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- MYA
- Million Years Ago
- Mammal-Like Reptiles
- These creatures were a reptilian family of animals that appeared in the last part of the Paleozoic Era, during the Permian period. Their technical name is Synapsid. These creatures became very large, some approaching 20 feet. They were well defined as carnivores and herbivores, just like dinosaurs. Some of their features were very similar to modern mammals, and it is likely some even had fur. It is widely accepted that, as they suffered at the hands of both extinction events and the rise of dinosaurs, they evolved into smaller forms that became the small mammals that lived throughout the Mesozoic, literally under the feet of the dinosaurs.
- Mammals
- Mammals are a major group of animals, a Class under the taxonomic system of classification. They have a number of characteristics that define them. They are warm-blooded, have some kind of hair or fur, and they give birth to live young (as opposed to laying eggs). Mammals also tend to have relatively large brains compared to other Classes of animals.
- Mammoth
- This was a relative of modern elephants and along with Mastadons (another prehistoric elephant-like beast), were the largest land animals after the dinosaurs disappeared. Mammoths seemed to flourish in the ice age and were well adapted to the cold. They had long, shaggy fur coats and layers of fat to insulate them. They were plant eaters who became extinct less than 10,000 years ago. In fact, mammoths are found in near pristine condition in the far north frozen in the ice. Efforts are currently under way to clone a mammoth and if successful, it would mark the first time that an extinct prehistoric creature has been brought back to life.
- Man
- How many people, beyond scientists and serious students, would recognize our species if we simply labeled it sapiens? The scientific classification for all modern humans is Homo sapiens. The genus Homo has been identified as far back as 2.3 million years; other ancestors of ours have been dated much farther back in time, but they are not of the same genus. As an example, Lucy, the small 3.2 million-year-old fossil that exhibits many of the characteristics that we use to define our human family, is from the genus Australopithicus. One of the ways we define members of the Homo family is not so much how they look, but rather what they could do. All Homo members could use tools. The exact appearance on Earth of modern humans is still the subject of debate. Prior to our present form, about 100,000 years ago, Neanderthal man was the dominant form of our species. Recent discoveries in the Middle East show caves that were used by both Neanderthal and modern humans between 35,000 and 45,000 years ago. The last Neanderthals seem to have died out no later than about 30,000 years ago. Why did they disappear? They were physically much stronger than modern humans and their brain was actually a bit larger on average. One theory is that they were simply not as aggressive as the new form of human. Perhaps we killed off our smarter, more passive ancestors (an unfortunate trait that seems to continue even today). An interesting fact to also consider is that, until as recently as 20,000 years ago (only about 1,000 generations), the human race was all one race - any skin color or other outward characteristics such as the shape of eyes and body hair distribution had not developed. These adaptations were all accomplished as a result of adjusting to the different climates to which humans migrated.
- Mantell, Gideon
- An amateur fossil hunter in England, Mantell found and named several of the first dinosaurs known to science. This was in 1822, almost 20 years before the word dinosaur existed. His first discovery was an Iguanodon tooth, which he named and incorrectly believed to be the ancestor of modern iguanas.
- Marine
- Refers to water or the seas, such as a marine reptile (one that lives in the sea).
- Marine Reptile
- Primarily, this term is used to refer to a group of extinct animals that lived from the late Paleozoic (about 280 mya) through the Mesozoic and went extinct along with the dinosaurs. There were several groups of these creatures, some of which grew very large - over 50 feet - and they included the mosasaurs and plesiosaurs. All of these animals breathed air, and laid eggs on land.
- Metabolism
- Metabolism is the chemical process, or combination of processes, which a body uses to maintain or fix itself. An example of metabolism would be the way a body generates heat (or doesn't if it is cold-blooded).
- Mosasaurs
- These were a family of sea reptiles that included Clidastes, Mosasaurus and Tylosaurus. These creatures looked like a long lizards with fins and a large head filled with sharp teeth. They, along with plesiosaurs, were the top predators of the sea. Tylosaurus could grow as large as 45 feet long.
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