| AR | the branch of anthropology that studies prehistoric people and their cultures |
|---|---|
| AR | extinct primitive toothed bird of the Upper Jurassic having a long feathered tail and hollow bones |
| AR | extinct primitive toothed bird of the Upper Jurassic having a long feathered tail and hollow bones |
| AR | extinct primitive toothed bird with a long feathered tail and three free clawed digits on each wing |
| AR | primitive reptile-like fossil birds of the Jurassic or early Cretaceous |
| AR | the time prior to 2,500 million years ago |
| AR | (geology) formed in the earlier of two divisions of the Precambrian era |
| AR | the time prior to 2,500 million years ago |
| AR | little evolved from or characteristic of an earlier ancestral type |
| AR | so extremely old as seeming to belong to an earlier period |
| AR | the use of an archaic expression |
| AR | give an archaic appearance of character to, as in poetry |