Things With Feathers is a Tumblr where paleoartist and scientific illustrator Emily Willoughby will post science, illustration, dinosaurs, feathers, fossils, and occasionally a little bit of silliness.
I’m actually somewhat unsure whether you mean birds of prey or deinonychosaur dinosaur by “raptor” (the rules of thumb for feathering in dromaeosaurs and troodonts are essentially the same, and both groups belong to the clade Deinonychosauria), but given whom you’re asking, I’ll assume the latter. There are a number of effective “how-to” feathering guides for deinonychosaurs that I’ve come across, so I’ll link to a few of them here. Keep in mind that these should serve as a general guide only, specific taxa should be researched at the source, and that phylogenetic bracketing invokes different traits depending on which taxon you’re feathering.
Common Errors for Velociraptor by Tomozaurus
Velociraptor Infographic by ChrisMasna
Feather Evolution by me
Tips for Drawing Prehistoric Raptors by Grays-Raptor-Flock
Feathered Dino Arm/Wing PSA by SageKorppi
Hi there, it is going well! An average professional piece with full background and a lot of detail can take me in the range of a few days to a few weeks, whereas my absolutely most involved paintings to date have taken on-and-off work spread out over several months. My current job requires that I do a relatively high-quality piece in a matter of around 4 days, so that’s been my rate of production for the past few months.
I’ve learned over the course of being a scientific illustrator that improvement entails not just increasing the objective quality of work, but learning how to achieve the same quality in less time.
Albatrosses are soarers, not gliders, and they’re among the most specialized of all flying vertebrates. Microraptorines lack many of the adaptations for soaring found in birds like the albatross - an elongated humerus, the presence of tertiary feathers, and an extraordinarily high aspect ratio, to name a few.
Gliding by definition is an energy-efficient mode of locomotion that involves movement from higher ground to lower, and is a totally separate phenomenon from soaring.
Color studies are relatively unlikely to happen for taxa for which we only have the holotype. Melanosome studies also require extraordinary, fine-grain preservation of the fossil. It’s more likely if future specimens of the genus are found, but I wouldn’t hold my breath.
No, I don’t agree that legwings (or pennaceous feathered “trousers”) would have necessarily gotten in the way of walking. Two reasons come to mind, and one comes from functional morphology and the other from evolutionary logic. First, assuming these structures would impede walking requires a certain lack of imagination: we don’t yet know for sure how an animal like Microraptor would have held its legwings, but one reasonable idea is that they were splayed in a manner not dissimilar to fancy pigeons, which have little trouble walking despite being selectively bred for this admittedly unnatural trait. Another idea is that they folded and overlapped like regular wings do, with the metatarsal section of the legwing being under some amount of muscular control and folding under the tibiotarsal section. Matt Martyniuk draws his Microraptor legwings in such a manner. In either case, the feet are relatively unimpeded by the structures.
Another important point to keep in mind comes from how evolution itself works - and doesn’t work. Walking (and running, leaping, and other ambulatory activities) is an invaluable part of the tetrapod legacy, and it’s only given up in cases of extreme adaptation to other ways of life that make the loss worthwhile. One example is loons, grebes and other diving birds whose entire morphology is built around their capacity to dive at high speeds. In these animals, their ability to walk on land is severely limited by the exaggerated posterior placement of the feet. Swifts and hummingbirds (a group whose order name literally means “footless” because early naturalists thought they didn’t have them) are another example, and their feet are useful for almost nothing but clinging. This is because they are extraordinary specialist flyers, some of the best in the world.
Microraptor, however, has been demonstrated to NOT be an aerial specialist! (Nor does it seem to be a specialist of any other sort, including its diet.) It’s very unlikely that it would have lost performance of such a basic function without evolving a comparable specialty. In my view, Microraptor was a fairly generalized crappy glider that was reasonably adept at walking, running, climbing and leaping.
I would not choose to restore a tyrannosaur with pennaceous feathers, which so far appear to be restricted to maniraptoriform dinosaurs.
It’s hard to know for sure. Most Mesozoic dinosaurs described with feathery “pants” did not have actual legwings, which is a term that I think should be reserved for lift-generating surfaces, as in Microraptor and the newly-described Changyuraptor. Modern hawks are good examples of fluffy pants in a non-aerodynamic role, and it’s difficult to say that even something as large as a tyrannosaur would have definitely not had something along those lines. Yutyrannus (a tyrannosauroid, but not a tyrannosaur) had filamentous feathers covering almost the entire body, possibly down to the feet.
True legwings and voluminous feathered pants seem restricted to Maniraptora so far, but I wouldn’t rule out filamentous feathers extending down to the pes in tyrannosaurs and other larger groups.
I vaguely recall the episode (is that the one with the unfortunate attachment of primaries to the third manual digit?) but I don’t remember the specifics of the chase scenario. I definitely don’t think it’s totally outside the question that Sinornithosaurus could have been using its wings and tail to glide (or “descent-slow”) from higher to lower ground, certainly.
Gliding is such a fundamentally different aerodynamic process from flying that it’s difficult to pin a hypothesized “maximum” size and weight on it. It might be easier to ask how long feathers can grow while retaining function and rigidity, and there may be an answer to that. As we see with Changyuraptor's elongated retrices, evolution imposes different restrictions and functions on the anatomy of an animal at greater sizes. Your question also rests somewhat on the definition of “glide” - even a large dromaeosaur could probably slow its descent very slightly with a lift-generating surface, so the line between “true” gliding and “descent slowing” might be as fuzzy as Tianyulong's tuchus.
Does anyone have a recommendation for a field guide app on reptiles & amphibians for iPhone? Eastern North America preferred, but North America in general also fine. Thanks a lot in advance!