FIRST DISCOVERY OF A TERTIARY PLATANISTOID
FOSSIL FROM ASIAZHOU KAIYA
Department of Biolog_y, Nanjing Normal CollegeZHOU MINGZHEN
Institute of Vertebrate Paleontology and Paleoanthropology

ZHAO ZHONGRU
ivfuseum of Guangxi

ABSTRACTA new genus and species of Lipotidae, Prolipotes yujiangensis collected fromthe bank of Yujiang River and considered roughly as Miocene in age, is thefirst discovery of Platanistoid fossil from Asia. The holotype is a fragment ofmandible with teeth, including posterior part of symphysial portion and initial part of free portion of mandibular rami. Comparison of the new specimen with the mandible of Lipotes and Kampholophos indicates that Prolipotes
yujiangensis is the fossil odontocetes species most closely related to Lipotes known
thus far.

The superfamily Platanistoidea is a declining group consisting four modernfamilies which are found in areas far away from each other. Lipotidae occurs inChina. Platanistidae is found in the Indian subcontinent. Another two live inSouth America: Iniidae lives in Amazon and Orinoco river basins and Pontoporiidae occurs in coastal central Atlantic waters of South America. In each family only one or two species restricted to very narrow areas are living. Our knowledge concerning the history of the Platanistoids is still scanty. Fossil studies indicate that they were widely distributed in America, Europe and Africa during
Miocene and Pliocene. No Platanistoid fossil from Asia, however, has been reported so far. A fragment of mandible belonging to Lipotidae collected from thebank ofYujiang River in Guiping County, Guangxi in 1981 and considered roughly as Miocene in age is the first discovery of Platanistoid fossil from Asia.
SYSTEMATICS

Order CETACEA Brisson, 1762
Superfami.ly PLATANISTOIDEA Simpson, 1945
Family LIPOTIDAE Zhou, Qi.an et Li., 1978
Prolipotes, new genus
Type species: Prolipotes yujiangensis
Diagnosis: See diagnosis of Prolipotes yujiangensis (generic type).
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ZHOU, ZHOU AND ZHAO

Prolipotes yujiangensis, new species(Figs 1-3, Plates I-II)
Holotype: A fragment of mandible with teeth, including posterior part of symphysial portion and initial part of free portion of mandibular rami.
Type locality: Bank of Yujiang River 500 m SE of Oucun village in Mengwei
Commune, Guiping County, Guangxi Zhuang Autonomous Region, People's Republic of China. Coordinates of the type locality are 23°l 7'20"N latitude,110°3'30"E longitude.
Age: The specimen was collected from "Yongning Group" (upper part?) ofTertiary age. At first the " Yongning Group " was considered to be as new Tertiary (Pliocene ?) in age according to the molluscs discovered. Later the geological age of this Group was revised on the basis of a large number of fossils of reptiles(crocodiles) and mammals found successively from Yongning Group beds or corresponding beds in Baise and Yangle Basins (Tiandong and Tianyang County), assigned Early Tertiary and further determined Late Eocene to Early Oligocene inage (Tang et al., 1974). Our Platanistoid fossil was found from the upper part ofthis Group and is oflater age. Its differences from the extant species are not very
big. The phylogenetic history of the superfamily indicates that they probably
arose at the end of Early Tertiary. At present, in the light of the general stratigraphic condition of the type locality and data for the geohistorical distribution of
Platanistoidea, we suggest that the new specimen is of Miocene age.
Diagnosis: Mandibular symphysis long, its posterior end very thick; deep longitudinal furrow between two tooth rows; anterior part of two rami in shape of acurve where they join symphysial portion; teeth closely spaced; crowns of teeth
slightly compressed antero-posteriorly, their upper half recurved interiorly, cingulum rounded and broad; enamel of crowns ornamented with irregular verticalstriae and ridges; tip of roots not widen to form an anterior and posterior projection.
Description: The mandibular symphysis is very long, its preserved posterior partmeasures 80 mm in length. A deep broad longitudinal furrow extending gently
to the posterior end is found between the two tooth rows of the symphysial portionof the mandible. The posterior end of mandibular symphysis is slightly thinner than
the anterior break (seven teeth from the posterior end of mandibular symphysis ),about half of the height of the lingual side of the anterior end of the free portion ofthe ramus. The preserved free portion of the two rami is very short. The anterior part of the two rami is in the shape of a curve where they join the symphysialportion. The angle between the two lines extending from the anterior end of thetwo rami is about 37.5°. Several mental foramens located below the lst, 3rd and6th-7th teeth respectively before the hind extremity of the mandibular symphysis,
are found at the labial side of the lower jaw.
Additional one is found on the left mandible below the 5th tooth situated before the posterior end of the symphysis. A faint groove runs longitudinally below
the mental foramens near the lower rim of the mandible.
Eight teeth (two broken) and two alveolus are found on the preserved right
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Fig. 1.

Sci. Rep. Whales Res. Inst.

No. 35, 1981

Prolipotes yujiangensis, holotype, occlusal view of mandible, X 1.5.

175

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ZHOU, ZHOU AND ZHAOTABLE 1.

MEASUREMENTS (MM) OF MANDIBLE, HOLOTYPE
LeftRight

Length of mandible as preserved
100.0
Length of free portion of ramus as preserved
13.7Height of labial side of anterior end of ramus
27.0
21.5 1>Height of labial side of anterior break of mandible
Thickness of mandibular symphysis at posterior end
Thickness of mandibular symphysis at anterior breakTransverse diameter of mandible at posterior end of symphysial portion
Transverse diameter of mandible at front edge of the 3rd tooth before
posterior end of symphysis
Transverse diameter of mandible at front edge of the 6th tooth before
post!"rior end of symphysis
Length of tooth row of last six teeth of symphysial portion
57.5ll•>Symphysialportion

111.6
27.7
27.0
23.8 2 >
15.0
18.3
51.0
40.0
32.0
55.6

Eight teeth from posterior end ofsymphysial portion.
Six teeth from posterior end of symphysial portion.

mandible, of which three are located on the free portion of the ramus. Only thelower half of the anteriormost part of the free portion of the left ramus has beenpreserved and all of the preserved nine teeth (four broken) of the left mandible aresituated on the symphysial portion. The alveoli are transversely elliptical in outline, about 7 mm in antero-posterior and 6 mm in labio-lingual diameter. They
are located on the mid-line of the mandible of the symphysial portion. The position of the three teeth on the anterior part of the free portion of the right ram us isslightly lateral to the lingual side.
The teeth are closely spaced. The intervals are about 3 mm between theanterior teeth and 4 mm between the hinder ones. In the posterior part of thesymphysial portion, there are as an average one tooth per 9.2 mm on the rightmandible and one per 9.6 mm on the left. The crown of the teeth is inclined
labially conspicuously and slightly compressed anterior-posteriorly. Its upper half
is recurved interiorly and places the apices of the mandibular teeth which areslightly worn in an upward direction. The lower half of the lingual side of thecrowns is a broad, rounded cingulum where the largest diameter of the crown cross.
The enamel of the whole crown is ornamented with irregular vertical striae andridges. The bases of the crowns constrict to join the roots. The exposed portion
TABLE 2.

MEASUREMENTS (MM) OF RIGHT MANDIBULAR TEETH, HOLOTYPE01>

2345

Length of labial side of root above alveolus
3.5
3.7
4.2
3.5
3.9
Length of lingual side of root above alveolus
3.1
3.3
3.6
3.6
3.2
3.5
Greatest anteroposterior diameter of exposed portion of root 6.2
6.2
6.0
6.2
6.4
6.5
Greatest labio-lingual diameter of exposed portion of root
5.8
5.9
6.1
6.0
5.9
4.6
Greatest anteroposterior diameter of crown
4.3
4.5
4.5
4.4
4.3
6.3
Greatest labio-lingual diameter of crown
6.3
6.4
6.3
6.2
6.0
7.8
Length of crown
7.8
7.7
7.5
7.4
7.21) Counting ahead from the lst tooth behind the symphysis, the Nos. are 0, 1, 2, 3, 4, 5 in proper order.
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177

AnA

8cFig. 2. Lateral view of part of teeth of right mandible, trace over radiographs, x I.
Arrow indicating posterior end of mandibular symphysis. An : anterior.
A. Prolipotes yujiangensis, holotype
B. Lipotes vexillifer, NNC (Nanjing Normal College) 7909
C. Lipotes vexillifer, NNC 7405of the roots is larger in diameter than the crowns and the anterior-posterior diameter of the former is larger than its labiolingual diameter. The radiograph of themandibular teeth shows that the base of the roots is not widen to form an anteriorand posterior projection.
Comparison: In the Yujiang specimen, the hind part of the mandibular symphysis as preserved is rather long. The intervals between the teeth are relatively
short, as an average there is one per 9.3 mm (right) or 9.6 mm (left) on the hindpart of the mandibular symphysis. The crowns are ornamented with vertical irregular striae and ridges, recurved interiorly and with a well developed cingulumon the lower half. The above mentioned characters resemble those of the Lipotesvexillifer. Rensberger (1969) has concluded that among the described fossil odontocetes only the Miocene Kampholophos serrulus is related to Lipotes vexillifer. But
the teeth of the former are widely spaced, only one per 21.3 mm on the posterior
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178

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FIRST DISCOVERY OF A TERTIARY PLATANISTOID FOSSIL FROM ASIA

179

part of the right mandible. In an old adult of Lipotes vexillifer (NNC 7405), theteeth along the posterior part of symphysial portion are closely spaced, or one per
9.3 mm (right) or 9.8 mm (left). The posteriormost teeth of Kampholophos serrulus
bear a prominent-based accessory cusp which is absent on the anterior teeth.
Their crowns are laterally compressed with vertical striae· and ridges which aremost prominent on the lower two-thirds of each crown. They are coarsest on thelabial and anterior sides (Rensberger, 1969). The structure of all the teeth of
Lipotes vexillifer is alike. The crowns are slight antero-posteriorly compressed withvertical striae and ridges which are most prominent on the upper two-thirds ofeach crown. They are coarsest on the lingual side. Since the differences of theteeth between Kampholophos and Lipotes are more than those between the Yujiang
specimen and Lipotes, it is beyond all doubt that the new specimen is the fossil
odontocetes species which is most closely related to Lipotes known thus far andshould be placed in the family Lipotidae.
Five mandibles of different ages of young and adult of Lipotes (NNC 5601,7808, 7909, 7907, 7405) were examined for comparison. The longitudinal furrow
between the tooth rows of the symphysial portion is shallow and narrow in theanterior part and descends abruptly to form a valley-like steep depression at about
last 3-4 mm of the posterior end of the mandibular symphysis. The posterior endof the mandibular symphysis is very thin, inferior to half of the thickness of thesymphysis at the 7th tooth before its posterior end (corresponds to the anterior
break of the Yujiang specimen), or less than one-third of the lingual height of thefront end of the free portion of the rami. The anterior part of the two rami is in
the shape of an acute angle where they join the symphysial portion. The verticalstriae and ridges of the crowns are relatively shallow and are fewer at anterior andposterior side. The base of the labial side of the crowns is comparatively smooth.
The tip of the roots widens to form an anterior and posterior projection. On thebasis of the above mentioned differences between the Yujiang specimen and Lipotes,
we therefore proposed to name the former as a new genus and new species.
Because of the paucity of the available material, which is confined to a fragment of lower jaw with corresponding teeth, the finding of the skulls and postcranial skeletons of this new species for the further studies of the characters of thegenus and species is expected.
We thank Wang Zhefu of the Institute of Vertebrate Paleontology and Paleoanthropology for took the photographs and Xu Xinrong of the Nanjing Normal
college for drawings.
REFERENCESBROWNELL, R. L. jR. and E. S. HERALD, 1972. Lipotes vexillifer. Mamm. species, 10: 1-4
FORDYCE, R. E., 1982. A review of Australian fossil cetacea. Mem. Nat. Mus. Viet. 43: 43-58.
GINGERICH, P. D., N. A. WELLS, D. E. RussELL and S. M. IBRAHIM SHAH, 1983. Origin of whales in epicontinental remnant seas: New evidence from the early Eocene of Pakistan. Science, 220 (4595): 403--406.
RENSBERGER, J.M., 1969. A new iniid cetacean from the Miocene of California. Univ. Calif. Puhl. Giol.
Sci., 82: 1-43.
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ZHOU, ZHOU AND ZHAOTANG Y., Y. You, Q. Xu, Z. Qru and Y. Hu, 1974. The lower Tertiary of the Baise and Yungle Basins,Kwangsi. Vertebrata PalAsiatica, 12 (4): 279-293.
ZHou, K., W. QIAN and Y. Lr, 1978. Recent advances in the study of the Baiji, Lipotes vexillifCr. J. Nanjing
Normal Coll. (nat. Sci.), (1): 8-13.
ZHou, K., W. QIAN and Y. Lr, 1979. The osteology and the systematic position of the Baiji, Lipotes vexillifCr.
Acta ,<::,ool. Sinica, 25: 58-7 4.
ZHou, K., 1982. Classification and phylogeny of the superfamily Platanistoidea, with notes on evidence ofthe monophyly of the cetacea. Sci. Rep. whales Res. Inst., 34: 93-108.

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FIRST DISCOVERY OF A TERTIARY PLATANISTOID FOSSIL FROM ASIA

EXPLANATION OF PLATESPLATE I

Prolipotes yujiangensis, holotype, X 1.
A, occlusal view; B, ventral view; C. lateral view.
PLATE II

Prolipotes yujiangensis, holotype, x 3.
lst tooth on the right mandible behind the posterior end of the mandibular symphysis, left,labial view; middle, lingual view; right, posterior view.

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181

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