists discover Earth’s youngest banded iron formation in western China

by University of Alberta, July 11, 2018 in ScienceDaily

Discovery provides evidence of iron-rich seawater much later than previously thought.

The banded iron formation, located in western China, has been conclusively dated as Cambrian in age. Approximately 527 million years old, this formation is young by comparison to the majority of discoveries to date. The deposition of banded iron formations, which began approximately 3.8 billion years ago, had long been thought to terminate before the beginning of the Cambrian Period at 540 million years ago.

The Early Cambrian is known for the rise of animals, so the level of oxygen in seawater should have been closer to near modern levels. “This is important as the availability of oxygen has long been thought to be a handbrake on the evolution of complex life, and one that should have been alleviated by the Early Cambrian,” says Leslie Robbins, a PhD candidate in Konhauser’s lab and a co-author on the paper.

Tiny fossils unlock clues to Earth’s climate half a billion years ago

by University of Leicester, May 9, 2018 in ScienceDaily

The research, published in Science Advances, suggests that early animals diversified within a climate similar to that in which the dinosaurs lived.

This interval in time is known for the ‘Cambrian explosion’, the time during which representatives of most of the major animal groups first appear in the fossil record. These include the first animals to produce shells, and it is these shelly fossils that the scientists used.

Data from the tiny fossil shells, and data from new climate model runs, show that high latitude (~65 °S) sea temperatures were in excess of 20 °C. This seems very hot, but it is similar to more recent, better understood, greenhouse climates like that of the Late Cretaceous Period.