Neobohaiornis

MEANING: New Bohai bird

PERIOD: Early Cretaceous

CONTINENT: Asia

Neobohaiornis is the smallest known bohaiornithid, weighing approximately 50 g in total body mass. It had robust teeth, and fossil evidence suggests it had skin or scales on the snout, lacking the keratinous beak of modern birds. Neobohaiornis was capable of flight and was fully feathered, including a pair of long streamer-like feathers at the end of the tail.

Abstract from paper: Enantiornithes are the most successful early-diverging avian clade, their fossils revealing important information regarding the structure of Cretaceous avifaunas and the parallel refinement of flight alongside the ornithuromorph lineage that includes modern birds. The most diverse recognized family of Early Cretaceous enantiornithines is the Bohaiornithidae, known from the Jehol Biota in northeastern China. Members of this clade enhance our understanding of intraclade morphological diversity and elucidate the independent evolution of this unique lineage. Here, we report on a new specimen of bohaiornithid, Neobohaiornis lamadongensis gen. et sp. nov., from the Lower Cretaceous Jiufotang Formation in western Liaoning, China. The holotype specimen is considerably smaller than all other known bohaiornithids (roughly half the size of Bohaiornis). The presence of complete fusion in compound elements strongly suggests it represents a mature or nearly mature individual, and therefore substantially increases the known size range of this clade. This specimen further differs from known bohaiornithids in that it exhibits reduced manual unguals and an increased number of sacral vertebrae, which indicates bohaiornithids evolved increased flight capabilities in parallel to other enantiornithine lineages, such as the Longipterygidae. Traces of the plumage, which are rarely preserved in bohaiornithids, reveal the presence of remiges with rounded distal margins and short crural feathers.

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Neobohaiornis is from the Early Cretaceous. The Cretaceous is the third and final geological period of the Mesozoic Era, with the Early Cretaceous making up roughly the first half, lasting from about 143 to 100 million years ago. The poles were ice-free, due to the relatively warm climate, and forests extended into high latitudes. The continued breakup of the continents created new coastlines and isolated landmasses, influencing the evolution of distinct dinosaur faunas.

It was a time of transition, as many groups of animals and plants began to take on more modern forms while others declined or disappeared. Pterosaurs continued to thrive, though early birds were becoming more diverse and widespread. Mammals remained small but adapted to a variety of ecological niches. In the oceans, ichthyosaurs and plesiosaurs were common, and early mosasaurs began to appear.

Dinosaurs remained the dominant land animals, with groups like iguanodontians, spinosaurids, and carcharodontosaurids rising to prominence. While sauropods declined in some regions, they remained abundant in the Southern Hemisphere. The first true ceratopsians appeared, and ankylosaurs replaced stegosaurs in their niche. Dromaeosaurs and other small theropods diversified. During this time, the first flowering plants evolved, gradually changing global ecosystems by providing new food sources for herbivores.

Neobohaiornis is an enantiornithean avialan. Enantiornithes is a diverse group of early birds, also known as the "opposite birds." They were the most successful group of Mesozoic birds, spanning the Cretaceous and found on nearly every continent. They ranged from sparrow-sized to birds with wingspans of a meter or more. The group's name refers to a distinctive detail of the shoulder: the joint between the scapula and coracoid is reversed compared to modern birds. Like other early birds, most retained clawed hands, conical teeth, and a reduced but often still visible bony tail base, though many also developed a pygostyle for supporting tail feathers.

Enantiornithes were capable fliers and occupied a wide range of ecological roles. Some were tree-dwelling insectivores, others fed on seeds, fish, or possibly sap, and their beaks and toe proportions vary widely, pointing to considerable ecological diversity. Exceptional fossils preserve elaborate plumage, including ribbon-like tail feathers in some males, suggesting sexual display was important. Many hatchlings appear to have been precocial, able to fly soon after hatching, a strategy quite different from most modern birds. Enantiornithes were wiped out at the end of the Cretaceous, leaving Neornithes, the ancestors of all living birds, as the only surviving avian lineage.