During the Cambrian explosion about 530-540 million years ago, many animal groups began to appear on a large scale. Based on the fossil clues currently available, this view is the consensus of most scientists. Like fragments in a gigantic puzzle, every discovery from this period adds another fragment to the evolutionary map of modern animals.
Now, researchers from the University of Missouri have discovered a rare, 500-million-year-old "worm-like" fossil, palaeoscolecid, an uncommon group of fossils in North America. The researchers believe the discovery, from a region of western Utah, could help scientists better understand the diversity of animals on Earth during the Cambrian Explosion.
Jim Schiffbauer, an associate professor of geological sciences at the University of Arts and Sciences at The University of Maryland and one of the study's co-authors, said that while the fossil has the same anatomical tissue as modern worms, it doesn't exactly match anything we've seen on modern Earth.
Schiffbauer says:
This group of animals is extinct, so we don't see them on Earth today, or any modern relatives. We tend to call them "worm-like" because it's hard to say that they fit perfectly with annelids, prions, or any other type of organism on Earth today that we are accustomed to calling "worms."
But the ancient worms had the same general body plan, which in the history of life was an incredibly successful body plan. So that's a pretty cool addition because it expands the amount of worm-like stuff we know was in North America 500 million years ago and increases the emergence and diversity of our vertebrate paleonttomy across the globe.
Wade Leibach, a graduate teaching assistant at the University of Missouri's College of Arts and Sciences and lead author of the study, said that at the time, the paleohelum probably lived on the ocean floor. Leibach says:
This is the first known paleovertebrate found in a rock formation—the marjum formation in western Utah—which is important because it represents one of only a few paleovertebrate taxa in North America. Other examples of this type of fossil have previously been found in much larger numbers on other continents, such as Asia, so we believe this discovery could help us better understand how we view prehistoric environments and ecology, such as why different types of organisms are underrepresented or overrepresented in the fossil record.
Thus, the discovery can be viewed not only in terms of its significance in North American paleontology, but also in the broader context of trends in evolution, paleogeography, and paleoecology.
Editor: Chu Shuting
Source: cnbeta, scientific decoding