Study Reveals Key Anatomical Adaptations in Macaroni Penguins

A team of anatomists from Midwestern University, in collaboration with SeaWorld San Diego and Scarlet Imaging, has published a detailed study on the limb musculature of the macaroni penguin (Eudyptes chrysolophus). The research, which appears in The Anatomical Record (2026), involved meticulous dissections of two macaroni penguins and comparisons with the anatomy of flying birds.

The findings provide a detailed anatomical reference that can inform veterinary care, injury treatment, and rehabilitation strategies for penguins in zoos and wildlife centers.

Wing Adaptations for Swimming

The study reveals significant modifications in the penguin's wing muscles compared to those of flying birds. The supracoracoideus muscle, responsible for lifting the wing, is larger in penguins. This increased size allows penguins to generate power during both the upstroke and downstroke of their flipper motion.

Furthermore, a unique configuration of shoulder muscles gives penguins a wing stroke with a stronger backwards component, which is essential for efficient underwater propulsion.

A Century-Old Hindlimb Mystery Solved

In the penguin's hindlimb, the research team identified a distinct muscle that had been debated by scientists for over a century. The researchers propose naming this muscle the adductor tibialis.

This muscle appears to help keep the penguin's legs tucked close together, contributing to the streamlined shape needed for swimming.

Evolutionary and Locomotive Insights

The research offers new information about how penguins evolved from flying ancestors into the powerful swimmers they are today. The study also notes that the penguin's specialized leg positioning and muscles contribute to its characteristic side-to-side gait on land.