To battle overheating, different giant dinosaurs devised different coping mechanisms
The sun can be harsh during summers. While smaller animals seek shade in the wild, larger ones are at risk of dying from stroke. But elephants and other large animals have devised methods to stay cool. And so did dinosaurs, thanks to certain regions in their heads. Now, new evidence has surfaced showing that different giant dinosaurs used different cooling means to keep themselves from dying of overheating.
Most modern-day animals use evaporation to cool their bodies by shuttling hot and cold blood in the blood vessels. The research team wanted to test whether dinosaurs did the same. Ruger Porter, Assistant Professor of Anatomical Instruction and lead author of the study, said, "One of the best ways to cool things down is with evaporation. The air-conditioning units in buildings and cars use evaporation, and it's the evaporative cooling of sweat that keeps us comfortable in summer."
Evaporative cooling, the study said, happens in regions where there's moisture, such as the eyes and especially the nasal cavity and mouth. "The brain and sense organs like the eye are very sensitive to temperature," said Porter.
To understand whether evaporation was playing a role in cooling, the team of scientists turned their attention to these evaporation regions in the modern-day relatives of dinosaurs: birds and reptiles. Earlier studies have shown that evaporation of moisture in the nose, mouth, and eyes cooled the blood on its way to the brain.
On the carcasses of birds and reptiles, they could see blood vessels in evaporative sites such as the nose, mouth, and eyes, with help from certain sophisticated instruments. They also precisely measured the bony canals and grooves that carried these blood vessels.
"The bony canals and grooves that we see in modern-day birds and reptiles are our link to the dinosaur fossils, said Porter, "we can use this bony evidence to restore the patterns of blood flow in extinct dinosaurs and hopefully get a glimpse into their thermal physiology and how they dealt with heat."
Following this, the scientists examined fossil records of dinosaur skulls. By looking at the bony canal sizes in different dinosaurs, scientists could assess the relative importance of the different sites of evaporative cooling based on the amount of blood flowing through them.
The results showed that different dinosaurs used different sites to cool their bodies. Giants like Sauropods used nasal cavity and mouth as cooling regions. Ankylosaurus used the nose. And Theropods like Majungasaurus and T. rex employed a huge air sinus in their snouts to do the job. However, smaller dinosaurs had a more balanced vascular pattern: they did not use any single cooling site.
The researchers are now expanding the project to include other dinosaur groups such as duck-billed hadrosaurs and horned ceratopsians like Triceratops to explore how thermoregulatory strategies varied among other dinosaurs and how these strategies may have influenced their behavior and even their preferred habitat," the press statement said.
The findings were recently published in the Anatomical Record.