Laopteryx Laopteryx Laopteryx is the name assigned to a pterosaur (flying reptile) from the Upper Jurassic Morrison Formation of Wyoming, United States; it was originally thought to be a bird. The genus was named in 1881 by Othniel Charles Marsh. The generic name is derived from Greek "laas", "stone", and "pteryx", "wing". The full species name given by Marsh was "Laopteryx priscum"; the specific name meaning "of venerable age" in Latin. However, Marsh incorrectly used the neuter form, while "pteryx" is feminine in Greek. (See grammatical gender.) This was in the 19th century emended to an, also incorrect, masculine "priscus" and
Cretaceous local subdivisions are still in use. As with other older geologic periods, the rock beds of the Cretaceous are well identified but the exact age of the system's base is uncertain by a few million years. No great extinction or burst of diversity separates the Cretaceous from the Jurassic. However, the top of the system is sharply defined, being placed at an iridium-rich layer found worldwide that is believed to be associated with the Chicxulub impact crater, with its boundaries circumscribing parts of the Yucatán Peninsula and into the Gulf of Mexico. This layer has been dated at 66.043 Ma.