Latin c- > Romance g-, any explanation?

From: Joao
Message: 29618
Date: 2004-01-15

Is there any explanation for the trend *c->g- present in some Romance words?
1- Latin cattus > Romance *gattu > Portuguese gato
2- Latin crupta (<crypta) > *grupta > Portuguese gruta
3- Latina crassa > *grassa > Portuguese graxa
 
 
 
Joao SL