bat: A type of winged mammal comprising more than 1,400 separate species — or one in every four known species of mammal. (in sports) The usually wooden piece of athletic equipment that a player uses to forcefully swat at a ball. (v.) Or the act of swinging a machine-tooled stick or flat bat with hopes of hitting a ball.
birds: Warm-blooded animals with wings that first showed up during the time of the dinosaurs. Birds are jacketed in feathers and produce young from the eggs they deposit in some sort of nest. Most birds fly, but throughout history there have been the occasional species that don’t.
common ancestor: Also known as shared ancestor. It’s an ancestor that two or more descendants have in common. Two siblings share a parent as a common ancestor. This also applies on the level of species and groups of organisms. Two or more species can share a common ancestor at the genus level. Two or more genera can share a common ancestor at the family level, and so on. Tigers and lions have a common ancestor, as do humans and Neandertals.
continent: (in geology) The huge land masses that sit upon tectonic plates. In modern times, there are six established geologic continents: North America, South America, Eurasia, Africa, Australia and Antarctica. In 2017, scientists also made the case for yet another: Zealandia.
dinosaur: A term that means terrible lizard. These reptiles emerged around 243 million years ago. All descended from egg-laying reptiles known as archosaurs. Their descendants eventually split into two lines. For many decades, they have been distinguished by their hips. The lizard-hipped line are believed to have led to the saurischians, such as two-footed theropods like T. rex and the lumbering four-footed Apatosaurus. A second line of so-called bird-hipped, or ornithischian dinosaurs, appears to have led to a widely differing group of animals that included the stegosaurs and duckbilled dinosaurs. Many large dinosaurs died out around 66 million years ago. But some saurischians lived on. They are now the birds we see today (and who have now evolved that so-called “bird-hipped” pelvis).
fossil: Any preserved remains or traces of ancient life. There are many different types of fossils: The bones and other body parts of dinosaurs are called “body fossils.” Things like footprints are called “trace fossils.” Even specimens of dinosaur poop are fossils. The process of forming fossils is called fossilization.
hatchling: A young animal that recently emerged from its egg.
insect: A type of arthropod that as an adult will have six segmented legs and three body parts: a head, thorax and abdomen. There are hundreds of thousands of insects, which include bees, beetles, flies and moths.
invertebrate: An animal lacking a backbone. About 90 percent of animal species are invertebrates.
prehistoric: An adjective for something that happened tens of thousands to millions of years ago, periods before people began deliberately recording events.
pterosaur: Any of various extinct flying reptiles of the order Pterosauria. These animals lived 245 million years ago to 65 million years ago. Although not true dinosaurs, they lived during the reign of dinosaurs. Among members of this order were the pterodactyls of the Jurassic and Cretaceous periods, which were characterized by wings consisting of a flap of skin supported by the very long fourth digit on each forelimb.
reptile: Cold-blooded vertebrate animals, whose skin is covered with scales or horny plates. Snakes, turtles, lizards and alligators are all reptiles.
species: A group of similar organisms capable of producing offspring that can survive and reproduce.
vertebrate: The group of animals with a brain, two eyes, and a stiff nerve cord or backbone running down the back. This group includes amphibians, reptiles, birds, mammals and most fish.