Complex sentence: Palatal and nasal skeletal features like choanae that are seen in modern amphibians indicate that incipient air breathing developed, as well as modification of the hyoid arch towards stapes development.
Split into simpler sentences: Palatal and nasal skeletal features like choanae that are present in these groups and are seen in modern amphibians. This indicates that incipient air breathing developed, as well as modification of the hyoid arch towards stapes development.