Paleontology in Maryland refers to paleontological research occurring within or conducted by people from the U.S. state of Maryland. The invertebrate fossils of Maryland are similar to those of neighboring Delaware.[1] For most of the early Paleozoic era, Maryland was covered by a shallow sea, although it was above sea level for portions of the Ordovician and Devonian. The ancient marine life of Maryland included brachiopods and bryozoans while horsetails and scale trees grew on land. By the end of the era, the sea had left the state completely. In the early Mesozoic, Pangaea was splitting up. The same geologic forces that divided the supercontinent formed massive lakes. Dinosaur footprints were preserved along their shores. During the Cretaceous, the state was home to dinosaurs. During the early part of the Cenozoic era, the state was alternatingly submerged by sea water or exposed. During the Ice Age, mastodons lived in the state.
Local Delaware people told myths about a creature called the "Grandfather of the Monsters" and Little People that may have been inspired by local dinosaur footprints. By the 1850s, formal scientific investigation of the local fossils had commenced. Early discoveries included Astrodon, the first scientifically described sauropod from North America. Maryland was home to one of the most significant Pleistocene mammal discoveries in American history: the early 20th century discovery of Pleistocene fossils in an Allegany County cave. The Miocene murex snail Ecphora gardnerae gardnerae is the Maryland state fossil. Astrodon johnstoni is the state dinosaur of Maryland.