Dinosaurs were warm-blooded, and we’re much more like mammals than reptiles in their growth and metabolism, according to a new research paper published by Stony Brook University paleontologist Michael D’Emic, PhD.
The new work — which found that dinosaurs grew roughly as fast as modern mammals do — is a re-analysis of the widely reported on 2014 Science paper that argued that dinosaurs weren’t ectothermic or endothermic, but rather in an intermediate category. This new work disregards those earlier conclusions to some degree.
“The study that I re-analyzed was remarkable for its breadth — the authors compiled an unprecedented dataset on growth and metabolism from studies of hundreds of living animals,” stated Dr D’Emic, a Research Instructor in the Department of Anatomical Sciences as Stony Brook, when referring to “Evidence for mesothermy in dinosaurs.”
“Upon re-analysis, it was apparent that dinosaurs weren’t just somewhat like living mammals in their physiology — they fit right within our understanding of what it means to be a ‘warm-blooded’ mammal,” he noted.
A recent press release in the subject provides more:
Dr D’Emic specializes in bone microanatomy, or the study of the structure of bone on scales that are just a fraction of the width of a human hair. Based on his knowledge of how dinosaurs grew, Dr D’Emic re-analyzed that study, which led him to the strikingly different conclusion that dinosaurs were more like mammals than reptiles in their growth and metabolism.
Dr D’Emic re-analyzed the study from two aspects. First, the original study had scaled yearly growth rates to daily ones in order to standardize comparisons.
“This is problematic,” Dr D’Emic noted. “Because many animals do not grow continuously throughout the year, generally slowing or pausing growth during colder, drier, or otherwise more stressful seasons. Therefore, 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.”
This is/was especially true for larger animals, and also for animals that lived in particularly harsh or seasonal environments — which most dinosaurs certainly did.
The new re-analysis also takes into account the fact that dinosaurs should probably be statistically analyzed as being within the same group as extant birds. As they are, after all, more or less the same overall lineage.
“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.”
Considering that the general modern opinion is that most/many dinosaurs were feathered or “haired”, warm blooded, and highly intelligent; and that the general opinion 100 years ago was nearly the exact opposite of this one; this certainly does go to show just how absolutely public perceptions can change over time.