Riograndia and Brasilodon break a jaw-joint ladder
A 26-specimen μCT sample found a dentary–squamosal contact in Riograndia but not Brasilodon, supporting iterative acquisition rather than a single ancestor-to-descendant jaw-joint ladder.
Represented range225.42–205.7 Ma
RegionsRiograndia Assemblage Zone, Candelária Sequence, Rio Grande do Sul, Brazil
In a 26-specimen μCT sample, Riograndia preserves dentary–squamosal contact whereas nine Brasilodon specimens do not, supporting homoplastic acquisition of the contact rather than a single progressive ancestor-to-descendant jaw-joint sequence.