archæopteryx

from The Century Dictionary.

• noun A genus of fossil reptilian Mesozoic birds discovered by Andreas Wagner, in 1861, in the lithographic slates of Solenhofen in Bavaria.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Paleon.) A fossil bird, of the Jurassic period, remarkable for having a long tapering tail of many vertebræ with feathers along each side, and jaws armed with teeth, with other reptilian characteristics.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Rare spelling of archeopteryx.