Ancestors of many modern animals originated in shallow water

(ORDO NEWS) — An international team of scientists has concluded that a large number of species during the Cambrian Explosion may have originated in the shallow waters of a river delta in present-day China.

The Cambrian Explosion – a dramatic increase in the number of fossilized living things – dates back to about 540 million years ago. And the Chengjiang biota, whose remains were found in southwestern China, is about 518 million years old and is considered one of the most famous formations of its kind.

Fossils of more than 250 species of living organisms have been found there , including worms, arthropods (ancestors of shrimp, insects, spiders, scorpions) and even the earliest vertebrates (ancestors of fish, amphibians, reptiles, birds and mammals).

The paleobiotic aspects of these life forms are well understood, but data on the sedimentary environment in which they originated are scarce and contradictory. But it is precisely such information that can shed light on the conditions under which the ancestors of modern living organisms were formed.

During the Cambrian explosion, living beings “turned around” from the so-called glancing reflection symmetry (look at charnia, whose prints are well known as an example of the Vendian fauna, and you will understand what is meant) to bilaterality – mirror reflection symmetry, when, relatively speaking, the left side of the creature copies the right side. That is, it was during the Cambrian explosion that almost all the ancestors of living organisms appeared.

ancestors of many modern animals originated in shallow water

Scientists from the Universities of Yunnan (China), Saskatchewan (Canada), Leicester (UK) and other scientific organizations concluded that the environment in which the Chengjiang biota developed was a shallow, nutrient-rich river delta affected by storm floods.

The researchers believe that the aquatic environment in which these organisms lived was shallower than previously thought. These waters were also well oxygenated.

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