Fossils: Sponges in 890 MILLION-year-old reefs in Canada may be the earliest known animal on Earth

The earliest known animals on Earth may have been found, in the form of sponges that lived 890 million years ago in what is today northwestern Canada, a study reported.

Paleontologist Elizabeth Turner of Laurentian University in Sudbury, Canada, found spongy structures in the tissue of rocks of the fossilized Little Dal reefs.

The small, tube-like structures resemble those in some species of modern sponges and were found around calcium carbonate reeds constructed by bacteria.

If the microstructures do turn out to be the remains of ancient sponges, they would be about 350 million years older than today’s oldest known sponges.

In addition, they would be proof that animal life arose 90 million years earlier than previously thought based on changing oxygen levels in the air.

It was believed that animal life only came on the scene after oxygen levels were ramped up in the so-called Neoproterozoic oxygenation event.

The earliest known animals on Earth may have been found, in the form of sponges that lived 890 million years ago in what is today northwestern Canada, a study reported. Pictured: The spongy microstructures paleontologist Elizabeth Turner found in rocks of the Little Dal Reefs

The small structures the researcher found in rocks around the bacterially produced calcium carbonate reefs resemble those in some species of modern sponges (pictured)

The small structures the researcher found in rocks around the bacterially produced calcium carbonate reefs resemble those in some species of modern sponges (pictured)

Sponges are the most well-known species of animals and prime candidates in the hunt for the Earth’s oldest biological fossils.

Analysis of the genome of sponges has shown that they first evolved during the early Neoproterozoic, between about 1,000 and 541 million years ago.

However, evidence of genuine fossil sponges from this period in the rock record was notably lacking.

In her study, Dr. Turner analyzed rock samples extracted from the Little Dal reefs, which were built up by a type of bacteria that produces calcium carbonate deposits.

Under the microscope, she identified branching networks of tubular (vermiform) structures that resemble the fibrous skeletons found in modern keratosis, or “horny” sponges, such as the kind used to make commercial bath sponges.

Each tube structure, Dr. Turner, contained and was surrounded by crystals of the mineral calcite, in addition to structures previously identified in calcium carbonate rocks thought to have formed from the decay of keratoses sponges.

In her study, Dr. Turner analyzed rock samples extracted from the Little Dal reefs, which were built up by a type of bacteria that produces calcium carbonate deposits.  Under the microscope, she identified branching networks of tubular (vermiform) structures that resemble the fibrous skeletons found in modern keratosis, or

In her study, Dr. Turner analyzed rock samples extracted from the Little Dal reefs, which were built up by a type of bacteria that produces calcium carbonate deposits. Under the microscope, she identified branching networks of tubular (vermiform) structures that resemble the fibrous skeletons found in modern keratosis, or “horny” sponges (as pictured)

Each tube structure (shown here under three magnification levels) contained and was surrounded by crystals of the mineral calcite, in addition to structures previously identified in calcium carbonate rocks thought to have formed from the decay of keratoses sponges.

Each tube structure (shown here under three magnification levels) contained and was surrounded by crystals of the mineral calcite, in addition to structures previously identified in calcium carbonate rocks thought to have formed from the decay of keratoses sponges.

“The millimetric to centimetric worm-shaped microstructured organism lived alone on, in and immediately adjacent to reefs built by calcifying cyanobacteria,” explains Dr. Turner in her paper.

She added that the alleged sponge “occupied microniches in which these calcimicrobes could not live.”

‘In the event that [the] vermiform microstructure is in fact the fossilized tissue of keratoses sponges, the material described here would be the oldest body fossil evidence of animals known to date.

In addition, she continued, it would provide “the first physical evidence that animals emerged before the neoproterozoic oxygenation event and survived through the [subsequent] ice ages of the cryogenic period.’

The study’s full findings were published in the journal Nature.

Paleontologist Elizabeth Turner of Laurentian University in Sudbury, Canada, found spongy structures in the tissue of rocks of the fossilized Little Dal reefs

Paleontologist Elizabeth Turner of Laurentian University in Sudbury, Canada, found spongy structures in the tissue of rocks of the fossilized Little Dal reefs

If the microstructures do turn out to be the remains of ancient sponges, they would be about 350 million years older than today's oldest known sponges.  Pictured: The field location in northwestern Canada where Dr.  Turner found the tube-like microstructures

If the microstructures do turn out to be the remains of ancient sponges, they would be about 350 million years older than today’s oldest known sponges. Pictured: The field location in northwestern Canada where Dr. Turner found the tube-like microstructures

THE NEOPROTEROZOIC OXYGENATION EVENT EXPLAINED

The neoproterozoic oxygenation event — believed to have occurred some 800 million years ago — marks the time when levels of oxygen in the air rose to the levels normally needed to sustain animal life.

This episode in Earth’s history saw oxygen levels in the atmosphere rise to 0.1-0.5 times the current atmospheric level — while oxygenating the deep ocean from the very first time as well.

However, the exact cause of the episode remains disputed by geologists – although tectonic activity is often put forward as a possible cause.

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