Fossil woods from the Upper Cretaceous to Paleocene of

Global Geology，14( 3) ∶ 192-208( 2011)

doi: 10. 3969 / j. issn. 1673-9736. 2011. 03. 04Article ID: 1673-9736( 2011) 03-0192-17

Fossil woods from the Upper Cretaceous to Paleocene ofHeilongjang ( Amur) River area of China and Russia

Kazuo Terada1，Harufumi Nishida2 and SUN Ge3，4

1． Fukui Prefectural Dinosaur Museum，Katsuyama，Fukui 911-8601，Japan;

2． Faculty of Science and Engineering，Chuo University，Tokyo 112-8551，Japan;

3． Key-Lab for Evolution of Past Life ＆ Environment in NE Asia，MOEC ( Jilin University) ，Changchun，130026 China;

4． College of Paleontology，Shenyang Normal University，Shenyang 110034，China

Received 5 May 2011，accepted 20 May 2011

Abstract : Fossil woods were collected from the Upper Cretaceous to Paleocene beds distributed around Heilong-jang ( Amur) River area of China and Russia． A total of 43 specimens were collected from Baishantou，Long-gushan，and Yong ＇ancun in Jiayin，China，and 85 specimens from Zeya-Bureya Basin lying southeast ofBlagoveshchensk in Russia． Selected specimens were sectioned and studied anatomically． The source depositsof almost all identifiable specimens belong to the Upper Cretaceous ( Campanian) Taipinglinchang Formationand the Paleocene Wuyun Formation in China，and the Paleocene Upper Tsagayan Formation in Russia． Al-though the results obtained are still far from complete，the taxonomic composition of the fossil woods showmarked stratigraphic differences between the two horizons beyond the K /T boundary in China． There is also astrong similarity in wood flora between the Wuyun Formation of China and the Upper Tsagayan Formation ofRussia． All identified specimens from the Taipinglinchang Formation are Xenoxylon latiporosum． This is one ofthe stratigraphically younger records of Xenoxylon，which is a conifer morphogenus of uncertain affinity mostcommon in the Triassic to Early Cretaceous． Only one specimen with possible derivation from either the Wuyunor the Maastrichtian Furao Formation in China was identified as Taxodioxylon sp． The Wuyun Formation yieldedboth conifers and dicotyledonous woods． The conifers include Taxodioxylon sequoianum of the Taxodiaceae，andProtopiceoxylon amurense，which is attributable to the extant genera Keteleeria or Nothotsuga of the Pinaceae，

both are at present endemic to China． At least two morphotypes of dicotyledonous woods were recognized，withone identified as cf． Hamamelidoxylon ，and the other diffuse porous wood is characterized by numerous hetero-geneous rays． From the Zeya-Buleya Basin of Russia，Taxodioxylon sequoianum and cf． Hamamelidoxylon sp．were identified from the Upper Tsagayan Formation． The similarity of wood composition in both Wuyun and Up-per Tsagayan Formations support lithological as well as biostratigraphic correlations proposed for the two forma-tions．Key words: K /T boundary; fossil; wood; Heilongjang; Amur; Zeya-Bureya Basin

IntroductionMuch fossil wood was collected from the strata

extending from the Upper Cretaceous to the Lower Pa-leocene in the Heilongjang ( Amur) River area of Chi-na and Russia during three field work seasons from

2002 to 2004． Specimens were mostly found ex situ，

and possible source horizons of the fossils were in-ferred，in most cases based on local geology，topogra-phy，and specimen features． Most samples were de-rived from two formations in China，namely the UpperCretaceous ( Campanian ) Taipinglinchang Formationand the Lower Paleocene Wuyun Formation ( Table1 ) ． Other samples were derived from the ( Santonian)

Yong＇ancun Formation，the ( lower-middle Maastrich-tian) Yuliangzi and the Furao Formations，though allwere poorly preserved． Most samples from Russia

were originated from the Danian Upper Tsagayan For-mation． The materials collected from the Kundur For-mation，which is correlated with the TaipinglinchangFormation of China，were too poorly preserved to de-serve anatomical study． Details of the field researchcan be found in Sun et al． ( 2002，2004，2005) ． Weconducted anatomical studies on selected specimensand describe here well-preserved and taxonomically i-dentifiable specimens in detail，though not all wereattributable to the species rank．

Table 1 Stratigraphic distribution of fossil wood specimens from Late Cretaceous -Paleocene beds of Heilongjiang RiverArea of China and Russia［Correlations based on Akhmetiev ( 2004) and Sun et al． ( 2005) ］

During field research in the Jiayin area of China，

a total of 43 specimens were collected in 2002，and16 in 2004． Most specimens were collected isolatedfrom their original deposits，except for a few in situspecimens． The specimens from the Yong＇ancun For-mation were two calcareous nodules ( C16-1，C16-2 )

containing degraded plant debris and two carbonizedwoods ( C04-1，C04-2 ) ． All were poorly preservedand not identifiable．

At around Longgushan Locality 20，pieces of si-licified woods were collected ( C11-1 to C11-7，C15-1to C15-13) ． Specimens C15-1 to C15-13 are probablyderived from the Taipinglinchang Formation ( Campa-nian ) ． Specimens C11-3 to C11-7 are believed tohave originated from either the Yulianzi ( low-mid

Maastrichian) or the Taipinglinchang Formation ( Fig．1，A，B) ． C11-1 and C11-2 were probably derivedfrom the Yuliangzi Formation．

Within collections from Baishantou locality，36specimens ( C13-5，C13-7 to C13-19，C14-1 to C14-8，C05-1 to C05-14 ) are inferred to have derivedfrom the Wuyun Formation ( Fig． 1，C-F ) ． In theBaishantou section where the Wuyun Formation is ex-posed the #8 layer is known to yield wood trunks ( Sunet al．，2002 ) ． Some woods were also collected fromthe #7 layer ( C05-4，C05-5) and #l0 layer ( C05-9，

C05-14) ． Specimens C13-1 to C13-4 probably origi-nated from the Furao Formation ( Maastrichian) ． C13-6 was embedded in sandy conglomerate of the FuraoFormation． All samples from the Furao Formation

391Fossil woods from the Upper Cretaceous to Paleocene……

A． Specimen C15-4 ( Xenoxylon latiporosum) on numberedrock． At the Longguhan locality，geological hammer forscale． B． Specimen C15-6 ( Xenoxylon latiporosum) ，penfor scale． C． Baishantou locality photographed during 2002field season． D． Baishantou Section #7 ( dark grey silty mudbelow) and #8 ( coal yielding trunk pointed by arrow) ． E．Specimen C14-7 ( Protopiceoxylon amurense ) ，marker penfor scale． F． Specimen C13-17 ( cf． Hamamelidoxylonsp． ) ．Fig． 1 Fossil wood and collection sites in Jiayin of Hei-

longjiang，China

were poorly preserved and not identifiable．Two specimens ( C11-1，C11-2) of possible ori-

gin in the Yuliangzi Formation were very poorly pre-served and were not identifiable．

In Russia，85 specimens were collected at fourlocalities，the Kundur ( 8 specimens) ，Arkhara-Bou-guchan Coal Mine ( 6 ) ，Bureja ( 43 ) and PioneerCoal Mine ( 28) areas． In this investigation，24 spec-imens from Belaya Gola，4 specimens from the Pio-neer coal mine，and 3 from the Arkhara-Boguchancoal field were sectioned．

The Arkhara-Boguchan coal field yields manywood trunks mainly from parallel laminated mudstoneat the lower part of the Arkhara-Boguchan section( Suzuki et al．，2004; Fig． 2，A，B ) ． All studied

specimens from the Arkhara-Bouguchan coal field( R12-1，R12-2，R12-6) were too poorly preserved todistinguish even coniferous or angiospermous affini-ties． The specimens from Pioneer and Belaya Golawere originated from lower part of the Upper TsagayanFormation ( Fig． 2，C-H) ． Specimens from the Kun-dur area were excavated from the Kundur Formation．Samples were concretions containing very poorly pre-served plant debris，and were not studied．

Materials and MethodsSelected specimens were thin-sectioned and

ground by hand to make microscope slides at the Re-search Center of Paleontology and Stratigraphy，JilinUniversity in Changchun，China or by Nichika Co． inJapan． Twenty-two specimens showed，to varying ex-tents，informative internal structures． Thin sectionswere photographed at Fukui Prefectural Dinosaur Mu-seum．

All specimens and microscopic slides from Chinaand Russia are deposited in the Research Center ofPaleontology and Stratigraphy，Jilin University，andthe Institute of Biology and Soil Science，Far EastBranch，Russia Academy of Science，respectively．

ResultsWith regards to the fossil woods from China，all

identified specimens from the Taipinglinchang Forma-tion were Xenoxylon latiporosum ( Table 1 ) ． Twospecimens from the Yuliangzi or Taipinglinchang For-mation ( C11-3，C11-4) were very poorly preserved，

and were only identified as coniferous wood． Only onespecimen with possible derivation from either theFurao or the Wuyun Formation was identified as Taxo-dioxylon sp．． The Wuyun Formation yielded both co-niferous and dicotyledonous woods． Of 20 studiedwood specimens from the Wuyun Formation at Bais-hantou，three were Protopiceoxylon，one was Taxod-ioxylon sequoianum，six were unidentifiable conifers，and eight were angiosperms ( including three cf．Hamamelidoxylon) ，one other type of diffuse-porouswood，and three very poorly preserved diffuse-porous

491 Kazuo Terada，Harufumi Nishida and SUN Ge

A，B． Arkhara-Bouguchan Coal Mine． A． Lower part of theArkhara-Bouguchan section showing one coal seam and un-derlying mudstone layer ( arrow) containing wood． B． Verti-cally compressed trunk and associated twigs in laminatedmudstone layer indicated in A． C-F． " Pioneer" Raichikhin-sk coal field． C，D． Wood-bearing mudstone layer at upperpart of " Pioneer" section． Horizontal rows of vertically com-pressed trunks are indicated by arrow． E． One of the speci-mens collected ( R9-5，not studied) ，marker pen for scale．F． Silicified trunk probably isolated from coarse to mediumgrained sandstone layer in lower part of the " Pioneer" sec-tion，geological hammer for scale． G，H． Bureya site，onthe other side of Ploskaya Gola over a small pond． H．Woods contained in coarse-grained pebbly sandstone layer( R11-1，R11-2，R11-3) ，geological hammer for scale．Fig． 2 Fossil wood collection sites in the Zeya-Bureya

Basin，Russia

woods． Two specimens were not informative．Most specimens from the Upper Tsagayan Forma-

tion in Russia were very poorly preserved． Of 24 stud-ied specimens from the Bureja site，only five were at-

tributable to either Taxodioxylon or Cupressinoxylonbased on the presence of prominent vertical resin ca-nals and the absence of horizontal resin canals，18were unidentifiable conifers，and one was identified ascf． Hamamelidoxylon． All specimens from the Pioneercoal mine were conifers，including one specimen ofTaxodioxylon sequoianum．

ConiferopsidaFamily incertae sedisXenoxylon latiporosum ( Cramer) Gothan

( Fig． 1，A，B，Plate Ⅰ，A-I)1868 Pinites latiporosus Cramer，． p． 176，pl． 40，figs． 1-8．1905 Xenoxylon latiporosum ( Cramer) Gothan，p． 37-38．1936 Shimakura，p． 278-281，text-fig． 4，pl． 14，figs． 7-8，

pl． 15，figs． 1-8，pl． 16，figs． 1-3，pl． 17，figs． 6-7．1944 Ogura，p． 349-352，pl． 3，G-H，text-fig． 1，A．1982 Du，p． 383-384，pl． 1，1-6．1986 Duan，p． 333，pl． 1，1-4，pl． 2，1-5．2004 Terada et H． Nishida，p． 33，fig． 1，1-5．

Specimens: C15-2，C15-3，C15-4，C15-5 ( insitu) ，C15-6，C15-12 ( all except C15-5 were foundisolated ) ． C15-3 has best preserved the internalstructure among the specimens studied，on which thefollowing description is based．

Locality: Near Longgushan，China ( approxi-mately N48°51． 6'; E130°16． 1')

Possible source horizon: Taipinglinchang For-mation

Description: Coniferous wood constituted of tra-cheids and ray parenchyma． Resin cells and resin ca-nals absent． Growth rings distinct and wide，markedby radially flattened latewood tracheids; ring width 6-9 mm． Transition from earlywood to latewood is ratherabrupt． Earlywood tracheids rectangular or polygonalin cross section，uniform in size，wide; 35-70 ( mean56. 2) × 40-90 ( mean 63. 3μm) in tangential × ra-dial diameters． Latewood very narrow，1-3 cells wide，

tracheids radially flattened，30-50 ( mean 45. 0 ) ×15-40 ( mean 22． 1μm) in tangential × radial diame-ters; walls about 4μm thick． Bordered pits distinct onradial walls of earlywood tracheids arranged contigu-ously in uniseriate rows; pits horizontally flattened andelliptical，about 15-20 ( mean 17. 5) × 25-32 ( mean


28. 3μm) in vertical x radial diameters with round tooval aperture，about 7. 5 μm in diameter; pits on tan-gential walls invisible． Tracheids usually occluded bythin-walled tylosoids，and look like septate tracheids．Helical thickenings unobserved on tracheid walls． Fu-siform parenchyma is absent． Rays wholly composedof parenchyma cells，entirely uniseriate，rather low，

1-14 cells tall or more，mostly 3-8，50-425 ( mean220μm) tall with 25 μm wide． Ray cells sometimesoccluded by a dark substance，but no crystals ob-served． Cross-field pits distinct， large window-likeand usually one per field，25-37 ( mean 32. 9) × 17-22 ( mean 20. 6μm) in radial × vertical diameters．

Affinity: The fossil woods are characterized bythe presence of ( 1 ) single，large and window-likecross-field pits，( 2) vertically compressed，elliptical，uniseriate and contiguous bordered pits on radial wallsof earlywood tracheids，( 3) entirely uniseriate rays of10 or less cells high，( 4) thin-walled tylosoids in thetracheids，and ( 5 ) the absence of axial parenchymaand resin cells or canals． Based on the above featuresthe fossils were assigned to Xenoxylon Gothan．

Twenty or more species of Xenoxylon have beendescribed from various localities of the Northern Hem-isphere ( Vogellehner，1968; Tsunada and Yamazaki，1987，Philippe and Thevenard，1996，Ding et al．，

2000) ． Among them，13 species were reported fromChina and ten of them have been described fromnortheast China，i． e．，X． conchylianum，X． elliptic-um，X． fuxinense，X． hopeiense，X． huolinhense，X．japonicum，X． latiporosum，X． liaoningense X． pei-dense，and X． yixianense ( Ding et al．，2000 ) ． X．watarianum is reported from the Late Turonian to San-tonian of Sakhalin，Russia ( Nishida and Nishida，

1986) ． Our specimens have ( 1) mostly single pit percross-field，( 2) exclusively uniseriate bordered pits，( 3 ) vertically compressed and horizontally flattenedbordered pits，( 4) rays of 10 or less cells high，and( 5) tracheids septation by thin-walled tylosoids． Jud-ging from the features described above，we assignedthe specimens to X． latiporosum．

The youngest record of Xenoxylon is from the

Maastrichian of Northern Alaska ( Spicer and Parrish，

1990) ． Our report therefore provides one of the youn-ger records of Xenoxylon，which are mostly excavatedfrom Triassic to the Early Cretaceous deposits．

ConiferopsidaTaxodiaceae

Taxodioxylon sequoianum ( Mercklin) Gothan( Plate Ⅱ，A-E)

1905 Taxodioxylon sequoianum ( Mercklin) Gothan1933 Shimakura，p． 533-538，figs． 1-6．1944 Ogura，p． 353-356，text． -figs． 1 B-C，pl． 4 A-C．

Specimen: C05-7，R13-11Locality: C05-7: Baishantou of Jiayin，8 km

from Furao in the direction N61 W ( approximatelyN49 18． 7; E129 32． 3 ) ，China; R13-11: PioneerCoal Mine，Russia ( approximately N49 40． 2; E12933． 8) ．

Possible source horizon: C05-7: BaishantouMember of Wuyun Formation; R13-11: Lower Sand-stone Subformation of Upper Tsagayan Formation．

Description: Coniferous wood constituted of tra-cheids with ray parenchyma and resin cells． Traumat-ic resin canals present but normal resin canals absent．Growth rings distinct with 2-7 layers of radially flat-tened latewood tracheids; ring width 1. 2-3. 6 mmwide． Transition from earlywood to latewood abrupt．Earlywood tracheids rectangular or polygonal in crosssection，uniform in size，wide; 25-30 ( mean 31 ) ×30-55 ( mean 44. 5μm) in tangential x radial diame-ters． Latewood tracheids radially flattened，25-30( mean 27. 7) × 13-25 ( mean 20. 3μm) in tangentialx radial diameters． Bordered pits somewhat indistinctbecause of poor preservation; rather dense and ar-ranged in almost 2 rows in earlywood tracheids; circu-lar，about 20μm in diameter，with elliptical aper-tures; pits on tangential walls not visible． Helicalthickenings are not visible． Resin cells indistinct be-cause of poor preservation． Rays uniseriate and rathertall; 1-29 mostly 2-6 cells，30-450 ( mean 146μm)

tall，20μm wide; consisting wholly of parenchymacells． Cross-field pit indistinct because of poor preser-vation，one or two taxodioid pits in a field．


Affinity: The described features fit well withthose of Taxodioxylon sequoianum． Taxodioxylon hasbeen reported from the Early Cretaceous to Cenozoicof Northern Hemisphere ( Yang and Zheng，2003 ) ．Three species of this genus have been described previ-ously from China: T． sequoianum，T． cryptomerioidesand T． szei ( Yang and Zheng，2003) ．

ConiferopsidaTaxodiaceae

Taxodioxylon sp．( Plate Ⅱ，F-I)

2004 Taxodioxylon sp． Terada et H． Nishida，，p． 34，fig．1，6-9．

Specimen: C13-1 ( found isolated)

Locality: Baishantou of Jiayin，6． 5 km fromFurao in the direction N71 W ( approximately N4917． 7; E129 32． 9) in China．

Possible source horizon: Either Wuyun orFurao Formation

Description: Coniferous wood constituted of tra-cheids，ray parenchyma and resin cells． Traumaticresin canals unobserved． Growth rings very distinctwith 5-16 layers of radially flattened and thick-walledlatewood tracheids． Transition from earlywood to late-wood is abrupt． Earlywood tracheids rectangular orpolygonal in cross section，uniform in size，wide; 25-45 ( mean 35. 6) × 25-55 ( mean 37. 5μm) in tangen-tial x radial diameters． Bordered pits on radial wallssometimes poorly preserved． Helical thickenings areinvisible． Resin cells distinct，sometimes observed instrand in earlywood，33-68 ( mean 58. 5μm) in verti-cal length; horizontal walls of resin cells smooth．Rays uniseriate and very tall; wholly consisting of pa-renchyma cells; 1-32，mostly 3-20 cells，30-350( mean 179. 1μm) tall，20μm wide． Cross-field pitindistinct because of poor preservation，one or twotaxodioid pits in a field．

Affinity: The specimen differs from Taxodioxy-lon sequoianum in the absence of traumatic resin ca-nals，and the possession of higher rays． These fea-tures are，however，not diagnostic enough to distin-

guish a different species．

ConiferopsidaPinaceae

Protopiceoxylon amurense Du( Fig． 1，E，Plate Ⅲ，A-I)

1982 Protopiceoxylon amurense Du，p． 384-385，pl． 2，1-9．1997 Wang et al．，p． 972-978，figs． 9-16．2004 Nothotsuga sp． or Keteleeria sp．，Terada et Nishida，

p． 34． fig． 2，1-5．Specimens: C13-11，C14-7 ( found isolated ) ．

Specimen C14-7 showed better preservation，on whichthe following description is mainly based．

Locality: Baishantou，8 km from Furao in thedirection N61 W ( approximately N49 18． 7; E12932． 3)

Possible source horizon: Baishantou Member ofWuyun Formation

Description: Coniferous wood mainly constitutedof tracheids，ray parenchyma and axial resin canals．Radial resin canals absent． Traumatic axial resin ca-nals sometimes present． Axial parenchyma is veryscarce but present near the growth-ring periphery．Growth rings distinct，marked by radially flattenedlatewood tracheids; ring width 1-3 mm wide． Transi-tion from earlywood to latewood is abrupt． Earlywoodtracheids deformed． Latewood tracheids radially flat-tened，20-50 ( mean 35. 8) × 18-30 ( mean 22. 5μm)

in tangential x radial diameters; walls about 6. 5μmthick． Bordered pits distinct on radial walls; pitsdense and oppositely arranged in 1-2 rows，and circu-lar; 26-30 ( mean 28. 3) × 15-20 ( mean 17. 7μm) invertical × radial diameters，with elliptical apertures a-bout 7. 5μm in diameter． Helical thickenings not visi-ble． Horizontal end-walls of epithelium cells of axialresin canals thick and nodular． Rays uniseriate，orbiseriate in part of axial resin canals，rather tall; 1-23cells，mostly 10，40-450 ( mean 185μm ) tall with25μm wide; mostly consisting of parenchyma cells;75-135 ( mean 101. 5 ) × 17-22 ( mean 19. 3μm) invertical x radial diameters; end-walls of ray parenchy-ma cells nodular and thick． Ray tracheid probably ab-sent but irregular-shaped parenchyma cells sometimes


present at ray margins． Cross-field pits indistinct andsmall; 3. 5μm in diameter，2-4 in number，and pi-ceoid．

Affinity: The fossil wood specimens are promi-nently characterized by the presence of axial resin ca-nals and the absence of radial resin canals． Thesecharacters are shared with extant Keteleeria Carriere( 1866) and Nothotsuga ( Hu ex Page ( 1988 ) of thePinaceae ( Yu，1956; Lin et al．，1995; 2000) ，anda fossil species Protopiceoxylon amurense Du，which iscompared with Keteleeria ( Du，1982; Wang et al．，

1997) ． According to Lin et al． ( 1995) ，Keteleeria isdistinguished from Nothotsuga in the absence of raytracheid，which rarely occurs in Nothotsuga． Marginalray cells similar to tracheids sometimes occur in Ketel-eeria． They are larger than usual medial cells，andhave a greater number of pits on radial walls and wavyexternal walls． Greguss ( 1955 ) considers such cellsas forms transitional to tracheids． Axial wood paren-chyma ( rather scanty) and crassulae are also charac-teristic of Keteleeria． The cross-field pitting is taxo-dioid in Keteleeria，while is either taxodioid or piceoidin Nothotsuga ( Lin et al．，1995 ) ． Although imper-fectly preserved and still plausible，structures similarto ray tracheid and piceoid pitting were observed inour specimen．

Du ( 1982) first described Protopiceoxylon amu-rense from the Jurassic to the Early Cretaceous of Hei-longjang Province． The same species was also repor-ted from the Late Cretaceous of the same province( Wang et al．，1997 ) ． Although these earlier de-scribed specimens were excavated from the Jiayin are-a，their source horizons are uncertain． In this studythe species was discovered from the Danian WuyunFormation． It is certain at least that Protopiceoxylonamurense existed during the Paleocene in Heilongjangarea．

MagnoliopsidaFamily incertae sedis

cf． Hamamelidoxylon sp．，( Fig． 1，F，Plate Ⅳ，A-I，Plate Ⅴ，A-E)

2004 Diffuse porous wood 1，Terada et Nishida，p． 34． Fig．2，6-9．

2004 Diffuse porous wood 2，Terada et Nishida，p． 34． Fig．3，1-6．Specimens: C13-16，C13-17，C13-18，C14-2

and R11-21． Specimen R11-21 has best preserved in-ternal structure among the specimens． The followingdescription is based on R11-21．

Localities: C13-16 to C13-18，C14-2: Baishan-tou of Jiayin，8 km from Furao in the direction N61 W( approximately N49 18． 7; E129 32． 3 ) ，in China;

R11-21: Bureya site，en route from Ploskaya Gola toBelaya Gola ( approximately N49 35． 4; E129 35． 4) ，

in Russia．Possible source horizons: C13-16 to C13-18，

C14-2: Baishantou Member of Wuyun Formation;

R11-21: Upper Tsagayan Formation．Description: Wood diffuse，porous composed of

numerous small vessels． Growth rings distinct，deline-ated by several layers of radially flattened fiber-trache-ids at the end of growth rings; ring width 0. 4-2. 4 mmwide． Vessels evenly distributed，numerous; roundand polygonal，almost solitary and sometimes 2-multi-ple; vessels 10-37 ( mean 23) × 20-50 ( mean 38μm)

in tangential × radial diameters; thin-walled． Perfora-tion plate exclusively scalariform with 40-50 bars，andscalariform pits in vessel element tails． Intertrachearyor inter-vessel pits opposite to scalariform． Helicalthickenings unobserved． Thin-walled tyloses abundantin vessels． Fiber-tracheids rectangular，square or po-lygonal in cross section; bordered pits distinct，circu-lar． Axial parenchyma rather inconspicuous． Crystalsnot observed． Rays exclusively uniseriate and rarely2-seriate，heterocellular with upright or square cells;80-600 ( mean 311μm ) tall and 12-18 ( mean14. 5μm) wide． Procumbent cells in the body ofrays，polygonal or vertically elliptical in tangentialsection，15-27 ( mean 20) × 25-55 ( mean 40μm) invertical x radial diameters． Upright or square cells inthe wing of rays，elliptical or oblong in tangential sec-tion，25-42 ( mean 28) × 17． 5-30 ( mean 21μm) invertical x radial diameters． Vessel-ray pits distinct，small，much reduced borders to apparently simple，


horizontally elongated oval or round to scalariform，2-4 ( mean 2. 6) × 2-7 ( mean 3. 6μm) in vertical x ra-dial diameters． Brown-colored substances sometimesobserved．

Affiny: In our previous tentative report the spec-imens were split into two morphotypes ( Terada andNishida，2004) ． This was due to poor preservation ofthe specimens． The new specimen from Russia addedanatomical details to indicate these two morphotypesshould be combined into one． The specimens arecharacterized by diffuse porous wood with numeroussmall vessels，the scalariform perforation plates withnumerous bars， the scalariform intertracheary pits，and the heterocellular and exclusively uniseriate rays．These characters are found in some extant genera offollowing families: Theaceae，Hamamelidaceae，Illi-ciaceae， Cercidiphyllaceae and Symplocaceae． A-mong these families，wood characterized by very nar-row rays occur in Schima，Cleyera ( Theaceae) ，Illici-um ( Illiciaceae ) and Hamamelis ( Hamamelidace-ae) ．

Of the above genera，Illicium seems to be mostcomparable to the fossils in gross anatomical features．Schima has scalariform perforation plates with manybars ( 15-20 ) and axial parenchyma crystals in com-mon． However，the fossils have 40-50 bars in perfora-tion plates，and lack crystals in parenchyma cells．Cleyera is similar to present fossils in having scalari-form perforation plates with 40-50 bars，and exclu-sively uniseriate rays． However，the vessels of Cleyeraare smaller ( 20-30μm in diameter) than those of thefossils and lack thin-walled tyloses． According to Car-lquist ( 1982) ，Illicium has both uniseriate and multi-seriate rays，and larger vessels ( 50-80μm in diame-ter) ． Rays of Illicium are more numerous and tallerand wider than those of the present fossils．

Morphogenus Hamamelidoxylon Lignier ( 1907 )

has been used to put fossil woods attributable to theHamamelidaceae． The wood structure of extant generaof the Hamamelidaceae is quite similar，and there isno good diagnostic feature for generic definition．Hamamelidoxylon is diagnostically characterized by

diffuse-porous wood structure，solitary vessels，scalar-iform perforation plates，apotracheal diffuse parenchy-ma，scalariform vessel-ray pits and uniseriate rays．However，the ray-vessel pits of the present fossilscharacteristically have much reduced borders or aresimple，horizontally elongated oval or round to scalari-form． Hamamelis and Hamamelidoxylon have exclu-sively scalariform vessel-ray pits． Vessel-ray pittingresembling the present fossil is seen in Schima，Cley-era ( Theaceae) ，Corylopsis ( Hamameridaceae) ，Illi-cium ( Illiciaceae) ． Corylopsis has wider rays ( 1-3 se-riate) than those of present fossil． Furthermore，ourfossil wood has fibre-tracheids with distinctly borderedpits． This character is not conspicuous in Hamamelid-oxylon ( Wheeler and Manchester，2002; Takahashiand Suzuki，2003 ) ． Fibre-tracheids with distinctlybordered pits resembling the present fossil are seen inIllicium ( Illiciaceae ) ． However，the wood structureof Illicium is different from those of the fossils beingstudied here as mentioned above． Therefore，we de-scribe the present fossil as cf． Hamamelidoxylon sp．

Magnoliopsidafamilia et genus indet．

"Diffuse porous wood"( Plate Ⅴ，F-I)

2004 Diffuse porous wood 3，Terada et Nishida，p． 34． Fig．2，1-5．Specimen: C14-3 ( in situ)

Locality: Baishantou of Jiayin，8 km from Furaoin the direction N61 W ( approximately N49 18． 7;

E129 32． 3)

Possible source horizon: Baishantou Member ofWuyun Formation

Brief notes: Preservation of this specimen isvery poor． This wood is characterized by numerousrays，which are heterogeneous，1-3 cells wide and of-ten vertically fused by singe rows of cells．

Discussion: There are many studies on Mesozoicfossil woods from northern China ( e． g． Chang，

1929; Zheng and Zhang，1982; Zhang，1983; Du，

1982; Zhang and Cao，1986; Duan，1986; Wang et


al．，1997; Ding et al．，2000a，b; Yang and Zheng，

2003) ． In Heilongjiang Province，at least 12 species( morphotaxa ) belonging to 8 genera ( Xenoxylon，

Protopiceoxylon， Cupressinoxylon， Taxodioxylon，

Glyptostroboxylon， Protocupressinoxylon， Protopodo-carpoxylon，Phoroxylon) have been reported from theMesozoic ( Zheng and Zhang，1982; Du，1982;

Wang et al．，1996，1997; Yang and Zheng，2003) ．Although more detailed classification and taxonomic aswell as biostratigraphic studies are needed，it is note-worthy that all of these earlier described species areeither coniferous or homoxylous wood，and no typicalangiospermous wood has been reported from the area．In our investigation，only a conifer species Xenoxylonlatiporosum was found from the Late Cretaceous Taip-inlingchang Formation．

The dominance of conifers in the Mesozoic woodflora of Heilongjang area，especially in the Late Creta-ceous，does not fit general worldwide increase of angi-osperms at that time． There are reports of Late Creta-ceous dicotyledonous woods from many other localities( Wheeler and Bass，1991) ，e． g．，Japan ( Takahashiand Suzuki，2003) ，North America ( Texas ( Serlin，

1982 ) ，Utah ( Thayn et al．，1985) ，Illinois ( Wheel-er et al．，1987 ) ，New Mexico ( Wheeler et al．，

1995) ) ，Europe ( Britain ( Crawley，2001 ) ，Bel-gium ( Meijer，2000 ) ) ，and Antarctica ( Poole andFrancis，2000; Poole et al．，2000 ) ． According toTakahashi and Suzuki ( 2003 ) ，38 % of total woodsamples from the Late Cretaceous of Hokkaido，Ja-pan，were dicotyledonous woods ( Albian 4%，Ceno-manian 21%，Turonian 52%，Coniacian 38%，San-tonian 48% ) ． However，the leaf assemblages fromthe Taipinlingchang Formation certainly include dicotleaves， e． g．， Trochodendroides， and Platanus( Zhang 1983; Golovneva et al．，2004) ． We have noevidence to clearly explain the absence of angiospermsin the fossil wood assemblages of the TaipinlingchangFormation．

Our study adds new geographic and stratigraphicoccurrence of Xenoxylon latiporosum． This species hasa wide distribution in the Northern Hemisphere，

chronologically appearing from the Late Triassic to theLate Cretaceous ( Vogellehner，1968; Tsunada andYamazaki，1987; Philippe and Thevenard，1996;

Ding et al．，2000 ) ． According to Tsunada andYamazaki ( 1987 ) ，Xenoxylon expanded its distribu-tion from Europe to Asia during the Late Triassic tothe Jurassic，then diminished in Europe in the LateCretaceous，and finally left relict populations in Sa-khalin in the Late Turonian to Santonina ( Nishida andNishida，1986 ) ，and in Alaska in the Maastrichtian( Spicer and Parrish，1990 ) ． Our new record of Xe-noxylon from the Santonian to Campanian of Heilong-jang area adds an important palaeophytogeographic ar-ea in which to test the predicted eastward shift of thegenus during the Late Mesozoic．

Philippe and Thevenard ( 1996) inferred that thedistribution of Xenoxylon was associated with a rela-tively wet and cool climate developed at boreal conti-nental margins． If such ecophysiological feature wasalso applicable to the Taipinlingchang Xenoxylon spe-cies，the palaeoclimate of Heilongjang area in theSantonian-Campanian could have been cool and hu-mid． Further floristic and palaeoclimatological studiesare needed to clarify this．

Protopiceoxylon amurense has an affinity withKeteleeria ( Du，1982; Wang et al．，1997) ． Ketelee-ria is endemic to southern China where warm-templateto subtropical climate dominates． Although Du( 1982) dated P． amurense to the Late Jurassic to theEarly Cretaceous，its source horizon was uncertain．The record of the same species from the Late Creta-ceous Jiayin Group by Wang et al． ( 1997) holds thesame biostratigraphic identification problem，becausethe Jiayin Group includes three formations，the Yon-gancun， the Taipinglinchang， and the Yuliangzi( Wang et al．，1997) ． Wang et al． ( 1997) inferredthat palaeoclimate of Heilongjiang area during the LateCretaceous was humid warm-temperate or subtropical，based on the palaeofloristic composition suggesting thepresence of mixed-coniferous-broadleaved forest． Thisclimatic reconstruction of the Late Cretaceous in Hei-longjiang area contradicts the cooler conditions in-


ferred from the presence of Xenoxylon． One explana-tion could be that the source deposits of previously de-scribed Protopiceoxylon amurense did not belong to theUpper Cretaceous but to the Danian，possibly theWuyun Formation． In this work，at least，Protopi-ceoxylon amurense originated from the Wuyun Forma-tion． Wang et al． ( 1997) also described Cupressioxy-lon and Taxodioxylon together with Protopiceoxylon，

but no Xenoxylon woods were described． Better stra-tigraphically controlled collection of wood specimens isnecessary to confirm the wood biostratigraphy in theHeilongjiang area． The finding of Protopiceoxylon sug-gests the dominance of a humid warm-temperate orsubtropical palaeoclimate in the Paleocene of thearea．Acknowledgement

This work has been supported by the followinggrants: NSFC Project 30220130698 to G． S．，and theGrant-in-Aid for Scientific Research no． 14255007from the Ministry of Education，Culture，Sports，Sci-ence and Technology of Japan to H． N．

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Explanation of PlatesPlate Ⅰ． A-I: Xenoxylon latiporosum ( Cramer) Gothan，

A-D． Specimen C15-3，E，F． C15-4，G，H． C15-2，I． C15-5． A，B，G． Cross-sections showing distinct growth rings withnarrow latewood． Scale bars: A = 500 m; B，G = 100 m．C，D，H，I． Radial sections showing numerous uniseriate，el-liptical and contiguous bordered pits and large window-likecross-field pits． Scale bars: C，H = 50 m; D = 10 m，I =100 m． E，F． Tangential sections showing uniseriate rays andtracheids with tylosoids． Scale bars: E = 100 m; F = 50 m．

Plate Ⅱ． A-E: Taxodioxylon sequoianum ( Mercklin )

Gothan，Specimen R13-11． A． Cross section showing distinctgrowth rings． Scale bar = 500 m． B． Cross section showingtraumatic resin canals． Scale bar = 100 m． C． Tangential sec-tion showing uniseriate rays． Scale bar = 100 m． D，E． Ra-dial sections showing numerous 2-seriate bordered pits and ind-stinct cross-field pits． Scale bars: D = 100 m; E = 50 m． F-I． Taxodioxylon sp．，Specimen C13-1． F． Cross section show-ing a distinct growth ring． Scale bar = 100 m． G． Tangentialsection showing uniseriate rays． Scale bar = 100 m． H． Ra-dial section showing indstinct cross-field pits． Scale bar = 50m． G． Tangential section showing smooth horizontal walls ofresin cells． Scale bar = 50 m．

Plate Ⅲ． A-I: Protopiceoxylon amurense Du，A-F． Speci-men C13-11，G-I． C14-7． A，G． Cross sections showing dis-tinct growth rings with axial resin canals． Scale bar = 100 m．B，H． Tangential sections showing uniseriate rays lacking ra-dial resin canals． Scale bar = 100 m． C． Tangential sectionshowing thick nodular end-walls of epithelium cells and biseri-ate rays． Scale bar = 100 m． D． Radial section showing rayparenchyma cells． Scale bar = 100 m． E，F，I． Radial sec-tions showing possible piceoid cross-field pits and uni- or bise-riate bordered pits． Scale bars = 50 m．

Plate Ⅳ． A-I． cf． Hamamelidoxylon sp．，A-H． Speci-men R11-21，I． C14-2． A，B，I． Cross sections showing dif-fuse porous wood with numerous small vessels． Scale bars: A，

I = 500 m; B = 100 m． C，D． Tangential sections showingexclusively uniseriate，heterocellular rays and abundant tylosisin vessels． Scale bars: C = 100 m; D = 50 m． E． Radialsection showing ray parenchyma． Scale bar = 100 m． F，G．Radial sections showing bordered pits of fiber-tracheids andscalariform perforation plates with numerous bars． Scale bars= 50 m． H． Radial section showing small，simple and ovalvessel-ray pits． Scale bar = 10 m．

Plate Ⅴ． A-E． cf． Hamamelidoxylon sp．，A-C． Speci-men C14-2，D，E． C13-17． A，D． Cross sections showing dif-fuse porous wood with numerous small vessels． Scale bars =100 m． B，E． Radial sections showing scalariform perforationplates and small vessel-ray pits． Scale bars = 50 m． C． Ra-dial section showing small，simple and oval vessel-ray pits．Scale bar = 10 m． F-I． " Diffuse porous wood" ． SpecimenC14-3． F． Cross section showing diffuse porous wood． Scalebar = 100 m． G． Tangential section showing multiseriate andvertically fused rays． Scale bar = 100 m． H，I． Radial sec-tions showing heterocellular rays and gummy deposits in ves-sels． Scale bars: H = 100 m; I = 50 m．


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Fossil woods from the Upper Cretaceous to Paleocene of