An international research team has discovered move evidence the inner workings of ancient Earth's creatures were actually quite similar to those of humans.

Scientists from the University of Arizona, China and the United Kingdom say they've unearthed a fossil creature buried more than half a billion years ago that clearly shows the first known cardiovascular system, complete with heart and blood vessels, in extremely well-preserved detail.

"This is the first preserved vascular system that we know of," said Nicholas Strausfeld, a professor of neuroscience at the University of Arizona and one of the world's foremost experts in arthropod morphology and neuroanatomy.

Strausfeld, who worked on the fossil analysis, indicated the findings shed new light on the evolution of body organization in the animal kingdom .

in an "invertebrate version of Pompeii"

The 3-inch-long fossil was entombed in dust-like particles, now preserved as fine-grain mudstone, during the Cambrian Period 520 million years ago in the area known today as the Yunnan province in China.

Found by co-author Peiyun Cong near Kunming,the province's capital and biggest city, the shrimp-like animal belongs to the species Fuxianhuia protensa, an extinct line of arthropods known for their advanced internal anatomy within a relatively basic body structure.

The Fuxianhuia in question appears to have perished with a multitude of other creatures in the researchers called an "invertebrate version of Pompeii," a reference to the Roman city that was buried, along with many of its residents, under a thick blanket of volcanic ash and pumice when Mount Vesuvius erupted in 79 A.D.

"Fuxianhuia is relatively abundant, but only extremely few specimens provide evidence of even a small part of an organ system, not even to speak of an entire organ system," said Strausfeld, who directs the UA Center for Insect Science.

"The animal looks simple, but its internal organization is quite elaborate. For example, the brain received many arteries, a pattern that appears very much like a modern crustacean," he said, adding that the Fuxianhuia's vascular system is actually more complex than what is found in many modern crustaceans.

"It appears to be the ground pattern from which others have evolved," Strausfeld said.

Those insights are included in the research team's study, "An exceptionally preserved arthropod cardiovascular system from the early Cambrian," published in Nature Communications.