Sometimes a giant leap forward in scientific knowledge raises more questions than it answers.
Take dinosaurs, for instance. For decades conventional wisdom held that these prehistoric creatures, who "ruled" the Earth for many millions more years than humans have, were basically oversized cold-blooded reptiles, whose distant descendants may be crocodiles or lizards.
Then this month a startling discovery was reported. North Carolina researchers found in South Dakota a fossilized, grapefruit-sized heart of a plant-eating dinosaur estimated to have died more than 65 million years ago, about the time the species suddenly became extinct.
Not only was this Mesozoic-age dinosaur's heart a rare find, it also yielded some highly valuable, and surprising, information. After being subjected to the wonders of the modern era's scientific technology -- a computer-enhanced CAT scan -- the heart was revealed to have had four chambers and an aorta.
What this means, say scientists, is that this vegetable-eating dinosaur, a Tescelosaurus, had warm oxygen-rich blood coursing through its veins. It was not an overblown, cold-blooded reptile dependent on the environment for its body heat, but was a warm-blooded mammal, not unlike humans.
And like warm-blooded animals, it was more energetic, active and smarter than cold-blooded creatures, capable of journeying great distances and adjusting to different climates. If this dinosaur had descendants, they would be birds, not crocodiles.
But what does all this dinosaur research matter, and why should anyone care? Well, first, there's just sheer curiosity. On a more practical level, what we learn about our "rulers of the planet" predecessors and why they inexplicably became extinct may help us protect our own species from suffering a like fate.