} Interestingly, the three phenomena you mention are all closely related.
} On April 13, 2063 in an exhibition game against the Toronto Blue Jays,
} Cleveland Native Americans pitcher Leroy Paige IV became enraged and
} vowed to kill everyone at the stadium who jeered him. He realized he
} would be unable to follow through on this threat without resorting to
} time travel, so he went out and purchased a cheap used Toyota Chronohop
} (2058 model). Unfortunately for Paige, the reason he picked the unit up
} for such a low price was the clock circuits in the Chronohop were
} malfunctioning. He returned to the day of the game repeatedly,
} identifying each booing fan and then going back to each person's
} conception and murdering their parents, but each jump made the clock
} chip overheat a bit more, sending him further back in time. But by now
} (then?) he was in such a frenzied rage of killing he didn't care,
} cracking the skull of any living thing that came within reach of his
} nanoparticle-alloy bat.
} It was in this genocidical fury that he inadvertently saved the life of
} a previously extinct species of dinosaur, one which was so big it
} dwarfed the Tyrannosaur by an order of magnitude. A female deposited
} her surprisingly tiny hatchlings in the trunk of the Chronohop while he
} was chasing her, and those hatchlings survived the trip.
} His rage somewhat abated, Paige attempted to return to his home time
} and stop himself from wreaking all this havoc on history, but he
} crashed into a giant redwood in a grove that stood (will stand?) where
} the stadium formerly existed, and was killed instantly.
} The Gargantusaur hatchlings survived, and a visiting Chinese biologist
} found them and took them home for study at Beijing University. They
} grew at a phenomenal rate and escaped, out of control, in just a few
} weeks. They also reproduced extremly quickly, and with no natural
} predators, the offspring thrived. Soon enormous herds of the 'saurs
} roamed China, forcing the human population (and every other species
} with a lick of sense) to flee. Within two years the country, as well
} as the rest of Asia, was overrun by the creatures and there was not
} enough room for the human population at all.
} As I write this, from my vantage point outside the time-space
} continuum, I see that the dinosaurs have destroyed or consumed all
} other living organisms and are eating one another at a rapid pace. One
} group dug so deeply into the earth they opened a fissure that released
} unprecedented jets of geothermal pressure through their caves into the
} atmosphere in a blast powerful enough to nudge the Earth out of its
} orbit into a rapid plunge toward the sun.
} Your only hope is to prevent time travel from ever being discovered.
} If you ever run across a nanophysicist student named Herbert Cheng,
} don't wait for him to publish anything - kill him immediately.
} So to answer your question, the chances of those events occurring are
} either 100% or nil depending on whether you believe time is immutable.
} You owe the Oracle a grandfather paradox.