Why were holosteans generally more efficient swimmers than chondrosteans?

Holosteans were generally more efficient swimmers than chondrosteans due to several key anatomical advancements that improved their propulsion and maneuverability.12

The primary factors contributing to this increased efficiency include:

• Tail Structure: Unlike the heterocercal (asymmetrical) tails of chondrosteans, which provided less effective propulsion, the tails of holosteans approached a homocercal (symmetrical) condition, allowing for more powerful and efficient movement.2
• Fin Ray Arrangement: Holosteans evolved an equal number of fin rays and basal elements, a structural improvement that enhanced their swimming capabilities compared to the more numerous, less organized rays found in chondrosteans.2
• Body Scaling: The thinning of body scales in holosteans reduced drag and contributed to a more streamlined form, further increasing their swimming efficiency relative to the thick, heavy ganoid scales characteristic of many chondrosteans.2

These evolutionary developments allowed holosteans to achieve a higher level of structural organization, marking a significant transition in the history of ray-finned fishes.2