Derek,
>> So perhaps the original dialect of composition had carya where the Pali
dialect had cariya?<<
Say them both, don't they sound practically the same? Maybe that was the
case. Also there is the fact that Pali was written down 400 years after the
Buddha in Sri Lanka. It may be that the ry > riy became more prominent.
Also there are 'rules' with the Pali language. For instance, aarya cannot
occur in 'theory' in Pali because of a long vowel before a
consonant-cluster, so it becomes ariya. Also some poetry may not follow a
strict meter. Lots of variables with these sorts of issues.
Sean