To this day, many still believe that many dinosaurs during the Mesozoic period were cold-blooded giants that dominated the land over other warm-blooded animals, but some scientists are arguing that some, if not many, of these building-sized animals were actually warm-blooded.
Professor Roger Seymour from the University of Adelaide’s School of Earth and Environmental Sciences is arguing that if large-sized dinosaurs were cold-blooded they would not be able to maintain the terrifying physical abilities that helped them rule the land.
Modern day saltwater crocodiles are vicious creatures that pack layers upon layers of muscles, and on average they have about a 50 percent muscle mass. To maintain a good body temperature, these 1-ton crocodiles bathe in the sunlight all day, and are able to retain what they soaked in by simply being large and slow. Large Dinosaurs, Seymour says, “could have done the same and enjoyed a warm body temperature without the need to generate heat in their own cells through burning food energy like warm-blooded animals.” However, in an effort make his case, Seymour poses the question: How much power could a crocodile-like dinosaur produce compared to a similar-sized mammal-like dinosaur?
Seymour and his colleagues from Monash University, University of California and Wildlife Management International, took to the water to answer this question. They drew blood and muscle lactate measurements from a 200kg crocodile and conducted analyses on the sample. The result of the analyses revealed that the crocodile can produce only 14 percent of the muscular power of a mammal at peak activity, and decreases with increasing body sizes.
According to the Professor, the lack of comparable muscular power production from the cold-blooded crocodile to that of a similar-sized mammal indicate that large-sized (crocodile-like) dinosaurs may have been warm-blooded instead.
“The results further show that cold-blooded crocodiles lack not only the absolute power for exercise, but also the endurance, that are evident in warm-blooded mammals,” he said. “So, despite the impression that saltwater crocodiles are extremely powerful animals, a crocodile-like dinosaur could not compete well against mammal-like dinosaurs of the same size.”
In an argument that goes in tune with ‘survival of the fittest’, Seymour argues that for dinosaurs to dominate the terrestrial ecosystem throughout the Mesozoic period, they must “have had more muscular power and greater endurance than a crocodile-like physiology would have allowed.” Meaning, it’s likely that these dinosaurs possessed mammal-like biological capabilities rather than that of cold-blooded animals of today.