A sponge-like fossil going back 890 million years might be the world's earliest ancient mammalAccording to a new study published in the scientific journal Nature, the fossils were discovered in Canada's Northwest Territories.

Oldest-Body Fossil

Cyanobacteria Microfossils
(Photo : Wikimedia Commons)

"The material described here would represent the oldest body-fossil evidence of animals known to date and would provide the first physical evidence that animals emerged before the Neoproterozoic oxygenation event and survived through the glacial episodes of the Cr," researchers said.

While most major animal groupings first emerge in the fossil record approximately 541 million years ago, the new discovery shows evidence of sponge fossils that might be 350 million years earlier.

Images of microscopically examined 30-m-thick rock slices from the about 890-million-year-old Little Dal reefs back up the petrographic investigation.

"The Little Dal vermiform tubules' shape, size, branching style, and polygonal meshworks closely resemble both spongin fiber networks of modern keratose sponges and vermiform microstructure either demonstrated or interpreted to be sponge-derived in diverse Phanerozoic microbial, reefal, and non-reefal carbonate rocks" the study concludes.

Predating Conventional Animals

Aplysina aerophoba (IMAGE)
(Photo : A. Riesgo)

Following the study's publication, author and Laurentian University sedimentary geologist Elizabeth Turner stated in a Nature article that if her findings are correct, animals existed "far, long before the first appearance of conventional animal fossils."

"That would indicate there's a long history of animals that weren't properly preserved," she speculated.

Turner had kept her contentious findings for more than two decades, according to Smithsonian Magazine.

While some are suspicious of Turner's findings, she told Nature that none of the known reef-building species from almost 900 million years ago, such as cyanobacteria or algae, could explain the tiny tube-like structures she saw in her samples.

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In Need of More Evidence

Some experts, including Turner, stated they needed more evidence to say the fossils discovered were sponge fossils. The paleontological community is split on the cause of death of creatures from before the Cambrian Period.

 

According to the Smithsonian Museum of Natural History, the Sponges were among the first creatures, with evidence indicating that they evolved more than 700 million years ago.

Sponges

Green and yellow sea sponges, Antarctica
(Photo : From Steve Rupp, National Science Foundation)

Sponges, which are multicellular creatures, require a small amount of oxygen to metabolize, and they feed by collecting food particles from water pushed through their bodies by specific cells.

"A sponge's basic body design consists of layers of cells around water-filled holes, which are supported by complex skeletal components. The evolution of increasingly sophisticated and diversified body designs will eventually lead to the formation of separate animal groupings, "the museum observes

According to Smithsonian Magazine, the sponges in Turner's rocks thrived around the time when the supercontinent Rodinia broke apart and swamped ancient Canada.

Living Beneath Frozen Seas

Agate Fossil Beds National Monument, Nebraska
(Photo : Wikimedia Commons)

According to Turner, the sponge might have lived beneath the frozen seas of the Earth by dwelling in cracks and holes of the ancient microbial reef and near to oxygen-producing photosynthetic cyanobacteria or other bacteria-derived nutrients.

She informed them, "There was undoubtedly a delightful and extremely plentiful supply of 'snot' for these filter-feeding creatures to devour."

Also Read: 5 Most Important Fossil Discoveries in the World

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