Study explains why dinosaurs never shrank to mouse size
A research team from the American Museum of Natural History and Princeton University published a study in the journal Evolution that uses a mathematical model to examine vertebrate body‑size evolution. The model shows that the smallest known dinosaurs, such as microraptors from the early Cretaceous (about 145 million years ago), weighed roughly 400 grams—about 200 times heavier than the bee hummingbird (Mellisuga helenae), the smallest modern bird, and also about 200 times heavier than the Etruscan shrew (Suncus etruscus), the smallest modern mammal.
The researchers suggest that competition with small mammals for resources prevented dinosaurs from occupying the ecological niche of very small body sizes. The model is based on energetic factors that describe how size influences physiological constraints. As co‑author Roger Benson put it, “We already knew dinosaurs prevented mammals from becoming large before the end‑Cretaceous mass extinction; here we propose mammals likewise limited dinosaurs from becoming small.”
Entities: American Museum of Natural History · Evolution · Microraptor · Princeton University · Roger Benson
Claims
What the coverage asserts, and how well corroborated each claim is across sources.
- [● 6 SOURCES] A research duo from the American Museum of Natural History and Princeton University published a study in the journal Evolution. (all articles)
- [● 6 SOURCES] The model is based on energetic factors that describe size‑dependent physiological constraints. (all articles)
- [● 6 SOURCES] The model indicates that the smallest known dinosaurs weighed about 400 grams. (all articles)
- [● 6 SOURCES] Microraptors are among the smallest known dinosaurs, living in the early Cretaceous about 145 million years ago. (all articles)
- [● 6 SOURCES] These smallest dinosaurs were about 200 times heavier than the smallest modern bird, the bee hummingbird (Mellisuga helenae). (all articles)
- [● 6 SOURCES] The smallest modern mammal, the Etruscan shrew (Suncus etruscus), weighs about 1.8 grams, making the dinosaurs roughly 200 times heavier. (all articles)
- [● 6 SOURCES] The researchers propose that competition with small mammals prevented dinosaurs from evolving smaller sizes. (all articles)
- [● 6 SOURCES] The study used a mathematical model to examine vertebrate body‑size evolution. (all articles)