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Miosengi butleri, gen. et sp. nov., (Macroscelidea) from the Kalodirr Member, Lothidok Formation, Early Miocene of Kenya



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Department of Anatomy, Arizona College of Osteopathic Medicine,
Midwestern University, 19555 N. 59th Ave, Glendale, Arizona 85308, USA,;
Museum of Paleontology,
1101 Valley Life Sciences Building, University of California, Berkeley, California 94720-4780, USA,
The only described taxa of early Miocene macroscelideans
(afrotherians previously referred to as elephant-shrews, but bet-
ter dubbed sengis to clearly distinguish them from the unrelated
Soricidae or true shrews) are Myohyrax oswaldi from the Ken-
yan sites of Karungu, Chamtwara and Songhor, and Arrisdrift in
Namibia (Senut 2003), Protypotheroides beetzi also from Nami-
bia, Miorhynchocyon spp. from a large number of localities in
Kenya, and Hiwegicyon juvenalis from Rusinga Island in Kenya
(Butler, 1984, 1995). The first three taxa respectively represent
the macroscelidid subfamilies Myohyracinae (Myohyrax and
Protypotheroides) and Rhynchocyoninae (Miorhynchocyon),
while Hiwegicyon (a taxon only known from a juvenile speci-
men) is of unknown affinities. The Macroscelidinae, the subfam-
ily that comprises most living sengis, is a ghost lineage through
this time interval. Older representatives of the Neogene subfa-
milies are unknown, although macroscelideans noted from
the late Oligocene of the Rukwa Rift Basin in Tanzania may
relate to those of the Neogene (Stevens et al., 2006; Stevens
et al., 2008). The first appearance of macroscelidines is the
middle Miocene locality of Fort Ternan (Butler, 1984, 1995),
where Pronasalio ternanensis occurs at approximately 13.7 Ma
(Pickford et al., 2006). However, the split of macroscelidines
from other sengi lineages has been hypothesized to occur by
the beginning of the early Miocene, based on the presence by
this time of its putative sister lineages the Myohyracinae and
Rhynchocyoninae. Additionally, some molecular phylogenies
suggest rhynchocyonines had split off in the Eocene to early
Oligocene (42.74.8 Ma) and the presence of divisions within
the Macroscelidinae such that the group comprising the extant
Petrodromus,“Elephantulus rozeti, and their sister taxon
Macroscelides diverged from the group containing other spe-
cies of Elephantulus in the late Oligocene to early Miocene
(21.33.3 Ma) (Douady et al., 2003). Thus, particularly given
the potential discrepancies of molecular clocks, early Miocene
representatives of Macroscelidinae are crucial to better under-
standing the evolution of the group.
Here we describe the first record of an early Miocene macro-
scelidine sengi that helps fill this gap in the subfamily’s fossil
record and provides insights into the morphological diversifica-
tion of the group. The new taxon is from the locality of Kalodirr,
located in northern Kenya about 30 kilometers west of the shore
of Lake Turkana and a few kilometers north of the road leading
from Lodwar to Kalakol (Fig. 1). A team from the National
Museums of Kenya led by Richard and Meave Leakey con-
ducted several field seasons at the site between 1983 and 1987.
They recovered a diverse mammalian fauna with a significant
small mammal component. The site is best known for its three
primate genera; Afropithecus turkanensis, Turkanapithecus kala-
kolensis, and Simiolus enjiessi (Leakey and Leakey, 1986a, b;
Leakey and Leakey, 1987). Although the primates have been
the subject of several studies (Leakey and Walker, 1997; 1988a;
Leakey et al., 1988b; Patel and Grossman, 2006; Rose et al.,
1992), the rest of the fauna is only now being formally described
(Grossman, unpubl. data). The new taxon represents the earliest
known member of the subfamily Macroscelidinae and is the only
macroscelidean known from the fauna.
Geological Setting and Age of the Fossils—the site of Kalo-
dirr (“Oryx” in the Turkana language) is located at the headwa-
ter of the Kalodirr River (3
20’N, 35
45’E) between the
Lokipenata Ridge and the Basalt Hills to the east (Boschetto
et al. 1992; Leakey and Leakey 1986a, b). The fossils were recov-
ered from sediments within the latest early Miocene Kalodirr
Member of the Lothidok Formation (Boschetto, 1988; Boschetto
et al., 1992). The age of the Kalodirr fauna can be well con-
strained based on K/Ar dating of the underlying Kalodirr tuffs
(17.510.2 Ma) and the overlying Naserte tuffs (16.80.2 Ma),
which divide the Kalodirr Member from the younger Naserte
Member of the Lothidok Formation. The Miosengi fossils were
found during sieving and their exact location within the member
is unknown
Sedimentological analyses indicate deposition via small mean-
dering stream channels (Boschetto, 1992). Environmental recon-
structions for the sites of Kalodirr and Moruorot based on the
mammalian fauna indicate that the site was probably a closed to
open woodland habitat (Grossman 2008a, b). This interpretation
is further supported by plant fossils from the site; these include
broad leaved forms, some possessing an acuminate tip ("drip
tip") indicating seasonally wet conditions (Boschetto, 1992). Ad-
ditionally, a number of fish, a pelomedusid turtle, and crocodilian
fossils also indicate the presence of lacustrine or fluvial water.
Institutional AbbreviationsKNM, Kenyan National Museums,
Nairobi, Kenya; KNM-WK, KNM specimens from the site of
Kalodirr, Kenya; KNM-FT, KNM specimens from the site of Fort
Ternan, Kenya; MVZ, Museum of Vertebrate Zoology, University
of California, Berkeley, California; UCMP, University of California
Museum of Paleontology, Berkeley, California.
Order MACROSCELIDEA Butler, 1956
Family MACROSCELIDIDAE Bonaparte, 1838
Subfamily MACROSCELIDINAE Bonaparte, 1838
MIOSENGI BUTLERI gen. et sp. nov.
(Figs. 2, 3)
Holotype—KNM-WK 17050, right mandible fragment with
m2 and the m3 alveolus (Figs. 2, 3).
Referred Material—KNM-WK 17326, right p2 or p3 (Fig. 3).
Type locality—Kalodirr, Kalodirr Member of the Lothidok
Formation, early Miocene, Kenya.
Etymology—The genus name is a combination of Mio- for the
Miocene and sengi, the word for macroscelidids in several Ban-
tu-based languages of central and southern Africa, and Swahili
of eastern Africa (Rathbun and Kingdon, 2006). Specific epithet
in honor of Dr. Percy Butler, whose work on sengis is unparal-
Diagnosis—Differs from other macroscelidines in relatively
lower crown height, and posterior wall of m2 talonid anteriorly
inclined and posteriorly-rounded (vs. vertical). Differs from
Journal of Vertebrate Paleontology 29(3):957–960, September 2009
2009 by the Society of Vertebrate Paleontology
Palaeothentoides and is similar to other macroscelidines in smal-
ler size; differs from Macroscelides, Petrodromus, and some
Elephantulus species in retaining m3; differs from Macroscelides
in having wider molars relative to length and a lower crown.
Differs from Pronasilio in having an m2 slightly mesiodistally
longer but with a lower crown; m2 lacking anterobuccal cingu-
lum; more gracile dentary. Miosengi butleri further differs from
Petrodromus, Paleothentoides, and Elephantulus, but is similar to
Macroscelides and Pronasilio, in retaining a salient hypoconulid.
Description—KNM WK 17050 is a right dentary fragment with
m2 and a small alveolus for a reduced, single-rooted m3. The m2
crown is of moderate height, with the talonid slightly lower than
the trigonid. It is mesiodistally longer than the m2 of Pronasilio
but has a lower crown (KNM WK 17050, length 2.24 mm, width
1.55 mm, height 1.60 mm vs. KNM FT 3409 [P. ternanensis],
length 1.87 mm, width 1.53 mm, height 2.11 mm). The trigonid is
dominated by the metaconid and a slightly lower protoconid.
These cusps are aligned mesiodistally and joined by a distinct
protolophid. The anterior margin of the tooth is formed by a
well-developed paracristid (or paralophid) arising from the pro-
toconid and sweeping mesiolingually to form a lingually open
trigonid. The paracristid is lower than the protolophid and termi-
nates in an abrupt dip slightly lingual of the tooth’s midline. The
paracristid of Miosengi butleri courses more lingually and
recurves. A small anterior cingulum is present low on the buccal
face of the paracristid, but is not as extensive as in Pronasilio.
The talonid is only very slightly lower than the trigonid. The
entoconid is slightly higher than the hypoconid. The hypoconulid
is a slight angulation of the hypolophid connecting the entoconid
and hypoconid, but is distinct, in contrast to younger macrosceli-
dines such as Paleothentoides, Petrodromus,orElephantulus. The
posterior profile of the crown is distinctly rounded and canted
anteriorly. This anterior slant is particularly discernable in lin-
gual view and is very different from the vertical posterior profile
of the m2 in Pronasilio or Paleothentoides or the anteriorly in-
clined surfaces formed by the posterior edge of the molars in
Petrodromus, Macroscelides, and Elephantulus. A prominent
cristid obliqua bends lingually from the hypoconid to join the
protolophid near the metaconid as in other macroscelidines. A
deep cleft opens the talonid basin lingually between the entoco-
nid and metaconid.
Direct comparisons with early Miocene Hiwegicyon are not
possible because it is only known from a deciduous dentition.
However, the m1 of H. juvenalis agrees in proportion with that
of P. ternanensis (Butler, 1984), and if these proportions hold
true for the m2 as they do in Pronasilio, this may serve to
distinguish between Hiwegicyon and Miosengi. Additionally,
Hiwegicyon lacks the rounded posterior margin on the lower
molar that is seen in Miosengi.
KNM-WK 17326 (Fig. 3) is a double-rooted premolar measur-
ing 1.64 mm in length, 0.76 mm in width, and 1.11 mm in height.
The protoconid is only slightly higher than the raised paracristid
FIGURE 1. Map showing occurrence of early and middle Miocene
faunas containing macroscelideans in Kenya. Localities in the Lake Vic-
toria region include early Miocene Songhor, Koru, Chamtwara, and
Rusinga, Maboku, and Mwafangano Islands, and middle Miocene Fort
Ternan (type locality of Pronasilio ternanensis).
FIGURE 2. Miosengi butleri, KNM WK-17050, holotype right mandi-
ble with m2 and alveolus of m3 in lateral, occlusal, and lingual views.
that extends almost directly anteriorly from its apex. The crown
has a short talonid formed by a raised crest, which is distinctly
lower than the trigonid. Comparing it with other macrosceli-
dines, the relative proportions of the trigonid and talonid and
the anteriorly directed paracristid are most similar to the p2 or
p3 of Palaeothentoides and to p3 in Elephantulus rupestris or
E. brachyrhynchus. It differs markedly from Petrodromus in
having a relatively high paracristid, suggesting that it may be
more closely related to the former taxa rather than to the Petro-
dromus-“E. rozeti- Macroscelides complex, unless Douady
et al. (2003) are correct in their hypothesis that the morphology
of the clade comprising Elephantulus species excluding E.”
rozeti represents the primitive condition for the entire subfamily.
The premolars anterior to p4 are not known in most Paleogene
macroscelideans; only from the late Eocene Herodotius (Simons
et al., 1991). However, in contrast to Herodotius, which also has
semi-molariform premolars, KNM-WK 17326 differs in having
the paraconid subsumed within a paracristid, rather than being a
distinct cusp. Macroscelidines (except Petrodromus) differ from
rhynchocyonines in having semi-molariform to molariform
p1through p3 in addition to the molariform p4 found in all sengis.
Pleistocene and extant macroscelidines share this trend for
molarization of the anterior premolar dentition with the Myohy-
racinae, where it is taken to hypsodont extremes. However, we
currently lack adequate sampling of the fossil record to establish
the timing and patterning of this transformational sequence.
We place Miosengi within crown Macroscelidea based on hav-
ing a well-developed lower molar paracristid with distinct para-
conid and a hypoconulid within a strong hypocristid (characters
12, 16 of Tabuce et al., 2001). It can also be included with the
unnamed clade comprising Macroscelidinae + Mylomygalinae
based on the shared possession of a lower molar cristid obliqua
that is directed towards the metaconid (character 15 of Tabuce
et al., 2001). However, it is important to note that at least some
specimens of Metoldobotes, which is placed outside of crown
Macroscelidea in Seiffert (2007), are reported to have well-de-
veloped lower molar paracristids and paraconids, distinct hypo-
conulids, and oblique cristids oriented toward the metaconids
(Characters 18426, 18430, 18441 in the supplemental information
of Seiffert, 2007).
We place Miosengi butleri within Macroscelidinae based on its
semi-molariform premolar (a condition shared with more
derived macroscelidines, excluding Petrodromus) and the lack
of any of the autapomorphies associated with the Myohyracinae
that can be evaluated in Miosengi (e.g., extreme hypsodonty).
Pronasilio has been regarded as the most primitive of the
macroscelidines due to its retention of a small m3 and having
molars in which the talonid is slightly lower than the trigonid
compared to later macroscelidines (Butler, 1984). Miosengi but-
leri differs from Pronasilio in the lower height of the m2 crown
and its rounded posterior margin suggesting that a lower crown
and rounded posterior margin may be more primitive. The pre-
molar assigned to M. butleri provides new data for the macro-
scelidines and suggests that the process of anterior premolar
molarization was well underway by the early Miocene. Although
we cannot assign the premolar to position with certainty, com-
parison of overall morphology with known Paleogene forms
demonstrates that M. butleri had slightly narrower yet more
semi-molariform premolars than observed in any Paleogene
macroscelidean. It also has a more pronounced paracristid and
talonid than seen in extant
Petrodromus, suggesting that it is
more derived in this feature. However, the relationships among
macroscelidines as well as myohyracines have not been formally
explored in a phylogenetic framework (and are beyond the
scope of the current paper), so hypotheses regarding dental
character polarities are tentative.
Pronasilio ternanensis is similar to the extant Elephantulus
brachyrhynchus in its overall dental row dimensions (Butler,
1984) suggesting that this animal weighed approximately 40-60g.
Miosengi butleri has a similarly sized lower second molar and
very likely was as small as P. ternanensis, both of which are
smaller than Paleogene macroscelideans such as Metoldobotes
and Herodotius. Macroscelidines are relatively smaller on aver-
age than other sengis, and M. butleri is one of the smallest
species within the group, demonstrating that the small size of
the Macroscelidinae was achieved early in the diversification of
the subfamily.
The discovery of Miosengi butleri also bears on questions re-
garding the biogeographic origins of taxa in younger East Afri-
can sites. The middle Miocene localities of Maboko and Fort
Ternan are distinct from older localities in the Lake Victoria
region of western Kenya due to the introduction of putatively
allochthonous species (Butler, 1984), possibly correlated with
indications of a change towards drier climates in the region
(Andrews and Walker, 1976; Cerling et al., 1997; Kappelman,
1991; Shipman, 1982, 1986). The early Miocene site of Rusinga
Island in western Kenya on the shores of Lake Victoria is rough-
ly contemporaneous with Kalodirr (Drake et al., 1988). Macro-
scelidids from Rusinga Island comprise Miorhynchocyon and
Myohyrax oswaldi. These two taxa are also known from slightly
older early Miocene localities within the Tinderet sequence
(Meswa Bridge, Songhor, Koru, Legetet, Chamtwara; Butler,
1984, 1995). However, there are no remains of macroscelidines
at these localities, suggesting possible ecological differences
between Kalodirr and other early Miocene sites and similarities
to the younger Fort Ternan, as suggested by Harrison (1992)
in discussing small catarrhine monkey distributions. M. butleri
demonstrates that the subfamily Macroscelidinae was morphol-
FIGURE 3. Miosengi butleri, m2 of KNM WK-17050 in lateral, occlu-
sal, and lingual views; and KNM-WK 17326, anterior lower premolar, in
lateral, lingual and occlusal views.
ogically distinct by the late early Miocene (16.6-17.7 Ma) and
likely lived several hundred kilometers farther north than the
localities of the Lake Victoria region. Thus, it appears that at
least some of the allochthonous faunal elements at Fort Ternan
in the middle Miocene (e.g., Pronasilio ternanensis) may have a
more geographically proximate origin within Africa, in contrast
to long distance dispersers that first appear in that fauna (e.g.,
Eurasian immigrants).
We thank E. Mbua, F. K. Manthi, M. Muungu and the staff of
the Paleontology Department at the National Museums of
Kenya for their patient and excellent support of AG; M. G.
Leakey for her help in gaining access to this material and her
support, encouragement and help to AG; N. J. Stevens for addi-
tional photography; and J.G. Fleagle, E. Seiffert, and D. M.
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Submitted October 29, 2008; accepted December 11, 2008.
... Current models indicate that Carnivora dispersed into Africa following the collision of the Eurasian and Afro-Arabian plates near the Oligocene-Miocene boundary. The earliest unequivocal African record of carnivorans is from the earliest Early Miocene site of Nakwai, West Turkana, northern Kenya, dated 23 Ma-15 Ma (Grossman and Holroyd, 2009;Rasmussen and Gutiérrez, 2009;Reynoso, 2014). Overall, however, Early Miocene records of carnivorans in the Turkana Basin are scarce (Savage, 1965;Anyonge, 1991;Werdelin and Peigné, 2010;Leakey et al., 2011;, and little material has been described. ...
... The localities of Kalodirr and Moruorot Hill are located within the Kalodirr Member (Lothidok Formation), between the Kalodirr and Naserte tuffs on the west side of Lake Turkana in Kenya (Figure 1). Kalodirr is located near the head-waters of the Kalodirr River (3°20'N, 35°45'E), extending from just south of the Lodwar-Kalakol road north to the Lokipenata Ridge (Leakey and Leakey, 1986a;Leakey and Leakey, 1986b;Boschetto et al., 1992;Grossman and Holroyd, 2009). Moruorot lies south of the Lodwar-Kalakol road and comprises two contemporaneous localities (Madden, 1972;Boschetto et al., 1992) (Figure 1). ...
... Sedimentological analyses indicate that deposition occurred via small meandering stream channels (Boschetto et al., 1992). Environmental reconstructions based on mammalian faunas indicate that the site was probably a closed to open woodland habitat (Grossman and Holroyd, 2009). Further support for this interpretation is provided by broad-leaved plant fossils from the site, some possessing an acuminate tip ('drip tip'), which indicates seasonally wet conditions (Boschetto et al., 1992, Collinson et al., 2009. ...
Full-text available
We describe new carnivoran fossils from Kalodirr and Moruorot, two late Early Miocene sites in the Lothidok Formation of West Turkana, Kenya. The fossils include a new species of viverrid, Kichechia savagei sp. nov., a new genus and species of felid, Katifelis nightingalei gen. et sp. nov., and an unidentified musteloid. We also report new records of the amphicyonid Cynelos macrodon. These new fossils increase the known diversity of African Early Miocene carnivorans and highlight regional differences in Africa.
... Some extant genera have been found in fossiliferous deposits, whereas others are unknown in the fossil record. Avery, 2019;Broom, 1948;Butler, 1969Butler, , 1987Butler, , 1995Butler & Greenwood, 1976;Butler & Hopwood, 1957;Corvinus & Hendey, 1978;De Graaf, 1961;Grossman & Holroyd, 2009;Hendey, 1978;Holroyd, 2009Holroyd, , 2010Hopwood, 1929;Mein et al. 2000;Pickford, 2015aPickford, , 2020Schlosser, 1911;Seiffert, 2003Seiffert, , 2007Senut, 2003Senut, , 2008Senut et al. 1996;Stromer, 1926Stromer, , 1931aTabuce, 2018;Tabuce et al. 2001;Wanas et al. 2009. ...
... Macroscelidinae and Rhynchocyoninae appear in the fossil record during the early Miocene of Africa; they are documented from several sites in Kenya, Namibia, and Uganda (Butler & Hopwood 1957;Butler 1969Butler , 1984Senut 2003Senut , 2008Grossman & Holroyd 2009;Holroyd 2010 for an overview). Besides these two extant subfamilies, Miocene macroscelidids are represented by the extinct Myohyracinae. ...
Chambius kasserinensis from the late Early or early Middle Eocene Chambi locality, central Tunisia, is undoubtedly the oldest known macroscelidid and possibly the basalmost representative of the order Macroscelidea. Hence, since its discovery in 1986, Chambius has played a key role in analyses focusing on afrotherian and eutherian phylogeny; for instance, as early as 1995, Butler’s review of fossil macroscelideans highlighted the central position of Chambius in the origin of the order. Despite this, Chambius remained poorly known until recently. Here based on new mandibular fragments, well-preserved upper molars and CT scan analysis of the holotype maxilla, Chambius is revised. Its dentition is first described in detail, providing a precise characterization of the genus. Chambius is notably defined by a submolariform P4 with a three-cusped talonid, a reduced talonid on M2, and a prominent metaconule on M¹⁻². Interestingly, the two transverse lophs of the upper molars are basically formed by preconulecristae, evoking the recently defined peculiar bilophodonty of paenungulates. Comparisons with other Paleogene and modern macroscelidids, European Louisinidae, and North American Apheliscidae are also made, allowing the various hypotheses about the origin and early evolution of macroscelidids to be reviewed.
... This diversity of Macroscelididae has been proposed as being remarkably depauperate (Rathbun 2009), especially considering the afrotherians likely have been isolated in Africa for approximately the last 130 million years (Hedges 2001). However, the fossil record indicates additional extinct sengis (about 10 extinct genera with about 20 species, Grossman & Holroyd 2009;Holroyd 2009Holroyd , 2010Holroyd & Mussell 2005;Tabuce et al. 2012). ...
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In 2003, a molecular phylogeny was published that examined the role of the Sahara Desert as a vicariant event in the evo- lution of sengis (also known as elephant-shrews.) The phylogeny included a single sample from the North African sengi, Elephantulus rozeti (Duvernoy, 1833), which was found to be more closely related to the sengi genus Petrodromus Peters, 1846 than to other Elephantulus. Here we independently test the monophyly of Elephantulus using an additional specimen of E. rozeti and similar phylogenetic analyses, and discuss additional morphological and behavioral data that support the phylogeny. We propose a revised taxonomy that reflects the current paraphyly of Elephantulus and the sister relationship of E. rozeti and Petrodromus, including a new genus name for the North African sengi, Petrosaltator rozeti gen. nov., nov. comb. We additionally define two tribes within the subfamily Macroscelidinae, the Macroscelidini (including Macros- celides, Petrodromus, and Petrosaltator), and the Elephantulini (including all other members of Elephantulus).
... Sedimentological analyses indicate deposition via small meandering stream channels (Boschetto 1988;Grossman & Holroyd 2009) at Kalodirr and Moruorot. Environmental reconstructions for the Kalodirr and Moruorot localities using the mammalian faunal assemblage suggest seasonally wet, closed-habitat woodland rather than forest (Leakey et al. 2011). ...
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Excavations at Kalodirr and Moruorot from the Lothidok Formation (ca. 17 mya) in the West Turkana Region of Kenya have yielded several cranial appendages, dentitions and postcranial fossils that can be attributed to either Climacoceratidae or the Giraffidae. An additional unusual and unique fossil, we describe in this paper for the first time, is, in our opinion, a novel stem-giraffoid cranial appen-dage. The Climacoceras from Kalodirr is the oldest representative of the genus, extending Climacoceratidae into the Early Miocene. We establish that by the end of the Early Miocene in Africa the Giraffoidea included at least two families, Climacoceratidae and Giraffidae, distinguished by different types of cranial appendages. Furthermore, the Giraffidae include at least two distinct lineages, represented by distinctive ossicones found at Kalodirr and Moruorot. Thus, we recognize that unlike at older sites where only Canthumeryx is recognized, by the later part of the early Miocene, Giraffoidea communities in East Africa include as many as three genera, and perhaps even four. This pattern of diversity in giraffoid communities persisted into the Middle Miocene and beyond.
... The depositional environment at Kalodirr is characterized by gentle fluvial systems, such as small meandering stream channels 60 (Boschetto et al., 1992). Evidence for permanent or semipermanent bodies of water comes from the presence of crocodilian, fish, and pelomedusid turtle fossils (Grossman and Holroyd, 2009). The mammalian fauna suggests that the site likely represents a woodland community characterized by both closed and Afromeryx, Hemimeryx, Libycosaurus, Merycopotamus, and Telmatodon by the presence of a paraconule on the upper molars. ...
Here we describe the first known skull and associated postcrania of the small bothriodontine anthracotheriid Sivameryx africanus, which fills an important gap in the current knowledge of morphological diversity within the Anthracotheriidae of Africa. The skull was recovered from the latest early Miocene sediments of the Kalodirr Member in the Turkana Basin of Northern Kenya, and the age is well constrained between two tephra dated to 17.5 ± 0.2 and 16.8 ± 0.2 Ma. A partial mandible of Sivameryx from Kalodirr is also described because it may belong to the same individual. The new anatomical data were incorporated into a genus-level phylogenetic analysis of Bothriodontinae that reveals that Sivameryx is the sister taxon to Hemimeryx and belongs to a clade of advanced bothriodontine anthracotheriids alongside the genera Merycopotamus, Libycosaurus, and Afromeryx. The new material of Sivameryx from Kalodirr greatly expands our knowledge of the cranial anatomy of the genus, because the skull of Sivameryx does not reveal any specializations for aquatic habitats, such as those seen in Libycosaurus. Here we suggest, based on the preserved cranial and postcranial evidence, that Sivameryx may have been a small browser that inhabited denser stands of vegetation at Kalodirr based on evidence from its narrow snout and well-developed labial musculature. However, its masticatory muscles were also relatively well developed, suggesting repetitive loading of the jaw when chewing tough vegetation.
... These reconstructions indicate that the earliest Macroscelideans such as Chambius [35,36] and Nementchatherium [37] were similar in body size to modern macroscelidine sengis such as Elephantulus or Petrodromus. Early members of the modern sengi subfamilies Rhynchocyoninae (Myorhynchocyon [38,39]) and Macroscelidinae (Miosengi [40]) are similar in size to their living relatives. Thus, there is little evidence to suggest that sengis underwent body size reduction during their evolution. ...
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The Gray-faced Sengi (Rhynchocyon udzungwensis) is a newly-discovered species of sengi (elephant-shrew) and is the largest known extant representative of the order Macroscelidea. The discovery of R. udzungwensis provides an opportunity to investigate the scaling relationship between brain size and body size within Macroscelidea, and to compare this allometry among insectivorous species of Afrotheria and other eutherian insectivores. We performed a spin-echo magnetic resonance imaging (MRI) scan on a preserved adult specimen of R. udzungwensis using a 7-Tesla high-field MR imaging system. The brain was manually segmented and its volume was compiled into a dataset containing previously-published allometric data on 56 other species of insectivore-grade mammals including representatives of Afrotheria, Soricomorpha and Erinaceomorpha. Results of log-linear regression indicate that R. udzungwensis exhibits a brain size that is consistent with the allometric trend described by other members of its order. Inter-specific comparisons indicate that macroscelideans as a group have relatively large brains when compared with similarly-sized terrestrial mammals that also share a similar diet. This high degree of encephalization within sengis remains robust whether sengis are compared with closely-related insectivorous afrotheres, or with more-distantly-related insectivorous laurasiatheres.
The lower Miocene of Rusinga Island (Lake Victoria, Kenya) is best known for its vertebrate fossil assemblage but the multiple stratigraphic intervals with well-preserved fossil leaves have received much less attention. The Hiwegi Formation has three fossil leaf-rich intervals, which span the entire formation from oldest to youngest: Kiahera Hill, R5, and R3. Here, we describe new fossil collections from Kiahera Hill and R3 and compared these floras to previous work from R5, as well as modern African floras. The oldest flora at Kiahera Hill was most similar to modern tropical rainforests or tropical seasonal forests and reconstructed as a warm and wet, closed forest. This was followed by a relatively dry and open environment at R5, which was reconstructed as a woodland to open tropical seasonal forest. The youngest flora at R3 was most similar to modern tropical seasonal forests and was reconstructed as a warm and wet spatially heterogenous forest. Floral composition of all three floras differed, but the Kiahera Hill and R3 floras were more similar to each other than either flora was to the R5 flora. The Kiahera Hill flora had few monocots or herbaceous taxa, was dominated by large leaves, and had higher species richness and greater evenness than the R3 flora. Our work, coupled with previous studies, suggests that the R3 landscape consisted of both closed forest areas and open areas with seasonal ponding. The absence of morphotypes from the R5 flora that were present in the Kiahera Hill and R3 floras provides evidence for local extirpation during the R5 time interval. Thus, this work indicates that the Hiwegi Formation on Rusinga Island samples multiple environments ranging from more closed tropical forests to more open woodlands in the Early Miocene and provides important context for the evolution and habitat preference of early apes.
Afropithecus turkanensis (17–17.5 Ma; Kalodirr, Buluk, Locherangan, Moruorot, Nabwal Hills; Kenya) and Morotopithecus bishopi (20.6 Ma; Moroto II; Uganda) are both large-bodied catarrhines from the early Miocene of eastern Africa with relatively primitive cranial and postcanine dental morphology. They are primarily differentiated by a temporal separation of ∼3.6 million years and by postcranial samples suggesting that M. bishopi was capable of orthograde postures and below-branch arboreality, while A. turkanensis was most likely a pronograde quadruped. Several researchers dispute the validity of the postcranial and dating evidence and argue that M. bishopi and A. turkanensis may be congeneric or even conspecific. Although A. turkanensis possesses a derived suite of specialized anterior dentognathic characters that are functionally convergent with extant pitheciins and associated with sclerocarp foraging and maxillary canine dietary function, a similar analysis of M. bishopi anterior dentognathic anatomy is presently lacking. The current study addresses this shortcoming via a detailed morphometric analysis of relevant A. turkanensis and M. bishopi specimens preserving the anterior palate, maxillary canines and incisors. Results indicate that the anterior dentognathic morphologies of A. turkanensis and M. bishopi are distinct and represent significantly dissimilar feeding adaptations. Specifically, M. bishopi lacks the elongated and anteriorly narrow premaxilla, lateral incisors that are more posterior and mesially positioned relative to the central incisors, and pronounced yet evenly distributed mesial curvature of the maxillary canine that are shared by A. turkanensis and extant pitheciins. Given that A. turkanensis anterior dentognathic morphology is functionally convergent with extant pitheciins to the exclusion of M. bishopi, it is likely that M. bishopi and A. turkanensis have dissimilar feeding adaptations. Although a systematic analysis is required to verify these species at the generic and species level, the absence of any substantial morphological similarity in their anterior dentognathic anatomy is most consistent with the interpretation that M. bishopi and A. turkanensis represent, at the least, different species.
Abstract Elephant-shrews or sengis (Macroscelidea, Afrotheria) are grouped into two subfamilies, Rhynchocyoninae with a single genus and four species, and Macroscelidinae represented by three genera and 13 species. Our current understanding of the evolutionary relationships within this group is largely based on a molecular phylogeny that suffers from incomplete species representation. We present the first complete phylogeny (with the exception of the recently described East African Rhynchocyon udzungwensis) for Macroscelidea based on mitochondrial and nuclear markers. Novel cytogenetic characters as well as previously described allozyme variation and various morphological features are evaluated and mapped to the molecular topology. Our analyses indicate that Elephantulus is paraphyletic, and that Petrodromus and Macroscelides should be subsumed in Elephantulus. A relaxed Bayesian dating approach supports the hypothesis that an arid-adapted Macroscelidinae lineage dispersed from east Africa at ∼11.5 MYA via an African arid corridor to south-western Africa. The timing of speciation within the east African Rhynchocyoninae (8–10 MYA) is coincidental with the diversification of some other forest specialists. In turn, divergence within the Macroscelidinae coincides with major aridification events across Africa.
Nementchatherium senarhense, gen. et sp. nov. from the Middle–Late Eocene of Bir El Ater (Algeria) is described and assigned to the subfamily Herodotiinae (Macroscelidea). This genus and the other primitive elephant-shrews are compared with the Louisininae (Hyopsodontidae, Condylarthra) from the Early Paleogene of Europe. These groups have been included in a phylogenetic analysis based on dental characters, in order to clarify the origin of Macroscelidea. Phylogenetic reconstruction suggests that Louisininae are belonging in the polyphyletic Hyopsodontidae except for Microhyus which is considered here as the sister-group the Macroscelidea. These results suggest a terrestrial interchange between Africa and Eurasia during the Early Eocene. The phylogenetic analysis suggests also that the Macroscelidea-Microhyus clade is closely related to the Proboscidea. Like molecular phylogenies, especially those concerning the African molecular clade (=Afrotheria), our results, provide evidence for a macroscelid-tethytherian relationship. However, if the Macroscelidea emerged from European “condylarth” at the Early Eocene as our data suggest, the Proboscidea are already differentiated in Africa during this period. Then, it seems that Macroscelidea and Proboscidea are paraphyletic. The assumption of a unique group of condylarthran type at the origin of Afrotheria (macroscelids, tethytherians, tubulidentates, tenrecid and chrysochlorid insectivores) cannot be excluded, but the current paleontological data do not fit with that hypothesis.
The genus Afropithecus Leakey & Leakey, 1986 contains fossil large hominoids probably of a single species, A. turkanensis, from four early Miocene sites east and west of Lake Turkana, Kenya. The type (KNM-WK 16999) is a palate, facial skeleton, and anterior part of the cranium of an adult, presumed male, individual. Apart from the type, there are many specimens of upper and lower teeth and several postcranial elements. Nearly all of these have now been described (Leakey and Leakey, 1986; Leakey et al., 1988; Leakey and Walker, 1985). There have been several discussions about the relationships of this genus and the tribe Afropithecini has been named for it together with Heliopithecus and Otavipithecus (Andrews, 1992). Not much has been written about the postcranial anatomy, but it has been favorably compared with Proconsul nyanzae (Leakey et al., 1988) and several functional analyses indicate that P. nyanzae was an arboreal, relatively slow-moving quadruped (Ward et al., 1993). It is likely that Afropithecus, like Proconsul, had a postcranial skeleton that is very close to the primitive hominoid condition.
New total-fusion K/Ar ages indicate that all of the fossiliferous formations that make up the lower part of the Early Miocene Kisingiri sequence in W Kenya at Rusinga Island, Mfwangano Island, and Karungu were deposited during an interval of <0.5Ma at approx 17.8Ma ago. This contrasts markedly with K/Ar ages previously published from these detrital-tuffaceous formations, which suggested that they were deposited over an interval of as much as 7Ma between 23-16Ma, overlapping the age-ranges of all other E African Early Miocene sites including Koru, Songhor, Napak, Bukwa, Loperot, Muruarot and Buluk. In addition, the analytical problems revealed by the new Kisingiri results cast doubt on biotite ages which provide dating for the most important sites. Thus, the strong differences between the Kisingiri fauna and those of Koru, Sonhor and Napak, long held to be due to ecology because of the apparent overlap in ages, may actually be due to a difference in time. If this view of the geochronology is correct, it may now be possible to identify adaptive trends and evolutionary succession in the E African Early Miocene faunas. -Authors
We propose a formal stratigraphic nomenclature for fossil-bearing strata exposed in the Lothidok Range of northern Kenya. About 1540 m of sedimentary and volcanic rocks are defined (in ascending order) as the Kalakol basalts (and Eragaleit beds), the Lothidok Formation (Moruorot, Kalodirr, Naserte, Lokipenata and Kalatum Members), the Loperi Basalts, and the Turkwel beds. These new units provide a stratigraphic context for fossils collected from the region since 1932, including the recently described primate taxaTurkanapithecus andAfropithecus, and also a framework for isotopic ages of the strata. Fossiliferous strata occur within the Eragaleit beds of the Kalakol basalts, the Kalodirr, Naserte and Kalatum Members of the Lothidok Fm., and the Turkwel beds of presently undifferentiated strata. On the basis of potassium-argon (K/Ar) dates on associated volcanic rocks, faunas of four ages are recognized: those from the Eragaleit beds (24–27·5 Ma; Late Oligocene), those from the Kalodirr and Naserte Members (17·8–16·8 Ma; latest Early Miocene), those from the Kalatum Member (13·8–12·2 Ma; Middle Miocene) and those from the Turkwel beds (<11·9 Ma).Turkanapithecus andAfropithecus derive from the lower part of the Lothidok Fm. (latest Early Miocene). Primate fossils have also been recovered from the Eragaleit beds (Late Oligocene), and the Kalatum Member (Middle Miocene). The assemblage of fossil higher primates from the Lothidok region appears to be distinct from those of western Kenya and Napak, and is perhaps more similar to that recovered from Buluk, northeast of Lake Turkana. Age determinations are also reported for a basalt that overlies fossiliferous strata at Loperot, situated about 90 km south of the Lothidok Range; faunas at Loperot predate 15 Ma.
It has become increasingly obvious over the past two decades that the fossiliferous strata at Fort Ternan, Kenya, are probably somewhat younger than 14 Ma, an age which has long been attached to the deposits. This realisation flows from geological and biochronological observations. In order to test the hypothesis, resampling of all the lava flows in the region of Fort Ternan was undertaken in 2003, especially those underlying the Fort Ternan Beds in the Kipchorion Gorge where the sequence is the most complete. Samples obtained from lava flows underlying and overlying the fossil beds were analysed for anorthoclase K/Ar and 40Ar/39Ar and biotite 40Ar/39Ar age determinations. The results reveal that the age of the fossiliferous sediments is ca 13.7±0.3Ma. Since Fort Ternan yielded the ‘core fauna’ that defines Faunal Set IV of the East African biochronological sequence this refinement of its age will impact on age estimates of neighbouring Faunal Sets, as well as on other faunas correlated to Fort Ternan, including those in Europe belonging to MN Zones MN 5, MN 6 and MN 7/8. To cite this article: M. Pickford et al., C. R. Geoscience 338 (2006).
A newly discovered early Miocene site in northern Kenya has yielded a partial cranium, several mandibles, isolated teeth and some associated postcranial elements of a large ape that is distinct from other known African and Asian hominoids. The new genus implies a greater complexity in the relationships between the Miocene hominoids and may offer useful evidence concerning the origin of the Asiatic and African large apes. The genus Sivapithecus has been reported from East Africa1 but the new material supports the hypothesis that this genus only occurs beyond Africa2, although having an African ancestry. The new genus presents a mosaic of characters which suggest an early radiation of Miocene hominoids.