text: megalomys audreyae megalomys audreyae , known as the barbudan ( ? ) muskrat or the barbuda giant rice - rat , is an extinct oryzomyine rodent from barbuda in the lesser antilles . described on the basis of a single mandible ( lower jaw ) with the first molar missing and an isolated upper incisor , both of uncertain but quaternary age , it is one of the smaller members of the genus megalomys . little is known about the animal , and its provenance and distinction from " ekbletomys hypenemus " , an even larger extinct oryzomyine that also occurred on barbuda , have been called into question . the toothrow in the lower jaw has a length of 8 . 7 mm at the alveoli . the third molar is relatively narrow and both the second and third molars have a wide valley between their outer cusps . history remains of megalomys audreyae were found by john walter gregory among cave breccia on barbuda around 1900 . the exact locality is unknown . in his 1901 description of oryzomys luciae , charles immanuel forsyth major mentioned the barbuda animal as another member of the megalomys group , but he never published a description of the latter . édouard louis trouessart gave the name oryzomys ( megalomys ) majori to it in his catalogus , but he did not describe it and therefore the name is a nomen nudum . in 1926 , arthur hopwood finally described it and named it megalomys audreyae after gregory 's wife audrey , following major 's intention . the oryzomyines of the caribbean were revised in 1962 by clayton ray , who examined the specimens gregory had found and redescribed them . he suggested that m. audreyae may in fact have come from barbados instead of similarly named barbuda , citing the occurrence of a different oryzomyine ( " ekbletomys hypenemus " ) in other cave deposits on barbuda , circumstantial evidence for the occurrence of a native rodent on barbados , uncertainty whether gregory ever visited barbuda , and biogeographical considerations . in the subsequent literature , m. audreyae has seldom been mentioned and never been further described . in a 1999 review of recent extinctions in mammals , ross macphee and c. flemming reported that m. audreyae had been recovered from a locality on barbuda known as darby sink , which had been radiocarbon dated to around 1200 ce . they also stated that m. audreyae and " ekbletomys " may in fact be identical . however , in 2009 samuel turvey suggested that two different rice rats were in fact present in material from barbuda , which would imply that m. audreyae is a valid species . description the only remains of megalomys audreyae that have been described in the literature are the original two specimens gregory found , a left upper incisor and a left mandible ( lower jaw ) . the upper incisor is not grooved and its diameter has a length of 2 . 6 mm and width of 1 . 5 mm , but exhibits no other significant characters . the mandible , which is severely damaged and lacks the condyloid , coronoid , and angular processes at the back of the bone , contains the second and third molar and part of the lower incisor , but the first molar is missing . the capsular process of the lower incisor , a slight raising of the mandibular bone at the back end of the incisor , is small . the preserved alveoli , the impressions left by the roots , show that the first molar was supported by large roots at the front and back and a smaller root in between these . the second molar is about square and shows the four main cusps commonly present in rodents : the protoconid , metaconid , hypoconid , and entoconid . a strongly developed mesolophid ( a crest ) is also present , as in most oryzomyines . the main valley between the cusps , the hypoflexid , is broad and v - shaped . the third molar is as long as the second , but it is narrower and the entoconid is poorly developed . again , the hypoflexid is broad and v - shaped . the length of the toothrow at the alveoli is 8 . 7 mm . the length of the second molar is 2 . 5 mm and the width is 2 . 2 mm . the third molar has a length of 2 . 5 mm and width of 1 . 8 mm . when clayton ray described " ekbletomys hypenemus " on the basis of abundant skeletal remains from both barbuda and antigua , he carefully distinguished it from m. audreyae , the only other native rodent recorded from those islands . m. audreyae is much smaller than " ekbletomys " ; for example , 72 specimens of the latter had the alveolar length of the lower molars ranging from 10 . 3 to 12 . 6 mm ( mean 11 . 6 mm , standard deviation 0 . 49 mm ; compare 8 . 7 mm for m. audreyae ) . in addition , the v - shaped and narrow third molar of m. audreyae contrast with the narrow , parallel - sided and broad third molar of " ekbletomys " . these characters , and others observable in species of megalomys represented by more complete material , convinced ray that m. audreyae and " ekbletomys " are not only distinct species , but indeed share no close relationship . instead , he proposed that the combination of large size , occurrence in the lesser antilles , and similarity in molar morphology indicated a relationship between m. audreyae and other species of megalomys , and he suggested that the similarly sized m. curazensis from curaçao , off venezuela , may be most closely related to m. audreyae .