Scientists have discovered a fossil with the earliest known example of a cardiovascular system. The 520 million-year-old fossil may help scientists understand the evolutionary origins of the heart.
The team that found and analyzed the fossil included researchers from the University of Arizona, the United Kingdom and China. The ancient shrimp-like creature was found in the Yunnan province in the southwest China. The fossil is around half a billion years old and is considered an early arthropod. The researchers published their findings in the online journal Nature Communications.
The creature, which scientists have named Fuxianhuia protensa, lived during the Cambrian explosion. This period in the Earth's history is characterized by a sudden explosion of life when, in a relatively short amount of time, a huge number of species suddenly appeared and thrived. One of the most remarkable aspects of the Fuxianhuia is its cardiovascular system. The shrimp-like organism had a well-developed cardiovascular system with a heart and blood vessels.
"This is the first preserved vascular system that we know of," said Nicholas Strausfeld, University of Arizona Regents' professor of neuroscience.
While the primitive cardiovascular system may be considered the precursor to the more advanced and well-developed cardiovascular systems seen in many modern animals, the researchers say that the internal organizational system of the animal's heart and blood vessels are remarkably similar to its more modern counterparts.
"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. "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."
The Fuxianhuia fossil is only around 3 inches long. However, it was remarkably well-preserved in a slab of fine-grained mudstone. The fossil's state of preservation allowed the scientists to reconstruct its cardiovascular system. Even more surprising is the fact that the heart and blood vessels of the Fuxianhuia appear even more advanced than the similar structures found in modern crustaceans and arthropods.
"This is another remarkable example of the preservation of an organ system that nobody would have thought could become fossilized," Strausfeld said.
"With that, we can now start speculating about behavior," Strausfeld explained. "Because of well-supplied blood vessels to its brain, we can assume this was a very active animal capable of making many different behavioral choices."
Aside from the well-preserved cardiovascular system, the fossil also gave scientists a good look at the creature's antennae, eyes and other external organs.
"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."
