This is why the reptiles may one day inherit the Earth, experts say

Dec 12, 2013 09:23 GMT  ·  By
Monitor lizards have unidirectional breathing, researchers at the University of Utah determined in a new study
   Monitor lizards have unidirectional breathing, researchers at the University of Utah determined in a new study

One of the potential reasons why lizards are so successful as a group is that they are able to extract oxygen from the air they breathe during both inhalation and exhalation. This capability is usually associated with birds, not land animals, and may hint at the fact that lizards may once again reign supreme on our planet in the distant future. 

Researchers from the University of Utah in Salt Lake City say that this research poses a series of very interesting questions. For example, it would be very interesting to know why this feature – called unidirectional breathing – appeared in lizards and, most importantly, why.

When birds were shown to be capable of unidirectional breathing, evolutionary biologists quickly figured out that this evolutionary adaptation had occurred to provide these creatures with the vast amounts of energy they needed to sustain prolonged flight.

But this line of reasoning does not necessarily apply to lizards. The new discovery forces scientists to conduct additional studies on the origins of unidirectional breathing. Another interesting thing to establish would be whether or not the trait evolved in parallel in these two groups of animals.

“To go and find a similar air-flow pattern in animals as distantly related [to birds] as monitor lizards is mind blowing,” comments evolutionary biologist Mathew Wedel, from the Western University of Health Sciences in Pomona, California. He was not a part of the research effort, Nature reports.

The advanced breathing mechanism was identified in the savannah monitor lizards (Varanus exanthematicus) by a team of scientists led by Colleen Farmer and Emma Schachner, both evolutionary biologists at UU. Their work is detailed in the latest issue of the top scientific journal Nature.

The team explains that the air lizards inhale does not return to the outside world via the same pathway it used going in. Humans exhale air through the same pathway, but monitor lizards have a series of dedicated chambers where air flows after exiting the lungs. These chambers extract oxygen yet again.

If unidirectional breathing occurred in the latest common ancestor of lizards, birds and crocodiles, then this adaptation may be no less than 270 million years old. The alternative explanation is that the trait appeared in what scientists refer to as parallel evolution, where the same adaptation appears in two unrelated groups of animals independently of each other.

The new findings “might explain something about why monitor lizards are so successful. Who knows when the next asteroid hits, maybe monitor lizards will inherit the Earth,” Wedel concludes.