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Dinosaurs were initially cold-blooded, but global warming 180 million years ago may have triggered the evolution of warm-blooded species, a new study found.
This raises the question "How did dinosaurs become warm-blooded?" The most obvious possible answers are: "Their immediate ancestors were cold-blooded, and dinosaurs began developing warm-bloodedness very early in their evolution." This implies that dinosaurs developed a significant degree of warm-bloodedness in a very short time, possibly less ...
Clues from fossilized eggshells and bones have now suggested that some dinosaurs were warm-blooded and others were not. Gleaning the answer matters because it sheds light on dinosaur behavior.
The Dinosaur Heresies: New Theories Unlocking the Mystery of the Dinosaurs and Their Extinction is a 1986 book written by Robert T. Bakker [1] [2] exploring extant evidence indicating that dinosaurs, rather than being cold-blooded and wholly lizard-like, were warm-blooded, agile creatures more similar to modern birds than to lizards or other reptiles.
A recent study has determined that dinosaurs may have been warm-blooded based on a re-assessment of previous research on animals? growth and metabolic rates.
In his 1986 work The Dinosaur Heresies, Bakker puts forth the theory that dinosaurs were warm-blooded. His evidence for this includes: Almost all modern animals that walk upright are warm-blooded, and dinosaurs walked upright. The hearts of warm-blooded animals can pump much more effectively than the hearts of cold-blooded animals.
It also prompted a debate over whether dinosaurs were warm-blooded like birds, contradicting the long-standing conception of them as slow, lumbering and cold-blooded.
Paleontologist John Ostrom's study of Deinonychus in the late 1960s revolutionized the way scientists thought about dinosaurs, leading to the "dinosaur renaissance" and igniting the debate on whether dinosaurs were warm-blooded or cold-blooded. Before this, the popular conception of dinosaurs had been one of plodding, reptilian giants.