Paleontologists from the School of Earth and Space Sciences, Beijing University, have studied many of the fossil embryos of the Marcuelia Hunanensis of the Marquelia family in recent years, but only now have they discovered a sample of the remaining tissues of the brain, and scientists have reported the discovery in the magazine Royal Society Open Science.
This is one of the embryos of the Marcuelia Hunanensis seaworm, a sister of modern pripulidams named because of its external resemblance to a human penis, and many of the remaining embryos of ancient worms have been discovered by researchers at different stages of development, but no adult has been identified.
An unusual discovery was made in fossil deposits in the western province of Hunan in China. Tiny embryos, not larger than 0.5 mm, were retained inside the limestone plate. Scientists dissolve the mineral using acid to extract the minerals of the grain.
After being released from the limestone, embryos were examined in a particle accelerator in Switzerland, and its powerful X-ray radiation allows for the taking of pictures of tiny embryos of worms; the sample rotates within the beam, creating more than 1,500 images of remains from different angles and is explained by scientists.
Usually, this analysis gives scientists only the appearance of a rigid outer shell of an animal, but in this case they are fortunate: this embryo had a clear, organized structure in its head that resembles a donut. By comparing the data with existing related species, scientists have concluded that this structure is the remains of a fossilized animal's ring brain. Moreover, in the tail of the worm, it has been possible to identify other structures that resemble muscles.
Researchers note that this is the first time that fossil neural tissue has been found in the ancient fossils of Orsten; the remains of this period are preserved in limestone by replacing animal tissues with calcium phosphate; it is believed that this process preserves only the outer body but not the soft tissue; a new discovery shows that this is not always the case, so that other discoveries containing fossil internal organs may be hidden in museums.