Yi qi: The Dragon of the Jurassic

The Jurassic Dragon takes flight!
Image Credit: Emily Willoughby, https://commons.m.wikimedia.org/wiki/File:Yi_qi_restoration.jpg

In a dense forest, full of hissing, rumbling and bellowing noises, a dragon perches on a branch. Using its sharp eyesight it locates its next meal; a large beetle crawling along a tree trunk 50 metres away. The dragon stretches its leathery wings and takes flight, swooping down silently with barely a flap towards its prey. However, just before the dragon can strike the beetle notices and unfurls its own wings in a desperate attempt to escape. But with a couple of quick flaps the dragon adjusts in mid-air and intercepts, snapping it out of the air with its toothy jaws. The beast lands and swallows the meal. But this is only a starter, and the little dragon surveys the forest again before moving on in search of the main course.

Believe it or not this really did occur in the Late Jurassic forests of China. But with one difference. The animal in question was not a mythological dragon, but a dinosaur named Yi qi.

The binomial name Yi qi, meaning “Strange Wing” in Chinese, is the shortest scientific name given to any dinosaur, and one of the shortest names of any animal living or extinct. It belonged to a family of theropod dinosaurs known as the Scansoriopterygidae (a real tongue twister of a name). Yi qi is one of only three known members of this group (the others being Epidexipteryx and Epidendrosaurus/Scansoriopteryx) and as a result relatively little is known about their evolutionary history and general lifestyle. The Scansoriopterygidae were part of a wider theropod order known as the paravians; which includes the dromaeosaurs (i.e. raptors) and all birds (that’s right ALL birds). However the Scansoriopterygidae seem (unless future discoveries say otherwise) to be an example of an evolutionary dead end as they are only known from sites from the Mid-Late Jurassic (and potentially Early Cretaceous) China and nowhere else.

Size comparison between Yi qi and a human being
Image Credit: Matthew Martyniuk, https://commons.m.wikimedia.org/wiki/File:Yi_scale.png

Yi qi was roughly the size of a pigeon with toothed jaws, forward facing eyes, sharp claws, long thick tail feathers and simple filament feathers covering its body, head and upper arms. The fossilised feathers are so well preserved that even the melanosomes (the small organelles that give feathers and other biological structures colour) were clearly preserved. Examination of the shape of these melanosomes, and comparison with melanosomes in living birds, showed that Yi qi had a black/grey body with reds and yellow colours on its arms. This gave it a distinctive contrasting colour scheme with the red/yellow arms perhaps used for signalling or species recognition. So far from this description Yi qi sounds more like a bird than a dragon! However when palaeontologists examined its forearms they made an astonishing discovery. An elongated third finger extended from both its hands and a long rod like bone (known as a styliform) jutted out from its wrist. These supported a skin membrane, known as a patagia, connecting the ends of its elongated fingers to the end of the styliform. It’s theorized that this membrane would also have stretched from the end of the styliform to the body, giving Yi qi “bat-like” wings (though another competing theory is that Yi qi would have had skin membranes like those of a modern gliding tree frog). These unique wings give Yi qi and its close relatives an appearance unlike any dinosaur, bird or pterosaur, one that draws comparisons with a dragon (specifically a “wyvern”). Whether Yi qi would have used these wings for powered flight or gliding (like a flying squirrel) is unclear. However it may have employed a combination of the two; long distance gliding (or as Buzz Lightyear would say “falling with style!”) and powered flapping for initial take off and manoeuvring through the air. Yi qi’s discovery also shows that flight had evolved in dinosaurs on multiple occasions, with the bat winged Yi qi being only one such evolutionary experiment.

The one and only Yi qi fossil. Note the feather covering around its body and head, as well as the styliform on its elongated wrist.
Image Credit: Kumiko, https://www.flickr.com/photos/kmkmks/27011985534/

All we know about Yi qi so far comes from one remarkable fossil that was discovered in 2007 in the Hebei province of China. It was found in the Mid-Late Jurassic age Tiaojishan formation of rocks. This is important as a large proportion of feathered dinosaurs are known from the Early Cretaceous onwards (20-30 million years after Yi qi). Therefore its discovery shows that feathers were present on dinosaurs far earlier than initially thought, with some palaeontologists suggesting that they originated even earlier than Yi qi. After its discovery the fossil was studied by a team led by the eminent Palaeontologist Xu Xang, who has described and named a whole menagerie of Chinese dinosaurs (e.g. the feathered tyrannosaur Yutyrannus). Yi qi was revealed to the world in a paper released in 2015 and it’s strange, dragon like appearance meant that it, like many dinosaur discoveries from China in the last few decades, made headlines around the world.

Yi qi is one of the most unusual dinosaur discoveries of the last decade. It proves, beyond a shadow of a doubt, that the world of palaeontology continues to unearth astounding discoveries. Discoveries that add more paint to the canvas that is the history of life on earth.

References/Further Reading

The original Xu et. al. 2015 paper describing Yi qi

Xu, X., Zheng, X., Sullivan, C. et al. A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings. Nature 521, 70–73 (2015). https://doi.org/10.1038/nature14423

A blog (originally from tetrapod zoology) published in Scientific American by palaeontologist Darren Naish on Yi qi and theories on its lifestyle and features

Naish, Darren “Yi qi Is Neat but Might Not Have Been the Black Screaming Dino-Dragon of Death”. Scientific American, May. 5, 2015, blogs.scientificamerican.com/tetrapod-zoology/yi-qi-is-neat-but-might-not-have-been-the-black-screaming-dino-dragon-of-death/

A blog written by Nick Garland and published in Earth Archives on Yi qi

Garland, Nick “Meet Yi qi, the dinosaur with bat-like wings and feathers”. Earth Archives, 2015, eartharchives.org/articles/meet-yi-qi-the-dinosaur-with-bat-like-wings-and-feathers/