Yinlong was discovered in an upper section of this formation which dates to the Oxfordian stage of the Late Jurassic, or 161.2 to 155.7 million years ago. Most other described ceratopsians are known from the later Cretaceous Period.
Yinlong was identified in an upper part of this formation, which corresponds to the Oxfordian stage of the Late Jurassic period, or 161.2 to 155.7 million years ago. Most other ceratopsians known are from the later Cretaceous epoch.