Canadian scientists report in a new study that this is one of the oldest examples in the fossil symbiosis fossil record, which is a long-term close interaction between two species.

About acorn bugs

These two marine worms are a bit strange, and their relatives still exist today.

The larger of the two is an acorn worm, which has an acorn-shaped head, a collar on its bottom, and a worm-like body, giving them the shape of a penis. The fossil specimen is about 5 cm long and 1 cm wide, and the size is similar to the cap of a drawing pen.

They have nothing to do with parasites such as earth or roundworms. Instead, they are “half-legs” closely related to sea urchins and chordates (and humans and other animals with backbones).

In more than 500 million years, the appearance of acorn worms has hardly changed.

Karma Nanglu, the lead author of the new study, said: “If there is a modern species next to me, the two look almost identical.” Published in Proceedings of the Royal Society B.

Nanglu, a postdoctoral researcher at the Smithsonian’s National Museum of Natural History in Washington, DC, and Jean-Bernard Caron, curator of invertebrate paleontology at the Royal Ontario Museum in Toronto, conducted the research.

In previous research, they found that although modern acorn worms dig soil in simple caves lined with slime, their ancient Cambrian relatives Use a protein called collagen in the seabed to make a strong, delicate tube.

Naglu said these pipelines were probably built as a defensive strategy to withstand predators from 506 to 508 million years ago that existed in the shallow waters where the Burgess Shale was formed.

At a site called Raymond Quarry in the Burgess Shale, the large acorn worm tube contained multiple acorn worms, indicating that they may have cooperated in construction.

The researchers suggested that they may also be minors living in houses built by adults, but there is no obvious evidence to prove this.

About mane worms

These test tubes also contain another tiny roommate-a worm with bristles the size of a sewing needle (not including its bristles).

Setaria worms, which scientists call polyhair et, are actually close relatives of of, and are tangled in loops, each with a pair of bristles. There are more than 10,000 modern species of various shapes and sizes, including some that resemble tiny fossil worms found in ancient acorn worm caves.

Interestingly, modern bristle worms are notorious house animals that live in caves, pipes, shells or even the bodies of many other animals, and there are even reports that they live with acorn worms.

He said that the use of another animal to build a house is “a very common symbiosis.”

It is not clear what is the acorn worm to get rid of this relationship. These two species do not have any specific body parts, suggesting that they are dependent on each other like some symbiotic animals.

This led the researchers to conclude that this may be a “common” relationship, where only bristle worms would benefit, while acorn worms would not be affected.

“Beyond Lucky” Fossil Discovery

Nan Lu said the discovery is exciting because there is very little behavioral evidence in the fossil record.

Nanglu said: “The interaction between the species perfectly preserved in the rock is really lucky.” “Then the second thing is…this is not the link between the two fossils that are easily fossilized. These parts are in Two of the rarest animals found in this exquisite detail.”

That’s because fossils tend to preserve hard things such as bones and shells, while fossils of mollusks are rare.

This new research was funded by the Smithsonian’s National Museum of Natural History and the Peter Buck Deep Time Postdoctoral Fellowship from the Natural Sciences and Engineering Council of Canada.

Professor Leif Tapanila, director of the Idaho Museum of Natural History, studies fossil evidence of animal interactions. He called the worm fossils “an amazing discovery” and said the evidence of their cohabitation was “convincing.”

Even though they are rare, they are not the oldest or only symbiosis example found in Cambrian fossils. In 2017, scientists at the Natural History Museum in London Reports on fossils of marine worms from China 520 million years ago with smaller worms attached to them.

Tapanilla also found Track fossils left by worms living on coral skeletons From a later period, the Ordovician. But he said that the type of cohabitation in this new study is different and provides evidence for the type of interaction he might expect in such a complex ecosystem.

He said: “Seeing animals that are closely linked, living in a common space… hints at the cooperation between two species that I think are still mysterious.”

“Like many cooperative symbiosis, are they helping each other and creating resources for each other? Maybe someone will come across fossils in the future… This will allow us to further explore this mystery.”