A catastrophic scene: a Tyrannosaur roaring atop a mountain as meteorite fragments explode all around him. Though this scene is both unrealistic and comically dramatic, it raises the question: how did the Great Extinction transpire?
WHEN DINOSAURS RULED THE EARTH
Widely successful between the Triassic and Cretaceous periods, an abrupt end to the rule of the dinosaurs came 65 million years ago. At the time, the massive landform Pangaea (One Earth) was breaking apart. Aside from Australia being part of the Antarctic landmass in those days, Earth from space in the late Cretaceous would look quite familiar. Gathering oceans between the dividing continents made marine life plentiful. Long-necked plesiosaurs and mosasaurs dominated the seas, along with Cretaceous crocodiles. Pterosaurs patrolled the skies alongside birds, preying on fish. Dinosaurs by the Cretaceous had reached phenomenal diversity, and unbelievable size. Large predatory roles were filled by tyrannosaurs and dromaeosaurs such as velociraptor. Smaller sauropods such as saltosaurus moved in herds across the wilderness, feeding on lush greenery.
THE K-T EVENT
The Cretaceous-Tertiary Extinction Event (K-T event) made extinct a great deal of macroscopic life on Earth. The fossil record indicates that no dinosaur species passed into the Tertiary (post-extinction) period. In addition to the loss of the dinosaurs, 50% of crocodile species died out, all Pterosaurs, 20% of turtles and cartilaginous fish (sharks, rays), alongside uncounted types of vegetation. While cumbersome dinosaurs – animals which consumed hundreds of pounds of living material – died, the K-T event seemed to have favored the survival of small mammals and amphibians.
There are many conjectures for what caused the Great Dying. From asteroid collisions to disease, volcanic eruption to climate change due to sulfur dioxide emission; there are many. The main hallmark of the K-T event was its non-discriminatory killing power. Many plant and animal species ceased to exist. The combination of an asteroid impact and the accompanying climate change it would evoke could explain the K-T event.
Could a herd of “duck-billed” dinosaurs have looked up on a fateful evening 65 million years ago and seen a white light streaking across the sky? Picture a ball of metal six miles across careening toward the Earth at 25 kilometers per second… A terrifying thought indeed. Although an asteroid would slow down as it nears Earth, the flaming ball of metal would strike so quickly that there would be no slow, streaking light; rather a flash, and a massive explosion. Our most recent brush with an asteroid occurred in 2010 when a 33 foot-wide asteroid traveled by Earth missing by 76,000 miles. If this asteroid would have hit, it would have packed the force of 100 kilotons of TNT; the atom bomb “Little Boy” yielded only 13-18 kilotons.
An Earth-killing asteroid could expel a massive heatwave around its epicenter, incinerating all life within an enormous radius. Dust clouds blown miles into the sky would settle into the atmosphere, obfuscating the sun, blocking heat. Firestorms started by runaway ignition from the heat blast could go on indefinitely. Alternately, if the asteroid touched down in the ocean, monstrous walls of sea water could flood inland areas for miles. With light, heat, and all of the Sun’s properties being impeded, photosynthesis would stop, and Earth would subsequently freeze.
Chilled temperatures could prove deadly, especially to dinosaurs who had been designed by evolution to consume vast amounts of food. Small early mammals were capable of burrowing, and efficient breeding, and needed very little food to survive.
In the end, our mammal ancestors had the winning edge, and that edge allows us to be here today; however, to the dinosaurs history bids a fond farewell.