Coming right around the Chinese New Year, top to bottom, are two highly scientifically-important dinosaurs hailing from the Aptian-aged (125-118 mya) Jiufotang Formation of China’s Liaoning Province:
Microraptor zhaoianus ranks alongside the late Jurassic Archaeopteryx and the closely-related Sinornithosaurus as one of the first theropod dinosaurs ever to have discovered with full feather and wing impressions. It measured about 80 cm (2.6ft) in length, had a wingspan of 99 cm (3.25 ft) and weighed about 1.25-1.88 kg, sported a uniquely black but iridescent plumage, and is the namesake of the Microraptoridae, a family of raven-sized dromaeosaurs that dominated the Jehol Biota of the Jiufotang and Yixian Formations and are particularly famous for sporting long flight feathers on both their legs and limbs. This “four-winged” configuration, which surprisingly resembles the hypothetical “Tetrapteryx” stage of bird evolution proposed by naturalist William Beebe in 1915, enabled Microraptor and its kin to glide from tree to tree in pursuit of small birds, lizards and mammals as well as achieving some sort of powered flight over short distances.
Psittacosaurus is a basal ceratopsian that is closer in phylogeny to creatures like Styracosaurus and Triceratops than to the more primitive Yinlong from the late Jurassic, and is one of the most well-preserved and best-studied genera of all non-avian dinosaurs. It reached the size of a pig or a retriever dog and lived throughout much of continental Eastern Asia 125-105 million years ago, and is known for having the most species described of any non-avian dinosaur, with 12 different species ranging from as far north as Siberia to as far south as Thailand. Two of these species were both found in the Jiufotang Formation - P.melieyingensis and P.mongoliensis, the type species which measured up to 2 meters (6.2 ft) long and weighed about 80 kg (44 lb). Psittacosaurus had highly-developed senses of smell and vision, a pair of protruding jugal (cheek) bones that were possibly used for display, and was active for short periods at day or night. Psittacosaurus also possessed self-sharpening teeth that were used for cropping and slicing tough plants, and unlike future ceratopsians, it lacked teeth for chewing and grinding food and thus used gastroliths (which would have been stored in a gizzard similar to those of modern birds) to wear down the leaves and bark that it ate as it passed through the digestive system. Psittacosaurus is also unique among ceratopsians for having a large, well-proportioned brain. This indicates that the dinosaur was capable of doing a wide range of complex social behaviors such as bird-like sleeping, nest-building and parental care. This is perhaps true with possible instances of overburdened Psittacosaurus parents brining in a nanny or another guardian to take care of large nests of more than a dozen hatchlings, as evidenced of fossils of adolescent females preserved with several hatchlings together. The Psittacosaurus of the Jiufotang Formation shared their temperate forest habitat with the basal ankylosaur Chuanqilong, several genera and species of paravians and pterosaurs, a large titanosaur, and the 10-meter-long Yutyrannus relative Sinotyrannus, and Psittacosaur hatchlings and occasionally adults were also preyed upon by the large, badger-like mammal Repenomamus. One fossil Psittacosaurus specimen that is on display at a German museum (SMF R 4970) preserves the scales, colors and integument that the living animal would have had, and they indicate that the particular Psittacosaurus had a counter-shaded reddish brown and beige pattern that was blurrier and less-defined compared to the striking orange-and-white colors of Sinosauropteryx (which was suited for a lifestyle of foraging in open areas) and was therefore useful for camouflaging the Psittacosaurus in the woods. The specimen also possessed a strange crest of yellow, keratinized, bristle-like structures protruding from the base of its tail that were quite similar to the thin, filamentous structures found on the heterodontosaurid Tianyulong, which also possibly indicates that feather-like structures or proto-feathers may have appeared early in the evolutionary history of the dinosaurs and were soon lost in the evolution of some dinosaur groups or retained in some form in the evolution of others.
