Specimens of Archaeopteryx feather's earlier discovery, von Meyer made the London fossil the type specimen of the genus ("Archaeopteryx") and species ("lithographica"), establishing it as the exemplar of the species' features. Its discovery and subsequent descriptions, a mere handful of years after Darwin's "On the Origin of Species", fulfilled the hope of a truly transitional form in its then-unique amalgamation of bird and reptilian characters. The specimen is preserved on two counter slabs broken originally into four pieces. The main, overlaying slab contains most of the skeletal elements, while only impressions and a few bone fragments are visible on the counter slab. This
Archaeopteryx or trunk-climbing lifestyle. This has been interpreted as evidence of theropod ancestry. In 1988, Gregory S. Paul claimed to have found evidence of a hyperextensible second toe, but this was not verified and accepted by other scientists until the Thermopolis specimen was described. "Until now, the feature was thought to belong only to the species' close relatives, the deinonychosaurs." The Thermopolis Specimen was assigned to "Archaeopteryx siemensii" in 2007. The specimen is considered to represent the most complete and best-preserved "Archaeopteryx" remains yet. The discovery of an eleventh specimen was announced in 2011, and it was described in 2014. It