A New Gymnospermous Wood from Raniganj Coalfield, India
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The Pa/aeobotanist, 26(3): 230-236, 1980. PALAEOSPIROXYLON - A NEW GYMNOSPERMOUS WOOD FROM RANIGANJ COALFIELD, INDIA M. N. V. PRASAD & SHAlLA CHANDRA BirbaI Sahni Institute of Palaeobotany, Lucknow-226 007, India ABSTRACT !,a/a.eospiroxy/oll ileterocel/u/aris gen. et sp. nov., collected from BonbahaI Colliery, Ra OlganJ Coalfield, West Bengal, India has been described. The salient features of. the wood are the presence of secretory cells in pith, endarch primary xylem, mIxed type of tracheid wall pitting and spiral thickenings in the secondary xylem. Key-words- Pa/aeospiroxy/oll, Gymllospermous wood, Upper Permian, Raniganj Coalfield (India). mmr ~RT*r ~~-~, 'lfmf ~ 'Z~ <r<ft;r3R"T'f~~- llTOliT ~ <n: 5ltIR ~ *m 'iRT ' ~ 'fi'n:rm-WR, ~ 'fi'n:rm-ffi;r, ~ <i<m1, mur ~ ~ ~~T• ~ ~~ 'f 0 5l;;rrRr q 'f 0 ;;rrRr 'fiT 'f1lFr fil;1;rr iTllf ~ I l'f'NfT it mcft ~T 'liT ~, ~ omr ~, fi:lfl!lQ 'fT~f.rI;T f'lTfu -m'f ~ ~ ~ it ~ ~ W 'liT'5OWT ifi mTT'f "f!\iUT ~ I INTRODUCTION xylem) from West Jamuria Colliery of the Raniganj Coalfield. In 1967, he also described Damudoxylon waltonii, Megaporo• have been described from Raniganj xylon krauselii and Trigonomyelon rani• SEVERAL fossil gymnospermous woods Coalfield by various authors Sahni, ganjense from West Jamuria Collier y, (1925 in Bradshaw); Sahni (1932); Fox, Raniganj Coalfield. (1934); Rao (1935); Maheshwari (1965,1967). However, so far no wood with secretory Shani (in Bradshaw, 1925) described a cells in the pith, endarch primary xylem, wood under the name Dadoxylon sp. from mixed type of tracheid pitting and spiral the Raniganj Coalfield near Asansol. Also thickenings in the secondary xylem tra• in 1932, Sahni described Dadoxylon cheids is known from the Raniganj Coal• zalesskyi from Kumarpur near Asansol field. Also this fossil wood is quite which Maheshwari (1967) revised as distinct from hitherto known woods of Kaokoxylon zalesskyi because of the pre• Indian Lower Gondwana and is therefore sence of sclerotic cells in the pith. Fox described as a new form genus. (1934) described Dadoxylon kumarpurensis from Kumarpur beds. In 1935, Rao described a new species of Dadoxylon, DESCRIPTION D. parbeliense from a sphaerosiderite col• lected from Parbelia Colliery. Maheshwari The material consists of a single piece (1965) described Dadoxylon ningahense from of petrified wood measuring 29 cm in the Ningah Colliery and Dadoxylon jamuri• length and 11 cm in diameter. The speci• ense (with pith, primary xylem & secondary men is carbonaceous and well-preserved. 230 PRASAD & CHANDRA-PALAEoSP1ROXYLON-A NEW GYMNOSPERMOUS WOOD 231 Palaeospiroxylon gen. novo the radial walls of tracheids 1-3 seriate, rarely 4 seriate (PI. 1, figs 7-9; Text-fig. Generic Diagnosis - Pith with secretory Ie-G). The radial diameter of the tra• cells; primary xylem endarch; secondary cheids is 60-104 (.Lm. Pitting is of mixed xylem with mixed type of pitting, spiral type, i.e. araucarioid and abietoid type of thickenings running clock wise and anti• pits are found in the same or in different clockwise. tracheids of the same specimen (PI. 1, figs 8, 9; Text-fig. ID-G). Pits measure from 14-20 [Lm in diameter, and they are Genotype - Palaeospiroxylon heterocellularis circular, bordered, separate (contiguous sp. novo when hexagonal). The pit pores are sub• circular, borders are not well-preserved at Pith heterogeneous, irregularly oval in many places. The crossfield pits are up shape, measuring 9 x4 mm in size, made to 9 (PI. 1, fig. 10; Text-fig. 11, K); circular• up of irregular parenchymatous cells inter• subcircular, bordered with subcircular pit mixed with dark secretory cells and secre• pores, measuring 6-12 [Lill in diameter. tory matter (PI. 1, fig. 1). The pith cells The spiral thickenings of both radial and in longitudinal section cylindrical in shape tangential walls of the tracheids measure with dark secretory matter in between up to 4-8 [Lm thick running clockwise• them (PI. 1, fig. 2). The primary xylem is anticlockwise, inclined at an angle of 40°• endarch (PI. 1, fig. 3). In cross section 60° (PI. 1, figs 11, 12; Text-fig. 1H, I). the primary xylem tracheids abutting the Quite often the tangential tracheid wall pith are 5-13 in number, circular-barrel in spirals are not preserved. The radial wall shape. The p;'otoxylem is formed by spiral spirals usually pass across the border of form tracheids followed by the scalariform the pits but otherwise they pass through metaxylem. The secondary xylem consists the space between the separate pits. In of b,Jrdered pitted tracheids. The secon• cross section the secondary wood tracheids dary xylem is pycnoxylic type, represented show broad transparent bands on the inner by early wood and late wood, showing side of the tracheids which represent the sharp growth rings (PI. 1, fig. 1). In cross spiral thickenings (PI. 1, fig. 13; Text-fig. section the early wood tracheids are 60-110 lL). in width, isodiametrical-polygonal in shape measuring 20 X 24-48 x60 [Lm in size with thin walls and wide lumen. The late Palaeospiroxylon heterocellular is sp. novo wood zone is represented by 4-8 compactly arranged tracheids, rectangular in shape Specific Diagnosis - Pith irregularly measuring 14 X 16-12 x24 [Lmwith thick walls oval, heterogeneous, parenchymatous cells and reduced lumen. The medullary rays in intermixed with dark secretory cells; cross section are plac~d at an interval of primary xylem endarch; secondary xylem 1-11 tracheids. The rays are homogeneous, pycnoxylic; growth rings sharply marked; uniseriate - partly biseriate, 1-18 Cells high. late wood 4-8 tracheids wide, rectangular, The ray cells are circular-barrel in shape compactly arranged; early wood tracheids measuring 18-40 [Lill in height and 14-24 [Lm isodiametrical-polygonal, 60-110 tracheids in width. The tangential tracheid walls wide; medullary rays homogeneous, 1-2 show uniseriate-partly bis·~riate, circular, s;:riate, 1-18 cells high; tangential tracheid bordered pits measuring 8-10 [Lm in dia• walls show 1-2 seriate, circular bordered, meter (PI. 1, fig. 6; Text-fig. IB). The separate-contiguous pits; radial tracheid tangential diameter of the tracheids is 36-88 walls show 1-3 seriate, rarely 4 seriate, [Lill. The height and seriation of medullary mixed type of pits; crossfield pits up to 9, rays have been studied from 2 cm away circular-oval, bordered with subcircular pit from the pith (PI. 1, fig. 4) and from the pores; radial and tangential walls of the outer most region of the wood (PI. 1, fig. 5; secondary xylem tracheids show spiral Text-fig. lA). This study has revealed thickenings running clockwise-anticlockwise, that the height and seriation of medullary inclined at an angl~ of 40°-60°. rays increases towards outer most region Holotype - Birbal Sahni Institute of of the wood (Tables 1, 2). The pits on Palaeobotany Museum specimen no. 35310. 232 THE PALAEOBOTANlST G D - ?=©Q) ©XQ) ==- c ~ ......• - H A J -~I!l0@eoIte @ - E - @<D© @@- €) -\ - er:liJ F I K TEXT-FIG. 1 PRASAD &. CHANDRA-FALAEOSPlROXYLON-A NEW GYMNOSPERMOUS WOOD 233 TABLE I-HEIGHT AND SERIATION OF MEDULLARY RAYS 2 em AWAY FROM PITH S. No. LARY20032204121(25)182(1)(4)(2)1161757(9)(1)20125(2)(1)(8)(3)83467591511101929(1)92012 40(10)(1)1(1)1(6) HEIGHT38(4)OF MEDULLARY42 RAYS39(1)IN TERMSOF RAYNo.CELLSOF RAYS (1) counts (4)(2)2 (1)(2) (1) rays.COUNTEDMEDUL- TotalIIIJIVIV*Figures in the3 brackets indicate the number of occurrence of biseriate or partly biseriate medullary Locality - Bonbahal Colliery, Raniganj secretory canals as well as secretory cells Coalfield, West Bengal, India. in the pith. Except for this small varia• Horizon & Age - Raniganj Formation, tion, the details of primary xylem and the Upper Permian. secondary xylem in the two genera are similar to the form genus Dadoxylon Endlicher (1847). Thus several form genera COMPARISON AND DISCUSSION of woods show little variation in the pri• mary xylem and secondary xylem but show While dealing with the classification of different kinds of pith. This problem has Palaeozoic gymnospermous woods, con• been discussed by Lepekhina (1972) while siderable emphasis is laid on the pith and dealing with the classification of Dadoxylae. its detail structures. For example, the Therefore the main emphasis was laid on form genus Kaokoxylon has been instituted the structure of pith, in addition to the by Krausel (1956) to accommodate woods characters of the primary xylem and the showing sclerotic nests dispersed in the secondary xylem. pith. Likewise the form genus Barakaro• However, mostly decorticated secondary xybn Surange & Maithy (1961) shows woods are found from the Palaeozoic sedi- TEXT-FIG. 1 - A. Tangential longitudinal section showing the height and seriation of medullary rays from the outer most region of secondary wood x 112. B. Tangential longitudinal section showing tangen• tial tracheid wall pits x 225. C. Radial longitudinal section showing uniseriate pits x 225. D. Radiallongi• tudinal section showing biseriate opposite pits x 225. E. Radial longitudinal section showing biseriate opposite contiguous pits x 225. F. Radial longitudinal section showing biseriate alternate contiguous pits x 225. G. Radial longitudinal section showing 3 seriate opposite-alternate pits x 225. H. RadiallongI• tudinal seclion showing spiral thickenings running clock-anti clockwise x 225. I. Radial longitudinal section showing spiral thickenings running over the pit border x 225. J, K. Radial longitudinal section showing crossfield pits x 225. L. Cross section showing broad transparent bands on the inner side of the tracheids representing spiral thickenings x 225. 234 THE PALAEOBOTANIST ments as the delicate, vulnerable primary xykm and the pith get easily detached or destroyed from the secondary wood, during the process of fossilization. Thus the taxo• nomy of Palaeozoic fossil woods follow two parallel series of generic names: 1.