text: ferugliotherium ferugliotherium is a genus of fossil mammals from the campanian and / or maastrichtian ( late cretaceous , around 70 million years ago ) of argentina in the family ferugliotheriidae . it contains a single species , ferugliotherium windhauseni , which was first described in 1986 . originally interpreted as a member of multituberculata , an extinct group of small , rodent - like mammals , on the basis of a single brachydont ( low - crowned ) molar , it was recognized as related to the hypsodont ( high - crowned ) sudamericidae after the discovery of additional material in the early 1990s . after a jaw of the sudamericid sudamerica was described in 1999 , these animals ( collectively known as gondwanatheria ) were no longer considered to be multituberculates and a few fossils that were previously considered to be ferugliotherium were assigned to unspecified multituberculates instead . since 2005 , a relationship between gondwanatheres and multituberculates has again received support . a closely related animal , trapalcotherium , was described in 2009 on the basis of a single tooth . about twenty teeth and a jaw fragment have been referred to ferugliotherium , but the assignment of many of these is controversial or has been superseded . the upper and lower incisors are long and rodent - like and have enamel on only one side of the crown . a fragment of the lower jaw shows that the tooth socket of the lower incisor was very long , extending below the fourth premolar ( p4 ) . the p4 is preserved in this fragment . it is blade - shaped and resembles multituberculate p4s . however , the determination of this fossil as ferugliotherium is in question . the identity of a few additional isolated premolars assigned to ferugliotherium , some resembling multituberculates , is also uncertain . the first lower molariform ( molar - like tooth ; mf1 ) is known from four examples , of which two were originally identified as upper molars of a different species ( vucetichia gracilis ) , which is now considered a synonym of ferugliotherium . they bear two longitudinal rows of three or four cusps and transverse crests and furrows . a single example each of the second lower ( mf2 ) and first upper molariform ( mf1 ) show that these teeth also had longitudinal cusp rows and transverse furrows and crests , but the mf2 had only two or perhaps three cusps per row and the mf1 had three longitudinal rows . although ferugliotherium teeth are much lower - crowned than those of the sudamericidae , they share an essentially similar pattern on the occlusal ( chewing ) surface of mf1 and mf2 , similar incisors , backward jaw movement during chewing , and enamel with small prisms . ferugliotherium is thought to have been a small animal , with a body mass of about 70 g ( 2 . 5 oz ) , and may have eaten insects and plant material . its remains have been found in two geological formations of southern argentina , where it is part of a mammal fauna that also includes the sudamericid gondwanatherium and a variety of dryolestoids . taxonomy ferugliotherium windhauseni was named in 1986 by argentinean paleontologist josé bonaparte on the basis of a single second lower molar ( m2 ) from the late cretaceous los alamitos formation of argentina . both the generic name , ferugliotherium , and the specific name , windhauseni , honor geologists who studied the geology of patagonia : egidio and anselmo , respectively . bonaparte created a new family , ferugliotheriidae , for the new species and tentatively assigned it to multituberculata , an extinct group of mammals that was diverse during the late cretaceous , mostly in the northern continents ( laurasia ) . in subsequent years , other finds permitted a more confident assignment to multituberculata . in 1990 , bonaparte described vucetichia gracilis on the basis of what he interpreted as two upper molars of a relative of gondwanatherium within the order gondwanatheria , a small mammalian group that was at the time known only from argentinean fossils and thought to be related to xenarthrans as part of a group called paratheria . the generic name , vucetichia , commemorates argentinean paleontologist guiomar , and the specific name , gracilis ( latin for " slender " ) , refers to the animal 's small size . however , in 1990 david w. krause and bonaparte argued that gondwanatheria , including ferugliotherium ( family ferugliotheriidae ) , gondwanatherium , and sudamerica ( family sudamericidae ) , should be placed within multituberculata . two years later , krause , bonaparte , and zofia kielan - jaworowska described additional material of ferugliotherium ( which they tentatively placed in the multituberculate suborder plagiaulacoidea ) and suggested that the supposed upper molars of vucetichia were in fact heavily worn first lower molariforms ( mf1 ) of ferugliotherium . in 1993 , krause described an unworn mf1 of ferugliotherium and confirmed that vucetichia was based on worn specimens of ferugliotherium and therefore a synonym of the latter . in the same year , he and bonaparte argued once again that ferugliotherium , gondwanatherium , and sudamerica formed a closely related group of multituberculates , which they called the superfamily . kielan - jaworowska and bonaparte described a lower jaw fragment with a multituberculate - like lower fourth premolar ( p4 ) from los alamitos in 1996 and tentatively identified it as ferugliotherium . on the basis of the morphological features of the jaw fragment , they argued that gondwanatherians were not closely related to any other multituberculate group , and consequently placed them in a suborder of their own , gondwanatheria . in 1999 , rosendo pascual and colleagues described a jaw of sudamerica . because some of this jaw 's features were thought to be incompatible with a multituberculate identity , they regarded gondwanatheres ( including ferugliotherium ) as mammalia incertae sedis . however , in 2009 yamila gurovich and robin beck argued in favor of a close relationship between gondwanatheres ( including ferugliotherium ) and multituberculates . the controversy is partially due to disagreement over the assignment of two upper premolars and the jaw fragment described by kielan - jaworowska and bonaparte in 1996 ; gurovich and beck identify these as ferugliotherium , while kielan - jaworowska and others regard them as indeterminate multituberculates . in the 2000s , some possible close relatives of ferugliotherium were discovered . an enigmatic tooth from the paleogene of peru , lacm 149371 , was described in 2004 as possibly related to the family ferugliotheriidae . kielan - jaworowska and colleagues described a p4 from the la colonia formation ( late cretaceous of argentina ) as a new multituberculate genus , argentodites , in 2007 , but gurovich and beck noted close similarities between this p4 and the p4 in the possible jaw fragment of ferugliotherium and suggested that it represented ferugliotherium or a closely related species . a single mf1 from the allen formation ( late cretaceous of argentina ) was described as another ferugliotheriid genus , trapalcotherium , in 2009 . description ferugliotherium is known from isolated teeth , the assignment of some of which is controversial . the material from the los alamitos formation , which is mostly in the museo argentino de ciencias naturales bernardino rivadavia ( macn ) in buenos aires , with one tooth in the museo de la plata ( mlp ) in la plata , argentina , has been thoroughly described ; while there are additional ferugliotherium fossils from the la colonia formation , they have not been described in detail . although the fragmentary nature of the known fossils of ferugliotherium makes it impossible to determine its dental formula with certainty , gurovich suggested that it had one incisor ( possibly two in the upper jaw ) , no canines , one or two premolars , and two molars on each side of the lower and upper jaws . however , on the basis of comparisons with sudamerica , which is known to have had four lower molariforms ( molar - like teeth , either premolars or molars ) in its lower jaw , pascual and ortiz - suggested in 2007 that ferugliotherium may also have had four lower molars . ferugliotherium was much smaller than the sudamericids gondwanatherium and sudamerica , and its body mass is estimated to have been about 70 g ( 2 . 5 oz ) . unlike the hypsodont ( high - crowned ) sudamericids , ferugliotherium has brachydont ( low - crowned ) molariform teeth that are supported by at least two roots , not a single massive root . the direction of wear on the teeth indicates that ferugliotherium , gondwanatherium , and sudamerica all had jaw movement ( i.e. , the lower jaw moved backwards during the power stroke of chewing ) — a feature otherwise only seen in multituberculates among mammals . incisors three fragmentary ferugliotherium lower incisors ( macn pv - rn 701a , , and 701c ) are known from the los alamitos formation . another incisor , macn pv - rn 970 , was assigned to ferugliotherium by bonaparte in 1990 , but it is much larger than the other three incisors , which are otherwise similar , and probably represents gondwanatherium instead . only the tips of the three incisors are preserved . they are laterally compressed , with an estimated width of 1 . 3 mm and height of 2 . 4 mm in 701a . the medial side ( towards the middle of the mouth ) is flat , but the lateral side ( towards the sides ) is convex . there is enamel only on the lower ( ventral ) side . a large wear facet is present at the tip , forming an angle of about 35 ° with the ventral margin in 701a . the three incisor fragments are identified as ferugliotherium because of their size and provenance and the presence of a restricted enamel band . they show features , such as lateral compression , an acute angle at the tip , small curvature , and an irregular cross section , that are usually seen in lower , not upper incisors in mammals with procumbent incisors , such as rodents and multituberculates . four specimens ( macn pv - rn 702a through ) are thought to represent second upper incisors ( i2 ) of ferugliotherium . 702a ( height 1 . 5 mm ; width 1 . 1 mm ) and are slightly larger than 702c ( height 1 . 2 mm ; width 0 . 9 mm ) and . the smaller incisors cannot be lateral incisors ( i3 ) , because 702c 's wear facet is stronger than would be expected in an i3 ; therefore , all four upper incisors are identified as central incisors ( i2 ) . to explain the size difference , krause and colleagues suggested that ferugliotherium was variable in size or that the smaller incisors were deciduous precursors of the larger permanent tooth . they considered it less likely that multiple species with similar incisors were present . the upper incisors have enamel only on the dorsal side . the wear facet at the tip is preserved only in 702c , forming an angle of 52 ° with the dorsal side , and is more concave than the facet in the lower incisors . 702a – d are recognizable as upper incisors because they have a less acute angle at the tip and are less laterally compressed , more curved , and elliptical in cross section . incisors of ferugliotherium and gondwanatherium are similar in overall shape and share a restricted band of enamel — a feature otherwise seen only in multituberculates among mesozoic mammals . the incisors of sudamerica are also similar . mandible with lower premolar macn pv - rn 975 , a fragment of the mandible ( lower jaw ) preserving one premolar , was discovered in 1991 and tentatively identified as ferugliotherium by kielan - jaworowska and bonaparte in 1996 , but this assignment remains controversial . the poorly preserved and worn premolar is a bladelike tooth , resembling multituberculate fourth lower premolars ( p4 ) . the premolar is 4 . 8 mm long and bears eight faint ridges on both the labial ( towards the lips ) and lingual ( towards the tongue ) sides . on the labial side , the four ridges at the back are more widely separated than the four in front of them . the back and front margins of the tooth are parallel and there is no small cusp on the labial side . there are two roots ; the one at the front is larger than the one at the back and bears a furrow . the lower border of the enamel cover is marked by two semicircular extensions of the enamel on the front side , but there is only one such extension at the back . by its size , the number of ridges , and apparently greater length than height , it differs from all known multituberculate first , second , and third lower premolars , indicating that it is a p4 . the dentary ( lower jaw bone ) itself is robust and short . the length axis of the p4 makes an angle of about 58 ° with the length axis of the jawbone . the bone is concave on the lingual , but convex on the labial side . there is a diastema ( gap ) between the p4 and the incisor that would have been in front of it , as in the jaw of sudamerica . gurovich estimated the length of the diastema as 2 . 5 mm . there is a rounded mental foramen ( an opening in the labial side of the jawbone ) , with a diameter of 0 . 7 mm , located about 0 . 8 mm below the dorsal margin of the bone and 1 . 5 mm in front of the p4 . although the incisor itself is not preserved , its alveolus ( the housing of the root ) is in part . as in sudamerica , it extends far into the dentary , passing below p4 . the alveolus is 1 . 5 mm wide below the front root of p4 and 1 . 4 mm at the back of the jaw fragment . although the height of the alveolus cannot be determined because the lower side is broken away , the incisor must have been quite deep . when it was discovered that sudamerica had four molariform teeth and no bladelike premolar in its lower jaw , pascual , kielan - jaworowska , and colleagues removed macn pv - rn 975 from ferugliotherium , which they expected to have the same dental formula as its fellow gondwanathere sudamerica , and identified it as an indeterminate multituberculate instead . pascual and colleagues argued that molariform teeth as seen in sudamerica could not have evolved from the bladelike p4 of ferugliotherium , and that it was unlikely that additional molars had been added in sudamerica . in 2004 and 2007 , kielan - jaworowska and colleagues aligned the dentary with the multituberculate suborder " " because the p4 is rectangular in labial view , not curved as in the suborder cimolodonta . this feature was also used to distinguish macn pv - rn 975 from the single p4 assigned to argentodites , which was tentatively placed in cimolodonta . gurovich , guillermo rougier , and colleagues , on the other hand , maintain that the dentary is referable to ferugliotherium and that the p4s of argentodites and macn pv - rn 975 are very similar . the alveolus of macn pv - rn 975 fits the lower incisors attributed to ferugliotherium in size and the blade - like premolar is of the size expected for an animal with molariforms the size of ferugliotherium teeth . if the dentary and premolars ( whose identification has been similarly controversial ; see below ) do not belong to ferugliotherium , then , gurovich and beck argue , the los alamitos formation would contain two mammals ( ferugliotherium and a multituberculate ) similar in size and morphology , and therefore presumably occupying similar ecological niches — and one of those would be represented only by molariforms and incisors and the other only by premolars and a jaw fragment among the available fossils . furthermore , they noted that the transition from blade - like to molariform premolars had actually been observed in the fossil record of the extinct kangaroos , and that the first molariform in sudamerica and gondwanatherium is laterally compressed , suggesting that it may have derived from a blade - like tooth . gurovich and beck attributed the difference in shape between the macn pv - rn 975 and argentodites p4s to the extensive wear of the former , and suggested that the two are similar enough that they probably represent at least closely related species . other premolars krause and colleagues identified a single tooth , macn pv - rn 251 , as a possible deciduous anterior ( i.e. , not p4 or , the deciduous version of p4 ) lower premolar of ferugliotherium . it is minuscule , with a length of 0 . 85 mm and width of 0 . 5 mm ( assuming the tooth is oriented correctly ) . it bears two serrations ( small projections ) at the tip of the crown — one around the middle of the crown and the other at what may be the back of the crown , where it is highest . two prominent ridges descend from each serration towards the front down the sides of the tooth . no roots are preserved , but the rounded surface of the lower side of the tooth suggests they may have been resorbed , which would indicate that the tooth is deciduous . krause and colleagues suggested that the tooth may have been the frontmost premolar , whether deciduous or permanent . however , kielan - jaworowska and bonaparte wrote that this tooth does not match the partial jaw macn pv - rn 975 , which has no alveoli in front of p4 , and pascual and colleagues agreed in 1999 that the tooth probably does not belong to ferugliotherium . bonaparte had identified another tooth , macn pv - rn 252 , as a possible ferugliotherium lower premolar in 1990 , but this fossil is very fragmentary and according to krause and colleagues , it cannot even be proven to be a mammalian tooth . krause and colleagues identified two teeth , macn pv - rn 249 and 250 , as anterior upper premolars . 249 bears two longitudinal rows of cusps . one row ( row a ; possibly the lingual one ) includes four cusps , the other ( row b ) includes at least two , but is damaged . in row a , there are three ridges ( at the front , middle , and back ) extending from the tip of the base of each cusp . the second and third cusps are largest and most widely separated from each other . in row b , one cusp bears three ridges , of which one extends towards the other cusp in the row and the two others towards row a ) and the other cusp is damaged . 250 is more fragmentary , but bears at least five cusps and may represent the same tooth position as 249 , though it would come from the opposite side of the mouth . the microstructure of the enamel of this tooth has been studied . with a width of about 55 μm near the tip of a cusp , the enamel is thin . the enamel prisms are straight , small , and rounded and there is little material between the prisms . small , rounded prisms are also seen in gondwanatherium , sudamerica , and other gondwanatheres , but in few multituberculates . even in those multituberculates that do have small prisms , the prism sheath is closed , but the sheath is incomplete in gondwanatherium and possibly ferugliotherium . krause and colleagues wrote that these two teeth resemble multituberculate deciduous anterior upper premolars , particularly second and third premolars ( p2 and p3 ) , and used this as one of their arguments for identifying ferugliotherium as a multituberculate . however , as with the dentary macn pv - rn 975 , the two upper premolars were excluded from ferugliotherium and identified as multituberculates by kielan - jaworowska and colleagues after the discovery of the jaw of sudamerica . gurovich continues to identify them as ferugliotherium on the basis of their size and provenance and other similarities between ferugliotherium and multituberculates . lower molariforms five putative lower molariforms of ferugliotherium are known from the los alamitos formation ( macn pv - rn 20 , 174 , 175 , and 253 and mlp 88 - iii - 28 - 1 ) . these teeth include the holotypes of ferugliotherium windhauseni ( macn pv - rn 20 , the only second lower molariform , or m2 ) and vucetichia gracilis ( macn pv - rn 174 ) . the best - preserved mf1 is mlp 88 - iii - 28 - 1 . the crown is unworn and complete and there are no roots , suggesting that the tooth had not yet erupted when its owner died . krause , who first described the tooth in 1993 , identified it as a right molar , but the subsequent discovery of the jaw of sudamerica made it clear that ferugliotherium molariforms had been reversed , and mlp 88 - iii - 28 - 1 is actually from the left side of the jaw . the tooth is 2 . 2 mm long and 1 . 5 mm wide . the crown is roughly rectangular , with rounded corners , and bears two longitudinal rows of cusps . the lingual row consists of four cusps , which are smaller and lower than the three labial ones . the cusps in this row become smaller and lower from the front to the back . two ridges descend from the tip of each cusp to the lingual and labial sides . the labial ridges on the first and fourth cusp only reach the base of the cusp , but those on the second and third cusps join ridges descending from the first and second labial cusp . in the first three cusps , the lingual ridge extends to near the lingual margin of the tooth and then turns backward ; the end of the ridge is lingual to the next cusp . in the fourth cusp , the ridge hardly extends posteriorly , but rather , forming the posterior margin of the tooth and joining a ridge descending from the last labial cusp . the labial cusp row includes three , larger cusps , each of which bears two ridges that descend lingually into the valley between the two cusp rows . the front ridge of each pair ends in the central valley , and the back ridge joins a ridge from a lingual cusp . the ridge pattern results in the presence of three transverse furrows between the main cusps . another mf1 , macn pv - rn 253 , is almost unworn , but damaged : only the front two lingual cusps and the first two cusps and part of the third in the labial row are preserved . this tooth is similar to mlp 88 - iii - 28 - 1 in all respects . however , gurovich suggests that it may also be an m2 . macn pv - rn 174 , which is heavily worn , and macn pv - rn 175 , which is not only heavily worn but has also undergone severe abrasion , were originally identified as upper molars of vucetichia gracilis by bonaparte in 1990 . the roots of macn pv - rn 174 are preserved ; at the front and back of the tooth , there is a pair of roots , which are fused near their bases . it has small enamel prisms . krause and colleagues suggested in 1992 that 174 and 175 were mf1s of ferugliotherium on the basis of similarities with 253 , and krause confirmed this in 1993 by describing the complete mf1 mlp 88 - iii - 28 - 1 . the related ferugliotheriid genus trapalcotherium is known from a single mf1 , which is similar to ferugliotherium mf1s but different in some morphological details ( see trapalcotherium : relationships ) . the holotype , macn pv - rn 20 , is a right mf2 according to both krause and colleagues ( 1992 ) and gurovich ( 2005 ) , but gurovich considered the side that krause and colleagues thought was lingual to be labial , and vice versa . the latter interpretation is used in the following description . it is almost square , but at the front it is slightly narrower than at the back . the labial side of the tooth is taller and less worn than the lingual side . there are two rows of cusps , and each lingual cusp is connected to each labial cusp by a broad crest , with one or more fossas in the middle . one of the two labial cusps may have been divided into two smaller cusps . the two crests are separated by a deep furrow . the enamel prisms of this tooth are small , like those of the premolar macn pv - rn 250 . transverse ridges between the cusps , as seen in ferugliotherium , are known in only one multituberculate , essonodon , but the ridge pattern in essonodon is more complicated and the animal lacks the prominent furrows of ferugliotherium and differs in numerous other features . on the other hand , overall patterns of cusps and ridges are essentially similar among ferugliotherium , gondwanatherium , and sudamerica , indicating that the three are closely related . upper molariforms a single tooth , macn pv - rn 248 , is currently identified as a ferugliotherium upper molariform . in 1992 , krause and colleagues labeled it as a right mf1 , but gurovich identifies it as a left mf1 or possibly even a right mf1 . lacm 149371 , an enigmatic tooth from the paleogene of santa rosa , peru , may represent an upper molar of an animal related to ferugliotherium . like the latter , it has cusps that are compressed from front to back and that are connected to the center of the crown by low crests . macn pv - rn 248 is somewhat damaged and almost rectangular , but slightly narrower at the back than at the front . the tooth bears three longitudinal rows of cusps . the middle row consists of five cusps , the labial row ( assuming it is a left m1 ; if it is from the right , " lingual " and " labial " should be reversed ) includes two or perhaps three cusps , and the lingual row includes probably four cusps . the lingual and middle rows extend across the entire length of the tooth , but the labial row is shorter , extending across about 70 % of the length . the middle row is oriented obliquely with respect to the length axis of the tooth , so that it converges with the lingual row towards the back of the tooth . the front lingual corner of the tooth is missing , but it appears that the first cusps in the lingual and middle rows are connected by two ridges , one at the front margin of the tooth and one at the back of the cusps . a deep fossa ( basin ) lies between the two cusps and their connecting ridges . behind these two cusps , a transverse furrow extends across the width of the tooth . the second lingual and middle cusps are also connected by a crest , which is somewhat weaker than those connecting the first cusps . another transverse furrow extends behind the second cusps and also separates the second middle cusp from the labial row . a third furrow , behind the third lingual and middle cusps , also separates the first from the second labial cusp . three ridges descend from the fourth lingual cusp : one connects to the fourth middle cusp , one ends blindly between the fourth lingual and middle cusps , and one connects to the fifth middle cusp . the second labial cusp , which is larger than the first one , is superficially divided into two smaller cusps by an indentation on its lingual side . there are vertical grooves at the bases of the cusps . range and ecology remains of ferugliotherium come from two formations in the late cretaceous of southern argentina , the los alamitos and la colonia formations . these and the allen formation ( which has yielded trapalcotherium ) are all dated to the campanian ( 84 – 71 million years ago ) and / or maastrichtian ( 71 – 66 million years ago ) , the penultimate and ultimate stages of the cretaceous . the la colonia formation may be somewhat younger than the other two , while the los alamitos formation has been considered campanian , and can be dated to the campanian or maastrichtian on the basis of palynology . the allen formation is likely maastrichtian , but not latest maastrichtian . the los alamitos formation is located in southeastern río negro province , in the vicinity of the town of and was probably deposited in a marshy environment . in 1983 , it yielded the first mesozoic mammal to be found in argentina , , and since then , the mammalian fauna has expanded to 14 species . most of those belong to the archaic mammalian group , but the fauna also includes the gondwanatheres ferugliotherium and gondwanatherium . the dryolestoids and and the two gondwanatheres are the most common mammals . other fossils found in the los alamitos formation include fish , frogs , turtles , snakes , dinosaurs such as secernosaurus , gastropods , and other invertebrates . the la colonia formation outcrops in north - central chubut province , and the mammalian fossils come from the chico valley . the formation includes fluvial ( river ) , deep - sea , and near - shore deposits , and the mammalian fauna probably comes from an estuary , tidal flat , or coastal plain . the la colonia formation also contains dryolestoids , such as and , as well as a ferugliotheriid and the putative multituberculate argentodites . in addition , the la colonia formation has yielded fossils of a wide array of other animals , including crocodiles , plesiosaurs , lungfish ( ) , and dinosaurs ( including carnotaurus ) . the high - crowned sudamericids were probably herbivores , but the lower - crowned ferugliotherium was more probably an insectivore or omnivore , like similar multituberculates such as mesodma , which is thought to have eaten insects , other arthropods , seeds , and / or nuts . it may have used its incisors for gnawing or slicing , and the blade - like p4 may also have been used for slicing hard plant parts , such as seeds . the wear patterns on ferugliotherium teeth independently suggest that the animal may have eaten some plant material .