Overview

• Fossils of Brasilodon quadrangularis and Riograndia guaibensis provide new insights into mammalian jaw and middle ear evolution.
• CT scans show Riograndia had a 'mammalian-style' jaw joint 17 million years earlier than previously known.
• The study indicates that mammalian jaw features evolved multiple times in different cynodont groups.
• Findings suggest early mammalian evolution was more complex and varied than previously understood.
• Researchers plan further investigations into South America's rich fossil record to deepen understanding of mammalian origins.