Scientists have uncovered a collection of “extraordinary” microfossils that preserve muscular tissue from a 535 million-year-old organism. The fossils were discovered in the Kuanchuanpu geological formation in China’s southern Shaanxi Province. The findings were published in the journal Proceedings of the Royal Society B by the Royal Society.
This geological stratum in China is rich in fossils, which have helped shed insight into the Cambrian boom, which began some 540 million years ago.
Cambrian eruptive period
The Cambrian epoch lasted around 539-485 million years. The Cambrian explosion is the name given to the explosion that occurred at the beginning of the Cambrian epoch.
Over many million years, the explosion was characterized by an unprecedented emergence of organisms, including the initial appearance of most of the main animal groupings we know today.
The microfossils discovered in the newest study originate from the early Cambrian period, known as the Fortunian Age.
It is unclear which animals the fossils belong to. However, the researchers believe the preserved muscle tissue is from a species known as cycloneuralians. The presence of retained muscle or nerve tissue among these cycloneuralins is new discovery and has never been heard of before.
What is the significance of this discovery?
The discovery is remarkable because it sheds light on early animal muscular systems, which are often not survive in the fossil record yet are critical in understanding early animal behavior.
“Such fossils are extremely rare—literally a needle in a haystack,” Shuhai Xiao, a researcher in Virginia Tech’s Department of Geosciences and one of the study’s authors, told Newsweek.
The cycloneuralian category contains animals with worm-like bodies, such as roundworms and mud dragons. The group initially occurs in the fossil record at the start of the Cambrian epoch, and numerous species are still alive today.
The researchers reveal three fossil specimens, measuring only a few millimeters across, that they claim show surviving cycloneuralian muscle tissue from the proboscis—a type of sucking apparatus.
Among the specimens, NIGP179459 is the best preserved, having five successively larger rings with interconnected features that the researchers interpret as surviving probosci’s muscle tissue.
According to the researchers, it is unclear why the muscle tissue was kept in isolation from the host animal.