Science continues to find surprising secrets from the past. A 290 million-year-old fossil was discovered in the United States and changes what was known about respiration in terrestrial animals.
The respiratory system of the so-called Captorhinus was useda species of extinct lizard that lived in the period Lower Permian (between 290 and 273 million years ago), surprised researchers for multiple reasons.
The remains of this animal were found mostly in North America, but remains of other similar specimens also appeared in Africa. In particular, the fossil studied was in a paleontological site in Oklahoma, and is now kept in the Royal Ontario Museumin Toronto.
The main references of the study are Robert Reisz y Ethan Mooneyfrom the biology department of the University of Toronto Mississauga, Ontario (Canada). According to experts, their exceptional conditions made it possible to reconstruct how these first reptiles breathed using their rib cage.
What was this animal discovered in North America breathing like?
«Respiration by costal aspiration was a fundamental evolutionary innovation for conquest of the terrestrial kingdom by amniotes (mammals, reptiles, birds and their common ancestor)», says the abstract presented in the study and published in the journal Nature.
It indicates that current amniotes breathe thanks to an integrated thoracic system, where the rib muscles actively control the entry and exit of air. This differentiates them from their anamniote relatives, which use more passive mechanisms, such as breathing through the skin or mouth.
As they explain, this difference extends until the Paleozoic era, but the evolutionary transformation between these breathing modes is not documented and is largely uncertain in the absence of soft tissue fossils.
«We present the mummified Permian reptile Captorhinus, which includes a covered with three-dimensional skin, remains of native proteins and a shoulder girdlery rib cage complete with preserved cartilage,» he highlights about the discovery.
It delves into the fact that what was found are the oldest known preserved cartilage and protein remains in a terrestrial vertebrate. «High-resolution neutron computed tomography and histological data reveal previously undescribed structures,» the study details.
The experts assured that the skeletal reconstruction of the ancient reptile revealed «the precise relationships between the rib cage and the shoulder girdle, and its fundamental role in the evolution of terrestrial respiratory and locomotor regimes».
This finding substantially changes expectations about soft tissue preservation in deep geological time to reveal the possible ancestral respiratory mechanism of amniotes and its impact on the evolution of terrestrial vertebrates.
