P"t"cobo/(/lIisl 48 (1999) . 49-95 0031-0174/99/49-95 $200

Further contribution to the Siwalik flora froUl the Koilabas area, western

2 2 MAHESH PRASAD!, 1.S. ANTAL"!,I ,pp TRIPATHI AND VINAY KUMAR PANDEy

JBirbal Salllli Inslirute of Paloeobo!any. 53 University Rood, LllcknOIV 226 007. Indio. JBotany Department. M.L.K. Post Crodllate College. Bairamplll; Uf!or Pradesh. Indio.

(Received I February 1999: revised version accepted 10 June 1999)

ABSTRACT

Prasad M, Antal JS, Tripathi PP & Pandey VK 1999. Further contribution to the Siwalik tlora from the Koilabas area. western Nepal. Palaeobotanist 48( I) : 49-95

The present study on fossil plants comprising well preserved leaf and fruit impressions from the Siwalik sediments exposed near KoilJbas in western Nepal is the first detailed and systematic work. The tloral assemblage recovered from these sediments is impoverished both in quality and quantity as consti­ tuted by 25 species belonging [022 genera and 15dicotyledonous families of angiosperms. This assemblage adds significant data to the Siwalik Palaeobotany. On the basis of present assemblage as well as already known data from the area. the palaeoclimate. palaeoecology and phytogeography of the area during Mio­ Pliocene in the Himalayan foot hills have been deduced. The significance of the physiognomic characters of the fossil leaves in relation to climate has also been discussed.

Key-words-Leaf & fruit impressions. Angiosperm, Morphotaxonomy. Siwalik (Churia) Formation. PalJeoclimate. Phytogeography, Koilabas. Nepal. mu~ ~ qftql:fi ~~ ~ Cfil11(T\ICSlI*1~ em~IClIRtCfiCl:;H~Ri\1fld-q

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INTRODUCTION fact, Nepal is a middle strip of Him~layaconsisting or high hills and pl~inareas which can physic,lIly be divided into 1'01­ HE Kingdom of Nepal is a 1,lnd-locked country lowing six zones namely. Terai plain. Midlands. Churia Hills. Tphysiogmphically sandwitched between in the north Higher Hi malayan zone, Mahabhar,ll Hill and Inner Himalayan and in the south. Nearly two-third of the country, in the Valley. northern parr. is hilly and one third is Terai plain in south which constitute the northern edge orIndo-Gangetic plain. In The fossiliferous locality, Koilabas (27"42' : 82"20') lies

(!) [Jil'bal Salmi l"slillllC of P,dacobolany. India so THE PALAEOBOTANIST

83° '<3'to 0,° 30' 82° GENERAL GEOLOGY 2'f'-- Sec'. N 2'f The Siwaliks represent clastic sediments of fresh water o,~ 25 SO km·l molasse which accumulated in a long narrow foredeep formed to the south of the rising Himalaya in the third episode of r I 1'1 V ,,... - ===i Himalayan uplift during Middle Miocene. These sediments accumulated under four different environments like, lacustrine, channel and flood plains, outwash plain and piedmont. The Siwalik Formation ranges in age from Middle Miocene to Middle Pleistocene and is underlain by the Lower Tertiary-Upper Muree/Dharmsala sediments. On the basis of lithology and palaeontological data it has been subdivided into Lower, Middle and Upper Siwaliks. Lithologically, the Siwaliks represent a great thickness of detrital rocks, such as coarsely bedded sandstones, clays and conglomerates meas­ uring between 5000-5500 m in thickness. The area of present study falls in Dang section of west­ ern Nepal Himalaya. In Nepal Himalaya the Siwalik Forma­ tion is often called Churia Group which lies south of the Main Boundary Thrust (Text-figure 2). This group pinches in Narayangarh and swollens in Nawalpur due to development of valley and again it is thin in Butwal and thickens maximum to Dang area where two valleys-Dang and Rapti valleys de­ veloped. The detailed lithology and stratigraphy of the Siwalik 83 84° (Churia) Group of Nepal have been given by Auden (1935), LEGEND Lehner (1943), Hagen (1959), Bordet (1961), Gleinnie and ====Mqtollqd Qood Ziegler (1964), Ohta and Akiba (1973), Sharma (1977,1980), -- 5trqam _._. tnt

80° 82° 84° 86° 88° ( -.-."\\ I 30° \"..J~_., ...... 30°1--;\ / T I B ET f.t '" / ...... '. 1ft '~."",,"\,.."\. Brahmaputra -

28°

26° 26°~~Q".9.

::.: OUTCROPPI~f'.,. :.::.; SIWALIK ';; FORMATIO o SO 100 1.«" I ,

80° 86° 88°

Text figure 2-Showing Siwalik Formation in and around Koilabas area. (After Glennie & Ziegler, 1964).

is composed of rounded boulders consisting mainly ofquartz­ been identified belonging to several dicotyledonous families. ite cemented with clay. With a view to generate more palaeobotanical data for pre­ cise reconstruction of Siwalik floristics and interpreting the The fossil locality Koilabas is situated in the Dang sec­ palaeoenvironment and phytogeography of the area, further tion of the Churia Hills in western Nepal. In this area, the investigation of leaf and a fruit impressions collected from Lower Churia Formation is observed from Koilabas to Darwaja Koilabas, western Nepal have been undertaken. The containing fine grained sandstone beds with variegated clay morphotaxonomic study reveals the presence of some more and some pebbles. From Darwaja to Masot Khola the rocks new taxa which have been discussed and described in the represent the Upper Churia Formation. In Garudbir pass the present communication. Lower Formation is found thrusted above the Upper Forma­ tion (Sharma, 1977). According to Chaudhuri 's three fold di­ vision of Churia (Siwalik) Hills, this area from Koilabas to MATERIAL AND METHOD Darwaja falls in Lower Churia (Siwalik) Formation and be­ The fossil locality Koilabas lies at Indo-Nepal border in yond Darwaja to Chor Khola onward the rocks are supposed western Nepal (Text-figure 1). The sections belonging to the to be belonging to Middle Churia (Siwalik) Formation which Lower Siwalik beds containing excellently preserved leaf-im­ is predominantly arenaceous in nature. pressions are well exposed on both the sides of Koilabas Nata Systematic study on plant megafossils especially leaf (also known Dang Nata). The leaf-impressions are found both impressions from Koilabas area has been carried out by on grey as well as brown calcareous shales but are more com­ Tripathi & Tiwari (1983), Prasad & Prakash (1984), Prasad mon and well preserved in the grey shale. A rich collection of (1990a, b, 1994e). A number of taxa (about 55 taxa) have well preserved leaf-impressions was made from Dang Nata 52 THE PALAEOBOTANIST before Darwaja. More than 50 specimens of leaf-impressions secondaries, angle of di vergence about (40°) narrow acute, were collected and have been described in the present com­ altemate, seemingly unbranched: tertiary veins (30) fine, fairly munication. preserved, angle of origin AO-RR, percurrent. seemingly unbranched, oblique to right angle in relation to midvein, pre­ The leaf-impressions are devoid of cuticles. They were dominantly alternate, close to distant. Further details could studied morphologically with the help of either hand lens or not be seen. low power microscope under reflected light. In order to iden­ tify the leaf-impressions, a number of herbarium sheets of Holotvpe-Specimen 110. K 20. extant taxa were examined at the herbaria of National Botani­ Locality-Koilabas Nola section near Koilabas Village, cal Research Institute, Lucknow, Forest Research Institute, Koilabas, western Nepal. Dehradun and Central National Herbarium, Sibpur, Howrah, Horiz.on & Age-Lower Siwalik, Middle Miocene. West Bengal. The leaf-impressions have been described fol­ lowing the terminology given by Hickey (1973) and Dilcher Etymology-From the Siwalik Formation. (1974). Affinilies- The most characteristic features of the present The photographs of leaf-impressions showing various fossil leaf such as symmetrical elliptic shape, entire margin, morphological characters were taken on cut-film on Pan-phot eucamptodromous, venation, the nature of secondary veins which arise narrow acutely and run upward to a greater length Camera. In almost all the cases the leaf-impressions have been and percun·ent. somewhat distantly placed tertiary veins indi­ found closely resembling the modern leaves. The photographs cate that the present fossil leaf shows close resemblance with ofthe comparable modem leaves showing similar features were the modern leaves of the genus Miliusa Leschen. ex A.Dc. of also taken at the same IKlgnification and have been pasted the family Anonaceae. In order to find out the specific affin­ along with those of the fossi I leaves in plates to show close ity, the herbarium sheets of all the available species of this similarity. All the figured specimens have been deposited at genus were critically examined and concluded that the leaves the Post-Graduate Department of Botany, M.L.K. College, of Miliusa thoretii Finet & Gagnep. (C.N. Herbarium sheet Balrampur, Uttar Pradesh. no. 14317) show closest affinity with the fossil leaf in shape, size and venation pattern (PI. I, fig. 2; PI. 2, fig. 2). SYSTEMATICS Fossil records and comporison-So far, there is no record DICOTYLEDONS of any fossil leaf resembling the genus Miliusa from the Ter­ Family-ANONACEAE tiary sediments of India and Nepal. The present fossil leaf forms its first record from the Siwalik sediments of Koilabas, Genus-MILIUSA Leschen. Ex A.Dc. Nepal and is being described herewith as Milillsa SilVOlica sp. MILIUSA SIWALICA sp. nov. nov., the specific epithet indicates its occurrence in the Siwalik (PI. J, fig. I; PI. 2, fig. I) sediments. Material-The present species is based on a well pre­ The genus Milillsa Leschen ex A.Dc. consists of about served incomplete specimen with its counter part which is 40 species distributed mostly in Indo-Malayan region and devoid of cuticle. . Out of which, 7 species are Indian. Miliflsa thoretii Finet & Gagnep with which fossil shows close resemblance Description-Leaf simple, symmetrical. elliptic. pre­ grows in India mainly in Sikkim, Khasi Hills, Travancore, served size 9.5 x 4.5 cm; apex broken; base indistinct: margin Mysore, Kanara and Konkan (Willis, 1973: Gamble, 1972). entire; texture coriaceous: petiole not preserved: venation pin­ nate, eucamptodromous: pri mary vein (Ill) single, prominent. Genus-ANONA Linn. stout, slightly curved, thicker at the basal region; secondary ANONA KOILABASENSIS sp. nov. veins (2°) 3 pairs visible, 0.8 to 3.5 cm apan, curved up and run upward to a greater length and joined to their superadjacent (PI. J, figs 3-5)

PLATE 1 IAII l'igllIC' arc of n"llIl,,1 siZe lInkss olhcrwisc menlioncd)

I. /v/i/il/so S/l\'({!iC({ sr. nov. - Fossil Icar sllowillg Sh~lpC.silL and Vella­ in shapc. si/c "nd n"llIre of bJse.

lion fX!IIUll. S. AI/OIIU /.:oilo!>osc!I.\i.'i<;p.110V. - A ran or ro~:-:.iI k~lr!ll~Ig.lliI'icu [0 <.;IHl\\

2. MililiSo ,/wr"'ii Finel & Gagnep - M()(km k"I',howillg ,illliLII. 5h"pe. delails of ven'ilion . .x 1.75.

size and v~llaliollpallcrn. 6,7. Seclfriclnco mio('e/lic(I Prasad ef 01. - Fossil ICHVC:-' showing ')I1<.1pc.

J. AIIOIIO Koi/o/HIIt'//.li.1 'po nov. - Fossil leaf showing shape. ,i/.c' and size and Il~llllrL'of basL'. apex and \'CIll.llioll pJlt~l'll.

v~l1aLionpaltcm. X. Secllrido('{/ ilio/J/Jelidicli/{/fi/ Has,. - Modem leal' sho\\ ing SlIllII"1 ~ AlJoJJa /.:.oi!o/;o.\('I1.\is \p. no\'. - Another lossil k~Jfshowing variation sh"pc. sib:' and n'lllllT of base ,,"d apex "uLl \·...n"l;on pallun. « w a: « 0.n « ~ « o...J ~ w :r: I- 2: o c:<: u. « c:<: o ...J U. ~ :J ~ Vl W ~ o I­ oZ f= :::J c:l c:<: '- Z o U a: w :r: ~ :::J u. I 54 THE PALAEOBOTANIST

Material-It consists of 5 specimens of different sizes. to sinuous. They are well preserved and devoid of cuticles. Fossil record and comparison-As far as the author is Description-Leaves simple, symmetrical, narrow ellip­ aware there is no record of fossil leaves of the genus Anona tic, preserved size 5.0 x 2.2 cm and 10.5 x 4.0 cm; apex slightly Linn. from Tertiary sediments ofindia, and abroad. The present broken; base obtuse, normal; margin entire; texture leaf-impressions from Siwalik sediments of Koilabas form the chartaceous; petiole indistinct; venation pinnate, first fossil record and hence is being described as a new spe­ eucamptodromous; primary vein (1°) single, prominent, stout, cies, Anona koilabasensis. curved in apical portion, uniform in thickness; secondary veins The genus Anona Linn. consists of about 120 species (2°) about 14 pairs visible, 0.8 to 2.0 cm apart, curved up and distributed in tropical regions. Only four introduced fruit spe­ joined to their superadjacent secondaries, angle of divergence cies are found to grow in India (Willis, 1973). The modern mainly right angle to acute (85° to 55°) usually alternate some­ comparable taxon Anona laurifolia Linn. is a medium sized times opposite, rarely branched; intersecondary veins present, evergreen tree distributed in south east Asian regions, espe­ simple, abundant; tertiary veins (3°) fine, abundant, angle of cially in Java (Backer & Brink, 1963). origin usually RR, percurrent, straight to sinuous, sometimes, branched, oblique in relation to midvein predominantly, alter­ Genus-FISSISTIGMA Griff. nate, close to nearly distant. FISSISTIGMA MIOELEGANS sp. nov. Holotype-Specimen no. K 25. (PI. 6, figs 3, 4, 6) Locality-Koilabas Nala section near Koilabas Village, Koilabas, western Nepal. Material-This species is based on two leaf-impressions which are almost complete and devoid of cuticles. Horizon & Age-Lower Siwalik, Middle Miocene. Description-Leaves simple, almost symmetrical, nar­ Etymology-From the type locality of Koilabas. row elliptic; preserved size 7.5 x 2.2 cm and 7.0 x 2.0 cm; Paratype-Specimen nos. K 22, 23, 26, 27. apex acute; base obtuse; margin entire; texture thick chartaceous; venation pinnate, eucamptodromous; primary Affinities-The diagnostic features of the present fossil vein (1°) single, prominent, stout, almost straight; secondary leaves are symmetrical narrow elliptic shape, obtuse base, veins (2°) about 12 pairs visible, 0.4 to 0.9 cm apart, alternate entire margin, eucamptodromous venation, abundant simple to sub-opposite, angle of divergence about 60°, acute, moder­ intersecondary veins, right angle to acute angle ofdivergence ate, uniformly curved up; seemingly unbranched, of secondary veins, percurrent sometimes sinuous and close intersecondary veins present, simple, rare; tertiary veins (3°) to nearly distant tertiary veins. These features collectively in­ fine, poorly preserved, angle of origin usually RR, percurrent dicate that the fossil leaves belong to the family Anonaceae. straight to sinuous, branched, oblique in relation to mid vein. Critical examination of the herbarium sheets of a number of predominantly alternate and close. genera of this family it was found that the leaves of the genus Anona Linn. show nearest affinity with the fossil leaves. Al­ Holotype-Specimen no. K 16. though the modem leaves of a few species of Mitrephora (BI.) Paratype-Specimen no. K 4. Hook.f. & Th. and Polyalthia BI. also show resemblance in having intersecondaries as well as in nature ofsecondary veins, Locality-Koilabas Nala section near Koilabas Village. but they differ in the course of tertiary veins. Koilabas, western Nepal. A comparative study of all the available species of the Horizon & Age-Lower Siwalik, Middle Miocene. genus Anona Linn. was done and concluded that the leaves of Etymology-From extant species Fissistigma elegans Anona laurifolia Linn. (CN. Herbarium sheet nos. 11668 and plus prefix 'Mio'. 11667) show closest affinity with the fossil leaves in shape, size and venation pattern. In both modem and fossil leaves Affinities-The most important characters exhibited by the intersecondaries are frequent and the tertiaries are straight the present fossil leaves such as narrow elliptic shape, acute

PLATE 2 (All figures are of nalUral size unless otherwise mentioned)

I. Miliusa siwalica sp. nov. - A pan of fossil leaf magnified to show and nature of base, apex and details of venation. details of venation. x 2. 5. Gvnocardia odorata R. Br. - Modern leaf showing similar shape. size, 2. Miliusa Ihorelii Finet & Gagnep -A pan of modern leaf magnified to and venation pattern. show similar details of venation. x 2. 6. Garcillia Ilepalellsis sp. nov. - Fossil leaf showing. shape. size. apex 3.4. GYllocardia mioodorata sp. nov. - Fossil leaves showing shape. size and its venation pattern. PRASAD er at.-FURTHER CONTRIBUTION TO THE SIWALIK FLORA FROM THE KOILABAS AREA, WESTERN NEPAL 55

PLATE 2 56 THE PALAE0130TANIST apex, obtuse base, entire margin, eucamptodromous venation, liptic; preserved size 6.5 x 3.2 cm and 7.5 x 3.1 cm: apex moderate acute angle of divergence of secondary veins, pres­ acute to seemingly acuminate: base obtuse, slightly ence of intersecondary veins, and percurrent, straight to sinu­ inequilateral; margin entire; texture Ihick charIaceous: peti­ ous tertiary veins indicate its resemblance with the modern ole broken; venation pinnate, eucamptodromous; primary vein leaves of the genus Fissisligma Griff. of the family Anonaceae. (1°) single, prominent, stout, slightly curved; secondary veins After a detailed comparison of the present fossil leaves with (2°) 9-10 pairs, 0.6 to 1.2 cm apart, uniformly curved up, an­ all the available species of this genus it is concluded that the gie of divergence 50°-60°, moderately acute, sometimes fossils come closer to Fissisligma kOrlhallaii Mig., F branched, alternate to opposite; intersecondary veins present. ma/1.ubreallll1l Hook.f. and F elegam Hook.f. Th. Further, a frequent, simple; tertiary veins (3u) very fine, angle of origin critical examination of the herbarium sheets of these species usually AO, percurrent, almost straight, sometimes branched suggests that the leaves of F elegans Hook.f. Th. show clos­ oblique in relation to midvein, predominantly alternate and est affinity with the fossils (CN. Herbarium sheet no. 13815; close. PI. 6, figs 5, 7). The leaves of other two species can be Holotype-Specimen no. K 32. differentiated in having more number of secondary veins; Moreover their course and arrangement also differ from Paralype-Specimen no. K 39. fossils. Localily--Koilabas Nala near Darwaja, Koilabas, Fossil record and comparison-So far, three fossil western Nepal. leaves resembling the genus Fissisligllla Griff. have been Horizon & Age-Lower Siwalik, Middle Miocene. described from the Siwalik sediments of India and Nepal. Lakhanpal (1969) described a fossil leaf as Fissisligma senii Affinilies- The elliptic shape, acute to acuminate apex, from the Siwalik sediments of Jawalamukhi, Himachal obtuse base, entire margin, moderate acute angle ofdivergence Pradesh. Same species has also been reponed by Prasad el ofsecondary veins, presence of frequent interseconclary veins al. (1997) from the Siwalik sediments of Seria Naka at Indo­ and percurrent tertiaries are the diagnostic features of the Nepal Border in Gonda District of Uttar Pradesh. Both these present fossi I leaves. Besides, the present fossi Ileaves are also leaf-impressions have hccn compared with the extant characterised by slightly unequal base as well as lamina on Fissisligllla wallichii (Hook.f. & Th.) Merill and have been eilher side of midrib. These features collectively indicate that found different from the present fossil leaves in the nature the present fossil leaves shows closest resemblance with the of secondary veins which arise more acutely and run upward modern leaves of Secllridaca inappendiclilalO Hask. (CN. to a little distance. In 1992, Lakhanpal and Awasthi reported Herbarium sheet no. 36383; PI. I, fig. 8) of the family a fossil leaf under Fissisligma siwalika from, the Siwalik Polygalaceae. sediments of Jawalamukhi, Himachal Pradesh, India. This Fossil record and comparison-Three fossi I leaves re­ fossil is large in size (14.5 x 5.3) having oblanceolate shape sembling the extant taxa Secllridaca inappendiclllaia have and rounded apex. So it is also different from the present been described so far under Secllridaca miocenica from the fossils. As the present fossils are entirely different from al­ Siwalik sediments of Seria Naka at Indo-Nepal Border in ready known species. they have been described as a new Gonda District of Uttar Pradesh (Prasad el al., 1997). The species, Fissisligma mioelegans. present fossil leaves also come closest with the above known The genus Fissisligma Griff. contains about 60 species fossil leaves and hence they are described under the same spe­ distributed in tropical Africa, China, northeast Australia and cies Secllridaca miocenica Prasad el al. in Indo-Malayan region (Willis, 1973). F elegans Hook.f. & Th. with which the fossils show closest resemblance is a large The genus Securidaca Linn. comprises 80 species dis­ climber widely distributed in Malaya peninsula, Malucca and tributed all over tropics exclusively Australia. Only one spe­ Penang (Ridley, 1967). cies is found in India (Willis, 1973). The modern compara­ ble taxon Secllridaca inappendiculata Hask. is a large woody Family-POLYGALACEAE climber growing in the moist deciduous forests of eastern Bengal, Aracan, and Tenasserim. It is also found in the Genus-SECURIDACA Linn. Kochin Hills near Myitkyina and Java (Gamble, 1972: SECURIDACA MIOCENICA Prasad el al. 1997 Hooker, 1872).

(PI. I, figs 6, 7) Family-FLACOURTIACEAE

Malerial- This species is based on two specimens. The Genus-GYNOCARDIA R. Br. specimens are somewhat poorly preserved but almost com­ plete and devoid of cuticles. GYNOCARDIA MIOODORATA sp. nov. Descriplion-Leaves simple, slightly asymmetrical, el- (PI. 2, figs 3, 4) PRASAD ef rd.-FURTHER CONTRIBUT10N TO THE SIWALIK FLORA FROM THE KOILi\I3AS AREA. WESTERN NEPAL 57

PLATE 3 (All figures arc of natural size unless otherwise mentioned)

1.1. Carcl/I/II IIcpa/CIIS/.I sp. nov - Fossil leaves Showll1g. shape. size and s. /SO/Hcm slImliUt sp. nov. - Fossil leaf ,howlng shape. "ze. nature of venation pallern. base and ilS venatiol1 pallern 3 Cllrcill;a COIVII Linn. - Modern leaf showing slIllilm. shape. size and 6 /slIp/cra 001"l/C01l51.1 sp. nov. - Modern ICJf shOWing simlbr. shape.

vcn~tlonpallcrn size and vCI1~lJonp~lIcrn.

~ CarClIl/llllc/}{//ClIS/; sp 1101'. - A pan 01' fossil leaf magnilied 10 show 7 /sop/el'll j"{\lIJ!/UI sp. nov. -A pan of fnssil leaf magnified 10 show dewils or venal ion. x 3. detail> of venal Ion paltem. x 1. 58 THE PALAEOBOTANIST

Material-The present species is based on two well pre­ resemblance. It is moderate sized evergreen tree distributed served leaf-impressions. Of them, one is al most complete and in northern and eastern Bengal and Assam; Chittagong and the other is broken at apex. The leaf-impressions are devoid . Its wood is used in Chittagong for planking and of cuticles. posts and the pulp of the fruit in Sikkim to poison the fishes (Gamble, 1972). Description-Leaves simple, symmetrical, elliptic, pre­ served size 9.0 x 4.0 cm and 9.0 x 5.0 cm; apex slightly bro­ Family-CLUSIACEAE ken. seemingly acute; base acute; margin entire; texture chartaceous; petiole not preserved; venation pinnate, Genus-GARCINIA Linn. eucamprodromous to nearly brochidodromous; primary vein GARCINIA NEPALENSIS sp. nov. (1°) single, prominent, stout, al most straight; secondary veins (2°) 6 pairs visible, 0.7 to 3 cm apart. uniformly curved up (PI. 3, figs 1,2,4; PI. 2, fig. 6) and joined to lheir superadjacent secondary, sometimes form­ Material-The present species consists of two specimens ing loop in the apical portion. angle of divergence about 60°, which are almost complete with some cuticular remains. moderate acute, alternate to sub-opposite, seemingly unbranched; tertiary veins (30) still fine. angle of origin RR, Description-Leaves simple, almost symmetrical, nar­ percurrent, the tertiaries arise from midrib looking like a row elliptic, preserved size 7.7 x 2.1 cm and 7.8 x 2.5 cm; intersecondary veins but they join the secondary veins mising apex slightly broken, seemingly acute; base acute: margin below them; sometimes branched, oblique to right angle in entire: texture coriaceous; petiole preserved, small, 0.3 cm relation to midvein, predominantly alternate and close to dis­ visible, normal; venation pinnate, eucamptodromous; primary tant. Further details could not be seen. vein (1°) single, prominent, stout, almost straight; secondary veins (2°) more than 20 pairs visible, closely placed, less than Holotype-Specimen no. K 40. 0.5 cm apart, angle of divergence about 55°, acute, moderate, Parorype-Specimen no. K 55. almost uniformly curved up, alternate to opposite. sometimes branched, intersecondary veins present, simple, frequent. 2-3 Locality-Koilabas Nala section near Koilabas Village, intersecondaries in between two secondary veins; teniary veins Koilabas, western Nepal. (30) fine abundant, poorly preserved, angle of origin AO, HoriZOIl & Age-Lower Siwalik, Middle Miocene. percun'ent, almost straight, branched. oblique in relation to midvein, alternate to opposite and close. Further details could Etymology-From the extant species G. odorata plus not be seen. prefix 'Mio' for its Miocene age. Holorype-Specimen no. K 3 I. A/finities- The present fossi I leaves are characterised by symmetrical, elliptic shape, acute apex and base, entire mar­ Paratype-Specimen no. K 62. gin. eucamptodromous to brochidodromous venation, mod­ Localiry-Koilabas Nola section near Darwaja, Koilabas, erate acute angle of divergence of secondary veins, RR, close western Nepal. to distant having oblique to right angle in relation to midvein, perCLln'enttertiaries. The nature of tertiary veins arising from Horizon & Age-Lower Siwalik, Middle Miocene. midrib giving an appearance of intersecondary veins is also Etymology-From country name to which fossil locality an important distinguishing character. After a detailed study belongs. of the herbarium sheets of different families it was found that the above features are found in the modern leaves of Affinities-The diagnostic features of the present fossi I Gynocardia odorata R.Br. of the family Flacourtiaceae (C.N. leaves such as narrow elliptic shape, acute base and apex. Herbarium sheet nos. 33497, 33499; PI. 2. fig. 5). entire margin, closely placed secondaries and presence of intersecondary veins collectively suggest its resemblance with is Fossil record and comparison-So far, there no record the family Clusiaceae. These features are found common in of fossil leaf of the genus GYllocardia R.Br. from the Tertiary the genera. Kavea Wall., Calophvllum Linn. and Gareinia sediments of India and abroad. Thus, present fossil leaves form Linn. of this family. Critical examination of the herbarium the first record from the Siwalik sediments of Nepal and have sheets of these genera and the present fossils revealed that the been described here as Gynocardia mioodora/a sp. nov. leaves of Calophylluln Linn. differ in the angle of secondary Tlie genus Gynocardia R.Br. consists of only one spe­ veins which is almost right angle. The genus Kavea Wall. can cies G. odolOw R.Br. with which the present fossils Show close be differentiated in being larger size with more angle ofdiver-

PLATE 4 Di/J/emC(lIp"s koi/tlhtlsensis sr. nov. ' Fossil lear in natural size sbowing sbape, size and venation pallern. PRASAD el ol.-FURTHER CONTRIBUTION TO THE SIWALIK FLORA FROM THE KOILABAS AREA. WESTERN NEPAL 59

PLATE 4 6U THE PALAEOBOTANIST gence of secondary veins. The only genus Garcillia Linn. DIPTEROCARPUS KOILABASENSIS sp. nov. comes closest with the present fossils. Further, in order to find (PI. 4. fig. I) out the nearest species a number of herbarium sheets of all the available species (about 20) were studied in detail and con­ Material-The present species is based on a single well cluded that the leaves of Garcinia cowa Linn. resembles the preserved leaf-impression which is devoid of cuticles. present fossil leaves in shape, size and ven

PLATES (All figures are of nalural size uMess olherwise menlioned)

Shorcrt elliropi:ijolia sp. no\'. - Fossil lear showing shapc, size and to show similar details of vcnJlion. X 3.5. venation pallern. 8,9. IJmcc{/ d{/rl-l'ajellsis sp. nov. - Fossil leaves showing shape. sil(O and

2.3. ShOrNI elliropi~ijoliasp. nov. - Otller rossil leaves showing variation nature or base and apex. in shape. size and nalure of base. IU. IJmcca lllOlIi, Wall. - Modern lear showing similar shape. size. na­

4. 5. ShorNI lropi~ljoli{/(Thw.) Ashton - Modern leaves showing similar ture of base and apex. variation in shape. size and nalure of base. t t. IJmcea dm....ajclIsis sp. nov. -A parl or fossil leaf magnirietlto sllow 6. Shore{/ cll/rapi:ijolia sp. nov. -A pan of fossil leaf magnified to show details or venation. X 2.5. details or venation. X 3.5. 12. Umc!!{/ lIlollis Wall. -A ran or modern leaf magniried to show simi­ 7 SllOr,,{/ Impi:ljolia (Thw.) Ashton -A ran or modern [car magnilied lar details or venation. X 2.5 PRASAD ef ol.-FURTHER CONTRlBUTION TO THE SIWr\UK FLORA FROM THE KOILABAS AREA. WESTERN NEPAL 61

-== ..:::­ ~ ,..::::

4 5

12

PLATE 5 62 THE PALAEOBOTANIST with the present fossil leaf in all morphological characters. nate, eucamptodromous; primary vein (1°) single, prominent. stout. thicker towards basal region, straight; secondary veins Fossil record and comparison-A number of fossil leaves (2°) about 10 pairs visible, 0.5 to J.8 cm apan, angle of diver­ showing close similarity with the genus Diplerocarpus Gaertn. gence 60u-65u, acute moderate, alternate, uniformly curved have been described from the Teniary sediments of both In­ up, curving more pronounced near the margin, run upward to dia and abroad. They are Diplerocarpus ontiqu/lS Heer and a lillie distance joining to the superadjacent secondaries, D. olovillllS Heer from the Teniary of Sumatra (Heer. 1883); unbranched; tertiary veins (30) moderate in thickness, not so D. labuanus Geyler, D. nordenspioldi Geyler and abundant, angle oforigin RR, perculTent, mostly straight some­ Diplerocwplfs sp. from the Teniary of Labuan (Geyler, J887); times sinuous, rarely branched, oblique in relation to midvein Phylliles diplerocarpoides Crie 1888 from the Pliocene of prominently alternate and close to nearly distant. Further de­ Java, D. siwaliclls Lakhanpal & Guleria 1987 from the Siwalik tails are not clearly seen. sediments of Jawalamukhi. Himachal Pradesh. This species has also been described from Siwalik sediments of Koilabas, Holorype-Specimen no. K 50. western Nepal (Prasad. 1990b). Surai Khola, western Nepal Localily-Koilabas Nala section near Imlibasa, Koilabas, (Awasthi & Prasad, 1990) and Kathgodam, Ullar Pradesh, western Nepal. India (Prasad, 1994c). On comparing the present fossil with the above already known species, it has been observed that it Horizon & Age-Lower Siwalik. Middle Miocene. does not show similarity with any of them. The present fossil Elymology-After the Siwalik Formation. leaf differs from most of them in being larger in size. The Affinilies- The most important features of the present course of secondaries is also not common in any of the above fossil leaf are narrow elliptic shape, acute apex. obtuse. specimens. This has. therefore, been described as a new spe­ inequilateral base, eucamptodromous venation, straightly run­ cies Diplerocarpus koilabasensis. ning upward secondary veins whose curvature is pronounced The genus Diplerocarplfs Gaenn. contains about 76 spe­ near the margin, percurrent and close to distant tertiary veins. cies distributed in India and western (Willis, 1973). These features collectively indicate that the fossil leaf belongs Out of which, 17 species are Indian and 5 are endemic in to the genus Isoplera Scheff. ex Br. of the family Ceylon. Two are found in south India and rest in eastern Ben­ Dipterocarpaceae. In the genus Isoplero Scheff ex Br. only gal, Myanmar and Andaman Island. The extant species two species were available for consultation in the CN. Her­ Diplerocarplls lurbina!us Gaenn.f., with which the fossil barium, Sibpur, West Bengal. However, after a detailed com­ shows closest affinity, is a large evergreen tree occurring in parison of fossil leaf with the extant leaves of this genus it the forest of Cachar and Chillagong Hills. It is also common was found that the leaves of Isoplero bomeonsis show closest in the tropical forest throughout Myanmar (Gamble. 1972). affinity with the fossil (CN. Herbarium sheet no. 52123: PI. 3, fig. 6). Genus-ISOPTERA Scheff. Ex Br: Fossil record and comparison-So far there is no record ISOPTERA SIWALICA sp. nov. of fossil leaves of Isoptera Scheff. ex Br. from the Teniary sedi ments of any part of the world. Therefore. it has been de­ (PI. 3, figs 5, 7) scribed as lsoptera siwa!ica sp. nov., the specific epithet indi­ Malerial- This consists ofonly one well preserved speci­ cates its occurrence in the Siwalik sediments. men which is complete and devoid of cuticles. The genus Isoplera Scheff. ex. Br. contains only three Descriplion-Leaf simple, symmetrical, narrow elliptic; species found to grow in tropical forests of western Malaysia preserved size 9.2 x 3.3 cm; apex slightly broken, seemingly (Willis. 1973).lsoplera bomeonsis with which the fossil speci­ acute: base obtuse, slightlyinequilateral; margin entire; tex­ men shows closest affinity, is an evergreen tree distributed in lUre thick, chanaceous; petiole not preserved: venation pin- the forest of Myanmar, Java and Sumatra.

PLATE 6 (All figures arc or na[ural si;cc unless o[herwisc mentioned)

Agltlitl 1I!!I)(tfcl/Si.1 sp. nov, - Fossil leaf showing shape. sizc ano I'en,,- 6, I:inisfiglllil II/ioe!cgtll/S sp. nov. -A pan of fossil le"r 1Il;,gniflcd 10 tion r>anern. show dctails of venation. x 2.5. 2. Agltlitl lIelwlell.>i; sp. nov. -A p"n or fossil Ie"r magnificd [0 show 7 Fi,I,li,l/iglllil el!!gtllls Hool.:.F. &. Th. - Ar"n of modcrn Ic"f Illagnilicd de[ails 01'\'cna[ion, x 2.2. to show similar details of venation, , 2.5.

3.'" Fi,ni,l/igllw /IIitlclegtll/,l sp. nov. - Fossil leaves showing shapc. si;ce. 8, N<,p!rl.'filil/l IJ(tftleogltlfJrtli1l Prasad 1.'1 /If. - Fossi I Ie,,,· showi ng shape. nature of base. apex "no I'cna[ion Iw[[c,.n, SiLC and venation pattern.

5, Fi,,,i;li~l/lii!!legtlllS Hool.:.r. &. TIL - Modcl'll le,d' sholling simil",. 9. NI.'I,!rl.'lill/ll gltlfJl'II/II NOJ'Onh. - Modcrn leaf showing silllil'n' ,I"'rc. sh"pe. sizc "nd vcnation pancrn. sizc and vcoation panern. PRASAD e( ol.-FURTHER CONTRIBUTION TOTHE SIWALIK FLORA FROM THE KOILt\BAS AREA. WESTERN NEPAL 63

PLATE 6 64 THE PALAEOBOTANIST

Genus-SHOREA Roxb. Fossil record and comparison-Seven fossil leaves re­ sembling the genus Shorea Roxb. have been described from SHOREA EUTRAPIZIFOLIA sp. nov. the Tertiary sediments of India and abroad. Seward (1935) (PI. 5, figs I, 2, 3, 6) reported two leaves under the form genus Diplerocarpophyllum, D. blumii and D. gcralivcnse from Material-This species is based on three leaf-impressions the Tertiary of showing resemblance with the extant which are devoid of cuticle. genus Shorca Roxb. Merrill (1923) described two fossil Description-Leaves simple, symmetrical, elliptic to nar­ leaves, viz., Shorea guiso and S. polyspcrmum from the row elliptic; preserved size 4.4 x 2.3 cm, 5 x 2.2 cm and 5.5 x Pliocene of Philippines. Recently, three more fossil leaves 2.0 cm; apex seemingly acute; base acute to obtuse; margin have been reported from the Siwalik sediments of India. entire; texture coriaceous: petiole not preserved; venation pin­ These are Shorea siwalika Antal & Awasthi (1993) from nate, eucamptodromous: primary vein (1°) single, prominent, Siwalik sediments of Ramthi River, Darjeeling District, West stout, almost straight; secondary veins (20) about 8 pairs vis­ Bengal; Shorea neoassamica Prasad (1994c) from the ible, 0.4 to 0.8 cm apart, angle of divergence about 60°, acute Siwalik sediments of Kathgodam, Uttar Pradesh and Shorea moderate, uniformly curved up, usually alternate, seemingly mioccnica Antal & Prasad ( 1996b) from Ghish River near unbranched, intersecondary veins present, simple: tertiary Oodlabari, Darjeeling District, West Bengal. The present veins (30) fine, poorly preserved, angle of origin usually RR, fossil leaves have been compared with all the above known percurrent, almost straight, sometimes branched, oblique in species and found that these are different from them in being relation to midvein, predominantly alternate and close. Fur­ smaller in size having intersecondary veins. The course of ther details could not be seen. secondary and tertiary veins is also different from them. Thus. in being different, the present specimens have been described Holotype-Specimen no. K 9. under a new specific name Shorea eutrapizijoLia. Paratype-Specimen nos. K 44, 19. The genus Shorea Roxb. contains about 180 species Locality-Koilabas Nala section just before Imlibasa, distributed from Ceylon to South China, western Malaysia Koilabas, western Nepal. and Malaccas. Out of 12 species in which five are endemic in Ceylon, three are found in Myanmar, two in south Horizon & Age-Lower Siwalik. Middle Miocene. India, one in Assam and one in the well known Sal forest in Etymology-From the extant species Shorea trapizifolia northern and central India. Shorea lrapizijolia (Thw.) plus the prefix 'eu'. Ashton with which the present fossils show closest resem­ blance is an evergreen tree found to occur in Ceylon Ajfinities- The characteristic features of the fossil leaves (Ashton, 1972). such as elliptic to narrow elliptic shape, acute apex, acute to obtuse base, entire margin, eucamptodromous venation, mod­ Family-SIMAROUBACEAE erately acute angle of divergence of secondary veins, pres­ ence of intersecondary veins and RR, percurrent tertiaries Genus-BRUCEA J.F. Mill. indicate that these are closest to the extant Shorea trapiZlJolia BRUCEA DARWAJENSIS sp. nov. (Thw.) Ashton of the family Dipterocarpaceae (CN. Her­ barium sheet no. 29; PI. 5, figs 4,5, 7). (PI. 5, figs 8, 9, II)

PLATE? (All figures are of natural size unless otherwise mentioned)

I. Slvill/ol1ia palacoscllH,cl1ckii Prasad & Awasthi. - Fossil leaf showing 8. Dalbergia clIllrara Linn. - Modern leaflet showing similar Shape. size shape. size and venation pallern. and nature of base. apex and venation pallern. 2. Swill/ol1ia schwcl1ckii. Teysm. - Modern leaf showing similar shape, 9. CYI/Ollleirtl pala('oiripa sp. nov. - Fossil leallels showing shape. size size and venation pallern. and its ven~lionpallern.

3. POl1gamia kathgodal1/1!l1sis Prasad. - Fossil fruit showing its morpho­ 10. CYl10lllerrtl iripa KOle\. - Modern le~fletsshowing similar shape. size logical features. and venation pallern. 4. POl1gamia glabra Vent. - Modern fruit showing similar morphological II. Mil/ellia illllibasel/sis sp. nov. - Fossilleaflel showing shape. size and

fe~tures. venation pallern. 5. Dalbergia miovoillbilis Prasad 1'1 al. - Fossil leaf showing shape. size 12. Mil/ellia brtll/disialla Kurz. - Modern leaflet showing similar shape. and venation pallern. x 2.5. size and venation pallern. 6. Dalbergio "olllbilis Roxb. - Modern leaf showing similar shape. size 13. Mil/Cilia illllibasellsis sp. nov. -A pan of fossil leallet magnilied 10 and venation pallern. x 2,5, show details of venation. X 4. 7 Dalbcrgio coc"lrrtlltl sp. nov. - Fossilleallet showing shape, size 'lI1d 14. M. LJrtll/disialla Kurz. -A pan of modern Ieaflel magnified to show nalure of apex. base and venation pallern. similar details of venalion. x 3. PRASAD et ({I.-FURTHER CONTRIBUTION TO THE SIWALIK ['LORA FROM THE KOILABAS AREA. WESTERN NEPAL 65

6

4 ~ 1

8

PLATE 7 66 THE PALAEOBOTANIST

Material-The present species is based on two Ieaf-i 01­ palaeotropical species. Out of which, only two species are pressions which are almost complete and devoid of cuticles. found in India and Myanmar. Brucea Illoilis Wall., with which the fossils show closest affinity is an evergreen shrub growing Description-Leaves simple, slightly asymmetrical at in north east Himalaya and Sylhet ascending to about 6.000 basal portion, narrow elliptic; preserved size 5.4 x 1.3 Col and ft. It is also common in Kochin Hills, Karan Hills and 5.8 x 1.3 Col; apex attenuate; base acute, inequilateral; margin entire: texture coriaceous: petiole preserved in one specimen, Tennasserim in Myanmar (Gamble, 1972). 0.4 Col long, normal; venation pinnate, eucamptodromous; Family - SAPINDACEAE primary vein (10) single, prominent, stout, almost straight; secondary veins (2°) about 10 pairs visible, less than 0.5 Col Genus - NEPHELIUM Linn. apart, angle of divergence about 65°, acute, moderate; uni­ NEPHELIUM PALAEOGLABRUM Prasad et al. 1997 formly curved up, alternate to opposite, seemingly unbranched; U tertiary veins (3 ) fine, poorly preserved, angle of origin usu­ (PI. 6, fig. 8) ally RR, percurrent, straight, oblique in relation to midvein, Material-This species is based on a single, well pre­ alternate to opposite and close. Further details could not be served leaf-impression. seen. Description-Simple, symmetrical; narrow obovate to Holorype-Specimen no. K 58. elliptic; preserved size 8.2 x 5.0 Col; apex broken; base acute; Pararype-Specimen no. K 64. equilateral; margin entire; texture chartaceous; venation pin­ Locality-Koilabas Nala section near Darwaja, Koilabas, nate, eucamptodromous; pri mary vein (I U)single, prominent. western Nepal. stout, almost straight; secondary veins (2°) about 7 pairs vis­ ible; 0.7 to 1.5 Col apart, angle of divergence about 60u, mod­ HoriZOIl & Age-Lower Siwalik, Middle Miocene. erate acute; uniformly curved up and joined superadjacent vein, Etymology-After Darwaja, a place in Koilabas Nala seemingly unbranched usually alternate, rarely sub-opposite; from where fossils were collected. tertiary veins (3°) tine, angle oforigin RR, sometimes branched, percurrent; oblique in relation to mid-vein, sometimes nearly Affinities-The main diagnostic fealUres of the fossil leaf right angle, predominantly alternate and close. such as narrow elliptic shape, attenuate apex, inequilateral, acute base, coriaceous texture, eucamptodromous venation and Specimell lIo.-K 2. the course of secondary and tertiary veins strongly suggest Locality-Near Darwaja in Koilabas Nala, Koilabas, that the fossil leaves show their affinity with the leaves of western Nepal. extant genus Brl/cea J.F. Mill of the family Simaroubaceae. Herbarium sheets of all the available species of the genus Horizon & age-Lower Siwalik, Middle Miocene. Brucea J.F. Mill. were examined and it was found that the Affinities -In overall morphological fealUres the present leaves of Brl/cea mol/is Wall. show closest affinity with the fossil leaf resembles closely with the extant leaves of present fossil leaves (CN. Herbarium sheet nos. 77233 and Nephelilllnglabrum Noronh. of the family Sapindaceae (CN. 77234; PI. 5, figs 10, 12). Herbarium sheet no. 95476; PI. 6, fig. 9). Fossil record and cOll1parison-There is no fossi Irecord Fossil record alld comparison-Four fossil leaves re­ of the genus Brucea J.F. Mill. from the Tertiary sediments of sembling the genus Nepheliul11 have been described from Ter­ India and abroad. The present fossils show their first occur­ tiary sediments ofIndia and abroad. These are Nephelil/lI1jovis rence in the Siwalik sediments of Nepal and therefore have Unger 1875 from Tertiary of Europe, N. verbereriall/(m Geyler been assigned as Brucea darwajensis sp. nov. 1875 from Tertiary of Borneo and N. oligocenicllm Awasthi The genus Brl/cea J.F. Mill. contains about 10 & Mehrotra 1995 from the Oligocene of Makum Coaltield,

PLATE 8 (All figures are or natural size unless otherwise meillioned)

Anisophy/ll'a siwalica Prasad & Awasthi. - Fossil lear showing shape. 5. Dios[Jyros drll'\mjl'lIsis sp. nov. - Fossil lear showing shape, size and size ,and its venation pallern. venation pallern. 2. Allisophyllea siwaliw Prasad & Awasthi. -A pan of rossil lear mag­ 6. Diospyrus darwajemis sp. nov. -A pan or rossil lear magniried to nilied to show details of venation. X 3. show details of venation. X 2. 3. Sv::.rgillill lIIiooecid{'l/wlis sp. nov. - Fossil leaf showing shape. size 7. Helieia coerreliw sp. nov. - Fossil k'lf showing shape. size and its and its venation pallern. venation pallern. 4. Sy::..\-gilllll occidl'lIlUlis Bourd. - Modern leaf showing similar shape. 8. Helieia euerrl'liw sp. nov. -A pan or rossil lear magnified to show size and venation pallern. details or venation. x 2.5. PRASAD ('I ot.-FURTHER CONTRIBUTION TO THE SIWALIK FLORA FROl'v1THE K01LABAS AREA, WESTERN NEPAL 67

4

PLATE 8 68 THE PALAEOBOTANIST

Assam, India and N. palaeoglabrul11 Prasad el at. 1997 from at right angle, RR, percurrent. straight to curved tertiary veins the Siwalik sediments of Seria Naka near Tulsipur, U.P. On are the important features of the present fossil. These features comparison of present fossil leaf with those of above men­ indicate that the fossil belongs to the modern leaves of the tioned species. It has been found that the species described genus Aglaia Lour. of the family Meliaceae. A critical exami­ from Seria Naka i.e., N. palaeoglabrum shows closest resem­ nation of the herbarium sheets of a number of species of this blance with present fossil in almost all the morphological fea­ genus suggests that the leaves of Aglaia euryphylla Koord. & tures. Valeton (C.N. Herbarium sheet no. 80785) has nearest affin­ ity with the fossil leaf. The extant Neplzeliul11 glabmJrl Noronh. is an evergreen tree found to grow in Malayan archipelago (Hooker, 1872). Fossil record and comparison-As far as the author is aware there is no record of the fossil leaves resembling the Family-MELIACEAE genus Aglaia Lour. Although, a fossil wood resembling this Genus-AGLAIA Lour. genus has been described as Aglaioxylon mandalensis from the Deccan Intenrappean beds of Parapani. Mandla District AGLAIA NEPALENSIS sp. nov. of Madhya Pradesh (Trivedi & Srivastava, 1982). The present (PI. 6, figs 1,2) fossil forms the first occurrence of the fossil leaves of this genus in the Siwalik sediments of Koilabas, western Nepal Malerial- This species is based on a well preserved leaf­ and has been assigned as Aglaia nepalensis sp. nov. impression which is devoid of cuticle. The genus Aglaia Lour. consists of200-300 species found Descriplioll-Leaf simple, symmetrical, narrow elliptic; in China, Indo-Malaya, Australia and Pacific. Of these, 23 preserved size 7.5 x 3.0 cm; apex broken; base indistinct; species are distributed in India, Myanmar and . margin entire; texture thick, chartaceous; venation pinnate, Aglaia euryplzylla Koord. & Valeton, with which the fossil eucamptodromous; primary vein (1°) single, prominent, stout, leaf resembles closely. is an evergreen tree found to grow almost straight; secondary veins (2°) about II pairs visible, mainly in Java. 0.3 to 1.0 cm apart, usually alternate rarely sub-opposite, an­ gie of divergence 70°-800. wide acute to nearly right angle. Family-ANACARDIACEAE uni formly curved up, curvature is more pronounced near the margin before joining superadjacent secondary, unbranched, Genus-SWINTONIA Griff. intersecondary rarely present, simple; tertiary veins (30) fine, SWINTONIA PALAEOSCHWENCKII poorly preserved. angle of origin usually RR, percurrent, straight to curved, convex, rarely branched, oblique in rela­ Prasad & Awasthi 1996 tion to mid vein, predominantly alternate and close. Further (PI. 7, fig. I) details could not be seen. Malerial-This is based on a single incomplete leaf-im­ Holotype-Specimen no. K 86. pression which is devoid of cuticle. Locality-Koilabas Nala section near Koilabas Village. Descriplion-Leaf simple, symmetrical, seemingly nar­ Koilabas, western Nepal. row elliptic, preserved size 4.5 x 3.0 cm; apex broken; base Horizon & Age-Lower Siwalik, Middle Miocene. obtuse, indistinct on one side of midrib; margin entire; texture thick, chartaceous; petiole preserved, 0.6 cm long, normal; Etymology-After the name of country to which fossil venation pinnate, eucamptodromous; primary vein (10) sin­ locality belongs. gle, prominent, stout, almost straight; secondary veins (2°) only Affinilies-Medium size of leaf with narrow elliptic shape, 6 pairs visible, 0.3 to 1.2 cm apart, lowest two pairs closely u 1l eucamptodromous venation, wide acute angle of divergence placed, alternate, angle of divergence 60 to 80 , wide acute of secondary veins, basal 1-2 pairs of secondary arise nearly to right angle, lowest pair arises mainly at right angle, uni-

PLATE 9 (All figures are of nalural size unless olherwise menlioned)

I. Phl/!Olllllll, miorelicl/llI/l/s sp. nov. - Fossil le~llelsshowing shape. similar type of base, apex and ven:llion pallern. x 2.2. size and ilS 4.lrrangelllcllton ;j twig. 5. PltrllOJlflll15 koilovaseJlsis sp. nov, - Fossil lenllel magnified 10 show 2. PitylloJl,it w relicl/llI/l/s Poi .. - Modern Ieallets showing similar shape, details of venation. size and arrangemelll. 6. PItVllllll/ltliS collllmJloris Muell.Arg. -A modern Ieallet magnilied 10

3. PhvlloJlIIJlIs mioreliclIllI/liS sp. nov. -A fossille~lletmagnified to show show similar details of venation. naturc of base. apcx and venation. x 2.2. 7. AJlledeslI/o ,ill'o!ico sp. nov. -A fossil leaf showing venation 4. Pln'lIolIIlllls reliclIllI/lis Poir. -A modern leallet magnified to show pattcrn. PRASAD el ol.-FURTHER CONTRIBUTION TOTHESIWALIK FLORA FROM THE KOILABAS AREA. WESTERN NEPAL 69

2

} .

5 .4 6 PLATE 9 70 THE PALAEOBOTANIST

formly curved up and joined to their superadjacent secondar­ Material-It consists of a single fruit-i mpression. ies without any pronounced curvature, unbranched Description-Fruit flattened, oblong with decurved intersecondary veins present but poorly preserved; tertiary points. much thickened on suture; size 2.3 x 1.1 cm; wings veins (30) fine, poorly preserved, angle of origin usually RR, absent. percurrent, straight to curved, sometime branched, oblique in relation to mid vein, predominantly alternate and close. Specimen-Specimen no. K 66. Specimen-Specimen no. K 108. Locality-Koilabas Nala section near Darwaja, Koilabas. western Nepal. Localiry-Koilabas Nala section near Darwaja, Koilabas, western Nepal. Horizon & Age-Lower Siwalik, Middle Miocene. Horiz.on & Age-Lower Siwalik, Middle Miocene. Affinities-In all morphological features the present fos­ Affinities-Symmetrical elliptic shape, obtuse base, en­ sil fruit shows closest affinity with the extant fruit of Pongamia gfabra tire margin, eucamptodromous venation, wide acute to right Vent. of the family Fabaceae (C.N. Herbarium sheet angle of divergence of secondary veins, closely placed and no. 15650; PI. 7, fig. 4). with more angle of divergence of lowest pair of secondary Fossil record and comparison-The genus Pongamia is presence of intersecondary veins and RR, percurrent, closely well known in the fossil record by the occurrence of its petri­ placed tertiary veins strongly indicate that the present fossil fied woods, fossil leaves. and fruit-impressions from the Ter­ shows closest affinity with the extant leaves of Swintonia tiary sediments of India and abroad. A number of fossil woods schwenckii Teysm. of the family Anacardiaceae (C.N. Her­ have been described from Tertiary sediments of India under barium sheet no. 37034; PI. 7, fig. 2). form genus Millellioxylon Awasthi (Prasad, 1994b). So far, Fossil record and comparison-So far, three fossil leaves three fossil leaflets have been recorded from the Siw

[

2

PLATE 10

Amedeslllo S;IVO(;CO sp. nov. - Fossil lear showing share. size and size. nature of base and apex. venation pallern. 4. P(n-((I/1l/(1II.1 col/IIII/I/{{ris l11ucll. Arg. Poir. - Modern lealkls showing AlI/{'deslI/o II/OI/WI/IIII/ BI. - Modern leaf showing similar shape. size similar shape. size. nature of base and apa. and venation pallern. 5. CYI/ol//{'/m (J{{({{{'()iri(J1I sp. nov. -A pan of fossi I leartel l11agni lied to 3 Phv((ol//(II/s koi(o!Jos{'l/.Iis sp. nov. -A rossil leaflel showing shape. show details of venation. x 5. inequilateral; margin entire: texture chartaceous: petiole not Holotype-Specimen no. K 121. preserved; venation pinnate, eUC:lInptodromous; primary vein Locality-Koilabas Nala near Darwaja, Koilabas, west­ O (J ) single, prominent, stout, almost straight; secondary veins ern Nepal. (2°) 1-8 pairs visible, 3.0 to 0.7 cm apart, alternate to oppo­ Horizon & Age-LowerSiw:.J1ik, Middle Miocene. site, angle of divergence about 55 u·60u acute, moderate, uni­ formly curved up and join their superadjacent secondary. low­ Erymology-From the extant species D. c{(l(raw plus cs[ pair closely placed, seemingly unbranched. intersecondary the prefix 'eo'. veins present, simple; teniary veins (3°) nne, poorly preserved, Affini(ies-The dignostic fealUres of the present fossil angle of origin usually AO, percurrent and join intersecondary leallet such as asymmetrical. elliptic shape, emarginate Jpex, veins, oblique in relation to midvein, predominantly alternate acute base, entire margin, chartaceous texture, and close. eucamptodromous venation, closely placed secondary veins 72 THE PALAEOBOTANIST with moderate angle ofdi vergence, presence of intersecondary upper mixed savanah and Eng forests throughout Myanmar, veins and percurrent tertiaries strongly suggest its resemblance the Shah Hills, south wards. with the extant leaves of Dalbergia culTrata Linn. of the fam­ ily Fnbaceae (CN. Herbarium sheet no. 130595; PI. 7, fig. 8). DALBERGIA MIOVOLUBILIS Prasad et al. 1997 Fossil record and cOlllpariSOIl-The fossil leaflets resem­ (PI. 7, fig. 5) bling the genus Dalbergia Linn.f. are known from different Material-This species is represented by only one speci­ parts of the world under the genera Dalbergia Linn. and men which is almost complete and devoid of cuticle. Dalbergites Berry. So far, about 40 species of Dalbergia Linn.f. and 3 species of Dalbergites Berry have been described Description-Leaflet almost symmetrical, elliptic; pre­ from India and abroad (Etlingshausen, 1869; Schimper, 1874: served size 1.6 x 0.9 cm; apex broken; base nearly obtuse, Geyler, 1875; Berry, 1909, 1916, 1939; Knowlton, 1917; slightly inequilateral; margin entire; texture thick chnrtaceous; Principi, 1921; Hollick, 1924; Ball, 1931; Salomon-Calvi, petiole preserved, 0.2 cm visible, normal: venation pinnate, 1934: MacGinitie, 1937, 1941; LaMotte, 1952; Heer, 1959; eucamptodromous: primary vein (1°) si ngle, not so prominent, Lakhanpal & Awasthi, 1984; Prasad, 1990b. 1994a, e, Prasad weak; secondary veins (2°) more than 12 pairs visible. closely et al., 1997). Besides, there is one more leaflet resembling placed, alternate to opposite, angle of divergence 55°. acute, that of Dalbergia described under the form genus Phyllites by moderate, uniformly curved up, branching not clear, Tanai (1972) from the Tertiary of Japan. These species have intersecondary veins present; tertiary veins (30) fine, poorly been reported from Africa, Austmlia, France, , Green­ preserved, angle of origi n RR-A 0, percurrent.someti mes land, Japan, Sumatra, U.S.A., West Indies and India. Besides, branched, oblique in relation to midvein, alternate to opposite and close. Further details not observed. two fossil fruits resembling Dalbergia sissoo have also been described from the Indian Tertiary sediments. Lakhanpal and Specimen-Specimen no. K 82. Dayal (J 966) described it from the Siwalik sediments of Localit)'-Koilabas Nala section near Darwnjn, Koilabas, Balugoloa, Himachal Pradesh. Later, Awasthi and Mehrotra western Nepal. (1995) reported other fossil fruit under Leguminocarpon dalbergioides from the Oligocene of Makum Coalfield, As­ Horizon & Age-Lower Siwalik, Middle Miocene. sam, India. Thus. from fossil records it is clear that the genus A/finities- The most important distinguishing features of Dalbergia Linn.f. was cosmopolitan in distribution in geo­ the present fossil leaflet such as small size, nearly obtuse base. logical past. entire margin, small petiole, eucamptodromous venation, Four fossil leatlets resembling Dalbergia Linn.f. have closely placed secondary veins arising at moderate acute an­ been described from the Siwalik sediments of India and Ne­ gie from the midvein, presence of intersecondary veins and pal. These are Dalbergia miosericea Prasad I990b, D. siwalika percurrent tertiaries collectively indicate that the fossillenflet Prasad 1994e from the Siwalik sediments of Koilabas, west­ shows closest affinity with the extant leaflets of Dalbergi{{ ern Nepal, Dalbergia cf. D. sissoo Prasad 1994a from the I'olubilis Roxb. of the famil y Fabaceae (CN. Herbarium sheet Siwalik sediments of Haridwar. Uttar Pradesh, D. lIliol'olubi/is no. 130772; PI. 7, fig. 6). Prasad et al. (1997) from the Siwaliks of Seria Naka at Indo­ Fossil record and comparison-So far, about 42 species Nepal Border, U.P. and Dalbergia sp. Lakhanpal and Awasthi of Dalbergia Linn.f. are known from the Tertinry sediments (1984) from the Siwalik sediments of Bhikhnathoree, Bihar. of India and abroad (Prasad et al., 1997). The present fossil The present fossil leaflet was compared with the available leaf was compared with all the avai lable species and concluded known species of Dalbergia Linn.f. and found that none of that the fossil leaflet described from the Siwalik sediments of them shows similarity with the present fossil. Seria Nab (Gonda District) at Indo-Nepal Border shows clos­ Although the fossil leaflet described as Dalbergia est affinity in shape and venation pattern and hence has been miosericea Prasad somewhat shows resemblance in the nn­ described under the same species. This fossillenflet was also ture of apex but differs in course of secondary vei ns and hav­ compnred with the extant taxa D. I'oll/bilis Roxb. but it is larger ing obtuse base instead of acute base in the present fossil. in size with somewhat distantly placed secondnries. We would Thus, being different this fossil leatlet is assigned to n new like to mention that these variations in the morphological fea­ species Dalbergia eocllitrata. tures may be due to different ecologicnl conditions of the regions. Th'e genus Dalbergia Linn.f. consists of about 300 spe­ cies of tropical to sub-tropical region of the world (Willis, The extant taxa D. I'oll/bilis Roxb. with which the fossil 1973; Hooker, 1879). About 36 species are reported to occur shows closest affinity is a large climbing shrub growing in in India (Gamble, 1972). Dalbergia cllitrata Linn. with which central and eastern Himalaya from Kumaon to Sikkim. Bihar, the fossil shows closest resemblance is a moderate sized de­ Central Provinces, south and west India and Myanmar(Gam­ ciduous tree common in all deciduous forests specially the ble, 1972). PRASAD et al.-FURTHER CONTRIBUTION TO THE SIWALIK FLORA FROM THE KOILABAS AREA, WESTERN NEPAL 7.\

Genus-CYNOMETRA Linn. ary veins too, is also different from them. In view of these Ihe present fossil leatlet has been described as a new species CYNOMETRA PALAEOIRIPA sp. nov. Cynollletra palaeoiripa. The specific epithet indicates its re- (PI. 7, fig. 9; PI. 10, fig. 5) semblance with extant C. iripa Kotel. • Material-This species is based on two well preserved The genus Cynol71etra Linn. consists of about 60 tropi­ and complete leanets attached with a small twig. cal species. Of which five are found to occur in the Indian Description-Leaflets asymmetrical, elliptic, 2.1 x 1.0 region. The extant taxa C. iripa, with which the fossil shows cm and 2.5 x 1.0 cm; apex slightly broken, seemingly wide resemblance, is distributed in Indo-Malayan region. acute; base wide acute; margin entire; texture chartaceous; petiole very small, indistinct; venation pinnate, Genus-MILLETTIA W. & A. eucamptodromous to brochidodromous: primary vein (1°) sin­ MILLETTIA IMLIBASENSIS sp. nov. U gle. prominent, stout, almost straight: secondary veins (2 ) (PI. 7, figs 11.13) about 8 pairs, 0.2 to 0.5 cm apart, alternate to subopposite, angle of divergence about 60°, acute, moderate, uniformly Material-This species is based on a single well pre­ curved up and joined to their superadjacent secondary, some­ served, almost complete leatlet impression, which is devoid times forming loop, rarely branched, intersecondary veins of cuticle. present, simple, frequent; tertiary veins (3°) fine, angle ofori­ Description-Leaflet symmetrical, narrow elliptic; pre­ gin RR-AO, percun'ent, straight to sinuous, branched, oblique served size 4.3 x 1.6 cm: apex wide acute; base obtuse: mar­ in relation to midvein. predominantly alternate, close. Further gin entire; texture chartaceous: petiole not preserved; vena­ details are not clearly seen. tion pinnate, eucamptodromous; primary vein (Ill) single. Holotype-Specimen no. K 80. prominent, stout, almost straight, thicker towards basal half region. Secondary veins (2°) about 10 pairs, 0.3 to 0.6 cm Locality-Koilabas Nala section near Darwaja, Koilabas, apart, alternate to subopposite, angle of di vergence about 60", western Nepal. acute, moderate, uniformly curved up and joining to the Horizon & Age-Lower Siwalik. Middle Miocene. superadjacent secondary, unbranched, intersecondary veins present, simple; tertiary veins (30) fine, angle oforigin usually Etymology-From extant species Cynollletra iripa plus RR, percun"ent, straight to sometimes sinuous, oblique in re­ suffix 'palaeo'. lation to midvein, predominantly alternate and close. Further Affinities-The most characteristic features ofthe present details could not be seen. fossil leaflets are asymmetrical elliptic shape, wide acute apex Holotype-Specimen no. K 114. and base. entire margin. chartaceous texture. eucamptodromous to brochidodromous venation, closely Locality-Koilabas Nala section near Imlibasa. Koilabas, placed secondary veins arising at moderate angle of diver­ western Nepal. gence, presence ofintersecondary veins and perculTent, straight Horizon & Age-LowerSiwalik, Middle Miocene. to sinuous tel1iary veins. These features are found common in the extant leaflets of the genus Cynometra Linn. of the family Etymology-After a place, Imlibasa in Koilabas Nala Fabaceae. In order to find out its specific affinity, the her­ from where the fossil was collected. barium sheets of about 12 species of this genus have been Afjinities- The most characteristic features of the present critically examined and concluded that the extant leaflets of fossil leaflet are symmetrical, narrow elliptic shape. wide acute Cynollletra iripa Kotel (eN. Herbarium sheet nos. 138727, apex, obtuse base, entire margin, chartaceous texture, 138745; PI. 7, fig. 10) closely match in shape, size and vena­ eucamptodromous venation, moderate acute angle of diver­ tion pattern. gence of secondary veins, presence of intersecondary veins Fossil record and cOlllfJarison-Awasthi and Prasad and RR, percurrent, straight sinuous tertiary veins. These fea­ (1990) described the fossil leaflets resembling the genus tures are found common in the genus Millenia W. & A. of the Cynometra Linn. from the Lower Siwalik sediments of Surai family Fabaceae. A critical observation of a number of her­ Khola, western Nepal under C. siwalika. Later, Antal and barium sheet of more than 30 species of Millettia W. & A. Awasthi (1993) reported another species C. tertiara from the indicates that the present fossil is very similar to the extant Lower-Middle Siwalik ofOodlabari, Darjeeling District, West leaflets of Millellia bralldisiano Kurz. (eN. HerbariuJll sheet Bengal. Both these fossil leaflets are compared with the present 110.112443; PI. 7, figs 12, l4). fossil leaflet and found that the present fossil is entirely dif­ Fossil record alld comparison-So far, 12 fossilleatlets ferent specially being smaller in size. The course of second- showing resemblance with Mil/ettia W. & A. have been re- 74 THE PALAEOBOTANIST corded from allover the world. They are M. impressa (Harms) origin, forming triangul

Holotype-Specimen no. K 47. Material-It consists of a well preserved al most com­ plete leaf-impression which is devoid of cuticle. Localily-Koilabas Nala section near Darwaja, Koilabas, western Nepal. Descriplion---Leaf simple. symmetrical. narrow oblanceolate; preserved size 13.2 x 4.2 cm; apex broken; base Horizon & Age-Lower Siwalik, Middle Miocene. obtuse; margin entire; texture coriaceous; petiole not pre­ Elymology-From extant taxa Syz)'gium occidenlalis plus served; venation pinnate, eucamptodromous to prefix'Mio'. brochidodromous; primary vein (I") single, prominent. stout, almost straight; secondary veins (2°) 7-8 pairs visible. 0.5 to Affinilies- The important distinguishing features of the 2.0 cm apart, lowest pair closely placed, usually alternate, fossil leaf are very narrow ell iptic shape, attenuate apex, acute rarely subopposite, angle ofdivergence about 50", acute, mod­ base, entire margin. eucamptodromous venation, presence of erate, uniformly curved up and join to their superadjacent sec­ intersecondnry and intramarginal veins and RR-AO, ondary at obtuse angle, sometimes join before meeting the percurrent, tertiary veins. These morphological features sug­ margin and giving the appearance of brochidodromous type gest that the present fossil leaf shows its affinity with the leaves of venation pattern, seemingly unbranched: intersecondary of extant genus Syz)'gium Gaertn. of the family Myrtaceae. A veins rarely seen; tertiary veins (3°) fine, angle of origin RR, critical examination of the modern leaves of about 50 species percurrent, straight to sinuous, branched, oblique in relation of the genus was done and found that the modern leaf of S. to midvein, predominantly alternate. close; quatelllary veins occidenlalis Bourd (Eugenia occidenlalis) closely resembles (4°) still fine with RR angle of origin, branched. forming the present fossilleaf(C.N. Herbarium sheet no. 66156; PI. 8, orthogonal to polygonal meshes. fig. 4). Holotype-Specimen no. K 12. Fossil record and comparison-So far, six species of Syzygiulll Gaertn. based on fossil leaves, have been reported Locality-Koilabas Nala section near Darwaja, Koilabas. from the Tertiary sediments of India and abroad. These are western Nepal. Syzygillm floribulldoides Engelhardt (Muller, 1934) from the Horizon & Age-Lower Siwalik, Middle Miocene. Middle Miocene of West Germany; S. chaneyi Huzioka & Takahasi 1970 from the Eocene of Japan; S. kachchense Etylllology-After a place Darwaja in Koilabas Nala from Lakhanpal & Guleria 1981 from the Eocene of Kachchh, In­ where the fossil was collected. dia; S. miocenicum Prasad & Prakash 1984 from the Siwalik Affinities-The most characteristic features of the present beds of Koilabas, westelll Nepal; S. palaeobraCiealll11l Awasth i fossil leaf like nan'ow oblanceolate shape, obtuse base. eillire & Lakhanpal 1990 from the Siwaliks of Bhikhnathoree, Bihar; margin, coriaceous texture, eucamptodromous to and S. palaeocumini Prasad & Awasthi 1996 from the Siwalik brochidodromous venation, course and nature of secondary sediments of Surai Khola, western Nepal and Antal & Prasad vein, rare OCCUITenceof intersecondary veins, RR, percurrent, 1997 from the Siwaliks of Darjeeling District, West Bengal. straight to sinuous tertiary veins undoubtedly indicate its re­ On comparing the present fossil with the already known spe­ semblance with the leaves of Diospyros Linn. of the family cies it is found that none of them is si milar to the present fos­ Ebenaceae. In order to find out its nearest modern equivalent, sil and hence it is being described as a new species-So about 55 species of Diospyros Linn. were examined critically miooccidenlalis. and found that the present fossil leaf shows closest affinity The genus SYZygi1l11lGaertn. consists of about 500 spe­ with the leaves of extant Diospyros dasyphyllea Kurz. (FR.!. cies of trees, shrubs and rarely climbers. They are Herbarium sheet no. 39889). palaeotropical in distribution (Willis, 1973). There are79 spe­ Fossil record and cOll1parison-The fossil leaves show­ cies in India, of which about 76 species are indigenous which ing close resemblance with those of Diospyros have been de­ thrive in moist localities along the banks or in the beds of scribed under two generic names, i.e., Diospyros Linn. and streams. It occurs in wet evergreen, semi-evergreen. moist DiospyrophyllulI1 Velenovsky. The later consists of only one deciduous, littoral and swamp, dry evergreen and dry decidu­ species Diospyrophylllllll provecllllIl Velenovsky 1889 from ous forests of tropical India. S. occidentalis with which the the Upper Cretaceous of Bohemia. However, Diospyros Linn. fossil specimen shows closest affinity is found in the Indian contains about 70 species reported from different pal1s of the region. world. viz., Africa, Bohemia. Canada, Europe, England. Greek. , Japan, Panama, and U.S.A. (Schilllper. Family-EBENACEAE 1874; Heel'. 1874; Lesquereux. 1878, 1891-92; Probost. 1884: Genus-DIOSPYROS Linn. Berry, 1916, 1918, 1919, 1930; Principi. 1921; Gothan, 1933; Salomon Calvi, 1934: Hollick, 1936; MacGinite, 1937. 1941; nov. DIOSPYROS DARWAJENSIS sp. LaMotte, 1952; Jahnichen, 1958: Chaney & Axelrod, 1959; (PI. 8, figs 5, 6) Kilpper. 1969; Huzioka & Uemura, 1973; Tanai, 1976). Thus 76 THE PALAEOBOTANIST it is obvious that this genus was cosmopolitan in distribution nate and close; quaternary veins (4u) still fine, angle of origin in the geological past. From the geological distribution of fossi I RR, forked, forming orthogonal to polygonal meshes. Diospyros it is evident that its earliest record goes back to the Holotype-Specimen no. K 10. Upper Cretaceous (Velenovsky, 1884). Locality-Koilabas Nala section near Darwaja, Koilabas, So far, seven species have been reported from the Siwalik western Nepal. sediments of India and abroad. These are Diospyros embryopterisites Verma 1968 from the Middle Siwalik of Horizon & Age-Lower Siwalik, Middle Miocene. Hardwar, Uttar Pradesh. India; D. lI1iocenica Prasad & Awasthi Etymology-From extant taxa H. erretica plus prefix 'eo'. 1996, D. miokaki Awasthi & Prasad 1990 from the Lower Siwalik sediments of Surai Khola, western Nepal; D. Affinities-The most important distinguishing features of kathgodall1ensis Prasad 1994c and D. palaeoebenul71 Prasad the fossi Ileal' such as oblanceolate shape, cuneate base, entire I994d from the Lower Siwalik of Kathgodam, Uttar Pradesh, margin, chartaceous texture, eucamptodroJl1ous venation, dis­ India; D. pretoposia Prasad 1990'1and D. koilabasensis Prasad tantly placed secondaries with moderate angle of divergence 1990a from the Lower Siwalik sediments of Koilabas, west­ running upward to a little distance, presence of intersecondary ern Nepal. The later species has also been reported from the veins and RR, percurrent, straight to sinuous, tertiary veins Lower-Middle Siwalik of Darjeeling District, West Bengal, strongly suggest that the present fossil leaf shows closest af­ India and D. IlIlsipurensis Prasad et af. 1997 from the Lower finity with the modern leaves of Helicia erretica Hook.1".of Siwaliks of Seria Naka, at Indo-Nepal Border, in Gonda Dis­ the family Proteaceae (C.N. Herbarium sheet no. 13457). trict of Uttar Pradesh, India. The present fossil leaf is com­ Fossil record and comparison-As far as the author is pared with all the above available species and found entirely aware there is no fossi I record of the genus Helicia Lour. from different from them in the course and nature of secondary and the Indian subcontinent. Therefore, the present fossi Ileal' form tertiary veins. Therefore, it has been described under a new its first record from the Siwalik of Koilabas, western Nepal species Diospyros darwajensis. and it has been assigned as He/icia eoerretica sp. nov. The genus Diospyros Linn. consists of about 500 spe­ The genus Helicia Lour. consists of about 90 species dis­ cies of trees or rarely shrubs distributed in tropical and mild tributed in Europe, South-east Asia, Indo-Malaya, and east­ temperate regions of the world, a few in South Africa and ern Australia. Of these, only 8 species are found to occur in North America (Hooker, 1882; Purkayastha, 1982). About 55 the Indian region. H. erretica HookJ., with which fossil re­ species are found in the Indian region. D. dasyphyllea Kurz., sembles closely, is a small evergreen tree found in the forests with which the fossil resembles closely, is an evergreen tree of Sikkim and Shan Hills of Martaban. It is common in of Martaban Hills. Darjeeling forests chiefly in open ground (Gamble. 1972).

Family-PROTIACEAE Family-EU PHORBI ACEAE Genus-HELICIA Lour. Genus-PHYLLANTHUS Linn. HELICIA EOERRETICA sp. nov. PHYLLANTHUS MIORETICULATUS sp. nov.

(PI. 8, figs 7, 8) (PI. 9, figs 1. 3) Material-It is represented by a well preserved almost Material-This species is represented by seven leaflets complete leaf-impression and it is devoid of cuticle. attached on a twig. Description-Leaf simple, symmetrical, oblanceolate: Description-Leaflets symmetrical. elliptic, average size preserved size I 1.5 x 4.0 cm: apex broken; base cuneate; 2.5 x 1.3 cm; apex wide acute: base wide acute to obtuse; margin entire: texture chartaceous; petiole preserved, 0.8 cm margin entire; texture thick charlaceous; petiolule small, 0.2 long, normal; venation pinnate, eucamptodromous; primary to 0.3 cm long; venation pinnate, eucamptodromous; primary vein (10) single, prominent, stout, almost straight; secondary vei n (1°) single, promi nent. stout, al most straight: secondary veins (2°) 5-6 pairs visible, 1.3 to 2.8 cm apart, usually alter­ veins (20) 5-6 pairs, less than 0.5 cm apart, alternate to oppo­ nate, seemingly unbranched, angle of divergence about 600 site, unbranched, angle of di vergence about 55°, acute moder­ acute, moderate, lowest pair ofsecondary arising more acutely, ate, uniformly curved up and join their superadjacent second­ curved up and run upwards to a little distance and join to their ary; intersecondary veins occasionally seen; tertiary veins (30) superadjacent secondary; intersecondary veins present, sim­ poorly preserved, fine, angle oforigin RR, perculTent, straight, ple, frequent: tertiary veins (3°) fine, angle of origin RR, oblique in relation to midvein, predominantly alternate and perCLIn'ent,straight to sinuous, branched. oblique in relation close. to midvein. right angle near the margin. predominantly alter- Holotype-Specimen no. K 130. PRASAD el al.-FuRTHER CONTRIBUTION TO THE SIWALIK FLORA FROM THE KOILABAS AREA, WESTERN NEPAL 77

Locality-Koilabas Nala section near Darwaja, Koilabas, Malerial-It is based on a single complete leaf-impres­ western Nepal. sion which is devoid of cuticle.

Horizon & Age-Lower Siwalik, Middle Miocene. Description-Leaflets symmetrical; preserved ~ize4.8 x 1.7 cm; narrow elliptic; apex obtuse; base acute; margin en­ Etymology-From extant taxa Phyllanlhus reliclllatlis plus prefix 'mio'. tire: texture coriaceous; petiolule preserved, small, 0.2 cm long: venation pinnate, eucamptodromous; primary vein (JU) sin­ U Affillilies- The diagnostic features of the present fossil gle, prominent, stout, almost straight; secondary veins (2 ) leaves such as small size, elliptic shape, wide acute apex and about 7-8 pairs visible, 0.3 to 0.7 cm apart, alternate to base, entire margin, eucamptodromous venation, closely subopposite, seemingly unbranched, angle ofdivergence about placed secondary arising at moderate angle ofdi vergence, rare 6OU,acute, moderate, uniformly curved up and join to their intersecondary veins and RR, percun'ent, straighttel1iary veins superadjacent secondary; intersecondary veins present, sim­ undoubtedly indicate their resemblance with the genus ple, frequent; tertiary veins (3°) fine, poorly preserved, angle Phyllallllllls Linn. of the family Euphorbiaceae. In order to of origin RR-AO, percurrent, straight to sinuous, branched, find out the nearest resembling species a number ofherbarium oblique in relation to midvein, predominantly alternate and sheet of about 55 species were critically examined and con­ close. Further details could not be seen, cluded that the present fossils show affinity with the extant Holotype-Specimen no. K 138. leaflets of Phyllanlhus relicula/us Poir in shape, size and ve­ nation pallern (C.N, Herbarium sheet no. 13875; PI. 9, figs 2, Locality-Koilabas Nola section near Darwaja, Koilabas, 4) western Nepal. Fossil record and comparison-Four fossil leaves are Horizon & Age-Lower Siwalik, Middle Miocene. known so far showing close resemblance to those of Etymology-After the fossil locality Koilabas from where Phyllanlhus (= Glochidioll) from the Siwalik sediments of the fossil was collected. India and Nepal. Of these, three are from India and one is from Nepal. They are Glochidioll siwalica Prasad 1994c from Affinities-The important distinguishing features of the the Lower Siwalik sediments of Kathgodam, Unar Pradesh, present fossil are narrow elliptic shape, obtuse apex, acute India; Glochidioll palaeohirslllUln Antal & Prasad J996a from base, entire margin, small petiolule, eucamptodromous vena­ the Lower Siwaliks of Oodlabari, West Bengal, India; tion, somewhat closely placed secondaries with moderate acute Phyllalllhlls siwalica Prasad 1994d from the Lower Siwaliks angle of divergence, presence of intersecondary veins and of Kathgodam, Uttar Pradesh, India and Phyllanlhus percurrent tertiary. These features are found common among palaeoreliculatlls Prasad & Awasthi 1996 from the Lower the species of the genus Phy/lanlhus Linn. of the family Siwalik sediments ofSurai Khola, western Nepal. A compara­ Euphorbiaceae. After a critical examination of those species tive study of both the above known fossil leaves as well as it has been concluded that the extant taxa Phy/lanlhlls present fossil specimens indicates that the present fossils dif­ collllll1naris Muell. Arg. shows closest affinity with the present fer in being smaller in size and having different course and fossil in all morphological features (C.N. Herbarium sheet no, arrangement of secondary veins. The fossil leaf described 401998; PI. 9, fig, 6; PI. 10, fig. 4). under Phyllanlhus palaeoreliculailis and comparable with the Fossil record and comparison-So far five fossil leaf­ same extant species differs in the nature of apex and having lets resembling the genus Phyllalhus Linn. are known from more secondary veins as compared to the present fossils. Thus, the Siwalik sediments of India and Nepal. The present fossil being different, the present fossil is assigned to a new species has been compared to those of all already known fossils and P mioreticliialus. found that it is entirely different from them either in shape or The genus Phyllanlhlls Linn. contains about 600 species in the nature of secondary and tertiary veins. Thus, bei ng di f­ distributed in tropical to subtropical regions of the world ex­ ferent, it is assigned to a new species Phyl/anthlls clusively Eurasia and North Asia. It is a large genus compris­ koilabasensis. ing the plants varying in sizes, many of them more or less The modern comparable taxa Phyllanlhlls collul11naris shruby. Phyllalltlllls reliculatus Poir. with which fossil shows is a small deciduous tree of mixed forests in Myanmar. It is closest affinity is a struggling shrub distributed throughout common all along the rivers (Gamble, J972). the greater part of India, Myanmar, and Sri Lanka. In the drier region it is commonly found in ravines and along streams Genus-ANTEDESMA Linn. (Gamble, 1972). ANTEDESMA SIWALICA sp, nov. PHYLLANTHUS KOILABASENSIS sp. nov. (PI. 9, fig. 7; PI. 10, fig. I) (PI. 9, fig. 5; PI. 10, fig. 3) Material-This species is represented by two well pre- 78 THE PALAEOBOTANIST served nlmost complete lenf-impressions. Allolla koilabasel1sis sp. nov. Descripliol1-Lenf simple, symmetricnl, n

Table I-A list of fossil taxa recovered from the Siwalik sediments of Koilabas, western Nepal. Fossil Taxa Modern Equivalents References Anonaceae Milillsa siwalica sp. nay. M Ihorelii Finet & Gagnep. Anona koilabasensis sp. nay. A. la/lri[olia Linn. Dillelliaceae DiLlenia palaeoindica Prasad & Prakash D. indica Linn. Prasad & Prakash, 1984 Polygalaceae Secllridaca miocenica Prasad el al. S. inappendiCitLala Hask. Flacourtiaceae Ryporosa prekllnslelri Prasad R. kllnsleLri King. Prasad, 1990a Gynocardia mioodorata sp. nov. G. odorata R. Br. Clusiaceae Meslw lerliara Lakhanpal Mferrea Linn. Prasad, 1994e Kayea kalagarhensis Prasad K. j10ribllnda Wall. -do- Garcinio nepalensis sp. nay. G. cOIVa L. Dipterocarpaceae Isoplera siwalica sp. nay. I. borneonsis Br. Diplerocarp/ls siwaLiclls Lakhanpal & Guleria D. Illberculalus Roxb. Prasad, 1990b D. koiLabasensis sp. nay. D. IlIrbinalus Gaerln.f. Hopea mioglabro Prasad H. glabra W. & A. Prasad, 1994e Shorea ellirapizifolia sp. nay. S. lrapizifolia Thw. Rutaceae Evodia koilabasensis Prasad E. fraxinifoLia Hook. f. Prasad, 1994e MlIrraya khariense Lakhanpal & Guleria M paniclllaia (Linn.) Jacq. -do- AlLanlia l11iocenica Prasad A. lIlonophylLa Corr. -do- Simaroubaceae Brucea danvajensis sp. nay. B. lIlollis Wall. Meliaceae ChLoroxylon palaeoswielenia Prasad e. slvielenia DC. Prasad, 1990b AgLaio nepalensis sp. nay. A. ellryphylla Koor. & Valelon Rhamnaceae Fissisligma l11ioeLegons sp. nay. F eLegans Hook.f. Thw. Prasad. 1994e Zizypll/(s miocenica Prasad Z. jlljuba Lam. Sapindaceae Filicilllll koiLobosensis sp. noy. F decipience Thw. Prasad, J994e Ellphorea nepalellSis sp. noy. E. longana Lamk. -do- Olophora l11iocenica sp. noy. O.ji·lIIicosa Blume -do- Nephelillm palaeoglabrum Prasad el al. N. gLabrulll Noronh. Sabiaceae Sabia eopanicliLala Prasad S. panicliLala Seem. Prasad, 1994e Anacardiaceae Swinlonia pa!aeosc!1H:enckii Prasad & Awaslhi S. sc!lIvenckii Teysm. Bouea koiLabasensis Prasad B. bllrmanica Griff. Prasad, 1994e Tapiria chorkholiense Prasad T hirsllla Hook.f. -do- Mangi{era sOl11eshwarica Lakhanpal & Awaslhi M indica Linn. -do- Fabaceae Albizia siwalica Prasad A. Lebbek Gamble Prasad, 1990b Pongalllia kalhgodamensis Prasad P glabra Vent. Cassia nepalensis Prasad e. hirSllla Linn. Prasad. 1990a e. lIIiosiamea sp. nay. e. siamea Lam. Prasad, 1994e e. neosophora sp. noy. e. sophora Wall. -do- Da(bergia eoclllirala sp. noy. D. cuLlrala Linn. Dalbergia miosericea Prasad D. sericea Boj. Prasad, 1990a D. siwalika Prasad D. sissoo Roxb. Prasad, 1994e D. lIIiol'olllbilis Prasad el al. D. \'oLlibilis Roxb. Mil/ellia silvalica Prasad M. ol'alifolio Kurz. Prasad, 19903 M. koilabasensis Prasad M. lIlaeroslachyo Coll.& Hems!. Prasad, 1990b PRASAD el al.-FURTHER CONTRIBUTION TO THE SIWALIK FLORA FROM THE KOILABAS AREA. WESTERN NEPAL 81

M. illlblibasensis sp. noy. M. bral/disiana Kurz. M. lIliobrondisiana sp. noy. M. bralldisialla Kurz. Prasad, 1994e Ormosia robllslOides Prasad O. robltsloides Jacq. Prasad, 1990'1 Cynomelra palaeoiripa sp. noy. C. iripa Kotel. Salllanea si\l'alica Prasad S. samail Men'. Prasad, J994e El1/ada palaeoscandens Awasthi & Prasad £. scal/dens Benth. -do- Combretaceae Anogeisslls eosericea Prasad & Prakash A. sericea Brandis Prasad & Prakash, 1984 Clycopleris jloriblll/doides Prasad C. jloribllnda Lam. Prasad, 1990a Termil/alia koilabasel/sis Prasad T al/gllslljolia Jacq. -do- T siwalica Prasad T pyrijolia Kurz. -do- T panandl/roensis Lakhanpal & Guleria T !Omenlosa W.A. Prasad, 1994e CombrelLim sallllii Antal & Awasthi C. decandrum Roxb. -do- Lythraceae Lagerslroemia siwalika Prasad L. lallceolala Wall. Prasad, I 994e Woodjordia I/eojntlicosa Prasad 'III jrulieosa Kurz. -do- Anisophylleaceae Anisophyllea siwalica Prasad & Awasthi A. apelala ScorL Myrtaceae SYZygi1l111miocenicc/II// Prasad & Prakash S. clavijlorulIl Roxb. Prasad & Prakash, 1984 S. miooccidenlalis sp. noy. S. oeeidenlalis Bourd. Caprifoliaceae Lonicera mioqllinqlleloclllaris Prasad L. quinqlleloeularis Hardw. Prasad, 1990a Rubiaceae Randia miowallichii Prasad R. lValliehii Hook.f. Prasad, 1994a Morinda silValika Prasad M. 1II1/bellalaLinn. Prasad, 1994e Ebenaceae Diospyros koilabasemis Prasad D. 11l0n/({IIaRoxb. Prasad, J990a D. pre!Oposia Prasad D. loposia Ham. -do- D. dwwajel/sis Prasad D. dasyphyllea Kurz. Apocynaceae TabemaemOl/lana precoronaria Prasad T corol/aria Willd. Prasad, J990a Carissa koilabasel/sis Prasad C. palleinervia A. Dc. Prasad, 1994e Loganiaceae Caerlnera siwalica Prasad C. bieleri (D.Willd. E. Petit) Prasad, 1990a Solanaceae Dalllra miocenica Prasad D.jaslllosa Linn. Prasad, 1994e Oleaceae Allacolosa miolllwniellsis sp. noy. A. lllWlliellsis Men'. Prasad, 1994e Verbenaceae ViIO:prenegundo Prasad V.neglllldo Linll. Prasad, 1990a \I si waIica Prasad V.pllbeseells Yahl. -do- Lauraceae CinllamOI//1/1Ill1IioinllCl/l11IPrasad C. il/llClllm Meissn. Prasad, 1990a Moraceae FicIIs precl/I/ia Lakhanpal F cltl/ia Ham. Prasad. 1990a F relllsoides Prasad F relltsa Linn. -do- F nepalensis Prasad F glaberrilllCi Blume -do- Protiaceae Helicia eoerreliUl sp. noy. H. ('(reliea HookJ. Euphorbiaceae Phyllanlhus koilabasel/sis sp. noy. P colllll11lluris Muell-Arg. P lIIiorelicl/lall/S sp. IlOY. P relielllallls Poir. AI/ledesma siwalica sp. noy. A. 1/101l!OIlIIl/lBI. 82 THE PALAEOBOTANIST

Table 2-Present day distribution and forest types of comparable taxa of fossils recovered from the Siwalik sediments of Koilabas, western Nepal.

Fossil Taxa Modern Equivalents Distribution Forest type Anonaceae Miliuso Silvolico sp. nov. M. Ihorelii Finet & Gagnep. India, China Moist deciduous AIIOIIOkoi/oba.\ellSis sp. nov. A. /awijo/ia Linn. Java Evergreen Dilleniaceae Di/ Ll?I1iopa/oeoilldico D. illdica Linn. India. Myanmar Moist evergreen Prasad & Prakash. 1984 Polygalaceae SeCllridaca miocellica Prasad S. illappeildicu/Ola Hask. N.E. India, Java Evergreen to Moist el al. 1997 deciduous Flacourtiaceae Ryparosa prekulIsle/ri R. kUllsleiri King. Malaya Evergreen Prasad, 1990a Gynocardio mioodorata sp. nov. G. odoraw R.Br. N.E. India. Burma Evergreen Clusiaceae Mesuo lerliam (Lakhanpal) M.lerreo Linn. North east India, Myanmar, Evergreen Prasad, 1990a Malaya Kayea ka/agorhellsis K. .f7oribullda Wall. North east India, Myanmar Evergreen Prasad, 1993 Garcillio Ilepa/ellsis sp. nov. G. cOlVaL. N.E. India, Bangladesh, Burma Evergreen Dipterocarpaceae Isoplem siwalico sp. nov. I. bomeollsis Br. Java, Burma Evergreen Diplerocarpus si\\'alicus D. tubercu/alus Roxb. North east India, Myanmar, Evergreen to moist (Lakhanpal & Guleria) Prasad, South east Asia deciduous 1990b D. koiLabasellSis sp. nov. D. lurbina/us Gaertn.f. N.E. India, Bangladesh, Burma Evergreen Hopea miog/abro Prasad, 1994e H. g/abm W. & A. South India Evergreen ShorNI ewrapizijolia sp. nov. S. /rapizijo/io Thw. Ceylon Evergreen Rutaceae Evodia koi/abasellsis Prasad, E. fraxinijo/ia Hook. f. North east India, Malaya. Evergreen 10 Moist 1994e Nepal deciduous Murraya khariellsis (Lakhanpal & M. pallicu/ato (Linn.) Jacq. Sub Himalayan region. Myanmar, Moist deciduous to Guleria) Prasad. 1994e Andman, Sri Lanka, Australia evergreen Ai/aillia miocellica Prasad, 1994e A. monophyl/o Corr. South and North India, Evergreen Myanmar, Andman Simaroubaceae Bmcea dan\"{/jensis sp. nov. B. I/Iol/is Wall. N.E. India, Burma Evergreen Meliaceae Ch/oroxy/on pa/aeos\vielellia C. slVielellio DC. India, Sri Lanka Moist deciduous Prasad, 1990a Ag/aia Ilepa/ellsis sp. nov. A. euryphyl/o Koor. & Java Evergreen Valeton Rhamnaceae Zizyphw; I/Iiocellica Prasad, 1994e Z. jujuba Lam. India, Myanmar Deciduous Fissisligma mioc/egalls sp. nov. F c/egalls Hook.fThw. Malaya, Malucca Evergreen Sapindaceae

Filicium koi/abascilsis F decipiellce Thw. South Indi~l,Sri Lanka, Evergreen Prasad. 1994e Tropical Africa E"phorco Ilepa/ells'is E. /OllgOIlOLlmk. South and North India, Evergreen to moist Prasad. 1994e Myanmar, Malaya deciduous Olophom l1Iiocellica Q.lmlicosa Blume. Malaya Evergreen Prasad, 1994e PRASAD {;'{ al.-FURTHER CONTRIBUTION TO THE SIWALIK FLORA FROM THE KOILABAS AREA. WESTERN NEPAL 8:;

Nephel ill 111 palaeoglobmm N glabmm Noronh. Malaya Evergreen Prasad el 01., 1997 Sabiaceae Sabia eopaniClilala S. panicillolo Seem. Sub-Himalayan region, Evergreen t.o moist Prasad, 1994e Myanmar, Malaya deciduous Anacardiaceae Swinlonia polaeoschwenckii S. sc!nvenckii Teysn. India, Burma, Malaya Evergreen Prasad & Awasthi, 1996 BOllea koilabasensis B. bllrmanica Griff. South India, Andman, Evergreen Prasad, J994e Myanmar Tapiria chorklIoliense T IlirslllO Hook. f. North east India, Nepal, Moist deciduous Prasad, 1994e Manglfera somesfzwarico M. illdica Linn. India, Malaya Evergreen to (Lakhanpal & Awasthi) Prasad, deciduous 1994e Fabaceae Pongalllia ka/hgodamensis P glabra Vent. India, Sri Lanka, Malaya Evergreen to moist Prasad 1994a deciduous Albizia siwalica Prasad, J990b A. lebbek Gamble North east India, Myanmar Moist deciduous Cassia lIepalensis Prasad, 1990a e. hirSllla Linn. Central India Deciduous e. miosiamea Prasad, 1994e e. sialllea Lam. India, Myanmar, Malaya Moist deciduous e. neosopllOra Prasad, 1994e e. sopllOra Wall. South east Asia Moist deciduous Dalbergia ellcili/rara sp. nov. D. cullrola L. India, Burma Moist deciduous D. miovoilibilis Prasad el al., 1997 D. voillbilis Roxb. India, Nepal Moist deciduous D. lIIiosericea Prasad, J990b D. sericeo Boj. Sub-Himalayan region, Deciduous Madagascar D. siwoliko Prasad, 1994e D. sissoo Roxb. Sub-Himalayan region, Deciduous Mil/cilia siwalico Prasad, 1990a M. ovallfolio Kurz. Sub-Himalayan region, Moist deciduous Myanmar M. ill/libas-ensis sp. nov. M. bralldisiana Kurz. Myanmar Moist deciduous M. koilabasellsis Prasad, 1990b M. macroslachya ColI.& Myanmar Evergreen Hems!. M. miobrandisiano Prasad, 1994e M. brandisiono Kurz. Myanmar Moist deciduolls Ormosia mlnts/oides Prasad, 1990b O. robllsra Jacq. Northeast India, Myanmar Evergreen Samanea siwoliko Prasad, 1994e S. salllon MelT. Tropical Africa, America Evergreen En/ado palaeoscandens (Awasthi E. scandens Benth. India, Burma Moist deciduous & Prasad) Prasad, 1994e Cynome/ra palaoirripo sp. nov. e. irripa Kote!' India Moist deciduous Combretaceae Anogeisslls eosericea Prasad & A. sericeo Brandis Central India Deciduous Prakash, 1984 Clycoplerisjloriblilidoides e. jloribllnda Lam. North east India, Myanmar, Deciduous Prasad, 1990a Western Peninsula Terminalia koilobasensis T ongllslijolio Jacq. Malaya Evergreen Prasad, 1990a T siwalica Prasad, 1990a T pynfolia Kurz. Myanmar Evergreen to moist deciduous T panandhroensis (Lakhanpal & T lomenlOsa W.A. Sub-Himalayan region, Moist deciduous Guleria) Prasad, 1994e Myanmar Combrellim sahnii (Antal & e. decondmm Roxb. Sub-Himalayan region, Deciduous Awasthi) Prasad, 1994e Bangladesh, Central India Lythraceae Lagerslraemia silvalico L. lallceolora Wall. Western Peninsula Moist deciduous Prasad, 1994e 84 THE PALAEOBOTANIST

Woodfordia neofrulicosa W frlllicosa Kurz. Sub-Himalayan region, Moist deciduous Prasad, 1994e Tropical Africa, Arabia, Both Peninsula Anisophylleaceae AI/isophy!!ea siwalica Prasad & A. aperala Scorl. Malaya Evergreen Awasthi, 1996 Myrtaceae Syzygium mioceniccum Prasad & S. clavif70rum Roxb. North east India, Andman, Evergreen to moist Prakash, 1984 Myanmar deciduous Syzygium miooccidenla!is sp. nov. S. occidenlalis Bourd. India Moist deciduous Caprifoliaceae uJIlicera mioqllinque!ocularis L. quinquelocularis Hardw. North west Himalaya, Nepal, Deciduous Prasad, 1990a India Rubiaceae Randia miowallichii Prasad, 1990a R. wallichii Hook. r. North east India, Myanmar, Evergreen Andman Morinda siwalica Prasad, 1994e ul11/Jellala Linn. South and North east India, Evergreen Sri Lanka, Malaya Ebenaceae Diospyros koilabasensis D. monlana Roxb. India, Myanmar, Sub-Himalayan Deciduous Prasad, 1990a region D. preroposia Prasad, 1990a D. roposio Ham. North east India, Bangladesh, Evergreen Sri Lanka D. darwajensis sp. nov. D. dasyphyllea Kurz. Martaban Evergreen Apocynaceae Tabernaemonlana precoronaria T. coronaria Willd. Sub-Himalayan region, Deciduous Prasad, 1990a Sri Lanka, Myanmar Carissa koi!abasellsis C. paucinervia A. Dc. North east India, Myanmar Evergreen Prasad, 1994e Loganiaceae Gaerlnera siwalica Prasad, 1990a G. bieleri (D. Willd.) Tropical Africa Evergreen E. Petit Solanaceae Dalura miocenica Prasad, 1990a D. fasluosa Linn. India, Malaya, Tropical Africa Deciduous Oleaceae Anacolosa mioluzoniensis A. luzoniensis Merr. South east Asia Evergreen Prasad, 1994e Verbenaceae Vilex prenegllndo Prasad, 1990a V negundo Linn. India, Sri Lanka, China Deciduous V siwalica Prasad, 1990a V pllbescens Vahl. India, Myanmar Evergreen Lauraceae Cinnamo711um mioillllclum C. inllClUI11Meissn. Myanmar, Malaya Evergreen to moist Prasad, 1990a deciduous Moraceae Ficus precllnia (Lakhanpal) F cunia Ham. Sub-Himalayan region, Deciduous Prasad, 1990a Assam, Myanmar F relusoides Prasad, j 990a F relusa Linn. India, Malaya Evergreen F nepa!ensis Prasad. 1990a F glaberril1la Blume India, Malaya Evergreen Protiaceae Helicia eoerrelica sp. nov. H. errelica Hook.f. N.E. India, Martaban Evergreen Euphorbiaceae Phyl/anl!nts koilabasensis sp. nov. P collulllllaris Muell.Arg. Burma Deciduous P miorelicu!allls sp. nov. P reliclllallls Poir. India, Burma, Ceylon Deciduous Anledesma siwalica sp. nov. A. nlOlI/onlllll BI. Malaya Evergreen PRASAD et al.-FURTHER CONTRIBUTION TOTHESIWALIK FLORA FROM THE KOILABAS AREA, WESTERN NEPAL 85

SOl/th Indianj70ra - The Neogene flora of south India is palaeoclimate or pulaeoecology of a particular area is to com­ known from the Cuddalore Sundstones, Neyveli lignite und pare the fossil floras with the modern vegetation and to know Varkala beds. The Cuddalore Sandstones are well known for the existing climatic conditions, It is rather difficult to deduce the occurrence of petrified woods which have been studied in the precise palaeoecology of an area prior to the Tertiary Pe­ detail by Awasthi, 1974. 1975a, b, 1977a, b, 1979, 1980, 1981), riod, because the modern vegetation is quite different from The Neyveli lignites in Tumil Nadu are rich in almost 'III bo­ those of earlier periods, The study becomes more accurate as tunical entities such as carbonised woods, leuf-impressions we go from Pulueocene upward until the Pliestocene as the und compressions. stems, roots, pollen, spores, algal and fun­ modern equivalents of the fossil forms still exist in the presem gal bodies. The plunt megafossi Is from this area have been day vegetation and obviously the fossils could satisfactorily studied by Ambwani (1982), Awasthi (1984), Awasthi und be compared and identified with the modern taxa, Agurwal (1986) and Agarwal (1989, 1991). Thus, the Tertiary fossil plants are supposed to be the reliable indicators of past climate specially those that are ref­ The study on the carbonised woods from the Varkala beds erable to modern taxa, The accuracy of interpretations based in Kerala Coast reveals the occurrence of a number of taxa on them is inversely proportional to the geological ages of the belonging to different angiospermous families (Awasthi & deposits from which the fossils are collected, As the plant Ahuja, 1982; Awasthi & Panjwani, 1984; Awasthi & fossils for the present study have been collected from the Mid­ Srivastava, 1989, 1990, 1992; Srivastava & Awasthi, 1994, dle Miocene sediments and the modern equivalents of these 1996; Srivastava, 1998). After comparison of the present fossil forms still exist in the forests. it has, therefore become Koilabas assemblage with those of south Indian floral assem­ easier to deduce the palaeoclimate and palaeoecology of the blages it has been surmised that most genera like of Mesua, Koilabas area in the Himalayan foot-hills of western Nepul Diplerocarpl/s, Hopea, Shorea, Mangijera, BOl/ea, Carcinia, during sedimentation. £/lphorea: Albizia, Cassia, Mil/ellia, Pongamia. Cynometra, Anogeissus, Terminalia, Anisophyllea.. Lagerslroelll ia, The other parameters for deducing palaeoclimate are the Diospyros and Cillllomol1lum are found common in both of physiognomic characters of plant fossils. In the presence of them. exclusively leaf-impressions in any floral assemblage, this parameter plays a deciphering role in interpreting the WeSlern Indianjlora - It includes the area of Rajasthan palaeoclimate and palaeoecology. Further, this is an independ­ and Kutch, From the Tertiary (Palaeogene and Neogene) of ent of systematic relationship of the species and therefore, it Kutch a large number of fossil woods, leaves, fruits and seeds is likely that the en'ors in interpretation are minimum, have been reponed by Lakhanpal and Guleria (1981, 1982) On the basis of plant megafossils especially leaf-impres­ and Guleria (1983, 1984). While, from Rajasthan area only sions. the interpretation regarding palaeoclimate and fossil woods are known belonging to different families of palaeoecology can be drawn by two methods: angiosperms and gymnosperms (Lakhanpal & Bose, 1951; Guleria, 1990), A comparison of the present Koi labas assem­ (i) Nearest living relative method, i.e., from comparison of the leaf-impressions with the extant taxa, blage with that of Western Indian flora shows that the com­ (ii) Foliar physiognomy method. i,e., from study of the struc­ mon genera Mesl/a, Dipterocarpus Murra)'a, Mangijera, tural features of leaf-impressions. Pongamia, Albizia, Millellia, Cassia, Cynomelra, Terminalia, Syzygium, Lagerslroemia, Diosp.vros, Cinnamol11ullland Ficus Neareslliving relative melhod are common, which obviously indicates that there was more This extrapolates known climatic requirement of mod­ or less equituble climate und homogeneity in the floristic com­ ern taxa with the comparable and related taxa in the past. The position of various Neogene assemblages in the Indian sub­ plant fossils recovered from Koilabas localities have been continent. compared with their modern equivalents and it has been ob­ served that a few of them still exist in the area, Therefore, it is PALAEOCLIMATE AND easier to infer the palaeoclimate of the region during sedi­ PALAEOECOLOGY mentation,

The present is the key to the past. The principal basis to The fossil plants obtained so far from the Siwalik any study of the past is the principle of 'Uniformity in the sediments of the Koilabas area comprise 79 elements which order of nature'. This principle implies on the physical and were compared with modern taxa (Table I), The present habit biological processes which like todays environment as well and habitat of the recorded taxa show that they mostly occur as vegetation must have been in the operation since past. Like­ in the tropical evergreen and moist deciduous forests of north wise, the type of weuther variation and cl imatic conditions as east India, Bangladesh, Myanmar and Malaya and adjoining observed today must also occulTed in the past. Cain (1944) areas receiving higher rainfall (Gamble, 1972; Hooker, 1879. further opines that upproach to the study of 1882, 1885; Champion & Seth, 1968; Desch, 1957; see Ta- 86 THE PALAEOBOTANIST

Table 3-Distribution of comparable extant taxa of fossils recovcred from the Siwalik sedimcnts of Koilahas in various tropical forest types.

TROPICAL FOREST TYI'ES Wet Semi Moist Littoral Dry Thorn Dry Modern Equivalent TAXA evergreen evcrgrcen deciduous and Swamp deciduous forcst evergrccn forest forest forest forest forest forest 2 3 4 5 6 7 8 AI/olla f(lun)o!w + + + A1ilillsa '!lOre/if + + + Dillen/a indica + + + SeCtlrit/aca iuofJpel1dicll/ofa + RY{Joro!:J{/ kUlls/elFi + Crllocordia O(/O,.Of(f + + MeS/la jerrea + + Karea flarilJllndn + Careiuia COH'U + + Di/JferocoljJus !/therclllmus + D. rurbillo!fo + + /-Iopm glalml + !sopfera flOrI/col/sis + + Slwrca Iropl~ljolia + + + f."odia jra.rilli(olia + + A1urraya pW/lcu/(1/(l + + AI!O/Ilio II/ol/op/ly/la + [Jruc(!a mollis + + Cltloroxvlol/ 5~\'iel('l1l(1 + + Ag/dia ellnp',,"'al + + Zi~rpi/llsjlljlliJa + + FilieililJl decipienst + Neplteliullt Mlabrwl1 + £/fpllOrco longOI/O + + O/Opl/ol'{I/rlllicosa + Sabia palliclI/a/({ + + [JO[(('{} !Jurll/on/co + Su'/wonia sc/ll1'(,Jlckij + + 7{1/);ria Ilir~lIf{/ + MallgiJera illdica + POl/galllfa g/ahra + + I\II)i~1/IIdJI'ek + • • C(Jssw IIlr5u/(/ + + C. !(l(!\'igu!a + C. sioHl(!o + C. sopllora + + Dnlhergia Se,.iCl'a + D. cili/raw + + D. j;SSOO + D. ,'all/hili, + + Mil/ellio ()I'olijolia + A1. uwcnHfnc!lra + + M. IJralldij;aJl(1 • Orf1/osio rohu.\fo + + CYI/omerra iripo + + So/}/ol/en .\{llflnl/ + EJlwda scoudell.\ + + Anogeisslis sericea + Cahcopleris floribllilda + + Terml/lOlia O!/glislIjolia + + T I'yrifolta + + + T lOlIIelllO:W + COII/OreliOll decal/dru/JI + + LogeTSlro('J/Iw lal/ceolala + + WoodjoiYlia jrlllicOSiI + + illli.wpll.l'lIeil ill'ell/liI + + Sy:ygill/II c!ol'ijloruJI/ + + + + S, oecidellwli, + LoJliC(Jro quinque/oculari.,> + • ROl/(Iiil \I'alliellii + • A10rillda IIl1lhel!ofa + Diospyro., JII{)}Jf(IJ/(J + + D. dils"pln'IIea + + D. fOIJOsia + Ta!Jerlloe/IIO/l1oI/0 c%l/orio + Carissa pallclJlervio • + Gocrfllera bidcr! + + + Da/Hra faj·lU(}.~a + Allocolosa III:OlliclI.\;\· + \'lfe.t lIe~f(/Jd(J + + V pl/!JCSU'1I5 . + C/I/lWIJIOIi/l/1I/ /1l/tCl/{lJ/ + + Flcu.\ ("Jillia + + F rCfl(sa + F glaher,-il11o + + He/lew era!lu/ + PI"'II(tl'fll/IS cvll/f/l/I/(I/';s + + + P ~clicul(l/ll5 + + + AI/fed(!jll/o IlIOJl/(1/1II1II + + r PRASf\D el (i/.-FURTHER CONTRIBUTION TO THE SIWALI K FLORA FROM THE KOILABAS AREA. WESTERN NEPAL 87 bles 2,3). Thus it may be surmised that a warm and humid three taxa, i.e., Dillellia pa!a('oindica. Daillra lIliOCfllica and climate prevailed in the Koilabas area at the time of deposi­ Allisophyl/ea siwalica. have entire margin indicating a warm tion in contrast to Ihe present relatively dry climate. The pre­ tropical climare (Table 4). dominance of evergreen elements in the assemblage further Besides, leaf size is another important indicator of cli­ indicates the prevalence of tropical (warm humid) climate with mate. It has been seen that leaf size distribution in any forest plenty of rainfall. Most of the taxa represented in the fossil type is correlated with available moisture and it is found big­ assemblage do not occur in the Koilabas area or all along the ger in the understory elements of humid evergreen forests but Himalayan foot-hills of both India and Nepal (Table 2). This decreases with low temperature or precipitation. Raunkiaer obviously indicates that changes in the climate must have taken (1934) suggested that the percentage of species having large place after the deposition of Siwalik sediments in the Koilabas leaves should be highest on the piedmont somewhat higher on are,l. the mounwin in order to correlate with precipitation. Further. The change in climate since the Middle Miocene can also Givinish (1976) has also postulated lhat optim<11size, as de­ be explained by a general global cooling and by the events termined by rhe balance between transpiration r<1leand within the region, particularly the Himalayan uplift and phytosynthesis. should be greatest in the tropics. decreases in shallowing ofthe Tethys sea which progressively ch~)ngedfrom the subtropics and increases in the warm temperate forests. marine through estuarine to fresh water environment According to Raunkiaer (I (34) and later modified by (Mukheljee, 1(82). These cl imate and physiographic changes Webb (1959) the leaf size may be measured typically by 5 made the environment hostile for the endemic nora which was size classes, viz., leptophyll (up to 0.25 sq cm). nanophyll gradually replaced by the present day mixed deciduous for­ (0.25-2.25 sq cm). microphyll (2.25-20 sq cm), mesophyll (20­ est. 182 sq cm) and macrophylJ (182-1640 sq cm). According to Foliar phvsiogno/ll)' /IIfl/lOd this classification the floral elements obtained from Koil

Phytogeography is the other important aspect of Terl71ina!ia pyrifolio. T 10lllen/osa, Sy~vgillll/c!avi/lonllll, palaeobotany which deals with the slUdy of fossil flora to know Ranc!ia wollicllii, D. diospyros, D. mOI1/al/a, D. IOposia. D. the past distribution and migration of vegetation especially dosyphvl/ea, Helicia errelica. Tobernaelllol/wl/o cOlDnoria. since Tertiary Period. In the orogenic movement of Himalaya, Carissa pallcinervia nnd FiclIs cllnia. This suggests thnt these Middle Miocene Period has been considered as the most im­ taxa were present during Middle Miocene in the foot-hills near portant. During this period severnl significant changes occurred Koilabas area but do not grow nowadays there and thus they in physiography, environment and floral characteristics. With have migrnted toward east in Assam, Bengal, Sikkim, the result. the older life forms which could not accommodate Meghalaya, Bangladesh and Myanmar because of better fa­ themselves to the new environment gradually perished and in vourable conditions. their place new plants or animals came into existence and flour­ Table 2 indicates that there are few taxa which are found ished. The geological events in the region strongly influenced to grow still at different altitudes in the foot-hills near Koilabas the phytogeography of the region during Siwalik Period ,md adjoining areas. These are Mil ITaya paniclllaw, Zizyplllls through the establishment of land connections between India jujuba, Manglfera indica, Dalbergia sissoo, D. \'oluhi!is, and South-east Asia (Smith & Briden. 1979). A number of Tel"ll1ina!io 10mel1losa, Combrelllll/ decondrll/I/, Wood/ordio plants migrated from South-east Asia to India via Myanmar jrlllicosa, Diospyros monlona, Dmllrojcls/uosa. Viiex negulldo and vice versa. With the result, many taxa. especially mem­ and Ficus cunea suggesting thnt they have susceptibility to bers of Dipterocnrpnceae and Fnbaceae which were present adopt in the new climatic conditions prevailing after Middle during the Palaeogene in South-east Asia appeared in the Miocene mainly due to further rise of Himalaya. Neogene on the Indian subcontinent.

The present day distribution of moderA equivalents of Leaf size No. of fossil taxa Percentage al179 species recovered from the Siwaliks ofKoilabas. west­ Leptophyll - - ern Nepal shows that they are presently known to grow in Nanophyll I 125 different geographical regions allover India, Nepal and other 50.50 places (Table 2). In India. they are distributed mostly in north Microphyll 41 east and southern regions wherever favourable climatic con­ Mesophyll 36 45.75 ditions are available. In this assemblage, there are those 18 Mncrophyll 2 2.50 taxa which are found to grow both in India and Malaya pe­ ninsula. They are Dillenia indica. Mesllajerrea. Securidoca Thus. the survey of the fossil plants obtained from the inappelldiclllaf{[. DiplerocorplIs luberculallts, Evoelio Lower Siwaliks of Koilabas area ,1nd the present day distribu­ Foxinijolio, Ellphoreo 10l1gana. Sabia pal1iculala, BOllea tion of their modern equivalents indicate that all the taxa can bUl"lual1ica, MOl1gljera indica, Swil1!Ol1ia sclllvenckii, Albi~iabe classified into 3 types: lebbek, Cassia siallleo, Dolbergia sericea, Pongalllia glabm. I. Extant taxa - Those taxa which have their living COUil­ Morillda IImbellata. Cinnamoll/IIIII inliClIIIII. FiclIs reilisa and terparts growing in or near the fossil locality. F glaberrima which clearly indicate that there has been a fair 2. Exotic taxa - Those taxa which grow in other parts of exchange of floral elements betwecn the two subcontinents India and Nepal. after the land connections wcre establ ished during the Miocene 3. Extinct taxa - Those taxa which have disappeared from Period. India and Nepal regions and now grow in other parts of Similarly. 7 taxa in the Koilabas nssemblage have a re­ the world. stricted distribution inlhe Malayan region. These are Ryparosa There may be two possible explanations for the diflcrcnl PRASAD el (d.-FURTHER CONTRIBUTION TO THE SIWALIK FLORA FROM THE KOILABAS AREA. WESTERN NEPAL 89

Table 4-Physiognomic characters of the fossil nora recovered from the Siwalik sediments of Koilabas area, western Nepal.

PHYSIOGNOMIC CHARACTERS Average Leaf Drip tips Nalure of Leaftexlure Leaf base Leaf Venation leaf size margin presence Petiole chartaceous shape Organi- pattern sq. cm entire(E) (P) normal(N) (CH) aCllte(A) zation C1ose(C) Fossil Taxa non- absenence indistinct( -) coriaceolls obtuse(O) Comp- Distant(D) enlire(N) (A) (CO) cuneate(C) ound indistinct(-) corcl:lte(CR) VS attenuate(AT) Simple indistinct (-) 2 3 4 5 6 7 8 9 Anona koi!abasensis 13.8 E CH 0 SC 49.5 Mi!iusa silva!ica 42.75 E CO SC Di!!enia pn!aeoindica 52.50 N CH SC SeC/Iridaea lI1iocenica 24.00 E CO 0 SC Ryparoso prekllnsle!ri 61.92 E N CO AS D Gynocardia lI1ioodorwa 32.75 E CO AS D Mesua lerliara 10.00 EPN CH A SC Kayea ka!agarhensis 41.60 E - N CO ASC Gareillia nepa!ensis 35.00 E N CO A SC DiplerocarpIIs silva!iclIs 66.00 EP N CH O,CR S D 190.00 E N CH 0 S D D. koi/abasellsis 236.25 E CO S C Shorea eUlrapiz.ijo!ia 13.25 E CO A SC Hopea miog!abra 28.44 E - CO A S D Isoplera siwa!ica 34.20 E - CH 0 S D fvodia koi!abasensis 20.90 E - CH 0 C C Murraya khnriense 07.30 E A CO AC D AI!onlia lI1ioeenica 05.22 E CH A C C Bnrcea danvajensis 08.27 EP N CO A S C Ch!oroxy!on 05.60 E CH A C C pa!oeoswielell ia Ag/ain nepa!emis 25.50 E CH C C Zizyphlls lI1iocenica 05.60 E CH 0 S D FissislignlO lI1ioe!egans 17.48 EP CO 0 S C Filicium koi!a!)asensis 26.25 EP N CH A SC fup/wren nepa!ensis 27.00 E P CO A S C Nephe!iwl1 pa!aeog/a/)J'{ull 41.00 E CO A S C OlOphora lI1iocenica 14.25 EAS CO S D Sabia eopal1iclI!ala 21.98 EP CH SC BOllea koi!abasellsis 12.00 EP N CO AS D Swil1{()l1ia pa!oeosc!llvellekii 13.50 E N CH 0 S C Topiria chork!lO!iellse 11.25 E CO 0 S D Mangijem somes!lll'ariea 26.40 E P N CH AS D A!bi;:ia Sill'o!ica 07.50 EAN CO AC D Cosssia. nepa!ellsis 10.08 EP CH 0 C D C. lI1iosiall1ea 05.25 E AN CH 0 C C C. neosophora 0380 E AN CH 0 C C Dn/hergia IIliosericea 14.40 EA N CH A C D D. ellC/rilrolO 06.46 EA CH A C C D. silVa!ica 07.20 E CH 0 C C 90 THE PALAEOBOTANIST

D, miovolubilis 02,00 E N CH A C C M, koilabasensis 28.40 E P CH A CD M, miobrandisialla 02,53 E CH 0 CD M, imlibasensis 07.48 E CH 0 C C Orl1losia robusloides 35,00 E P CH 0 CC Cynol1lelra iripa 02,80 E AN CH A C C Samanea siwaliea 02,00 E CH 0 C D Anogeissus eoserieea 10,75 E N CH 0 S D Calyeopleris f1oribulldoides 12.48 E P CO 0 S D Termillalia koilabasensis 11,20 E P CH AS D T siwaliea 35,60 E P N CO ASD T panandhl'Oensis 57,60 E N CO 0 SD Combrellll1l 15,75 E P CH S D paloeodeeandr1117l Lagerslroel1lia siwalica 42,00 E CH S D Woodfordia neofTillicoso 03.00 E CO CR CD Anisophylleo siwalica 20.80 N CH 0 SC Syzygillm l71ioeellielllll 24.44 E N CH CSC S. miooceidenlOlis 08.00 E N CH AS C LOllicera lIIioqllin 08.75 E CH 0 CD [flleloelllaris Randia l71iowallicllii 13.80 E N CH C SD Morinda siwaliea 07,56 E P CH S C Diospyros koilabasensis 09.00 E CH CR S D D. danllajellsis 55,90 E CO 0 S C D. preloposia 108.00 E N CO 0 SD Tabemael7101llalia 13,86 E P N CH C SD precorollaria Carissa koilabasellsis 05.60 E A CH ASD Cae 1'111era siwalica 12,00 E CH ASD Dalllra Illioeelliea 59,20 N P N CH A SC Allacolosa l1Iiolllzolliellsis 23.12 E AN CO A SD Vilex prelleg/lI1do 20.90 E P N CH ASC V siwaliea 31.50 E CH SC Cinnal1l01ll11111171ioinllellllll 06.48 E AN CH C S D Fiells preeullia 20.25 E CO CR SD F relllsoides 3J ,32 E PN CH A S C F Ilepalellsis 28.00 E CO 0 SD Helieia eoerreliea 42.00 E N CH A S C Phyllalllhlls koilabasensis 08.93 E AN CH A C C P llliorelie/dolllS 03.50 E A N CH A C C Anledesma siwaliea 47,15 E CH A SC palterns of plant distribution, The exotic taxa may have had a Nepal in the Neogene Period (Sande & Prakash, 1984; Prasad wider distribution in the Miocene, which subsequently con- & Awasthi, 1996; Prasad el ai" 1997), whereas during tracted perhaps due to a changing climate. On the other hand, Palaeogene the family Fabaceae was hardly represented and these taxa may have reached the Himalayan foot-hills in the Dipterocarpaceae was absent throughout the Indian subcollti- Koilabas area by dispersal mechanism from other subconti- nent. It indicates that these two families may have entered nents, most probably at the time of fonner existed land con- India during the Neogene after the establishment of land con- nections or from other areas of India and Nepal, but subse- nections with areas where they were flourishing in the quently became extinct. Palaeogene Period. The Koilabas assemblage is mainly represented by the Phytogeographically. Dipterocarpaceae may be regarded members of the tropical ramil ies Fabaceae, Dipterocarpaceae as an important family. The present and past distribution of and Anacardiaceae (Table I), The fossil record of these fami- the family indicates that it is pantropical and specially Delong lies shows that they were abundant in other parts of India and to tropical Asia except that twO genera Marquesa and MOIIOle,1 PRASAD et ci/.-FURTHER CONTRIBUTION TO THE SIWALI K FLORA FROM THE KOILABAS AREA. WESTERN NEPAL t) 1 which are distributed in the African regions. The fossil record hills of D:lljeeling District. West Bengal and its palaeoecological suggests that Dipterocarpaceae originated during the early and phytogeographical significance. Palaeobotanisl 42( I) : 14­ Middle Oligocene (Men'ii, 1923; Muller. 1970). Lakh:lI)pal 60. (1974) further envisaged that the family originated in western Antal JS & Prasad M 1995. Fossil leaf of ClillogYlle Salisb. from the Siwalik sediments of Darjeeling District, West' Bengal. Malaysia, where about two third of all dipterocarps species Geophytology 24(2) • 241-243. occur today (Desch, 1957). This region is also quite rich in Antal JS & Prasad M 1996a. Some more leaf-impressions fromlhe the fossil record (Lakhanpal, 1974; Bande & Prakash, 1986). Himalayan foot-hills of Daljeeling District, West Bengal. India. From western Malaysia dipterocarps spread east ward to Palaeobotanist 43(2) : 1-9. Phillippines and northward through Myanmar to India. The Antal JS & Prasad M 1996b. DipterocarpJceous fossil leaves from possible time of the southwest migration was Early Miocene Ghish River section in Himalayan fOOl hills near Oodlabari. when the land connnections between Malaya, Myanmar and Darjeeling District, West Bengal. Palaeobolanisl 43(3) : 73-77. eastern India were established. The abundance ofdipterocarps AnlJI JS & Prasad M 1996c. LeJf-impressions of Polyallhia BI. in such as Diplerocarpus, Anisoplera, Hopea, Dryobalanops in the Siwalik sediments of Darjeeling District. West Bengal. Geophytology 26(1): 125-127. eastem India as well as in southern India during Miocene­ AntJI JS & Prasad M 1997. Angiospermous fossil leaves from the Pliocene times indicates that they spread from eastern India Siwalik sediments (Middle-Miocene) of Darjeeling DistricI, West to south west to Sri Lanka via Himalayan foot-hills where Bengal. PJIJeobotanist 46(3) : 95-104. they are still flourishing. The occurrence ofdipterocarpaceous Antal JS, PrJsJd M & Khare EG 1996. Fossil woods from the Siwalik remains (fossil woods. leaves. fruits. flowers and seeds in the sediments of Darjeeling Dislricl, West Bengal. IndiJ. Himalayan foot-hills (Antal & Awasthi, 1993; Antal & Prasad, Palaeobotanist 43(2) : 98-105. 1996b; Awasthi, 1982: Prasad, 1994a-e; Prasad & Awasthi, Appel E, Rosier W & Corvinus G 1991. MagneloslraligrJphy of lhe 1996) and the Tertiary beds of Africa (Bancroft, 1933; Mio-Pleistocene SuraikholJ Siwalik in West Nepal. Geophy. Chiarugi, 1933) suggests that from eastern India the Journ. Int. V 105: 191-198. dipterocarps also spread westward into Africa most probably AryJ R & Awasthi N 1995. LeJf impressions from Kasauli FormJ­ via Arabia (Lakhanpal, 1970; Seward. 1935). tion, KJSJuli, HimachJI Pradesh Jnd their pJlaeoecological and palaeoenvironmental signillcJnce. SYlNp. Recelll AdvallCes ill In the floral assemblage recovered from Siwalik sedi­ geological.l'IL{(lie.\·ofliorrilll'esl Himalaya olld Ihefol'edl'ep. Ceol. ment of Koilabas area, three types ofelements have been iden­ SlirV. Ilidia. Lllckllow : 104-106 (Abst). tified, viz., (i) Evergreen, (ii) Evergreen and Moist deciduous Ashton PS 1972. Precursor 10 a lJxonomic revision of Ceylon and (iii) Moist deciduous elements (Table 2). The evergreen DipleroCJrpaceae. Blumea 20 (2) : 363. elements dominate the assemblage as compared to other ele­ Auden JB 1935. Traverses in the HimJIJya. Rec. geol. SUl'v.llldia 69 (2): 123-167. ments. This obviously indicates that the tropical evergreen AWJsthi N 1974. Occurrence of some dipterocarpaceous woods in forests were growing around Koilabas area during Middle the Cuddalore Series of south IndiJ. PalJeobotanist 21 (3) : 339­ Miocene as compared to the present mixed deciduous forests 351. in the region. It is further inferred that the evergreen taxa which Awasthi N 1975J. Revision of some dicotyledonous woods from were growing in the vicinity of Koilabas have got migrated to the Tertiary of south IndiJ. PJIJeobotanist 22(3): 186-191. other phytogeographical regions due to unfavourable climatic Awasthi N 1975b. Millellioxyloll il/diculll AWJsthi. a fossil wood of conditions prevailed after Mio-Pliocene Period most prob­ LeguminosJe from the CuddJlore Series of soulh India. ably due [0 the uplift of Himalaya. PalJeobolJnisl 22( I) : 47-50. Awasthi N 1977a. On two new fossil woods resembling Acknowledgements- We express 0111' gralilude 10 Professor A. K. ChrY.l'ophyllll1ll and Holoplelio from the Cuddalore Series neJr Sinho, DireCIOI; Birbal Salmi IIlSlilllle of Palaeobo!any, Llickno\V Pondicherry. Palaeobotanisl 24( I) : 21-25. for his cons!anl illcollmgelllenl and keell inleresl dllring Ihe progress Awasthi N 1977b. Revision of Hopeoxylon ilidicIIl/1 Navale and of Ihis work. We are Ihankfullo Ihe aUlhorilies of FareSI Researsh SllOreoxyloli speciosll/I/ Navale from the Cuddalore Series near InSlilUle. Dehradull und Cenlral Na1iOi101 Herbarilllll, Sibpul; Pondicherry. PJIJeobot:lnist 24(2) : 102-107. Ho\Vrohfor perlllissionlO consuillhe Herbaria. Our Ihanks are olso Awasthi N 1979. Three new leguminous woods from the Cuddalore due 10Shri Rallall Lal Mehmfor processillg Ihe manuscripl ill COIII­ Series near Pondicherry. Palaeoboranist 26(2): 157-166. plllel: Awasthi N J 980. 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