 The masseteric crests ( crests on the outer sides of the mandibles ) reach their front ends below the front border of the first molars . Usually , the capsular process ( a projection at the back of the mandible housing the root of the lower incisor ) is well @-@ developed . The enamel of the upper incisors is yellowish @-@ orange and the incisors are orthodont ( with their cutting edge perpendicular to the plane of the toothrow ) or slightly opisthodont ( with the cutting edge inclined backwards ) . In contrast , Akodon simulator has more <unk> incisors ( with the cutting edge oriented forwards ) and Akodon neocenus has more opisthodont incisors . The molars are more hypsodont ( high @-@ crowned ) than in A. caenosus , but are unlike the very hypsodont molars of A. budini . The molar rows are relatively longer than in A. polopi . There are 13 or 14 thoracic ( chest ) , 7 or 8 lumbar ( abdomen ) , and 23 or 26 caudal ( tail ) vertebrae . 
