Ancient 289-Million-Year-Old Mummy Discovered in Oklahoma Cave Reveals Origins of Human Breathing Mechanism

Harvard researchers discover the oldest costal breathing system in a mummified Permian reptile, identifying 289-million-year-old skin and proteins.

By: AXL Media

Published: Apr 8, 2026, 11:42 AM EDT

Source: Information for this report was sourced from EurekAlert!

A Discovery Frozen in a Permian Cave

The fundamental way humans breathe—by expanding the ribcage to draw air into the lungs—has been traced back to a lizard-like creature that lived nearly 300 million years ago. A new study published in Nature describes the extraordinary preservation of Captorhinus aguti, a small reptile found in a cave system near Richards Spur, Oklahoma. The site's unique conditions, characterized by oxygen-free mud and oil-seep hydrocarbons, acted as a natural mummification chamber, preserving the animal in its final "death pose" with its arm tucked beneath its body.

Visualizing Soft Tissue with Neutron Tomography

To study the delicate remains without damaging the specimen, an international team led by PhD candidate Ethan Mooney used neutron computed tomography (nCT) in Australia. The scans revealed a three-dimensional "wrapping" of scaly skin around the torso and neck, featuring an accordion-like texture similar to modern burrowing reptiles. Beyond the skin, the team identified a complete breathing apparatus, including a segmented cartilaginous sternum and intermediate ribs. This represents the first time such structures have been visible in the fossil record for an early amniote.

Evolutionary Shift from Amphibian to Amniote Breathing

Before this discovery, the understanding of early terrestrial respiration was largely based on amphibian strategies, which involve pumping air using the mouth and throat or absorbing oxygen through the skin. The costal aspiration system found in Captorhinus—using muscles between the ribs to compress and expand the chest—was an evolutionary "game changer." This method is far more efficient, supporting the high-energy, active lifestyles that allowed early ancestors of mammals and reptiles to dominate terrestrial environments.