MEANING: Strange bird
PERIOD: Early Cretaceous
CONTINENT: Asia
Novavis is an enantiornithean bird that lived in the Early Cretaceous of what is now China.
Abstract from paper: We describe a partial skeleton of an enantiornithine from the Changma locality of the Lower Cretaceous Xiagou Formation in northwestern China. The specimen is tentatively interpreted as a gastric pellet. The specimen preserves an unusually short pubis that is subequal in length to the ischium, an autapomorphy among enantiornithines, justifying erection of a new taxon, Novavis pubisculata nov. gen., nov. sp. The abbreviated length of the pubis suggests that the abdominal cavity in this species was proportionately shorter than in all other known enantiornithines. Although several muscles attach to the pubis, the mm. pubocaudalis internus and externus were probably the most functionally impacted by the increased distance between the pubes and caudal vertebrae and subsequent elongation of these muscles. In crown avians this would result in a decrease in the contraction speed of these muscles, which play a role in tail fanning and are thus important for flight during take-off and landing. Although the underlying function of the short pubis and changes in the size of the abdominal cavity are unknown, the widespread absence of aerodynamic tail musculature and plumage in enantiornithines may have relaxed pressures constraining the length of these muscles, such that elongation of these muscles through a shortened pubis was not detrimental to the aerodynamic abilities of these birds.
Novavis is from the Cretaceous. The Cretaceous is a geological period that lasted from about 145 to 66 million years ago. It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin creta, "chalk", which is abundant in the latter half of the period.
The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now-extinct flora and fauna, while dinosaurs continued to dominate on land. The world was ice free, and forests extended to the poles. During this time, new groups of mammals and birds appeared. During the Early Cretaceous, flowering plants appeared and began to rapidly diversify, becoming the dominant group of plants across the Earth by the end of the Cretaceous, coincident with the decline and extinction of previously widespread gymnosperm groups.
The Cretaceous (along with the Mesozoic) ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs, pterosaurs, and large marine reptiles, died out. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary (K–Pg boundary), a geologic signature associated with the mass extinction that lies between the Mesozoic and Cenozoic Eras.
Novavis is a Paravian. The evolution of birds began in the Jurassic Period, with the earliest birds derived from a clade of theropod dinosaurs named Paraves. The Archaeopteryx has famously been known as the first example of a bird for over a century, and this concept has been fine-tuned as better understanding of evolution has developed in recent decades.
Like other theropods, all paravians are bipedal, walking on their two hind legs. Most of the earliest groups were carnivorous, though some smaller species are known to have been omnivores. Paravians generally have long, winged forelimbs, though these have become smaller in many flightless species. The wings usually bore three large, flexible, clawed fingers in early forms. Over time, the fingers became fused and stiffened in some lineages, and the claws reduced or lost. An increasingly asymmetric wrist joint allowed the forelimbs to elongate and an elaboration of their plumage eventually allowed the evolution of flapping flight possible.