From Chris McGowan's handout:

Reptile Features                    Mammal Feature
--------------------------------    -----------------------
undiferentiated teeth               specialized teeth
teeth lack cusps                    cusps in teeth
multiple bones in lower jaw         one lower jaw bone (dentary)
joint between articular and         joint between dentary and
   quadrate bones                      squamosal bones
jaw a ball-and-socket affair        glenoid attachment
shallow lower jaw posterioral       lower jaw deeply posterior
relative small cranium              relative large cranium
single condyle                      dual condyle
does not have odontoid              odontoid
ribs in neck region                 no ribs in neck region
ribs from shoulder to pelvis        ribs in chest
legs USUALLY side-mounted           legs beneith body
finger/toe bones USUALLY greater    fingers/toe bones 2,3,3,3,3
   than 2,3,3,3,3
ilium vertical                      ilium slopes forward