Time and Place: About 128 million years ago, in the Barremian age of the Early Cretaceous
Yangavis is known from the Sihedang bed just above the Basalt Base of the Yixian Formation in Liaoning, China
Physical Description: Yangavis was a Confuciusornithid, a kind of proto-bird that convergently evolved a lot of birdie characteristics independent of the direct ancestors of modern birds. These were small-bodied dinosaurs, with the pygostyle that characterizes living birds - the shortened, fused tail that acts as a ball-and-socket joint to give the tail maximum flexibility and movement. Yangavis was about the same size as other Confuciusornithids - the size of a modern day robin or starling - except that it had huge, half-a-meter-long wings, much bigger than other members of the group. Yangavis had a small head and a toothless beak, and that beak is the main trait that Confuciusornithids evolved, much like modern birds, but independently.
Yangavis was a bit weird compared to other members of its group in other ways as well. It had a more rectangular jaw, and had ridges running on the outside of its beak. It had very long claws on its fingers, unlike those of other Confuciusornithids; it also had longer toes and a larger claw on its first toe than its relatives. This shows that reduction of these features was also unique for more derived Confuciusornithids, rather than inherited from the general group of proto-birds.
Diet: The diet of Yangavis is a bit of a question, as is the diet of all Confuciusornithids, due to the fact that they are toothless. However, the current dominating hypothesis is that these animals were piscivores, due to their association with lakes, and the remains of fish being found in the stomach of at least one Confuciusornis.
By José Carlos Cortés
Behavior: Yangavis was a small birdie dinosaur, and as such it would have been very skittish, probably in danger from larger dinosaur predators in its environment. As a Confuciusornithid, it did have rudimentary flight ability, but it was not the strongest of flappers. Instead, it might have used its longer wings in order to soar more over the lake system, only flapping when absolutely necessary. Though Yangavis hasn’t been found in large groups like its relatives, it probably would have been fairly social, all flying together to look for food. This flight would have been very odd due to the inability to raise their arms high; perhaps they utilized a flight ability not seen in modern birds. Yangavis would then dip down to the water, grabbing food from under the surface of the lake.
Though the original fossil of Yangavis was not found with extensive feather impressions, its relatives show possible sexual dimorphism in terms of feather shape on the tail. Presumed mails had long, ribbon-like feathers coming off of the tail, which could be raised and lowered by the flexible tailbone to display to females. It’s entirely possible that Yangavis also showcased similar behavior to one another, in order to attract mates and threaten rivals.
Ecosystem: Yangavis is from the Yixian Formation, one of the extremely diverse northern Chinese ecosystems from the Early Cretaceous that showcases the evolution of so many modern groups, especially birds, mammals, and flowers. This was a temperate forest environment, near an extensive system of volcanoes, surrounding complicated lake systems. However, Yangavis is from one of the earliest beds of that formation, a time when very few other animals are known. It lived alongside other birds - namely, the enantiornithine Monoenantiornis and the euornithine Iteravis, as well as a turtle, Jeholochelys, and two pterosaurs, Ikrandraco and Guidraco. Other creatures were probably present, of course, but they have yet to be found.
Other: Yangavis indicates that Confuciusornithids - this group of very basal proto-birds - was more morphologically diverse than previously thought.
~ By Meig Dickson
Sources under the Cut
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