text: afrasia djijidae afrasia djijidae is a fossil primate that lived in myanmar approximately 37 million years ago , during the late middle eocene . the only species in the genus afrasia , it was a small primate , estimated to weigh around 100 grams ( 3 . 5 oz ) . despite the significant geographic distance between them , afrasia is thought to be closely related to afrotarsius , an enigmatic fossil found in libya and egypt that dates to 38 – 39 million years ago . if this relationship is correct , it suggests that early simians ( a related group or clade consisting of monkeys , apes , and humans ) dispersed from asia to africa during the middle eocene and would add further support to the hypothesis that the first simians evolved in asia , not africa . neither afrasia nor afrotarsius , which together form the family afrotarsiidae , is considered ancestral to living simians , but they are part of a side branch or stem group known as eosimiiforms . because they did not give rise to the stem simians that are known from the same deposits in africa , early asian simians are thought to have dispersed from asia to africa more than once prior to the late middle eocene . such dispersals from asia to africa also were seen around the same time in other mammalian groups , including rodents and anthracotheres . afrasia is known from four isolated molar teeth found in the pondaung formation of myanmar . these teeth are similar to those of afrotarsius and eosimiidae , and differ only in details of the chewing surface . for example , the back part of the third lower molar is relatively well - developed . in the pondaung formation , afrasia was part of a diverse primate community that also includes the eosimiid bahinia and members of the families and sivaladapidae . etymology the name afrasia derives from the continental names " africa " and " asia " , and refers to the occurrence of primates on both continents . the species , a. djijidae , was named in memory of a young girl from village in central myanmar . evolutionary history afrasia djijidae was first described in 2012 on the basis of isolated teeth from the 37 - million - year - old pondaung formation , which is close to the village of in myanmar . prior to the discovery of a. djijidae , early asian simians were typically classified in two families , eosimiidae and . while eosimiids are generally considered the most basal simian clade ( a stem group of simians ) , the phylogenetic placement of is more disputed . are usually considered to share affinities with either eosimiids or crown simians ( those simians that are part of the smallest clade that contains the living simians ) ; the latter view is favored . were first described from findings in china in 1994 and are still best known there ( two genera are now known , eosimias and phenacopithecus ) , but have also been recorded in pakistan ( phileosimias ) and myanmar ( bahinia ) . all species had a small body size and a mix of primitive ( ancestral ) and derived traits ( . the largest eosimiid , bahinia , is from the pondaung formation , the same stratum as afrasia , and the morphology of its molars bridges the gap between the more primitive molars of eosimias and the more derived molars of the later eocene african simians . afrasia , on the other hand , is more comparable in size to the eosimiids from china . the upper molars of afrasia are nearly identical in morphology and size to those of afrotarsius , an animal known from to 39 - million - year - old deposits in libya ( species afrotarsius libycus ) and about 30 - million - year - old deposits in egypt ( a. ) . afrotarsius was originally described as a tarsier , but later suggested to be related to primitive simians . because of their close similarities , afrasia and afrotarsius are together placed in the family afrotarsiidae . a phylogenetic analysis placed afrasia as a sister group to afrotarsius , forming the family afrotarsiidae . afrotarsiidae was found to be most closely related to eosimiidae , and unrelated to tarsiers . the clade formed by afrotarsiidae and eosimiidae was designated as the infraorder by et al. in 2012 . are the sister group of crown simians . however , the classification of afrotarsius as a stem simian is not accepted by all researchers , and the phylogenetic claims and their implications rest on only the four molars of afrasia initially discovered . biogeography several hypotheses compete to explain the geographic origins of simians . of the two most popular views , one hypothesis states that simians originated in asia , while the other favors africa as their place of origin . both their ancient origins and the sparse fossil record in africa and asia complicate the debate . convergent evolution also makes it difficult for researchers to determine the relationships between fossils . also , the earliest fossils , which do not match up with molecular clock estimates for simian origins , have been found in both afro - arabia and asia . at the time , both land masses would have been separated by the tethys sea . the oldest undisputed simians from africa also date to the late middle eocene . afrotarsius was found in the dur at - escarpment in libya , which dates to 38 – 39 million years ago and also contains the and the . although diverse , these primates were all very small in size , much like eosimiids . simian classification for older fossils from africa are more contested . altiatlasius , the oldest suspected fossil primate known from the late paleocene of morocco , is too fragmentary to ascertain its true affinities . was popularly considered an early middle eocene simian ; however , less fragmentary remains uncovered between 2003 and 2009 suggest it was a type of , a group of strepsirrhine primates likely related to lemuriform primates ( lemurs and lorisoids ) . according to the team who discovered afrasia , headed by jean - jacques jaeger , the similarities in tooth morphology , body size and age suggest a phylogenetic relationship with afrotarsius despite the geographic separation . they suggested that simians from asia dispersed across the tethys sea to africa around the middle eocene , giving rise to afrotarsius . a reverse migration — as suggested by the african origins hypothesis for simians — is not favored due to the close phylogenetic relationship between the older asian eosimiids and afrasia . however , to explain the origins of , , and crown simians from the african fossil record , a higher simian clade also needed to disperse from asia to africa before the late middle eocene since neither afrasia nor afrotarsius could have given rise to this group . such dispersals from asia to africa were not uncommon , since rodents , anthracotheres , and possibly other mammalian fauna from asia arrived around the same time . anatomy afrasia is known from four isolated teeth : a first upper molar ( m1 ) , with a length of 2 . 13 mm and width of 3 . 06 mm ; a second upper molar ( m2 ) , the holotype , of 2 . 27 mm by 3 . 35 mm ; a second lower molar ( m2 ) of 2 . 09 mm by 1 . 41 mm ; and a third lower molar ( m3 ) of 2 . 05 mm by 1 . 27 mm . like other eosimiiforms , it was a small primate that weighed around 94 or 108 g ( 3 . 3 or 3 . 8 oz ) , which is estimated based on the measurements of its m2 and m1 , respectively . it is generally similar to other eosimiiforms in general and afrotarsius in particular ; some distinguishing features are the well - developed small cusps ( conules ) on the upper molars , the variable development of the lingual cingulum ( a shelf on the inner , or lingual , side of the tooth ) of the upper molars , and the unreduced talonid ( posterior portion ) on the m3 . its teeth are smaller than those of the eosimiids phenacopithecus , bahinia , and phileosimias . the m2 is similar to that of eosimiids and almost identical to that of afrotarsius libycus . it shows well - developed small accessory cusps ( the paraconule and metaconule ) that are connected to equally well - developed crests . the conules are stronger than in eosimias and bahinia , but weaker than in phileosimias . the stylar shelf , the outer area of the tooth , is broad , particularly at the metacone cusp . however , the shelf is better developed near the paracone cusp in afrasia than in afrotarsius , which makes the ( an invagination in the outer wall of the tooth ) more symmetrical in the former . the parastyle , a small cusp in the outer front corner of the tooth , is located more buccally ( towards the outer side of the tooth ) than in afrotarsius and is larger . the stylar shelf is larger than that of bahinia and phileosimias , but smaller than that of eosimias . the parastyle is also less developed than in eosimias , but the protocone , the main cusp on the lingual side of the tooth , is more expansive . the lingual cingulum is incomplete ; it is stronger in phenacopithecus . m1 is similar to m2 , but somewhat smaller . the is less apparent , the stylar shelf is narrower , there is no crest behind the metaconule , and the lingual cingulum is continuous . the condition of the parastyle more closely resembles that in afrotarsius . in m2 , the trigonid ( the front portion of the tooth ) consists of three very distinct cusps : the paraconid at the front , and behind it the paired protoconid ( on the buccal side ) and metaconid ( on the lingual side ) . these three cusps are less discrete in afrotarsius . the paraconid is distinct from the , the crest that connects it to the protoconid , and is located more lingually than in afrotarsius . between this cusp and the metaconid behind it , the central basin of the trigonid is open towards the lingual margin of the tooth . the protoconid has a v shape , with one arm reaching towards the metaconid and the other towards the paraconid . the back portion of the tooth , the talonid , is broader ; eosimias has a narrower talonid . the main cusps , the buccal hypoconid and lingual entoconid , are opposite each other on the margins of the tooth ( the entoconid is further to the front in phenacopithecus ) . a crest , the cristid obliqua , connects the front side of the hypoconid to the protoconid . it is nearly in line with the main axis of the tooth , contrasting with its more diagonal position in eosimias and phenacopithecus . a crest , the postcristid , descends from the hypoconid along the back margin of the tooth and almost reaches the entoconid , which is separated by a notch . it incorporates the third talonid cusp , the hypoconulid , which is indistinct in afrasia . in afrotarsius and eosimiids ( except the pakistani phileosimias ) , this crest reaches the entoconid . there is a cingulum , or shelf , on the buccal side of m2 . the last lower molar , m3 , is smaller and has a longer talonid , with a well - developed hypoconulid lobe at the back , and generally resembles that of phenacopithecus , but the trigonid is smaller . the paraconid is distinct . the hypoconulid lobe is longer than in afrotarsius and the entoconid is located further to the front . unlike on m2 , there is no notch between the hypoconulid and entoconid , though a shallow valley is present . range and ecology afrasia has only been found in the eocene pondaung formation of central myanmar , a rock unit which has been dated to about 37 million years ago using and fission track dating . this places it at the end of the stage , near the middle – late eocene boundary . although many tons of sediments in the area have been screened for fossils , afrasia is still known only from four teeth , suggesting that it was a rare species . since fossils were first discovered there in 1916 , a rich fossil fauna has been recovered in the pondaung formation . in addition to afrasia , primates found there include the eosimiid bahinia ; the , , and ; and the sivaladapids and .