During the Cambrian explosion, thousands of new species appeared during a relatively short amount of time. The earliest forms of many modern species first emerged during the Cambrian explosion.

But according to a new study, the evolutionary gas pedal wasn't on the floor during the entirety of the period. There were periods of accelerated speciation, as well as brief slowdowns. Authors of the new study determined the period's ebb and flow was caused by fluctuating oxygen levels.

"The complex creatures that came about during the Cambrian explosion were the precursors to many of the modern animals we see today," lead study author Tianchen He, postdoctoral researcher at the University of Leeds, said in a news release. "But because there is no direct record of atmospheric oxygen during this time period it has been difficult to determine what factors might have kick started this crucial point in evolution."

To map fluctuating oxygen levels during the period, scientists analyzed carbon and sulphur isotopes in ancient rock samples. When scientists compared the timing of oxygen fluctuations, they found it correlated closely with the increases and decreases in the abundance of Cambrian fossils.

"This strongly suggests oxygen played a vital role in the emergence of early animal life," He said.

Scientists measured changing isotope ratios and fossil abundance in the lower Cambrian strata of Siberia. The ubiquitous limestone deposits host rich fossil records and provided ideal samples for isotopic analysis. The deposits also represent an ancient marine ecosystem, which hosted the majority of species present on earth during the period.

"Combining our isotope measurements with a mathematical model lets us track the pulses of carbon and sulphur entering the sediments in this critical evolutionary cradle," said researcher Benjamin Mills. "Our model uses this information to estimate the global balance of oxygen production and destruction, giving us new insight into how oxygen shaped the life we have on the planet today."

Researchers detailed the results of their analysis this week in the journal Nature Geoscience.

Related Links
Explore The Early Earth at TerraDaily.com

Tweet

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

Ancient relative of the blue-tongued skink found in Australia
Washington DC (UPI) May 01, 2019
Paleontologists in Australia have unearthed the complete skeleton of an ancient lizard, an early relative of modern blue-tongued and social skinks. Analysis of the remains - the most complete lizard fossil yet discovered in Australia - suggests the 15-million-year-old reptile was remarkably similar to modern lizards. Scientists described the new species, Egernia gillespieae, this week in the journal Vertebrate Palaeontology. "This creature looked like something in-between a tree ... read more