BEIJING, June 8 (Xinhua) -- An international team of researchers has found evidence of a parasite-host relationship in 512-million-year-old fossils.

The team, led by researchers from Northwest University, analyzed a cluster of brachiopod fossils, discovered in southwest China's Yunnan Province. They found that some tube-like creatures are affixed to the exterior of the brachiopod's shells.

The creatures are positioned at the same level as the brachiopod's opening where it would take in food, and researchers believe the tube-like creatures stole food from the brachiopod. They also found evidence that brachiopods with encrusting, tube-like creatures didn't grow as large as those without tubes on them.

Parasite-host systems are pervasive in nature but are extremely difficult to identify in fossil records. Researchers believe this is the oldest known evidence of parasitic relationships found in fossil records.

The study reveals parasite-host animal systems in early Cambrian, and their emergence may have played a key role in driving the evolutionary and ecological innovations associated with Cambrian radiation, according to the research.

The research was published in the journal Nature Communications.