Help on RT ridges

[Chris Lavers <chris.lavers@nottingham.ac.uk>]

Dear all

Could anyone help a struggling writer with references/information on the
presence or otherwise of RT ridges in mammal-like retiles (I have the 1994
Hillenius paper *Evolution*, 48 (2), 207-229). 

[Is *Glanosuchus* the earliest therapsid with a ridge? Does everyone
believe that it's an RT ridge? Have any others been found (or found not to
be present) in later therocephalians? Have any since been found in
dinocephalians, dicynodonts or gorgonopsians? Do all cynodonts have them?]

Many thanks in advance for any assistance

Chris