New York, May 31: Dinosaurs were warm-blooded animals that had many traits in common with mammals, claims a new study.
The study counters other theories which say dinosaurs were either cold-blooded and reptile-like, or occupied a unique intermediate category of animals that were neither fully cold nor warm-blooded.
"Upon re-analysis, it was apparent that dinosaurs weren't just somewhat like living mammals in their physiology as they fit right within our understanding of what it means to be a 'warm-blooded' mammal," said Michael D'Emic, a Stony Brook University paleontologist.
The "re-analysis" refers to D'Emic's work revisiting yet another Science paper, published last year, which compiled a huge dataset on growth and metabolism of hundreds of living animals.
D'Emic looked at that study again, focusing on two primary aspects, reported Discovery News.
"The previous study underestimated dinosaur growth rates by failing to account for their uneven growth. Like most animals, dinosaurs slowed or paused their growth annually, as shown by rings in their bones analogous to tree rings," D'Emic noted.
Seasonal environments can also impact growth, and would have really affected dinosaurs.
The second argument is based on the widely held view that all dinosaurs did not become extinct: some evolved to become birds.
Today's birds are warm-blooded, so he argues that dinosaurs must have been this way too.
"Separating what we commonly think of as 'dinosaurs' from birds in a statistical analysis is generally inappropriate, because birds are dinosaurs -- they're just the dinosaurs that haven't gone extinct," D'Emic explained.
"D'Emic's study reveals how important access to the data behind published results is for hypothesis testing and advancing our understanding of dinosaur growth dynamics," noted Holly Woodward, assistant professor in the Center for Health Sciences at Oklahoma State University.
The study was published in the journal Science.