- Paleontology
- Paleontology is the study of creatures that have been extinct for many years. Paleontology is not always an exact science as it is based on what is considered the best and most current information. For example, from the T. rex skeletons which are available for study we know for certain that this dinosaur had two fingers on each hand, that it walked on its hind legs, and that it grew to over 40 feet. But it is impossible to tell what color it was, or exactly how long it lived, or how it cared for its young. For answers to these questions, paleontologists must make educated guesses based on information they do have and by comparing these extinct creatures with similar creatures that live today. One of the most interesting aspects about paleontology is that there seems to always be new discoveries, research techniques and information available to help refine theories about life in the past.
- Pangaea
- This is the name scientists have given to the single large landmass that existed at the beginning of the Triassic Period. During this time all of the land on Earth was combined into one super continent - Pangaea. It was dry in the middle and tropical around the edges. Pangaea began forming in the later part of the Paleozoic Era, about 300 million years ago, and it began to break up during the Jurassic Period of the Mesozoic Era. Having one large landmass allowed many creatures, including dinosaurs, to move about freely and thereby inhabit every corner of the Earth's land surface.
- Pelycosaur
- Pelycosaurs were a group of the mammal-like reptiles that included Dimetrodon.
- Period
- See "Geologic Time"
- Phylum
- See "Classification"
- Pikaia
- An important little creature in the history of life on Earth, Pikaia is the first known living thing with a backbone. Having this feature, it is possibly the ancestor of all vertebrate life on Earth, including humans. It was only about two inches long and lived in the sea 550 million years ago. It looked like a small fish without fins. Not too much is known about this creature. It is known from a very fossil rich formation of shale rocks in Canada that are called the Burgess Shale.
- Plate Tectonics
- Plate Tectonics is a very interesting concept. It deals with the idea that some time in the very distant future, the land that you are living on right now is probably going to get sucked down into the Earth and melted into molten rock! All the Earth's mountains will disappear. China and the United States will get closer together and Europe and the United States will get farther apart. Islands will disappear, new mountains will be created and the whole surface of the Earth will change - again. This process has been going on since the Earth was formed. Basically, the entire surface of the Earth, including the ocean floors, is floating on liquid rock. The entire surface is divided into huge Plates that are continually moving, bumping and grinding against each other. At some locations, new surface material emerges from the inside of the Earth. To make room for this new surface, an equal amount is subducted or sucked back down into the hot, liquid center of the Earth. Plate movement is what causes earthquakes and creates mountains. As recently as 30 million years ago, India was an island floating toward Asia. It eventually crashed into the south side of the Asian continent and has been pushing up the Himalaya mountain range ever since. These mountains are still growing! Plate Tectonics explain how it would have been possible for dinosaurs to live in what is now the totally frozen continent of Antarctica - this was not always at the South Pole.
- Plateosaur
- Plateosaur is the name given to a group of Late Triassic and Early Jurassic dinosaurs. These dinosaurs are often referred to as Prosauropods as they seemed to develop the characteristics seen in the giant sauropods that evolved during the Jurassic.
- Plesiosaurs
- These are a group of reptiles that lived in the sea during the Mesozoic Era. They are most recognized by their long necks, although some species have shorter necks. Like many predators in the sea, they were able to grow very large - some approached 60 feet in length. By using their long necks, they were able to get their heads into schools of fish to catch their food. They also would hunt at the surface and, through fossil evidence, it is known they sometimes would grab a flying reptile out of the air. These were air-breathing creatures, and it is believed they would climb onto shore using their flippers to lay their eggs much like modern sea turtles.
- Postcranial
- Postcranial refers to the entire skeleton except the skull. It is used frequently in paleontology, as many fossil skeletons are found without the skull. Many scientific descriptions will say "known from some postcranial materials."
- Predator
- These are any meat-eating (carnivorous) animals that actively hunt other animals.
- Prehistoric
- Using this word does not mean any specific time. It is generally used to refer to time periods before recorded history. What recorded means, however, is still being debated by scientists the world over.
- Premaxillary Teeth
- Teeth found in the front part of the upper jaw, below the nose.
- Preparator
- This is the term often used to describe someone who takes the fossilized remains of dinosaurs, or other prehistoric animals and plants, and puts them back together in order to display them. This is often a process that includes taking hundreds of fossil bone fragments and creating a whole bone, like a huge puzzle with no picture of what it is supposed to look like.
- Prey
- Any animal that is hunted by predators.
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