The Life of a planet is in it's atmosphere. Where have all the Dinosaurs gone? Did they succumb to a deadly plague? Were they frozen to death as a result of a massive meteor strike? OR were they eaten by colonizing Martians? The simple answer is: Probably Not! Here's why. The primordial Earth was much different than it is today. While the fossil record is incomplete, there is enough evidence to make a sound conclusion. Cosmologicly speaking, our little blue dot in space looked much different during it's formation. Owing to massive gravitational and techtonic stresses the heavier parts of the emerging planet would have been very hot, thus creating a thick carbon dioxide rich water vapor laden atmosphere. From space our Earth would have appeared grey and lifeless at that time. Jump forward a few eons, and as the Earth begins to cool, plant life develops. But not just any type of plants, large fleshy fast growing atmospheric eating machines. The extremely high amounts of carbon dioxide in the primordial atmosphere, while deadly to mammals, acts like Miracle Grow for these tropical plants. Combine that with an overabundance of steamy water vapor you've got a real global greenhouse. Jump forward a few more eons, the earth is cooler and the plant population is out of control. Enter the solution. To solve the massive problem of mass producing plants, you need a massive plant eating machine, to keep the massive plant eating machines in check, you need massive plant eating machine eaters. Thus commeth the age of the Dinosaurs. Jump forward a few more eons, all of this time since their arrival, the plants have been happily converting carbon dioxide, water vapor, an assortment of atmospheric gases. and low level sunlight into oxygen, nitrogen, some other gasses, and humus. With what result? The plants start changing to match changes in their food source. Instead of fat fleshy water laden plants we now find thinner woodier plants that get most of their moisture from the ground instead of the air, these plants grow more slowly, and have fewer offspring. But what about the Dinosaurs? With the change in atmosphere, came a change in plantlife, the primary food supply for the plant eating Dinosaurs. Over a period of a few million years the process continued with ever dwindling resources to sustain the Dinosaur population. As the plant eaters died out, so did the meat eaters. So what does the future hold for our little blue home? One day, sad to say, the Earth will look much like the planet Mars. Barren and devoid of life. You may be asking yourself, how can this be? Unfortunately basic physics is to blame. Mars, as we now know went through a similar formation process to that of the Earth. It also had a heavy vapor canopy that collapsed creating great rift vallies in the torrential flooding that followed. While space probes have detected water on Mars, they find that the once heavy atmosphere in now thin and unable to support life as we know it. So then where did the atmosphere go? Have you ever watched a tail form behind a comet? The Earth is venting atmosphere much like the tail of a comet. This slow but inevitable process is caused by the decrease in gravitational "attraction" in the upper atmosphere and the solar winds constantly bombarding the planet. The end result of a thinning atmosphere is a greater temperature variance between daily highs and lows. Climate changes. Decreased Ocean levels. Melting Ice Caps. etc. The Good news is that this is a naturally slow process, the bad news is that we may be accelerating it unnaturally.