289-million-year-old mummy fossil presents earliest evidence of rib-based breathing

Take a deep breath. Feel your ribs expand and your chest expand. This simple, rhythmic movement is a biological legacy that took almost 300 million years to form, and we finally have the “mummy” to prove it.

Paleontologists have uncovered a tiny, lizard-like fossil that rewrites the guide to how land animals conquered Earth.

Creature, Captorhinus agoutiHe died approximately 289 million years ago (early Permian period) in a cave in Richards Spur, Oklahoma, USA.

It was mummified in three dimensions, thanks to a strange mixture of anoxic mud and ancient oil leaks.

This unique environment preserved delicate soft tissues such as skin and cartilage, which often disappear over time, leaving the specimen frozen in its natural death position.

Exceptional protection

Fossil reveals oldest known evidence costal respiratory system. It showcases the ancestral mechanism that allows amniotes (reptiles, birds, and mammals) to breathe today.

“Captorhinus is an intriguing lizard-looking creature that is critical to understanding early amniote evolution,” said Ethan Mooney, a doctoral candidate in the Department of Organismic and Evolutionary Biology at Harvard University and co-chair of the study.

Despite its small size of just a few centimeters, this mummified fossil It contains organic molecules that are about 100 million years older than the previous record-holding dinosaur.

In this new study, the team used advanced neutron computed tomography (nCT) to look noninvasively inside the fossil.

It revealed a remarkably preserved “accordion-textured” structure. skin to wrap around the body of the animal.

This high-tech imaging, combined with examination of two other samples, allowed the reconstruction of the first complete respirator of the early amniote.

The researchers found a complete thoracic assembly, including a segmented cartilaginous sternum and several layers of ribs that anchor the ribcage directly to the shoulder.

He showed how these ancient reptiles transitioned to the complex, rib-powered respiration used by modern land animals.

rib assisted breathing

This discovery highlights a major evolutionary shift away from unproductive energy. breathe transfer of amphibians to the more powerful coastal aspiration system.

Before this, early amphibians swallowed air like water, using their throats to pump oxygen into their lungs. This was a tiring and inefficient process that limited an animal’s activity. captorhinus changed the rules.

Using his muscles to pull his ribs outward, he created a vacuum that pulled air deep into his lungs. This is known as costal aspiration. It was a huge upgrade. More oxygen meant more energy.

Greater energy allowed them to hunt, run and thrive in harsh inland regions where their amphibian cousins ​​could not pursue.

“We propose that the system found in Captorhinus represents an ancestral state of the type of rib-assisted respiration present in living reptiles, birds, and mammals.” in question Study co-author Professor Robert R. Reisz of the University of Toronto.

This tiny reptile represents the ancestral blueprint for nearly every land-dwelling vertebrate you see today.

Whether it’s a hawk soaring in the sky, a cheetah running across the savannah, or you sitting at your desk, we all use the rib-powered engine. captorhinus He pioneered in a dark Oklahoma cave during the Permian period.

These specimens, currently curated at the Royal Ontario Museum in Toronto, are available to the global scientific community for ongoing research.

The findings were published in the journal Nature On April 8th.