Genesis Prime

In 2133, Earth's orbit resembles Las Vegas and Halley's comet is on a collision course. The Earth Protection Agency has a plan to destroy the comet, but did not count on a scientist conducting a wormhole experiment at the same time.  Things go bad, and the scientist and his teenage children are forced to crash land on Earth.   They appear to have time traveled and soon discover that Earth is not what it once was. Dinosaurs roam the land and there's another type of creature that should never have existed – frightening creatures that only comes out at night.  

Their only hope of returning home is to figure out how they got here in the first place, and that won't be possible unless the only other civilized being on the planet agrees to help them. He is a mysterious but brilliant reptilian who has his own reasons to help them, and a better reason to let them die.