Fossil thought to be earliest bryozoan animal may actually be seaweed

A 515-million-year-old fossil as soon as regarded as the earliest recognized animal from a gaggle known as the bryozoans would possibly really be a seaweed.

Bryozoans, generally known as moss animals, are tiny, coral-like creatures that dwell in colonies in oceans and freshwater.

Nearly all main animal teams first seem within the fossil file between 541 and 520 million years in the past throughout an evolutionary occasion often known as the Cambrian explosion. Until two years in the past, the bryozoans had been the one animal group lacking from that occasion: the earliest fossil traces of bryozoans dated to 40 million years after it.

But in 2021, Paul Taylor on the Natural History Museum in London and his colleagues recognized the Cambrian fossil Protomelission gatehousei, unearthed in Australia and China, as a bryozoan – suggesting these animals didn’t arrive on the scene a lot later than different teams in any case.

Now, Martin Smith at Durham University, UK, and his colleagues have studied 12 new Protomelission-like fossils from Kunming in China, which underwent a type of preservation that maintained their tender tissues.

The crew discovered clumping formations of particular person tube-like buildings in a honeycomb sample – which may happen in each crops and animals. But they noticed no tentacles nor any frequently formed holes for tentacles to move by means of – the telltale indicators in later bryozoan fossils, says Smith. Instead, the researchers seen lengthy projections rising from the honeycomb that seem like flanges, buildings which are typical of sure sorts of inexperienced algae.

“You see these little conical flanges?” he says. “That’s not a good way to be an animal, really. But it’s a very good way to capture sunlight and be a photosynthesiser. This has shifted us from thinking ‘these are bryozoans’ to ‘these are definitely not bryozoans. These are seaweeds.’”

Specifically, the organisms look like a part of the Dasycladales order of inexperienced algae, he says.

Taylor, who wasn’t concerned within the new research, says it’s “an interesting and important discovery” that provides to the “jigsaw puzzle” about Cambrian sea life, nevertheless it doesn’t essentially show that Protomelission gatehousei wasn’t an animal.

In explicit, he questions whether or not the brand new fossils are actually Protomelission, particularly since there are important variations within the sizes of the specimens’ buildings.

Sara Pruss at Smith College in Northampton, Massachusetts, additionally has doubts about this. “Their whole argument really seems to hinge on that this new fossil that they have found is the same as has been found before,” she says. “It gave me a moment of pause.”

Even if it’s the identical, the lengthy projections might effectively be bryozoan tubular buildings, and the tender tentacle tissue would possibly merely not have fossilised, says Taylor. “Their absence is not at all surprising,” he says.

Nor is it significantly telling, says Pruss. “The absence of evidence is never good evidence, for a palaeontologist,” she says.

If the fossils are certainly algae, this might really assist higher clarify the atmosphere that supported the Cambrian explosion, says Smith. “Seaweeds are amazing habitats that can support this wealth of body plans that evolution was suddenly able to produce,” he says.