New Fossil Discovery Can Possibly Contribute 100s and Millions of Years to Evolution Research

Have you ever wondered how and when animals transitioned from one evolutionary stage to the next? When did animals first appear, where did they appear, and why did they appear? What were their personalities like?

For most of Earth's 4.5-billion-year existence, life has existed, but bacteria have dominated it.

Although scientists have been looking for evidence of biological evolution for almost a century, certain areas of the fossil record remain bafflingly mysterious, and uncovering evidence of Earth's first species has proven especially difficult.

Fossils

Sponges might have existed as long as 900 million years ago, based on these acceptable estimates. So, why haven't we discovered sponge fossils in rocks from those hundreds of millions of years ago?

Sponges do not have typical complex pieces is part of the solution to this issue (shells, bones). Although some sponges have an internal skeleton of small mineralized rods known as spicules, no credible spicules have been discovered in rocks dating from the concealed early animal evolution period. On the other hand, some sponges have a skeleton formed of strong protein fibers called spongin, which includes a unique, tiny, three-dimensional meshwork similar to that of a bath sponge.

The soft tissue of contemporary and fossil sponges has been calcified during decomposition, preserving them in the geologic record. A characteristic tiny meshwork of complexly branching tubes forms in the rock if the calcified aggregate solidifies around spongin fibers before they disintegrate. The branching pattern is distinct from that of algae, bacteria, or fungus, and it has been observed in limestones younger than 540 million years.

Microstructure

This same microstructure was recently reported in 890-million-year-old rocks from northern Canada by a geologist and paleobiologist who works on ancient limestone, claiming that it might be proof of sponges hundreds of millions of years older than the next-youngest undisputed sponge fossil.

Although the researcher's proposal appears to be outlandish at first glance, it aligns with standard predictions and assumptions in the paleontological community: the new evidence seems to validate an extrapolated timeline and a predicted identity for early animals that are already widely accepted.

If they are sponge fossils, animal evolution might be pushed back hundreds of millions of years.

The study's early potential sponges lived alongside limited cyanobacterial populations that provided oxygen oases in an otherwise low-oxygen environment before the Neoproterozoic oxygenation episode. Before more diversified creatures arose, these early sponges may have continued to live in similar habitats for hundreds of millions of years, presumably unmodified and unaffected by evolutionary pressure.

The presence of 890-million-year-old organisms further suggests that the contentious Cryogenian glacial periods - sometimes known as "snowball Earth" - that began approximately 720 million years ago had little impact on biological evolution.

Tackling Darwin's Dillema

The rare fossil material might shed new light on Darwin's conundrum. However, radical new ideas are seldom fully adopted by the scientific community without much debate, so I expect a lot of that. Nevertheless, a consensus may emerge based on more research at some time in the future, most likely years from now.

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