A year ago I created a series of 10 posters for Scholastic, Inc.
They depicted dinosaurs and some animals that existed along with them from the Triassic to the end of the Cretaceous. The posters when put together were over 15 feet long and were sold through the book club. (The colors and style are intentionally more “child like”)
Lythronax argestes by Andrey Atuchin
T. rex Reexamined | 1999 | 55.9x94cm - Styracosaurus | 1995 | 68.6x48.3cm By Kazuhiko Sano
I’ve seen a lot of hoo-ha on my dash and in various dinosaur tags lately about feathers on non-avian dinosaurs, so I thought some people might find this useful.
This is a diagram on feather evolution I did a while ago for a book I co-authored and illustrated (which is currently in press, stilllllll). The “stages” represented here are highly simplified from reality (the “interlocking” and “non-interlocking” barbule stages are basically combined into one, since it’s not really possible to tell them apart in fossils) due to making it as easy to understand as possible to a lay-audience.
The description, as written by the editor:
Stage 1 - Simple fibers: Hollow unbranched fibers, with no barbs or barbules. Found on Sciurumimus albersdoerferi.
Stage 2 - Bundles of fibers: Groups of unbranched fibers, each attaching to a central point. Found on Sinosauropteryx prima.
Stage 3 - Unbranched barbs: Rows of unbranched barbs attached to a central shaft. Found preserved in amber alongside troodontid teeth.
Stage 4 - Barbs and barbules: Rows of barbs attached to a central shaft, which branch further into barbules. Found on Protarchaeopteryx robusta.
Stage 5 - Fully-developed flight feathers: Barbs and interlocking barbules; asymmetrical shape. Found on Microraptor gui.
Some things to point out relevant to aforementioned dash hoo-ha: large, non-volant dromaeosaurs, including Utahraptor and other large genera, are most likely to have possessed stage 3 or 4 feathers. In life, these would have appeared similar to the remiges found on modern flightless birds like the ostrich, which has fairly shaggy vaned remiges on its arms.
Two important points: 1) As per phylogenetic bracketing, there is no reason whatsoever to assume that larger dromaeosaurs did not have these primitive sorts of remiges. 2) As per common sense, there is also no reason to assume that non-volant dromaeosaurs had asymmetrical stage-5 flight feathers, which are ONLY known from animals (both living and extinct) that had at the very least some rudimentary flight or gliding capabilities. Asymmetrical remiges are not “accurate” on large, obviously non-volant dromaeosaurs.
To illustrate the point, the modern kakapo parrot appears to be clearly in the process of losing its ability to fly, evolving instead a preference for a largely terrestrial lifestyle. It is considered “mostly” flightless. And, curiously, its remiges are also much less asymmetrical than related volant genera.
This is not a coincidence - in feathers, asymmetry, interlocking barbules and the mechanisms for maintaining them are more costly to produce, and these traits appear to slake off when a lineage loses volant capabilities.
Feathers did not evolve for flight, but stage 5 asymmetrical feathers (probably) did!
- A Megapnosaurus goes for a swim! An illustration to show how a dinosaur makes swimming tracks. Book illustration. Acrylics.
- A Dilophosaurus sitting in mud. Illustration for a scientific paper: Bird-Like Anatomy, Posture, and Behavior Revealed by an Early Jurassic Theropod Dinosaur Resting Trace. Acrylics.
Yutyrannus huali by Lida Xing and Yi Liu.
Dromaeosaurs by Jonathan Kuo
Dilophosaurus wetherilli ambushing a Scutellosaurus lawieri, by Stevie Moore. Prints available.
Baryonyx by Fabio Pastori