Archaeopteryx (if not colour banded) to some degree, so the darkness was attributed to such impurities. They also mention that a complete absence of air bubbles in the rock slabs is further proof that the specimen is authentic. Modern paleontology has often classified "Archaeopteryx" as the most primitive bird. It is not thought to be a true ancestor of modern birds, but rather, a close relative of that ancestor. Nonetheless, "Archaeopteryx" was often used as a model of the true ancestral bird. Several authors have done so. Lowe (1935) and Thulborn (1984) questioned whether "Archaeopteryx" truly was the first bird. They
Specimens of Archaeopteryx — limiting its ability to perch on branches and implying a terrestrial 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 the most complete and well preserved "Archaeopteryx" remains yet. This specimen first came to light