Evolution of terrestrial anatomy revealed by a derived stem tetrapod.

Westlothiana lizziae, a stem tetrapod from the Early Carboniferous, exhibits a mosaic of aquatic and terrestrial traits, revealing complex early limb evolution.

• Why it matters: Understanding the origins of terrestrial adaptations in tetrapods is crucial for unraveling how land-dwelling vertebrates evolved from aquatic ancestors, filling significant gaps in evolutionary knowledge.
• What they did: Researchers analyzed Westlothiana lizziae, using phylogenetic methods to examine its skull, limb, and other anatomical features, uncovering unexpected primitive and aquatic traits.
• The result: Findings show terrestrial features evolved gradually in an amphibious context before the tetrapod crown group, highlighting the mosaic nature of limb evolution and the need for more detailed anatomical data.