Savannah Monitor Lizards Have Mammal and Bird-Hybrid System for Breathing

The biologists studied CT scans of the lizards' entire lung labyrinth.
Loukia Papadopoulos

In what may be the oddest news this week, biologists have discovered that Savannah monitor lizards have a mammal and bird-hybrid system for breathing. What is even weirder is that the reason for this strange breathing apparatus is still unknown.


“We don’t know why animals have different types of lung air flow,” said in a statement lead author Robert Cieri, a postdoc at the University of the Sunshine Coast. “Why do humans have the lungs we have verses the lungs of a bird? That’s not a simple question. By answering that, maybe we can find out more about our own history.”

Supercomputers needed

To study the lizard's breathing apparatus, the researchers used CT scans of the entire lung labyrinth. But the physics were so complicated that they had to run them through two supercomputers, one from the Center for High Performance Computing at the University of Utah and the other from the National Science Foundation Blue Waters, to simulate airflow patterns at the highest resolution.

“This study is important in demonstrating it is possible to numerically analyze patterns of airflow in these extremely complicated lungs. This quantitative ability opens up new avenues to study the basic mechanisms of how aerodynamic valve work, and gives us better tools to piece together the evolutionary history of these patterns of flow and the structures that underpin them,” said University of Utah biologist Colleen Farmer, senior author of the study.

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Colleen is no stranger to unusual breathing patterns. The biologist already studied alligators and iguanas' airflow patterns.

A hybrid breath cycle pattern

What Farmer discovered about Savannah monitor lizards' lungs is that they function around a long branchial tube where smaller tubes branch off to distribute air into tiny chambers. These small chambers are equipped with holes in their walls, allowing air to flow also from chamber to chamber.

All these chambers result in an airflow that changes over the course of a breath cycle, a pattern that is a hybrid of a bird and a mammal breathing system. The study is published in The Anatomical Record.