#anchiornithid

Continuing my theme of choosing dinosaurs we know the colors of, my choice for day 1 of Archovember this year is Caihong juji!

In a dense Sequoia forest where the darkness is broken by only a single solarbeam, a Caihong curiously inspects a Kalligrammatid, seeing a face not unlike its own staring back from the strange insect's transparent wings.

#Archovember Day 1 - Your Choice!

In my ongoing effort to draw all the non-avian dinosaurs we know the colors of, I’ve chosen Anchiornis huxleyi!

The type species for the Anchiornithids (“near birds”), Anchiornis huxleyi was a crow-sized dinosaur living in the Late Jurassic of Liaoning, China. It was relatively common, as hundreds of specimens have been uncovered in this area. But what makes Anchiornis so unique and important is that it was the first Mesozoic dinosaur species to have its entire life appearance be known by man! Having hundreds of well-preserved fossils available allows us to extract a lot of information about not only its size and shape, but its skin, feathers, and even coloration. Anchiornis had long wing feathers on its arms and legs (though its leg feathers were not as long as those of Microraptorians), fluffy downy feathers all over its body, a feathered crest on its head, and feathers covering its feet.

Only two Anchiornis fossils have had their well-preserved melanosomes studied so far. By comparing the structure of these melanosomes to modern birds, paleontologists have been able to infer the life colors of Anchiornis! It had mostly gray and black body feathers and white forewing and hindwing feathers with black tips. Its tail colors remain unknown. The first specimen of Anchiornis to be surveyed for melanosomes also had red or rufous coloring on its crest, as well as rufous speckles on its otherwise black and gray head. However, the second specimen did not have any rufous coloration. This may be due to different preservation of melanosomes, different investigative techniques, the animals in question having regional differences or even being different species/subspecies, the second Anchiornis being younger, or sexual dimorphism.

Here’s some of the amazing diversity of Mammaliaformes of Jurassic China. Volaticotherium glides in pursuit of a tasty bug. Agilodocodon, an excellent climber, already got one and brings it back to its young in the trees. Some Docofossors are digging up the lawn. Castorocauda, the largest mammaliaform of the Mesozoic, is going for a swim. With the exception of Volaticotherium, these are all Docodonts, a group closely related to the crown group mammals, having branched off a little before the monotremes did. I wanted to show off how much more diverse and interesting Mesozoic mammals were than we usually imagine. They did a lot more than cowering from dinosaurs and being eaten by them!

By José Carlos Cortés 

Etymology: Rainbow

First Described By: Hu et al., 2018

Classification: Dinosauromorpha, Dinosauriformes, Dracohors, Dinosauria, Saurischia, Eusaurischia, Theropoda, Neotheropoda, Averostra, Tetanurae, Orionides, Avetheropoda, Coelurosauria, Tyrannoraptora, Maniraptoromorpha, Maniraptoriformes, Maniraptora, Pennaraptora, Paraves, Eumaniraptora, Avialae, Anchiornithidae

Status: Extinct

Time and Place: 161 to 160 million years ago, in the Oxfordian of the Late Jurassic 

Caihong is known from the Tiaojishan Formation of Liaoning, China 

Physical Description: Caihong was a small dinosaur, only reaching 0.4 meters in length, and weighing only a little more than a single pound. It was weird in a lot of ways when you got down to it - it is a rare example of a Paravian (birds and their closest relatives) with a bony crest on its snout, which was small and triangular shaped like most almost-birds at that time. In fact, beyond the bony crest, it had a head very similar to that of Archaeopteryx. The crests were long and bony, pointed sideways and curving upwards. It had tightly packed, slender teeth in the front of the jaws, which space out more towards the back - and in the middle they tend to curve the most. It had a short neck and a normal-sized torso, but weirdly enough Caihong had a fairly short tail for a dinosaur of its type. It had fairly short arms compared to other dinosaurs in its group (the Anchiornithids), indicating that any flight or gliding ability could have been poorer than usual - but it did have longer lower arms than upper arms, and longer wing feathers, indicating decent flight capabilities. Caihong also had very long fingers. Its hips were rather rectangular in shape, weirdly enough, unlike other paravians which usually had triangular-shaped hips. Caihong also had very long legs, with somewhat short toes and noticeable sickle claws (like other paravians). 

By Tom Parker, CC BY-SA 4.0 

Caihong is, of course, most notable for its coloration. Like other Anchiornithids, it was excessively fluffy. Fossils of Caihong include remains of the original plumage - not just impressions - which showcase the extreme density of the feathers. In fact, it’s a tad difficult to identify each individual one. These feathers were extremely long (though some were shorter and wavier than others) making them distinct from other dinosaurs - in fact, it had some of the longest feathers known in its group. These feathers preserve distinct coloration, which show that most of the body of Caihong were black and iridescent, like many living birds such as crows and ravens. More notably, coloration in the neck and head showcase iridescence like modern hummingbirds and trumpeters - giving Caihong a distinctive rainbow neck. In fact, it is the first Mesozoic Dinosaur found with such structures - called plate-like melanosomes - making it one of the gayest of non-avian Dinosaurs. Happy Pride Y’all. 

By Ripley Cook

Diet: Like other Anchiornithids, Caihong probably fed mainly on small animals and insects, which were extremely common in its environment.

Behavior: Like other Anchiornithids and Paravians in general, Caihong showcased a mixture of behavior indicating its intermediate position on the bird evolutionary tree - it could probably fly at least a little bit, but mainly used its wings for other behaviors that were in many ways flight-adjacent. Able to fly from tree to tree and place to place in its forested environment, it also would have engaged in Wing-Assisted-Inclined-Running, or WAIR. In WAIR, Caihong would flap its wings fast enough to jump onto a steep or vertical surface and run up it - using the lift generated by its wings to gain height. It could have balanced on top of prey with its claws, and flapped its wings to stay balanced, a behavior known as Raptor-Prey-Restraint, or RPR. However, given it mainly ate small food, it would have more often just trapped the food with its foot claw, and held it down with its (light) weight. It was a small birdie thing running about between the trees, and probably used its sparkling feathers on its neck and tail fan and wings more often for sexual display. 

By Anthony F. 

Given it was an active, warm-blooded animal, Caihong most likely took care of its young. Whether or not it lived in family groups, larger flocks, or mainly on their own is more of a question - they don’t seem to have been quite as common as their cousin Anchiornis. Overall, it was an agile and active small predator, and a very flashy one at that. 

By Scott Reid

Ecosystem: The Tiaojishan environment was a temperate rainforest, dominated by giant conifer and ginkgo trees, as well as horsetails, cycads, ferns, and clubmosses. Nestled in a valley with extensive lakes, rivers, and volcanic activity, it was an extremely lush environment - and didn’t experience the winters of the later Jehol biota. It probably had clear wet and dry seasons. This was an environment of fluffy creatures and flighted creatures. Here there were a variety of salamanders, lizards, and invertebrates. There were also very unique mammals and almost-mammals - Agilodocodon, a tree-climbing squirrel-like creature; Arboroharamiya, a rodent-like critter with a prehensile tail; Castorocauda, a beaver-like non-mammalian synapsid; Docofossor, a burrowing almost-mammal similar to the Golden Mole; Juramaia, a shrew-like stem-placental mammal; Megaconus, a hyrax-like creature; and Volaticotherium, a gliding colugo-like creature adapted to eat insects. 

Tiaojishan Environment by Julio Lacerda, used with permission from Pteros

This was also a land of pterosaurs - so many pterosaurs. There were long-tailed, crested, big-headed forms like Archaeoistiodactylus, Changchengopterus, Darwinopterus, Kunpengopterus, Pterorhynchus, and Wukongopterus. There were smaller-headed long-tailed piscivorous forms like Fenghuangopterus, Jianchangnathus, Jianchangopterus, and Qinglongopterus. And then there were the particularly fuzzy, blunt-snouted, big-eyed anurognathids Jeholopterus and Dendrorhynchoies. This cacophony of creatures showcased a transitional period in pterosaur evolution - with many of the more iconic Jurassic kinds living alongside the precursors to the giant Cretaceous pterosaurs we all know and love.

By Lucas Attwell, CC By-SA 4.0 

As for Dinosaurs, there was diversity abundant too. Caihong lived with many of its closest relatives: Anchiornis, Auornis, Eosinopteryx, Pedopenna, Xiaotingia, and Serikornis - all extremely fluffy, like Caihong, and coming in a wide variety of colors and sizes. This was the paradise of the Anchiornithids, showcasing a truly amazing diversity. They weren’t the only birdie dinosaurs, however - Yi, Scansoriopteryx, and Epidexipteryx flew (badly) from tree to tree, the weird dragons that they were. And, of course, there was one of the most notable fluffy Ornithischians - Tianyulong, the Heterodontosaurid, just to show how Ornithischians were a thing in the Tiaojishan, too. 

By Ashley Patch 

Other: The Anchiornithids have always been a very confusing group of dinosaurs, because they straddled the line between things commonly called birds (Archaeopteryx et al.,), and things that have always been kept outside of that grouping (Troodon et al.). And, as recent phylogenetic analyses have shown, this is an accurate description of their placement. The Anchiornithids - like Caihong - are literally in-between Archaeopteryx and Troodon, making them the Most Transitional Birdie Dinosaurs of all. Are they birds? Are they not birds? I tend to go with the line of thinking that most dinosaurs are birds, but for the sake of argument - they certainly blur the line. As more Anchiornithids are found and studied, even more will probably come to light about the evolution of dinosaurs towards more birdie traits throughout the Jurassic and then Cretaceous periods.

~ By Meig Dickson, edited by Henry Thomas

Sources under the Cut