520-million-year-old animal fossil fills gaps in evolution

The rare find could help scientists better understand anthropods.
Loukia Papadopoulos
Artist recreation of Kylinxia.jpg
Artist recreation of Kylinxia.

X. Wang 

A team from the University of Leicester, Yunnan Key Laboratory for Palaeobiology and the Institute of Palaeontology at Yunnan University, Chengjiang Fossil Museum, and the Natural History Museum in London, have discovered a 520-million-year-old fossil animal named Kylinxia that was kept in pristine condition.

As such, they have successfully managed to reconstruct it and now hope that it can help fill the gaps in understanding the evolution of species of ancient animals known as arthropods.

This is according to a press release by the institutions published in Tuesday.

CT scanner

The researchers used a CT scanner to image the species and found that it had three eyes on its head and powerful limbs for catching prey.

“The preservation of the fossil animal is amazing. After CT-scanning we can digitally turn it around and literally stare into the face of something that was alive over 500 million years ago. As we spun the animal around, we could see that its head possesses six segments, just as in many living arthropods,” said lead author of the study Robert O’Flynn, a PhD student at the University of Leicester School of Geography, Geology and the Environment.

The fossils were found in the Cambrian Chengjiang biota of China’s Yunnan Province. The area has been responsible for producing over 250 species of exceptionally preserved fossil organisms.

“Kylinxia, and the Chengjiang biota whence it came, are instrumental to building our understanding of early euarthropod evolution. I like to think that similar discoveries will continue to be made by Robert,” said professor Mark Williams, Robert’s primary supervisor at the University of Leicester, said:

Fossils of marine animals date as far back as half a billion years ago and are a true testament to a time when complex ecosystems were thriving in the world’s oceans.

The new fossil will add to the growing pool of data on the history of arthropods, animals whose bodies are divided into segments similarly to those found today in crabs, lobsters, insects, and spiders.

“Robert and I were examining the micro-CT data as part of his doctoral thesis in the hope of refining and correcting previous interpretation of head structures in this genus, Kylinxia. Amazingly, we found that its head is composed of six segments, as in, e.g., insects,” said professor Yu Liu from the Yunnan Key Laboratory for Palaeobiology.

A popular species

Anthropods are popular in fossil records but most only have their hard skeletons to identify them. Kylinxia, on the other hand, was found nearly complete, allowing scientists to effectively image the species. 

“Most of our theories on how the head of arthropods evolved were based on these early-branching species having fewer segments than living species. Discovering two previously undetected pairs of legs in Kylinxia suggests that living arthropods inherited a six-segmented head from an ancestor at least 518 million years ago,” said Dr Greg Edgecombe from the Natural History Museum.