International Journal of Primatology, Jun 13, 2012
Abstract The life histories of early hominins are commonly characterized as being like those of g... more Abstract The life histories of early hominins are commonly characterized as being like those of great apes. However, the life histories of the extant great apes differ considerably from one another. Moreover, the extent to which their life histories correlate with the two aspects of morphology used to infer the life histories of fossil species, brain size and dental development, has remained subject to debate. Increased knowledge of great ape life histories and, more recently, dental development—in particular ages at first molar ...
Generally warm and humid climate conditions during the late Miocene in southwest China provide ... more Generally warm and humid climate conditions during the late Miocene in southwest China provide a 'refugium' for hominoids in this region There were four stages of climate change during the late Miocene through Pliocene in the region, including four episodes of cooler climate
Age at lower first molar (M 1) emergence is a commonly used proxy for inferring life-history sche... more Age at lower first molar (M 1) emergence is a commonly used proxy for inferring life-history scheduling in fossil primates, but its utility is dependent on knowing to what extent extant populations vary in this datum and how this variation correlates with the scheduling of life-history variables. Here, we address the first of these issues among extant chimpanzees. While age at M 1 emergence has been documented in several live individuals from the Kanyawara population of Pan troglodytes schweinfurthii in Uganda, it has been estimated for only one individual of Pan troglodytes verus, based on a deceased animal from the Taï Forest in Côte d'Ivoire. To further explore interpopulation variation in this variable in chimpanzees, and using dental histology, we calculated ages at death for two wild-shot individuals of P. t. verus with erupting M 1 , both collected in Liberia during the mid-1950s, and estimated ages at M 1 emergence from the ages at death. The overall range for these two individuals is~4.2e4.6 yr, compared with an age of 3.7 yr for the individual from the Taï Forest, and <2.5e3.3 yr for the several individuals of P. t. schweinfurthii. While the absolute range of~2 yr in these samples combined is little greater than in captive chimpanzees, the disparity between the samples of P. t. schweinfurthii and P. t. verus is striking, although it cannot be determined if this disparity represents a subspecies difference or simply population differences expressed in two different subspecies. While life-history data are unavailable for the population to which the Liberian chimpanzees belonged, the difference in M 1 emergence ages between these individuals and those from Kanyawara still suggests caution when attempting even broad lifehistory inference in fossil apes and hominins based on age at M 1 emergence.
The Late Miocene sequence at Haritalyangar, Himachal Pradesh, India, has produced abundant remain... more The Late Miocene sequence at Haritalyangar, Himachal Pradesh, India, has produced abundant remains of the hominid Sivapithecus and the sivaladapids Sivaladapis and Indraloris. Also recovered from these sediments is an isolated and worn upper molar that was made the holotype of Krishnapithecus krishnaii and assigned to the Pliopithecoidea. However, the heavy wear and absence of definitive pliopithecoid features on the tooth rendered the assignment to this superfamily unconvincing. Here, we describe two lower molars from Haritalyangar that bear unmistakable pliopithecoid features and that are plausibly assignable to the same species as the type specimen of K. krishnaii. They convincingly demonstrate for the first time the presence of the Pliopithecoidea in South Asia. The new molars also reveal that K. krishnaii was perhaps the largest known pliopithecoid and that it possessed highly derived postcanine dental morphology. Because of its highly derived nature, it is difficult to determine its relationships within Pliopithecoidea, but a sister taxon relationship with either the Dionysopithecidae or Pliopithecinae is equally plausible; it is only distantly related to the Crouzeliinae. It is sufficiently distinct, however, from all other pliopithecoids to warrant placement in a separate family.
American Journal of Physical Anthropology, Oct 1, 2009
Sexual size dimorphism in the postcanine dentition of the late Miocene hominoid Lufengpithecus lu... more Sexual size dimorphism in the postcanine dentition of the late Miocene hominoid Lufengpithecus lufengensis exceeds that in Pongo pygmaeus, demonstrating that the maximum degree of molar size dimorphism in apes is not represented among the extant Hominoidea. It has not been established, however, that the molars of Pongo are more dimorphic than those of any other living primate. In this study, we used resampling-based methods to compare molar dimorphism in Gorilla, Pongo, and Lufengpithecus to that in the papionin Mandrillus leucophaeus to test two hypotheses: (1) Pongo possesses the most size-dimorphic molars among living primates and (2) molar size dimorphism in Lufengpithecus is greater than that in the most dimorphic living primates. Our results show that M. leucophaeus exceeds great apes in its overall level of dimorphism and that L. lufengensis is more dimorphic than the extant spe
Among primates, age at first molar emergence is correlated with a variety of life history traits.... more Among primates, age at first molar emergence is correlated with a variety of life history traits. Age at first molar emergence can therefore be used to broadly infer the life histories of fossil primate species. One method of determining age at first molar emergence is to determine the age at death of fossil individuals that were in the process of erupting their first molars. This was done for an infant partial mandible of Afropithecus turkanensis (KNM-MO 26) from the w17.5 Ma site of Moruorot in Kenya. A range of estimates of age at death was calculated for this individual using the permanent lateral incisor germ preserved in its crypt, by combining the number and periodicity of lateral enamel perikymata with estimates of the duration of cuspal enamel formation and the duration of the postnatal delay in the inception of crown mineralization. Perikymata periodicity was determined using daily cross striations between adjacent Retzius lines in thin sections of two A. turkanensis molars from the nearby site of Kalodirr. Based on the position of the KNM-MO 26 M 1 in relation to the mandibular alveolar margin, it had not yet undergone gingival emergence. The projected time to gingival emergence was estimated based on radiographic studies of M 1 eruption in extant baboons and chimpanzees. The estimates of age at M 1 emergence in KNM-MO 26 range from 28.2 to 43.5 months, using minimum and average values from extant great apes and humans for the estimated growth parameters. Even the absolute minimum value is well outside the ranges of extant large Old World monkeys for which there are data (12.5 to <25 months), but is within the range of chimpanzees (25.7 to 48.0 months). It is inferred, therefore, that A. turkanensis had a life history profile broadly like that of Pan. This is additional evidence to that provided by Sivapithecus parvada (Function, Phylogeny, and Fossils: Miocene Hominoid Evolution and Adaptations, 1997, 173) that the prolonged life histories characteristic of extant apes were achieved early in the evolutionary history of the group. However, it is unclear at present whether life-history prolongation in apes represents the primitive catarrhine pace of life history extended through phyletic increase in body mass, or whether it is derived with respect to a primitive, size-adjusted life history that was broadly intermediate between those of extant hominoids and cercopithecoids. Life history evolution in primates as a whole may have occurred largely through a series of grade-shifts, with the establishment of fundamental life-history profiles early in the histories of major higher taxa. These may have included shifts that were largely body mass dependent, as well as those that occurred in the absence of significant changes in body mass.
During the past decade, studies of enamel development have provided a broad temporal and geograph... more During the past decade, studies of enamel development have provided a broad temporal and geographic perspective on evolutionary developmental biology in Miocene hominoids. Here we report some of the first data for molar crown development in one hominoid genus, Sivapithecus. The data are compared to a range of extant and extinct hominoids. Crown formation times (CFTs), daily rates of enamel secretion (DSR), Retzius line number and periodicity, and relative enamel thickness (RET) were calculated in a mandibular first molar of Sivapithecus parvada and a maxillary first molar of Sivapithecus indicus from the Siwalik sequence of Pakistan. A CFT of 2.40 years for the protoconid of S. parvada and 2.25 years for the protocone of S. indicus lie within the range of first molar (M1) formation times for the majority of Miocene hominoids (1.96e2.40 years, excluding Proconsul heseloni), and are similar to an M 1 from Gorilla (2.31 years) and M 1 s from Pan (2.22e2.39 years). This is unlike the longer CFTs in modern humans, which appear to be linked with their extended growth period. In contrast to extant great apes and humans, daily rates of enamel secretion are rapid in the Sivapithecus M1s during the early stages of growth, which seems to be a common pattern for most Miocene apes. The rapid accumulation of cuspal enamel in the Sivapithecus molars produced thicker enamel than either Pan or Gorilla in a comparable period of time. Future studies on larger samples of living and fossil hominoids are needed to clarify trends in crown development, which may be better understood in the context of life history strategies coupled with good data on body mass and brain size.
A new species of fossil hominoid is described from the middle Miocene deposits at Pas xalar, Turk... more A new species of fossil hominoid is described from the middle Miocene deposits at Pas xalar, Turkey. It is the less common of the two Pas xalar species discussed by Martin and Andrews (1993), making up approximately 10% of the individuals in the Pas xalar hominoid sample according to analyses of the minimum number of individuals. To the diagnostic features of I 1 described by Alpagut et al. (1990) and Martin and Andrews (1993) can now be added further diagnostic features of all the anterior teeth, as well as both upper premolars and P 3. These include discrete, nonmetric features and metric differences at all the noted tooth positions. Attempts to distinguish the upper and lower molars of the two species have so far been unsuccessful, with the possible exception of M 3. The morphology of the new species is similar in most respects to that of Kenyapithecus wickeri from Fort Ternan, especially concerning maxillary morphology. They share robust and moderately deep maxillary alveolar processes, a restricted maxillary sinus with an elevated and uncomplicated floor, lacking the compartmentalization evident to varying degrees in many other taxa, and a zygomatic process that originates and turns laterally fairly high above the alveolar margin. There are also a number of distinctive similarities in the dentition, particularly for I 1 , C 1 , P 4 and P 3. The I 1 morphology in particular, with greatly hypertrophied lingual marginal ridges bounding a uniformly thickened basal crown area, is distinctive among Miocene hominoids. All of these similarities serve to reinforce the differences noted by others between the derived morphology of K. wickeri and the more primitive morphology of Equatorius africanus from Maboko and Kipsaramon. The new species differs from K. wickeri in morphological details of most of the anterior and premolar teeth that are known for both species, despite the general morphological similarity, and in the size of I 1 versus I 2. One striking feature of the new species is a relatively large incisive fossa, although it cannot be determined if this is associated with an open palatine fenestra, as in many early Miocene hominoids, or a minimally overlapping palate and nasoalveolar clivus, as in some middle and late Miocene hominoids.
meteorites, we have recently learnt a lot about mineral grains in space by characterizing them re... more meteorites, we have recently learnt a lot about mineral grains in space by characterizing them remotely. For example, one of the most surprising findings of the Infrared Space Observatory mission was the great variety of types of star around which finegrained silicates crystallize. It thus seemed certain that the young Solar System would also have contained interstellar silicate dust, as well as the other known grains, and there should be silicates from a variety of stellar environments in our meteorite collections. Silicates make up the bulk of chondritic meteorites, however, so searching for the presolar variety requires a more subtle approach than for carbonaceous and oxide grains-akin to inspecting the haystack straw by straw. It requires both admirable patience and an ingenious analytical technique. Nagashima's group has developed a micro-imaging technique 3 that uses an ion microscope to detect different isotopes (such as those of oxygen-16 O, 17 O and 18 O). In the images produced,any region of the meteorite that does not match isotopically the overall composition of the meteorite-and hence might be presolar in origin-shows up as a 'hotspot'. Nagashima et al. 1 have found hotspots in situ in the meteorites Acfer 094 and NWA 530: one micrometre-sized presolar grain made of the silicate olivine, plus five clusters of very fine-grained silicate that contain at least one presolar component. This technique is remarkable in that it has managed to compete with the new-generation ion probe, the 'NanoSIMS' , developed specifically for isotope-mapping over very small areas and hence perfect for the interstellar silicate search. In a parallel study, Nguyen and Zinner 4 have also reported presolar silicates in a sample of Acfer 094, news and views 904
Dental remains of Equatorius africanus from Kipsaramon, Tugen Hills, Baringo District, Kenya Fort... more Dental remains of Equatorius africanus from Kipsaramon, Tugen Hills, Baringo District, Kenya Forty-one isolated large hominoid teeth, as well as most of the mandibular and three maxillary teeth associated with a partial skeleton, were recovered from middle Miocene Muruyur sediments near Kipsaramon in the Tugen Hills, Baringo District, Kenya. The isolated teeth were collected as surface finds and the skeleton was excavated in situ at locality BPRP#122 dated between 15•58 Ma and 15•36 Ma. The majority of the teeth recovered at BPRP#122 are referable to a minimum of five individuals of the hominoid Equatorius africanus. Three of the teeth, however, are provisionally assigned to Nyanzapithecus sp. The new hominoids from Kipsaramon add to an increasing inventory of specimens that suggest greater large hominoid taxonomic diversity from the middle Miocene of Kenya than was previously recognized. It is suggested that there are two large-bodied hominoid species present at Mabako, only one of which is assignable to Equatorius.
International Journal of Primatology, Jun 13, 2012
Abstract The life histories of early hominins are commonly characterized as being like those of g... more Abstract The life histories of early hominins are commonly characterized as being like those of great apes. However, the life histories of the extant great apes differ considerably from one another. Moreover, the extent to which their life histories correlate with the two aspects of morphology used to infer the life histories of fossil species, brain size and dental development, has remained subject to debate. Increased knowledge of great ape life histories and, more recently, dental development—in particular ages at first molar ...
Generally warm and humid climate conditions during the late Miocene in southwest China provide ... more Generally warm and humid climate conditions during the late Miocene in southwest China provide a 'refugium' for hominoids in this region There were four stages of climate change during the late Miocene through Pliocene in the region, including four episodes of cooler climate
Age at lower first molar (M 1) emergence is a commonly used proxy for inferring life-history sche... more Age at lower first molar (M 1) emergence is a commonly used proxy for inferring life-history scheduling in fossil primates, but its utility is dependent on knowing to what extent extant populations vary in this datum and how this variation correlates with the scheduling of life-history variables. Here, we address the first of these issues among extant chimpanzees. While age at M 1 emergence has been documented in several live individuals from the Kanyawara population of Pan troglodytes schweinfurthii in Uganda, it has been estimated for only one individual of Pan troglodytes verus, based on a deceased animal from the Taï Forest in Côte d'Ivoire. To further explore interpopulation variation in this variable in chimpanzees, and using dental histology, we calculated ages at death for two wild-shot individuals of P. t. verus with erupting M 1 , both collected in Liberia during the mid-1950s, and estimated ages at M 1 emergence from the ages at death. The overall range for these two individuals is~4.2e4.6 yr, compared with an age of 3.7 yr for the individual from the Taï Forest, and <2.5e3.3 yr for the several individuals of P. t. schweinfurthii. While the absolute range of~2 yr in these samples combined is little greater than in captive chimpanzees, the disparity between the samples of P. t. schweinfurthii and P. t. verus is striking, although it cannot be determined if this disparity represents a subspecies difference or simply population differences expressed in two different subspecies. While life-history data are unavailable for the population to which the Liberian chimpanzees belonged, the difference in M 1 emergence ages between these individuals and those from Kanyawara still suggests caution when attempting even broad lifehistory inference in fossil apes and hominins based on age at M 1 emergence.
The Late Miocene sequence at Haritalyangar, Himachal Pradesh, India, has produced abundant remain... more The Late Miocene sequence at Haritalyangar, Himachal Pradesh, India, has produced abundant remains of the hominid Sivapithecus and the sivaladapids Sivaladapis and Indraloris. Also recovered from these sediments is an isolated and worn upper molar that was made the holotype of Krishnapithecus krishnaii and assigned to the Pliopithecoidea. However, the heavy wear and absence of definitive pliopithecoid features on the tooth rendered the assignment to this superfamily unconvincing. Here, we describe two lower molars from Haritalyangar that bear unmistakable pliopithecoid features and that are plausibly assignable to the same species as the type specimen of K. krishnaii. They convincingly demonstrate for the first time the presence of the Pliopithecoidea in South Asia. The new molars also reveal that K. krishnaii was perhaps the largest known pliopithecoid and that it possessed highly derived postcanine dental morphology. Because of its highly derived nature, it is difficult to determine its relationships within Pliopithecoidea, but a sister taxon relationship with either the Dionysopithecidae or Pliopithecinae is equally plausible; it is only distantly related to the Crouzeliinae. It is sufficiently distinct, however, from all other pliopithecoids to warrant placement in a separate family.
American Journal of Physical Anthropology, Oct 1, 2009
Sexual size dimorphism in the postcanine dentition of the late Miocene hominoid Lufengpithecus lu... more Sexual size dimorphism in the postcanine dentition of the late Miocene hominoid Lufengpithecus lufengensis exceeds that in Pongo pygmaeus, demonstrating that the maximum degree of molar size dimorphism in apes is not represented among the extant Hominoidea. It has not been established, however, that the molars of Pongo are more dimorphic than those of any other living primate. In this study, we used resampling-based methods to compare molar dimorphism in Gorilla, Pongo, and Lufengpithecus to that in the papionin Mandrillus leucophaeus to test two hypotheses: (1) Pongo possesses the most size-dimorphic molars among living primates and (2) molar size dimorphism in Lufengpithecus is greater than that in the most dimorphic living primates. Our results show that M. leucophaeus exceeds great apes in its overall level of dimorphism and that L. lufengensis is more dimorphic than the extant spe
Among primates, age at first molar emergence is correlated with a variety of life history traits.... more Among primates, age at first molar emergence is correlated with a variety of life history traits. Age at first molar emergence can therefore be used to broadly infer the life histories of fossil primate species. One method of determining age at first molar emergence is to determine the age at death of fossil individuals that were in the process of erupting their first molars. This was done for an infant partial mandible of Afropithecus turkanensis (KNM-MO 26) from the w17.5 Ma site of Moruorot in Kenya. A range of estimates of age at death was calculated for this individual using the permanent lateral incisor germ preserved in its crypt, by combining the number and periodicity of lateral enamel perikymata with estimates of the duration of cuspal enamel formation and the duration of the postnatal delay in the inception of crown mineralization. Perikymata periodicity was determined using daily cross striations between adjacent Retzius lines in thin sections of two A. turkanensis molars from the nearby site of Kalodirr. Based on the position of the KNM-MO 26 M 1 in relation to the mandibular alveolar margin, it had not yet undergone gingival emergence. The projected time to gingival emergence was estimated based on radiographic studies of M 1 eruption in extant baboons and chimpanzees. The estimates of age at M 1 emergence in KNM-MO 26 range from 28.2 to 43.5 months, using minimum and average values from extant great apes and humans for the estimated growth parameters. Even the absolute minimum value is well outside the ranges of extant large Old World monkeys for which there are data (12.5 to <25 months), but is within the range of chimpanzees (25.7 to 48.0 months). It is inferred, therefore, that A. turkanensis had a life history profile broadly like that of Pan. This is additional evidence to that provided by Sivapithecus parvada (Function, Phylogeny, and Fossils: Miocene Hominoid Evolution and Adaptations, 1997, 173) that the prolonged life histories characteristic of extant apes were achieved early in the evolutionary history of the group. However, it is unclear at present whether life-history prolongation in apes represents the primitive catarrhine pace of life history extended through phyletic increase in body mass, or whether it is derived with respect to a primitive, size-adjusted life history that was broadly intermediate between those of extant hominoids and cercopithecoids. Life history evolution in primates as a whole may have occurred largely through a series of grade-shifts, with the establishment of fundamental life-history profiles early in the histories of major higher taxa. These may have included shifts that were largely body mass dependent, as well as those that occurred in the absence of significant changes in body mass.
During the past decade, studies of enamel development have provided a broad temporal and geograph... more During the past decade, studies of enamel development have provided a broad temporal and geographic perspective on evolutionary developmental biology in Miocene hominoids. Here we report some of the first data for molar crown development in one hominoid genus, Sivapithecus. The data are compared to a range of extant and extinct hominoids. Crown formation times (CFTs), daily rates of enamel secretion (DSR), Retzius line number and periodicity, and relative enamel thickness (RET) were calculated in a mandibular first molar of Sivapithecus parvada and a maxillary first molar of Sivapithecus indicus from the Siwalik sequence of Pakistan. A CFT of 2.40 years for the protoconid of S. parvada and 2.25 years for the protocone of S. indicus lie within the range of first molar (M1) formation times for the majority of Miocene hominoids (1.96e2.40 years, excluding Proconsul heseloni), and are similar to an M 1 from Gorilla (2.31 years) and M 1 s from Pan (2.22e2.39 years). This is unlike the longer CFTs in modern humans, which appear to be linked with their extended growth period. In contrast to extant great apes and humans, daily rates of enamel secretion are rapid in the Sivapithecus M1s during the early stages of growth, which seems to be a common pattern for most Miocene apes. The rapid accumulation of cuspal enamel in the Sivapithecus molars produced thicker enamel than either Pan or Gorilla in a comparable period of time. Future studies on larger samples of living and fossil hominoids are needed to clarify trends in crown development, which may be better understood in the context of life history strategies coupled with good data on body mass and brain size.
A new species of fossil hominoid is described from the middle Miocene deposits at Pas xalar, Turk... more A new species of fossil hominoid is described from the middle Miocene deposits at Pas xalar, Turkey. It is the less common of the two Pas xalar species discussed by Martin and Andrews (1993), making up approximately 10% of the individuals in the Pas xalar hominoid sample according to analyses of the minimum number of individuals. To the diagnostic features of I 1 described by Alpagut et al. (1990) and Martin and Andrews (1993) can now be added further diagnostic features of all the anterior teeth, as well as both upper premolars and P 3. These include discrete, nonmetric features and metric differences at all the noted tooth positions. Attempts to distinguish the upper and lower molars of the two species have so far been unsuccessful, with the possible exception of M 3. The morphology of the new species is similar in most respects to that of Kenyapithecus wickeri from Fort Ternan, especially concerning maxillary morphology. They share robust and moderately deep maxillary alveolar processes, a restricted maxillary sinus with an elevated and uncomplicated floor, lacking the compartmentalization evident to varying degrees in many other taxa, and a zygomatic process that originates and turns laterally fairly high above the alveolar margin. There are also a number of distinctive similarities in the dentition, particularly for I 1 , C 1 , P 4 and P 3. The I 1 morphology in particular, with greatly hypertrophied lingual marginal ridges bounding a uniformly thickened basal crown area, is distinctive among Miocene hominoids. All of these similarities serve to reinforce the differences noted by others between the derived morphology of K. wickeri and the more primitive morphology of Equatorius africanus from Maboko and Kipsaramon. The new species differs from K. wickeri in morphological details of most of the anterior and premolar teeth that are known for both species, despite the general morphological similarity, and in the size of I 1 versus I 2. One striking feature of the new species is a relatively large incisive fossa, although it cannot be determined if this is associated with an open palatine fenestra, as in many early Miocene hominoids, or a minimally overlapping palate and nasoalveolar clivus, as in some middle and late Miocene hominoids.
meteorites, we have recently learnt a lot about mineral grains in space by characterizing them re... more meteorites, we have recently learnt a lot about mineral grains in space by characterizing them remotely. For example, one of the most surprising findings of the Infrared Space Observatory mission was the great variety of types of star around which finegrained silicates crystallize. It thus seemed certain that the young Solar System would also have contained interstellar silicate dust, as well as the other known grains, and there should be silicates from a variety of stellar environments in our meteorite collections. Silicates make up the bulk of chondritic meteorites, however, so searching for the presolar variety requires a more subtle approach than for carbonaceous and oxide grains-akin to inspecting the haystack straw by straw. It requires both admirable patience and an ingenious analytical technique. Nagashima's group has developed a micro-imaging technique 3 that uses an ion microscope to detect different isotopes (such as those of oxygen-16 O, 17 O and 18 O). In the images produced,any region of the meteorite that does not match isotopically the overall composition of the meteorite-and hence might be presolar in origin-shows up as a 'hotspot'. Nagashima et al. 1 have found hotspots in situ in the meteorites Acfer 094 and NWA 530: one micrometre-sized presolar grain made of the silicate olivine, plus five clusters of very fine-grained silicate that contain at least one presolar component. This technique is remarkable in that it has managed to compete with the new-generation ion probe, the 'NanoSIMS' , developed specifically for isotope-mapping over very small areas and hence perfect for the interstellar silicate search. In a parallel study, Nguyen and Zinner 4 have also reported presolar silicates in a sample of Acfer 094, news and views 904
Dental remains of Equatorius africanus from Kipsaramon, Tugen Hills, Baringo District, Kenya Fort... more Dental remains of Equatorius africanus from Kipsaramon, Tugen Hills, Baringo District, Kenya Forty-one isolated large hominoid teeth, as well as most of the mandibular and three maxillary teeth associated with a partial skeleton, were recovered from middle Miocene Muruyur sediments near Kipsaramon in the Tugen Hills, Baringo District, Kenya. The isolated teeth were collected as surface finds and the skeleton was excavated in situ at locality BPRP#122 dated between 15•58 Ma and 15•36 Ma. The majority of the teeth recovered at BPRP#122 are referable to a minimum of five individuals of the hominoid Equatorius africanus. Three of the teeth, however, are provisionally assigned to Nyanzapithecus sp. The new hominoids from Kipsaramon add to an increasing inventory of specimens that suggest greater large hominoid taxonomic diversity from the middle Miocene of Kenya than was previously recognized. It is suggested that there are two large-bodied hominoid species present at Mabako, only one of which is assignable to Equatorius.
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