Ornithosaurs

Part of speech: noun

Definitions

1. Extinct flying reptiles of the Mesozoic era, belonging to a group known as pterosaurs and distinguished by their wing membranes
2. Winged prehistoric reptiles that lived during the age of dinosaurs and were the first vertebrates capable of powered flight
3. Long-extinct reptilian creatures of the Mesozoic that glided and flapped through the skies using membranous wings

Etymology: Ornithosaurs were not dinosaurs at all, and the name shows the mistake. Richard Owen, the British anatomist, coined the group name "Ornithosauria" in 1859, combining Greek "ornis" (bird) and "sauros" (lizard), because he believed these flying reptiles were closely related to birds. Their wings, which were membranes stretched mainly along an enormously elongated fourth finger, were unlike anything in birds, so the bird connection was never convincing, and the name was kept only as an old label. The plural form "ornithosaurs" is simply the English plural of "ornithosaur", a noun built from the same two Greek elements: "ornithos", the genitive of "ornis", and "sauros". The English form is a modern scientific compound, not a word inherited from ancient Greek, since the Greeks had no concept of pterosaurs. Modern palaeontologists prefer the name "pterosaur", from Greek "pteron" (wing) and "sauros", and that term has largely replaced "ornithosaur" in scientific use. The older word survives mainly in older books and as a historical curiosity of early fossil study.