The earliest known avialan fossils come from the Tiaojishan Formation of China, which has been dated to the late Jurassic period (Oxfordian stage), about 160 million years ago. The avialan species from this time period include Anchiornis huxleyi, Xiaotingia zhengi, and Aurornis xui. The well-known early avialan, Archaeopteryx, dates from slightly later Jurassic rocks (about 155 million years old) from Germany. Many of these early avialans shared unusual anatomical features that may be ancestral to modern birds, but were later lost during bird evolution. These features include enlarged claws on the second toe which may have been held clear of the ground in life, and long feathers or "hind wings" covering the hind limbs and feet, which may have been used in aerial maneuvering.
The Oxfordian stage is also known as what?
late Jurassic period

Semantic-phonetic compounds or pictophonetic compounds are by far the most numerous characters. These characters are composed of two parts: one of a limited set of characters (the semantic indicator, often graphically simplified) which suggests the general meaning of the compound character, and another character (the phonetic indicator) whose pronunciation suggests the pronunciation of the compound character. In most cases the semantic indicator is also the radical under which the character is listed in dictionaries.
What are the most numerous characters?
Semantic-phonetic compounds

The level of Hellenistic achievement in astronomy and engineering is impressively shown by the Antikythera mechanism (150100 BC). It is a 37-gear mechanical computer which computed the motions of the Sun and Moon, including lunar and solar eclipses predicted on the basis of astronomical periods believed to have been learned from the Babylonians. Devices of this sort are not found again until the 10th century, when a simpler eight-geared luni-solar calculator incorporated into an astrolabe was described by the Persian scholar, Al-Biruni.[not in citation given] Similarly complex devices were also developed by other Muslim engineers and astronomers during the Middle Ages.[not in citation given]
What is the name of the 37 gear computer which noted the motions of the Sun and Moon?
Antikythera mechanism