Study Says Mammals Kept Non-Avian Dinosaurs Above 450 Grams, Not Physiology Alone
Updated
Updated · BIOENGINEER.ORG · Aug 6
Study Says Mammals Kept Non-Avian Dinosaurs Above 450 Grams, Not Physiology Alone
3 articles · Updated · BIOENGINEER.ORG · Aug 6
Summary
A new Evolution study found non-avian dinosaurs never shrank below about 450 grams, arguing that ecological competition—not physiology alone—set that lower size limit.
Mathematical models based on energy intake and reproductive output matched the body-size ranges of mammals, birds and turtles, but failed to explain why dinosaurs stayed much larger than expected.
Around 75% of living mammals and 90% of living birds are smaller than the smallest known non-avian dinosaur, and researchers say the fossil record still preserves other tiny vertebrates where tiny dinosaurs should appear.
The study points to small mammals as likely incumbents in miniature niches, while predation and habitat structure may have reinforced the barrier; birds later escaped it as flight opened new habitats and food sources.