It appears that the gorilla slit
off the hominid linage a lot sooner than the DNA suggested 8myr mark and
perhaps closer to 12myr. Everyone tends
to forget that a range of error means just that and outliers really count.
What we really know is that primates
and their cousins have been thriving for well over ten million years and the
proper description is the word thrive.
We are the ones that hunted them out of our own territory were we could.
Of course, our own natural territory was as circumscribed as theirs and it is
only recently that technical prowess changed all that.
Once again it is often forgotten
that by the time a change makes it into the fossil record it can be
ancient. Imagine a key change made in
one locale and prospering modestly there but generally cut off. Now imagine all that changing suddenly and
the genetic data is put into distribution.
It still takes millennia to do this.
For that reason one needs to be extremely cautious in accepting these
dates at all.
World's oldest gorilla fossil challenges evolutionary beliefs
Last Updated: Thursday, August 23, 2007 | 1:44 PM ET
SATURDAY, 6 OCTOBER 2012
The world's oldest gorilla fossil has been found in Ethiopia , defying earlier assumptions about ape
and human evolution, scientists at the National
Museum of Ethiopia
Scientists believe the nine teeth unearthed during an excavation near
"We used to believe, based on genetic information, DNA studies and molecular studies, that the splits between chimpanzees and the human line on one side and the gorilla line on the other side … happened around eight million years ago," said paleontologist Berhane Asfaw, who helped unearth the fossil. "But based on this new information, the split had to happen before 10 million years ago. It means that information has to be adjusted in every textbook."
The new species — dubbed Chororapithecus abyssinicus, a combination of the names Chorora, the area where the fossil was found, and Abyssinia, Ethiopia's ancient name — could indicate that the closely related gorillas and chimpanzees diverged as long as 12 million years ago, four million years earlier than previously thought.
Prior to the find, it was also thought that apes originated in
The fossil also represents the first discovery of a great ape in
However,
Since they found only teeth, scientists could not say what this newly discovered gorilla might have looked like. However, paleontologists said they were preparing to embark on an expedition to the region to seek more information.
Their findings will be published in Thursday's edition of the scientific journal Nature.
With files from the Associated Press
The resemblance between the individual teeth is actually pretty striking:
One of the kinds of confusion involved: this is the reconstruction of the much older Proconsul major which was originally said to be a possible Gorilla ancestor because it is very large. More recent evaluations say the teeth are more primitive and they are not closely related. These reltionships are all very close and all of the fossil apes close to the same age as each other, so that it is very hard to determine. Proconsul major is perhaps five million years older than Chororapithecus .
Chart showing the vagueness of the Margin for Error, which stretches for most of ten million years' worth of uncertainty in the Gorilla lineage:
###
This is a pretty good chart which avoids drawing the lines of descent, from same site as the chart above it. The two small forms at far right would be perfect matches for the corresponding modern reports with the addition of bushy head-hair to go along with their hairy bodies.
http://du-cote-de-chez-elysia-chlorotica.blogspot.com/
Please also refer to my earlier blog on Miocene Fossil Apes:
http://www.turkanabasin.org/humanevolution/hew-09/
http://en.wikipedia.org/wiki/Nakalipithecus
http://en.wikipedia.org/wiki/Ouranopithecus
https://www.jstage.jst.go.jp/article/ase/113/1/113_1_95/_html
HOMINOID TEETH WITH CHIMPANZEE-AND GORILLA-LIKE FEATURES FROM THE
MIOCENE OF KENYA
1) Chaire de Paléoanthropologie et de Préhistoire du Collège de France
2) Département Histoire de la Terre du Muséum National d’Histoire Naturelle
Released 2005/04/27 [Advance Online Publication] Released:
2004/07/13
This paper concerns four ape-like teeth from Kenya ,
one from the Ngorora Formation (12.5 Ma), and three from the Lukeino Formation
(5.9 Ma), collected by the Kenya
In this paper we restrict the term ‘hominid’ to encompass only those
hominoids that possess skeletal morphology indicative of habitual or obligate
bipedal locomotion. We do not employ it in the much wider sense that has
recently been used by some authors, in which even the
genera Pan and Gorilla are included in the family
Hominidae.
Bar 91’99 is an unworn right lower molar, probably the second (11.4 mm
mesiodistal × 9.4 mm buccolingual), although a case could be made for it being
a third molar. The apices of the protoconid and hypoconid are buccolingually
compressed and not very voluminous. They are located towards the buccal margin
of the tooth and they express minor buccal flare. The apices of the protoconid
and metaconid are 5.2 mm apart and the tooth is 9.2 mm broad at this level. The
protoconid and metaconid have low-relief, centrally directed crests which close
off a low walled mesial fovea. Anterior crests from these same cusps meet
mesially to wall off the anterior side of the mesial fovea, which is
buccolingually wide and mesiodistally short. The hypoconid has low crests
descending from its apex mesially and distally but not crossing the grooves,
which separate the cusp from its neighbors. There is a basal cingular enamel
fold between the protoconid and hypoconid and a tiny fold between the hypoconid
and hypoconulid. The hypoconulid has a crest descending obliquely anteriorly
into the talonid basin, but it is low and does not separate the basin from the
distal fovea. The postcristid reaches lingually towards the low cusplet present
between the hypoconulid and the entoconid.
The apices of the metaconid and entoconid are strongly buccolingually
compressed and peripherally positioned, a disposition that results in a
voluminous sunken talonid basin bordered by cusps that are somewhat trenchant
in appearance. The posterior crest of the metaconid descends towards a low,
peripherally positioned cusplet between the metaconid and entoconid. The
hypoconid extends beyond the midline of the crown and reaches this small
cusplet. As a consequence, the metaconid and entoconid do not touch each other.
A postentoconid crest descends obliquely towards another low cusplet located
between the entoconid and hypoconulid from which it is separated by narrow but
short vertical grooves on the posterolingual surface.
The occlusal basin is wide, deep, and long. The wall between the
anterior fovea and the talonid basin is low and the posterior fovea is not
clearly demarcated from it, and thus extends for almost the entire length of
the tooth. The occlusal surface of the enamel in the basin is wrinkled.
The main differences from molars of Pan paniscus (Figure
1B) concern the buccal cusps, which are slightly more internally positioned
in the fossil. In P. paniscus, the buccal cusps are even more peripherally
located than they are in the Ngorora tooth. Another difference between the
Ngorora tooth and P. paniscus lies in the height of the entoconid,
which is taller and more trenchant in P. paniscus. The anterior fovea is
buccolingually narrower in the fossil than in Pan. However, these are
relatively minor differences.
The Ngorora molar resembles lower molars of Pan
troglodytes from Mahale ,
Tanzania
Lower molars of the European genus Dryopithecus (Figure
1D–F) have peripheralized cusps, and broad but shallow occlusal basins (Begun,
2002). They also possess slight buccal cingula and some specimens have a
small accessory cusplet separating the metaconid and entoconid in the lingual
notch. The most significant differences between the Kenyan and European
specimens are the shallower occlusal basins and the less buccolingually
compressed lingual cusps that occur in Dryopithecus. In particular, the
Ngorora tooth resembles some of the central European D.
brancoi, especially specimens such as those from Salmendingen,
Trochtelfingen, and Ebingen (Figure
1D–F). It is not impossible that the Ngorora species is related to the
genusDryopithecus.
Comparison of the Ngorora tooth (Figure
1A) with lower molars of African fossil hominoids reveals that it does not
belong to any of the described Miocene forms, none of which possess the large
occlusal basin and peripheralized cusps that distinguish this tooth. The only
specimen with which it accords in morphology is the Ngorora upper molar (KNM-BN
1378), which has wide occlusal fovea and a large protocone, but this tooth is
appreciably larger than what would be expected to occlude with Bar 91’99.
Until now, no fossil chimpanzees and gorillas have been reported and
there has thus been a lack of evidence to test the molecular clock estimates of
the dichotomy between African apes and hominids. If the derived characters of
the Ngorora molar represent homologies shared with chimpanzees, then it would
indicate that thePan clade has its roots in the latter part of the Middle
Miocene, sometime prior to 12.5 Ma.
The dichotomy between chimpanzees and humans is usually estimated by
molecular biologists to be more recent than 6 Ma (Gagneux
et al., 1999; Stauffer
et al., 2001) and the split between chimpanzees and gorillas has been
estimated at 8–9 Ma by Wrangham
and Pilbeam (2001) and 7.7 Ma by Gagneux
et al. (1999). The only molecular biologists who have proposed an earlier
age for African ape origins are Arnason and co-workers (Arnason
et al.,1996, 1998, 2000; Janke
and Arnason, 2002), but their results are usually considered suspect by
others who appear to favor appreciably later divergence times (Bailey
et al., 1992; Adachi
and Hasegawa, 1995;Gagneux
et al., 1999; Stauffer
et al., 2001; Pilbeam,
2002).
The Ngorora specimen thus runs counter to the recent ideas of Pilbeam
(1996) who wrote that “the common ancestor of humans and chimpanzees
was probably chimpanzee-like, a knuckle-walker with small thin-enamelled cheek
teeth,” and Wrangham
and Pilbeam (2001) who postulated that the “6 mybp ancestor…would have
been thin-enam-elled, knuckle-walking, and females would have had black body
coats.” It is already known that 6 Ma hominids such as Orrorin
tugenensis had thick-enamelled molars with restricted occlusal basins and
were fully bipedal (Senut
et al., 2001; Pickford
et al., 2002). Instead the Ngorora fossil ape tooth accords with the
scenario published by Arnason
et al. (1996, 1998, 2000)
based on molecular evidence, of an early divergence (ca. 13.5 Ma)
between Pan and Homo.
Description
The Kapsomin tooth is a partial left upper molar (Figure
2A–D). It lacks the roots but the cervical line is partly preserved,
allowing estimation of cusp height. Also preserved are the entire paracone and
metacone, part of the hypocone and the distobuccal extremity of the protocone
(the crista obliqua). The distal fovea is complete. The tooth is 14 mm
mesiodistal. It is low crowned (7.3 mm from cervix to tip of metacone) and the
cusps are endowed with low but broad wrinkles.
The paracone and metacone are separated from each other by a narrow
slit-like buccal groove (Figure
2B). The part of the trigon basin preserved is relatively large and open,
the main cusps being peripherally positioned and the cusps not bulbous. The
mesial fovea is not preserved. Two low crests descend from the apex of the
paracone towards the midline of the crown (i.e. towards the mesial fovea). The
metacone sends a crest lingually and slightly anteriorly towards the protocone,
from which it is separated by a groove. The metacone has another, smaller crest
that descends obliquely distally directly towards the hypocone, bifurcating on
its way down the cusp. The anterior branch of the crest forms a low wall
between the trigon basin and the distal fovea. The distal cingulum reaches from
the base of the metacone to the hypocone and walls off the distal fovea on the
distal aspect of the tooth. The metacone and hypocone are spaced far apart, and
as a consequence, the distal fovea is buccolingually wide and slightly
obliquely oriented with the buccal end more mesial than the lingual one. The
apex of the hypocone is missing so it is not possible to provide detailed
measurements of the distance between its apex and those of the paracone and
metacone. We estimate the distance between the tips of the hypocone and
metacone at 7.5 mm. The distance between the tips of the paracone and metacone
is 6 mm. The distal margin of the crown is not markedly curved, suggesting that
it is not a third upper molar, but more likely a second or first. The surface
of the enamel is wrinkled but not as heavily as is usually the case in chimpanzee
molars. Enamel thickness measured radially (Schwartz,
2000) 2 mm below the tip of the preserved part of the hypocone is 1.6–1.7
mm (line in Figure
2C), but this figure is likely to be an overestimate of the true thickness,
as it is taken slightly obliquely due to the orientation of the fractured
surface of the cusp.
Comparisons with Orrorin tugenensis and Pliocene hominids
Bar 1757’02 is highly divergent from the teeth in the upper tooth row
of Orrorin (Figure
2F), not only in its greater dimensions, but also in its morphology. The
trigon basin and distal fovea in the upper molars of Orrorin are
restricted in size; the buccal cusps are more flared from apex to cervix, the
buccal slit is non-existent, the main cusps are lower crowned, the dentine
penetrance is low, and the enamel is less wrinkled. The Kapsomin ape tooth is
closer in size and some aspects of morphology to upper molars
of Australopithecus afarensis andPraeanthropus africanus. However,
the higher and less-inflated cusps, the steep, flat, and unflared buccal
surface, thinner enamel, and the greater dentine penetrance suggest that Bar
1757’02 is not from an australopithecine.
Comparisons with Gorilla gorilla
Upper molars of gorillas are generally longer than Bar 1757’02 but
there are small individuals that overlap in size; upper M1/s of Gorilla
gorilla range in mesiodistal length from 12.7 to 16.7 mm, M2/s from 13.4
to 17.9 mm, and M3/s from 12.0 to 17.0 mm (Pilbeam,
1969).
The crown morphology of Bar 1757’02 is similar in several respects to
that of molars of Gorilla gorilla (Figure
2G, H). In particular the mesio-distally short but bucco-lingually wide
distal fovea of the Lukeino tooth resembles that of Gorilla as does
its oblique orientation. Another resemblance lies in the degree and kind of
enamel wrinkling and the high dentine penetrance. In G. gorilla enamel
is generally considered to be thin (ranging from 0.98 to 1.63 mm on the
protocone and between 0.7 and 1.33 mm on the paracone: Schwartz,
2000), and in Bar 1757’02 it is 1.6–1.7 mm on the hypocone, which falls
slightly above the range of variation of Gorilla. This measure was
taken on a slightly oblique natural section of the tooth (Figure
2C), and the radial thickness would be slightly less than this figure.
Comparisons with Pan
Bar 1757’02 differs markedly from molars of P.
troglodytes and P. paniscus, not only in size, but also in morphology
(Figure
2E). M1/s and M2/s of P. troglodytes range in mesiodistal length
from 9 to 12 mm, and M3/s from 8.2 to 10.6 mm (Pilbeam,
1969). The trigon basins in molars of Pan are extensive and the
crests separating the basin from the mesial and distal foveae are quite low. In
any case, the distal fovea in Pan is reduced in buccolingual extent.
A further difference is the greater buccolingual compression of the apices of
the paracone and metacone in Pan.
Comparisons with Sahelanthropus tchadensis
Bar 1757’02 is larger than the upper molars in Sahelanthropus
tchadensis (Brunet
et al., 2002) (mesio-distal length is 14 mm in Bar 1757’02, compared to
10.9–11.5 mm in M1/, 13 mm in M2/, and 10.7–10.8 mm in M3/
ofSahelanthropus). Brunet
et al. (2002) describe the molars as having “low rounded cusps…,” in
which case they are different from the Kapsomin tooth. The enamel in the upper
molars of Sahelanthropus has been reported to be 1.71 mm thick in the
paracone of M3/ and 1.79 mm at the hypocone of M2/, which suggests that enamel
inSahelanthropus is approximately the same as in the Kapsomin ape in which
it is 1.6–1.7 mm on the hypocone. The enamel thickness of Orrorin was
originally (Senut
et al., 2001) said to be 3.1 mm on the protoconid of m/2 but this was a
typographical error that unfortunately carried through into both translated
versions of the text. The thickness measured radially near the tip of the
protoconid on the original fossil was 2.1 mm. The enamel thickness decreases
towards the cervix such that it is about 1.7 mm thick about 2 mm below the apex
of the cusp. Further study with a scanner is planned.
Comparisons with other Miocene hominoids
Bar 1757’02 differs in various features from most of the known medium
and large hominoids from the Miocene of Africa .
Molar morphology
in Kenyapithecus, Nacholapithecus, Otavipithecus,
and Afropithecus is quite different, these taxa possessing
non-peripheralized bulbous main cusps and restricted occlusal basins (Conroy
et al., 1992; Ward
and Duren, 2002).
In Proconsul and Ugandapithecus the cusps are not
peripheralized (Harrison,
2002; Senut
et al., 2000). The cusps in the upper molars
of Samburupithecus are inflated, and the occlusal basins are
extremely restricted (Pickford
and Ishida, 1998), which makes them very divergent from the Kapsomin tooth.
Ouranopithecus and Ankarapithecus from European Late
Miocene deposits have thick-enamelled molars with restricted occlusal basins
and low dentine penetrance, interpreted by de Bonis
et al. (1981) as features shared with Hominidae, from which we infer
that the genus is markedly different from the Kapsomin ape.
Discussion
It seems clear that the fragment of upper molar from Kapsomin (Bar
1757’02) represents a species distinct from O. tugenensis. Apart from its
greater dimensions, it has morphology that is different from the bunodont crown
with inflated main cusps and restricted trigon basin and foveae of the latter
taxon. Whereas the molars of Orrorinrecall those of later hominids
(Australopithecus, Praeanthropus, and even Homo) in overall crown
shape, bunodonty, cusp inflation, and basin restriction, Bar 1757’02 stands out
as anomalous, with its more peripheralized cusps, widely separated metacone and
hypocone, wide, obliquely oriented distal fovea, vertical and flat buccal
surface, high dentine penetrance, and thinner enamel with light wrinkling. The
tooth has high dentine penetrance as shown by the fact that if it were worn to
the same level as the M2/ in the Orrorin tooth row, which shows no
dentine exposure, the Kapsomin ape tooth would have a large dentine exposure
(the shadow at the apex of the protocone of the M2/ of Orrorin in Figure
2F is a small patch of chemical etching floored by enamel and is not an
exposure of dentine). The morphology of the dentine-enamel junction in the
Kapsomin tooth is best appreciated by examining the broken inner surface of the
Kapsomin tooth where it is clearly visible, showing the dentine penetrating
high into the hypocone (Figure
2C). In most of these features the tooth is closest to G. gorilla, yet
it is by no means a perfect fit with this species.
Metrically, the Kapsomin tooth is appreciably larger than any of
the Orrorin molars, but it falls within the range of metric variation
of the gorilla. It also falls within the range of variation of Pliocene fossil
hominids, includingArdipithecus, Australopithecus, and Praeanthropus.
Its relationships to Sahelanthropus are not clear as published
photographs of the latter do not reveal enough detail about crown morphology,
but descriptions of the fossil suggest major morphological differences.
We conclude that Bar 1757’02 reveals the presence of a second hominoid
in the Lukeino Formation, Kenya
Bar 1001’00 is a right upper central incisor that has been abraded
mesially and distally (Figure
3B). The preserved part of the crown is relatively low compared to root
length. In lateral view the labial and lingual surfaces form a wedge-shape; the
tooth is 8.7 mm thick labio-lingually near the cervix and narrows rapidly
incisally. It has lightly wrinkled enamel. The crown is unlike the
corresponding teeth of australopithecines and humans because there is no fossa
on the lingual side (Figure
3A). In hominids the crown is higher from cervix to incisal edge and the
lingual surface has a large fossa, sometimes with lingual ridges or pillars,
but usually possessing a scoop-shaped profile. In gorillas, in contrast, the
upper central incisors are often wedge-shaped, with no sign of a lingual fossa,
or if one is developed it is not very prominent. Comparison of the Kapsomin
upper incisor with those of gorillas reveals close similarities (Figure
3C) not only in size but also in shape and crown height relative to root
length. Even though these similarities are enhanced by the wear stage of the
Kapsomin incisor and that of the gorilla used for comparison, this is because
the underlying morphology is similar. Chimpanzee and hominid teeth worn as much
as the Kapsomin fossil do not develop a comparable wedge-shaped appearance in
lateral view, because the lingual surface of their teeth is basin-like.
An anonymous referee considered that this tooth is similar to A.L.
198-17a (Johanson
et al., 1982) and on this basis suggested that the Kapsomin tooth may
belong to an australopithecine. However, comparison of the specimens reveals
that they are divergent in morphology. The Hadar fossil has a restricted basal
lingual pillar bordered mesially and distally by hollows, as in other
australopithecine teeth, whereas Bar 1001’00 does not, its basal lingual part
being inflated right across the preserved part of the tooth, as in gorillas
with which we compared the tooth. Furthermore, the wear facet in A.L. 198-17a
is apical, flat, and at right angles to the long axis of the tooth, whereas
that in the Kapsomin tooth is steeply angled from incisal edge to cervix on the
lingual side, again as in gorillas. In apical view the Hadar tooth is a
mesiodistally elongated rectangle, slightly concave lingually with slight
projection of the basal tubercle, whereas the Kapsomin tooth is much broader
labiolingually. This is reflected in the dimensions of the teeth, the Kapsomin
specimens measuring 8.7 mm labiolingually near cervix and the Hadar specimen
only 7.1 mm. Larger upper central incisors from Hadar (A.L. 200-1a, A.L.
333x-4, and A.L. 333x-20) measure 8.5, 8.6, and 8.6 mm labiolingually,
respectively.
Discussion
The upper central incisor (Bar 1001’00) was initially attributed
to O. tugenensis (Senut
et al., 2001) because at the time of the discovery it was assumed that only
a single hominoid was represented at the site. With the discovery of Bar
1757’02, a partial upper molar, it became clear that a second, larger, hominoid
taxon was present at Kapsomin, leading to a re-evaluation of all the specimens
from the site. Because of its dimensions (labiolingual breadth 8.7 mm) and its
somewhat gorilla-like morphology and wear pattern, we now consider that the
upper central incisor belongs to this second hominoid rather than
to Orrorin.
Bar 2000’03 from Cheboit, Lukeino Formation, is an unworn right lower
molar lacking the roots, but preserving much of the cervical line (Figure
4). The apices of the two lingual cusps are buccolingually compressed and
peripherally located. The tips of the protoconid and metaconid are 5.4 mm apart
and the tooth is 10.5 mm broad at this level. The two buccal cusps are slightly
in advance of the lingual ones, and there is minor buccal flare. Because of the
peripheral positions of the main cusps, the occlusal basin is large and
elongated. The mesial fovea is wide but mesiodistally short. The hypoconulid is
small and is located slightly to the lingual side of the centre line of the
tooth and in a very distal position, and as a result the tooth has an elongated
trapezoidal outline (Figure
4). Because of this the tooth could be a lower third molar. The distal
fovea is thus small, but is not separated from the main occlusal basin by the
crests from the hypoconulid or entoconid, as these do not reach each other. The
tooth measures 12.7 mm mesiodistal by 11.1 mm buccolingual.
This tooth is morphologically compatible with Bar 1757’02, the upper
molar from Kapsomin. We consider it likely that the two specimens belong to a
single taxon.
This lower molar differs radically from those of O.
tugenensis of which it is a contemporary. The occlusal outline is long,
narrow, and trapezoidal compared with a wider, more rectangular outline
in Orrorin. The main occlusal basin is deep, wide, and long, compared with
the shallow, narrow, and short basin in Orrorin. The distal fovea is not
separated from the main basin, whereas in Orrorin it is. The buccal
flare is not as marked as it is in Orrorinand the lingual cusps are more
peripherally located. The main cusps are not as inflated as those
of Orrorin, suggesting that the tooth has thinner enamel and probably
greater dentine penetrance, but we have not yet had the opportunity to
determine these parameters. In Orrorin, the hypoconulid is located to the
buccal side of the midline, and is thus close to the hypoconid, whereas in Bar
2000’03 it is to the lingual side of midline, and far from the hypoconid.
Indeed this cusp is closer to the entoconid than it is to the hypoconid, the
opposite of the situation in Orrorin. In the latter genus, there is a
clear valley buccally between the hypoconid and the entoconid, whereas in Bar
2000’02, there is not even an indentation in the distobuccal wall of the tooth.
The latter tooth is also somewhat bigger than any of
the Orrorin lower molars.
Four ape-like teeth from the Miocene of Kenya
The morphology of the Ngorora tooth suggests that
the Dryopithecus lineage may have evolved in Africa and then invaded
Europe about 12–12.5 Ma, rather than evolving within Europe from a
thick-enamelled lineage such asGriphopithecus (Begun,
2002). If it is part of the Pan clade, then it would push back
the split between hominids and African apes to the Middle Miocene. If this
is so, then thick-enamelled apes such as Kenyapithecus possibly take on a
renewed significance for throwing light on the earliest stages in the evolution
of hominids, as thought by L. Leakey in the 1960s (Leakey,
1962, 1967, 1969, 1970)
even though the supposedly hominid features employed by Leakey in his proposals
have subsequently been interpreted as being related to sexual dimorphism and to
plesiomorphic features found in several Middle Miocene hominoids, rather than
to derived morphology shared with hominids (Pickford,
1985). It is more parsimonious to consider that thick-enamelled hominids
descended from thick-enamelled precursors rather than to hypothesize a
thin-enamelled intermediate stage, as has apparently become the fashion (Wrangham
and Pilbeam, 2001). What is required is a fresh look at the problem,
including the relationships between diet on the one hand and enamel thickness
and dentine penetrance on the other.
If the Kapsomin ape teeth belong to the gorilla clade, then they would
indicate that by about 6 Ma the lineage was a separate entity from the Pan + Homo clade.
Taken together, the Ngorora and Kapsomin ape teeth, and those of the early
bipedal hominid Orrorin, plead for considerably earlier split times
between the gorilla, chimpanzee, and hominid clades than most molecular
biologists have considered possible for the past three decades (Gagneux
et al., 1999; Stauffer
et al., 2001) but more in accord with the results of Arnason and his
colleagues (Arnason
et al., 1996, 1998, 2000; Janke
and Arnason, 2002).
The four teeth from Baringo district, Kenya ,
described here reveal the presence of ape-like hominoids in East
Africa during the latter part of the Middle Miocene and the Late
Miocene. They thus refute the statement byBegun
(2002) that “In actual fact, none of the many late Miocene African
fossil localities has any hominoids….” When we add them
to Samburupithecus from the Late Miocene of Samburu Hills, Kenya (9.5
Ma) (Ishida
and Pickford, 1997), Orrorin from Lukeino, Kenya (6–5.7 Ma) (Senut
et al., 2001), Sahelanthropus from Toros-Menalla, Chad (ca. 7–6
Ma) (Brunet
et al., 2002), and Ardipithecus from Ethiopia (White
et al., 1994, 1995),
it is clear that Late Miocene Africa was not devoid of hominoids until they
reintroduced themselves from Europe (Begun,
2002). Rather, it is more likely that chimp-sized Dryopithecus was
originally an African lineage that invaded western Europe about 12.5–12 Ma, and
while the evidence is scant, some of the large gorilla-sized hominoids from the
Late Miocene of Greece and Turkey could also be of African origin rather than
autochthonously evolved descendents
of Dryopithecus or Sivapithecus as envisaged by Begun
(2002). Despite the relative poverty of the African fossil record, the new
discoveries reveal that hominoids were more diverse in the Late Miocene of
Africa than they were in Europe (five genera now known in Africa compared to
three or perhaps four in Europe ).
We thank members of the Kenya Inuyama , Japan
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