What's wrong with bunny hands on dinosaurs? (2018)
Ever notice how many dinosaurs in movies look like they're holding invisible lattes? This deep dive into dinosaur anatomy explains why those 'bunny hands'—palms down, arms tucked in—are a paleontological impossibility, owing to fixed wrist structures incompatible with pronation. It's a fascinating look at how biomechanics dictate posture, debunking a widespread pop culture misconception with bone-by-bone precision.
The Lowdown
The article tackles a persistent inaccuracy in popular dinosaur depictions: the 'bunny hands' posture, where dinosaurs are shown with their palms facing downward, much like a bunny holding food. This common artistic choice, particularly prominent in films like Jurassic Park, is anatomically incorrect for virtually all dinosaurs, as the author meticulously explains.
- Human Pronation vs. Supination: The author first clarifies human forearm mechanics. Our ability to rotate our palms down (pronation) and up (supination) is due to the radius bone rotating over the ulna, facilitated by a specific, round radial head structure and an annular ligament at the elbow.
- Universal Bones, Different Structures: While all tetrapods share the same basic forearm bones, their shapes and articulations vary. Some animals, like elephants, have fused or fixed radius/ulna structures that limit or prevent rotation, leading to a permanently pronated (or fixed) limb position.
- Dinosaur Limitations: Examining sauropods (like Dreadnaughtus) and theropods (Neuquenraptor), the article demonstrates that their radius and ulna were massive and rigid, lacking the necessary rotational capability. The angular radial head in theropods, for instance, would have locked their forearms into a very limited range of motion, making full pronation impossible.
- Real Dinosaur Posture: Studies confirm that no known dinosaur could cross their radius over their ulna. This means their hands would have typically faced inward, or slightly outward, but never directly forward with palms down without an unnatural shoulder rotation. Even modern birds, living dinosaurs, cannot fully pronate their wings in this manner.
- Maniraptor Wrist Flexibility: While maniraptors (a group including raptors and birds) had incredible side-to-side wrist flexibility thanks to a 'semilunate carpal bone', this did not translate to pronation; they could not rotate their hands palm-down.
In essence, the 'bunny hands' seen in countless dinosaur illustrations and movies are a relic of outdated understanding, a biomechanical fantasy that doesn't align with the skeletal evidence.
The Gossip
Clarity Conundrum
Many commenters expressed initial confusion about the term 'bunny hands' and struggled to visualize the anatomical concepts of pronation and supination discussed in the article. Users helped each other clarify the exact position being debunked, often through physical demonstration or relatable examples, highlighting the challenge of conveying complex anatomical movements through text.
Pop-Science Palaeontology
The article's detailed debunking of a common dinosaur misconception resonated with users who enjoy accessible science communication. Several commenters praised the topic's suitability for short-form educational content and enthusiastically recommended YouTube series like 'Your Dinosaurs Are Wrong,' which similarly correct inaccuracies in popular dinosaur depictions.