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Description
Hyphalosaurus lingyuanensis, "submerged lizard," is a highly derived choristoderan from the Yixian Formation. It's close relative H. baitaigouensis (similar looking but with a longer neck and some proportional differences) is one of the most common vertebrates of the Jehol biota, with thousands of specimens known, many in private hands (I've personally seen a few in random fossil shops stateside, some with obvious "enhancements"). Some recent papers have finally given this guy the in-depth treatment it deserves, with a complete osteology, description of the skin and scales and reproduction (they were ovoviviparous, retaining soft-shelled eggs inside the mother but giving birth to live young. One newborn specimen even had two heads, the only Mesozoic example of polycephaly.

Hyphalosaurus means "submerged lizard," an apt name given that taphonomic evidence shows they preferred the deepest parts of the Jehol lake system. Contrary to early reports they are never found in the shallow, swampy waterways of the overlying Jiufotang Formation. The restoration here shows one individual in a dark lake bottom, scalation is based on preserved integument.

Description
Hyphalosaurus lingyuanensis, "submerged lizard," is a highly derived choristoderan from the Yixian Formation. It's close relative H. baitaigouensis (similar looking but with a longer neck and some proportional differences) is one of the most common vertebrates of the Jehol biota, with thousands of specimens known, many in private hands (I've personally seen a few in random fossil shops stateside, some with obvious "enhancements"). Some recent papers have finally given this guy the in-depth treatment it deserves, with a complete osteology, description of the skin and scales and reproduction (they were ovoviviparous, retaining soft-shelled eggs inside the mother but giving birth to live young. One newborn specimen even had two heads, the only Mesozoic example of polycephaly.

Hyphalosaurus means "submerged lizard," an apt name given that taphonomic evidence shows they preferred the deepest parts of the Jehol lake system. Contrary to early reports they are never found in the shallow, swampy waterways of the overlying Jiufotang Formation. The restoration here shows one individual in a dark lake bottom, scalation is based on preserved integument.