Early Record Of Indricothere (Mammalia: Perissodactyla: Hyracodontidae) From The Aral Sea Region Of Western Kazakhstan

6 Pages·1996·2.1 MB·

by  S G Lucas

PROCEEDINGS OFTHE BIOLOGICAL SOCIETY OF WASHINGTON
109(2):391-396. 1996.
Early record of indricothere (Mammalia: Perissodactyla:
Hyracodontidae) from the Aral Sea region of western Kazakhstan
Spencer G. Lucas and Robert J. Emry
(SGL) New Mexico Museum of Natural History and Science, 1801 Mountain Road N.W.,
Albuquerque, New Mexico 87104, U.S.A.;
(RJE) Department ofPaleobiology, National Museum ofNatural History,
Smithsonian Institution, Washington, D.C. 20560, U.S.A.
—
Abstract. Upper molar fragments of the indricothere rhinoceros Paracer-
atherium sp. are described from the ChiliktaFormation atAltyn Chokysu, north
of the Aral Sea in western Kazakhstan. Marine bivalves indicate the Chilikta
Formation is ofearly Oligocene (Late Rupelian) age, and thus provide the first
direct cross-correlation of an occurrence of Paraceratherium with the marine
timescale. This find extends the temporal range ofParaceratherium in the Aral
Sea region back from the late Oligocene to the early Oligocene, making it
consistent with the temporal range noted for the genus in China. Paracera-
therium thus had a geologically synchronous first appearance across Eurasia
during the late early Oligocene.
The largest land mammals of all time a much older occurrence of Paracerather-
were the indricotheres, giant rhinoceroses ium in this region that clarifies the temporal
that lived during the early to middle Ceno- distribution of the genus. In this article,
AMNH
zoic in Eurasia. Indricothere evolutionbegan refers to the Department of Verte-
during the middle Eocene with the pony- brate Paleontology, American Museum of
sized genus Forstercooperia and culminated Natural History, New York; and USNM re-
during the Oligocene-early Miocene with fers to the Department of Paleobiology, Na-
Paraceratherium (=Baluchitherium, =In- tional Museum of Natural History, Smith-
dricotherium), a rhinoceros that stood more sonian Institution, Washington, D.C.
than five meters tall at the shoulder, the larg-
est land mammal of &all time (Granger & Stratigraphy and Provenance
Gregory 1936, Lucas Sobus 1989).
One of the most important collecting ar- North of the Aral Sea, four rock-strati-
eas for fossils of Paraceratherium is north graphic units of Eocene-Oligocene are ex-
of the Aral Sea in western Kazakhstan (Fig. posed (Akhmetyev & Sychevskaya 1994)
1). Here, the most nearly complete skeleton (Fig. 2). The oldest, the Chegan Formation,
known of the genus was collected (Orlov is yellowish green, bentonitic marine shale
1939, Gromova 1959) from the Kumbulak with dinocysts and molluscs of late Eocene
Cliffs east of the town of Agyspe (Akespe) (Priabonian) age. The Kutanbulak Forma-
along Perovsky Bay on the northern shore tion disconformably overlies the Chegan, is
of the Aral Sea. This and other specimens as much as 28 m thick and is composed of
ofParaceratherium from the region north of mostly yellow, orange and brown, fine-
the Aral Sea are restricted to the Aral For- grained quartzarenite. It is unconformably
mation, strata of late Oligocene (Russell & overlain by the ChiliktaFormation, as much
& m
Zhai 1987) or early Miocene (Akhmetyev as 23 of shale and thinly interbedded
Sychevskaya 1994) age. Here we document shale-sandstone. The Chilikta Formation
.
392 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASfflNGTON
Miles 100 200 300
Kilomatefs 100 200 300 400 500
Russia
Novosibirsk
r''
yl
-/T'etropavlovsk'.
\
H^
Semipaiatinsk
Aktyubinsk
Lake^S^
Kazakhstan Zaysan
Ayaguz p
-^^Altyn-Chokysu mj
Aral
Sea LBaalkkehash ^^'
Kzyl-Orda
Alma-Ata • <
. / /C"*->^ Uzbekistan ^ •^ ^
Kyrgyzstan
-^ '. Tashkenty.'^
Turkmenistan \ China
\ .-Tc'-XC^-^
\ Tajikistan ^.
^
/,.
Iran C--^ ixj^;^-
I Afganistan ^' Pakistan
Fig. L Map ofKazakhstan showing location ofAltyn Chokysu north ofthe Aral Sea.
produces marine bivalves (especially Er- green, calcareous shale and claystone char-
genica cymlanica) that correlate it to the acterized in its lower part by numerous
Solenovo horizon of the Crimea-Caucasus lenses of the euryhaline bivalve Corbula.
of late Early Oligocene (late Rupelian) age All fossil mammal localities reported by
(Akhmetyev & Sychevskaya 1994). previous workers (Russell & Zhai 1987,
The Chagray Formation disconformably Bendukidze 1993, Akhmetyev & Sychev-
overlies the Chilikta Formation and is as skaya 1994) from north of the Aral Sea are
much as 33 m thick and mostly yellowish in the Aral Formation. We follow Russell
gray and brown, micaceous sandstone. The & Zhai (1987) in regarding these mammals
Aral Formation conformably overlies the as late Oligocene in age, but Soviet scien-
m
Chagray. It is at least 24 thick north of tists regard them as early Miocene in age
&
the Aral Sea (its top is everywhere eroded) (Akhmetyev Sychevskaya 1994).
and consists mostly of grayish yellow The new locality at which we collected
VOLUME 109, NUMBER 2 393
ARAL FORMATION
LU
LZU I<- previous records of Paraceratherium
LoU CHAGRAY FORMATION
o
— — — — — —
disconformity—
_J
o >
Paraceratherium reported here
_J
D<C CHILIKTA FORMATION
LU
KUTANBULAK FORMATION
— — — — — —
-- disconformity—
LATE
EOCENE CHEGAN FORMATION
Fig. 2. SummaryofEocene-OligocenestratigraphicunitsinAltynChokysuareashowingstratigraphiclevels
ofParaceratherium occurrences (lithology schematic).
Paraceratherium tooth fragments is in the Paraceratherium sp.
Ckilikta Formation on the escarpment of Fig. 3
Altyn Chokysu, a plateau about 20 km —USNM
Referredspecimen. 482243, ap-
northwest of the town of Saksaulskaya and
proximately 50 fragments of cheek teeth,
about 70 km northeast of the Kumbulak
UTM three of which, illustrated here, are parts of
Cliffs (Figs. 1-2). This locality is at ectolophs of rig—ht M', M^, and M^.
357737IE, 5238795N, zone 41, stratigraph- Description. The three largest tooth
ically well below Bendukidze's (1993)
"Shokysu" mammal locality in the Aral farreagpmoernttiso,nshoefreuprpeefrermroedlatroeacstol1,op2h,s.aFnrdag3-,
Formation. The fossiliferous horizon is a ment 1 is right M^ ectoloph from paracone
1.2-m-thick, white, fine-grained sandstone,
m through parastyle, and part of protoloph.
10.8 above the basemof the Chilikta For- Paracone forming thick rib on labial face of
mation, which is 14.4 thick at this loca- ectoloph and separated from parastyle by
tion. The Paraceratherium tooth fragments distinct cleft. Parastyle a more prominent
were associated with a sirenian rib, fish and anteriorly-projecting rib. Ectoloph
bones and teeth ofthe sand tiger shark Car- making sharp, nearly right-angled fold and
charias sp. becoming confluent with protoloph. Mini-
mum crown height at paracone 59 mm.
Systematic Paleontology Fragment 2 from anterior part of ecto-
loph of right M-. Preserves paracone as a
Order Perissodactyla Owen 1848 less prominent rib than on M^ ectoloph.
Family Hyracodontidae Cope 1879 Cleft between paracone and parastyle less
Subfamily Indricotheriinae Borisyak 1923 pronounced than on M^. Paracone crown
Genus Paraceratherium Forster Copper height about 66 mm.
1911 Fragment 3 part of posterior portion of
394 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASmNGTON
Fig. 3. Tooth fragments of Paraceratherium sp. from Altyn Chokysu compared to cast of holotype of
Paraceratherium asiaticwn. A-C, USNM 482243, Paraceratherium sp. from Altyn Chokysu: A, occlusal view
of fragment of right M^ ectoloph (fragment 1 in text); B-C, occlusal view of right M^ ectoloph (fragments 3
and 2, respectively, in text). D-E, AMNH 26972, cast of holotype of Paraceratherium asiaticum, left M'-^
(photographs reversed): D, occlusal; E, labial views. F-H, USNM 482243: F, anterior view offragmentofright
M- ectoloph (fragment 1 in text); G-H, labial views of fragments of right M^ ectoloph (fragments 3 and 2,
respectively, in text).
right M- ectoloph, probably from same inent basal cingulum on posterior edge of
tooth as fragment 2, but two pieces do not crown. Fragment 2 and 3 suggest total ec-
fit together. Blade-like metacone projecting toloph length of m—ore than 90 mm.
from rest of ectoloph occlusal edge. Prom- Identification. We compared these
———
VOLUME 109, NUMBER 2 395
tooth fragments to casts of upper dentitions Lucas (1994), who assigned it a late Oli-
of Paraceratherium asiaticum from the gocene-early Miocene age. The genus has
Turgay region of central Kazakhstan (Fig. a range ofnearly 10 million years, spanning
&
3: Granger Gregory 1936, figs. 2C-D). the late Rupelian (about 30-32 Ma) to early
AMNH
These casts are 26971, left P^-M^, Miocene (about 20-22 Ma).
AMNH
and 26972, right P^-M^ (cast ofho-
lotype ofP. asiaticum). They are very sim- Acknowledgments
ilar in size and morphology to the frag-
ments we collected atAltyn Chokysu. Frag- The National Geographic Society (Grant
ment 1 has a minimum crown height of 59 5412-95) and the Charles D. Walcott Fund
mm, about the same as that of AMNH of the Smithsonian Institution supported
26971, which is nearly 61 mm. Fragment 2 this research. M. A. Akhmetyev and E.
has a paracone crown height of about 66 Kordikova provided valuable advice and
mm, the same as on AMNH 26971. All oth- assistance in the field. R. Tedford allowed
er rhinocerotoid genera are much smaller, study of collections in his care. Two anon-
so we assign USNM 482243 to Parace- ymous reviewers provided helpful com-
ratherium sp. ments on the manuscript.
Discussion Literature Cited
Prior to this report, Paraceratherium oc- Akhmetyev, M. A., & E. K. Sychevskaya. 1994. Oli-
currences north of the Aral Sea were re- gocene-Mioceneboundary in Kazakhstan:Field
excursion guidebook. Paleontological Institute
stricted to the aral Formation and regarded ofthe Russian Academy ofSciences, Moscow,
as either later Oligocene or early Miocene 80 pp.
in age. However, Paraceratherium occur- Bendukidze, O. G. 1993. Small mammals from the
rences as old as late Early Oligocene Miocene of southwestern Kazakhstan and Tur-
("middle" Oligocene of some authors) are gay [in Russian]. Akademiya Nauk Gruzii In-
stitut Paleobiologii, Tbilisi, 144 pp.
well documented in Nei Monggol, China, Borisyak, A. A. 1923. On the genus Indricotherium
and the genus occurs in strata as young as n. g. (Family Rhinocerotidae) [in Russian].
late Ohgocene (Russell & Zhai 1987). Zapiski Rossiskaya Akademiya Nauk 35(6):1-
Specimens reported here establish a tem- 128.
Cope, E. D. 1879. On the extinct species of Rhino-
poral range of Paraceratherium in western
cerotidae of North America and their allies.
Kazakhstan coeval to that in China. They BulletinoftheUnitedStatesGeological&Geo-
thus eliminate the possibility that Parace- graphical Survey of the Territories 5(2):227-
ratherium first arose in China and only 237.
reached central and western Asia (Kazakh- Forster Cooper, C. 1911. Paraceratherium bugtiense,
stan) much later. aHilnleswofgeBnaulsuchoifsRthainn—ocperreoltiimdianearfyrnoomtitchee.—BuAgnt-i
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to the marine timescale. As stated above, on the gigantic extinct rhinoceros, Baluchi-
therium, from the Oligocene of Mongolia.
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1984). Paraceratherium thus emerges as a ceratherium biochron. Pp. 12—13 in P. A. Tleu-
much longer-lived genus than indicated by berdina & M. A. Akhmetyev, eds., Oligocene
396 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
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