Ancient Shrimp Reveals Oldest Complex Circulatory System

The fossil of a shrimp-like creature that lived nearly 520 million years ago, unearthed with preserved heart and blood vessels, now represents the oldest-known cardiovascular system.

According to lead study author and professor of neuroscience at the University of Arizona, Nicholas Strausfeld, this specimen is the first preserved vascular system known to science. The fossil was unearthed in the Yunnan province of Southwest China and dates back to the "Cambrian Explosion,"--a time in which the first major animal groups were just starting to appear.

"This is a significant discovery," said museum palaeontologists Dr. Xiaoya Ma, via a press release. "Traditionally, there was a wide assumption that such delicate internal organ structures could not survive fossilisation, a theory now challenged by the recent discoveries of nervous and cardiovascular systems. These were not only preserved, they were preserved in exquisite detail."

The species, dubbed Fuxianhuia protensa, provides evidence of a small part of an organ system and a glimpse into the elaboration of its internal organs. According to Strausfeld, it showed similarities to modern-day crustaceans.

"It appears to be the ground pattern from which others have evolved. Different groups of crustaceans have vascular systems that have evolved into a variety of arrangements but they all refer back to what we see in Fuxianhuia," he said. "Over the course of evolution, certain segments of the animals' body became specialized for certain things, while others became less important and, correspondingly, certain parts of the vascular system became less elaborate."

However, researchers are still speculating just how the Fuxianhuia became fossilized.

"Presumably the conditions had to be just right," Strausfeld said. "We believe that these animals were preserved because they were entombed quickly under very fine-grained deposits during some kind of catastrophic event, and were then permeated by certain chemicals in the water while they were squashed flat. It is an invertebrate version of Pompeii."

More information regarding the findings can be seen via the journal Nature Communications.