ancestor: A predecessor. It could be a family forebearer, such as a parent, grandparent or great-great-great grandparent. Or it could be a species, genus, family or other order of organisms from which some later one evolved. For instance, ancient dinosaurs are the ancestors of today’s birds. (antonym: descendant)
aquatic: An adjective that refers to water.
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.
Cretaceous: A geologic time period that included the end of the Age of Dinosaurs. It ran from roughly 145.5 million years ago until 65.5 million years ago.
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).
extinct: An adjective that describes a species for which there are no living members.
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.
geologic: An adjective that refers to things that are related to Earth’s physical structure and substance, its history and the processes that act on it. People who work in this field are known as geologists.
ichthyosaur: A type of giant marine reptile that looks similar to a porpoise. It’s name means “fish lizard.” It was not related to fish or marine mammals, however. And although not a dinosaur, it lived at the same time as dinosaurs.
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.
Jurassic: Lasting from about 200 million to 145.5 million years ago, it’s the middle period of the Mesozoic Era. This was a time when dinosaurs were the dominant form of life on land.
mammal: A warm-blooded animal distinguished by the possession of hair or fur, the secretion of milk by females for feeding their young, and (typically) the bearing of live young.
membrane: A barrier which blocks the passage (or flow through) of some materials depending on their size or other features. Membranes are an integral part of filtration systems. Many serve that same function as the outer covering of cells or organs of a body.
Mesozoic Era: An interval of geologic time from about 252 million to around 66 million years ago. Often called the Age of Reptiles, this era includes the Triassic, Jurassic and Cretaceous periods.
mosasaur: A type of extinct marine reptile that lived at the same time as dinosaurs.
penguin: A flightless black-and-white bird native to the far Southern Hemisphere, especially Antarctica and its nearby islands.
plesiosaur: A type of extinct marine reptile that lived at the same time as dinosaurs and is noted for having a very long neck.
reptile: Cold-blooded vertebrate animals, whose skin is covered with scales or horny plates. Snakes, turtles, lizards and alligators are all reptiles.
sea: An ocean (or region that is part of an ocean). Unlike lakes and streams, seawater — or ocean water — is salty.
species: A group of similar organisms capable of producing offspring that can survive and reproduce.