Yixianosaurus longimanus

Long-handed Yixian Reptile
Yixianosaurus longimanus
Time: 124.5 Ma ago
Location: Liaoning, China
Habitat: Lower Yixian Formation, temperate conifer and ginkgo forest set among a series of lakes fed by streams and runoff from a nearby range of active volcanic mountains.
Size: WS >50cm (1.6ft); BL ~90cm (3ft); TL unknown
Features: Large, primitive, stocky and powerfully-built ground birds. Known only from the wings and shoulder girdle. Manus longer than ulna and three free digits very robust. Three wing claws large and strong. Long, narrow remiges, total length unknown.
Biology: While the forelimbs were preserved in the only known fossil, they are known to have had long wing feathers, despite their basal position among winged birds. The long wings with hands longer than forearms are a condition evolved independently from more advanced birds and may hint at an unusual ecological niche not shared with other medium-sized carnivores in the same ecosystem. Probably carnivorous, using the strong wing claws to seize or subdue prey.

---------------------------------------------------------------------

This is a deleted scene from the ever-upcoming Field Guide. While I'm trying to include as many aviremigians as possible, even those known only from fragmentary specimens, I felt like this one crossed the line into the realm of the imaginary. It's one thing, in my mind, to include something like Pedopenna, known only from a lower leg, if it preserves some distinctive externally-visible features (small, bell-bottom shaped hind wings), or something like Philovenator (known only from the leg), which we can be reasonably sure looked pretty much like other derived troodontids.

But the fact is, we don't really have any idea what Yixianosaurus is. It's the Deinocheirus of the 21st century. I had restored it basically as I'd imagine a very primitive oviraptorosaur would look, sort of like a cross between Ornitholestes, Falcarius, and Protarchaeopteryx. I'd probably have kept it in if we had complete wing feathers--that would be useful to diagram, at least for artists. But even their length is a guess. So, despite being possibly the most basal known member of the Aviremigia, I had to give this guy the axe.