LOWER DEVONIAN lVIICROVERTEBRATES FROM LONGMENSHAN, SICHUAN, CHTNA :

PRELIMTNARY REPORT

SUSAN TURNER, SHI-TAO WANG & GAVIN C. YOUNG

TURNER S., WANG S-T. & YOUNG G.C. 1995. Lower Devonian microvertebrates from Longmenshan, Sichuan, China : preliminary report. [Microvertdbrds du Ddvonien infdrieur de Longmenshan, Sichuan, Chine : rapport prdliminaire]. GEOBIOS, M.S. n ° 19 : 383-387.

ABSTRACT

Microvertebrates from Pragian-Emsian marine limestones of Longmenshan comprise dominant acanthodian and placoderm scales, fewer chondrichthyan, actinopterygian and sarcopterygian remains. Preliminary assessment suggests close links with vertebrate communities elsewhere in southern China and eastern Australia ; cosmopoli- tan elements also occur.

KEY-WORDS : DEVONIAN, CHINA, PLACODERMI, CHONDRICHTHYES, ACANTHODII, OSTEICHTHYES.

RESUMI~

Les microvertdbrds des calcaires marins d'~ge Praguien-Emsien de Longmenshan comprennent essentiellement des dcailles d'Acanthodiens et de Placodermes et, en quantitd moindre, des restes de Chondrichthyiens, d'Actinop- tdrygiens et de Sarcopt~rygiens. Les ddterminations prdliminaires suggdrent des liens proches avec les communau- t~s de Vertdbrds de Chine du Sud et d'Australie orientale ; des dldments cosmopolites y figurent ausssi.

MOTS-CLl~S : D]~VONIEN, CHINE, PLACODERMI, CHONDRICHTHYES, ACANTHODII, OSTEICHTHYES.

INTRODUCTION Microvertebrate fossils were selected (W S-t) from Longmenshan section conodont sample resi- dues ; all have B. - y numbers (Institute of Geolo- gy, Beijing - IGB coll.). Co-operative work in Queensland took place under the auspices of Australian Research Council grants A38330338 and A39132723 and Unesco-IUGS IGCP 328, and at the Austral ian Geological Survey Organisation (then Bureau of Mineral Resources), Canberra.

GEOLOGY The Devonian of Ganxi-Shawozi sections is sub- divided into six stratigraphic units (see Fig. 1). Macrovertebrates in the Pingyipu Group (Gp, which yields no conodonts) include yunnanolepid antiarchs, macropetalichthyids, arthrodires and sarcopterygians (Wang 1988) from the Lochko- vian/Pragian littoral facies in the Longmen Gulf

tidal flat. The microvertebrates come from Pra- gian to Emsian marine limestones in the Bailiu- ping to Yangmaba Formations (Fm.) in platfor- mal deposits. Samples B1-35 and B69-83 yielded no microvertebrates but remains are particularly common in the Ganxi and Xiejiawan Fms (dehis- cens to perbonus conodont zones) in shallow wa- ter facies. The base of the Emsian is based on brachiopods. The base of the Middle Devonian is the base of Bed 93.

F I S H

Table 1/Fig. 2 summarise the stratigraphic dis- tribution of taxa. Dominant acanthodians include scales of possible poracanthodids and nostole- pids; Cheiracanthoides? ; gomphonchid scales and toothwhorl comparable with Gomphonchus liujingensis WANG N-Z, 1992 and G. guangxiensis (WANG) (Burrow in press) from South China and eastern Australia ; climatiid? spine with chevron

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ornament ; "Acanthodes cf. A. dublinensis" STAUF- FER similar to those elsewhere in late Early De- vonian (Wells 1944) ; Machaeracan thus sp. scales (cf. Wang 1992) - common throughout. Cheiracan- thoides comptus WELLS appears in the basal Em- sian and wi th Machaeracan thus predominates thereafter.

Abundant placoderm remains include buchanos- teid type scales with 10-40 stellate tubercles, a plicated fringe and a flat to rounded base ; mono- tubercular body scales ; possible petalichthyid or yunnanolepid scales with simple ridge and tuber- cle ornament - such placoderms occur in the Pingyipu Group jus t below the levels containing the scales recorded here.

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Figure 2 - Lower Devonian vertebrate microremains fFonl Longmenshan section : 1, IGB B53-y1.1, ptacodenn P5, trunk scale cf. Pilolepis ; 2, [GB B53-yl.2, placoderm? scale ; 3, IGB B48-y2.1, Iophosteiform or actinopterygian scale ; 4, IGB B53-yl.3, C2 Ohiolepis eft O. newberryi ; 5, IGB B48-y4.1, $3 dipnoan? toothplate fragment ; 6, IGB 53-yl.4, O6 lophosteiform spine. Scale-bar = 0.1 ram. Microvertdbr& du Ddvonien infdrieur de Longmenshan : l, IGB B53-yL1, Placoderme P5. cfi Pilolepis ; 2, IGB B53.yl.2, &aille de Placoderme? ; 3, IGB B48-y2.1, 4eailIe de Laphost4i[brrne ou d' Actinoptdryg~ien : 4, [GB B53-yl.3, C2 Ohiolepis cfi O. newberryi ; 5, IGB B48-y4.1, $3 fragment de plaque dentaire de Dipneuste? ; 6, [(-IB 53-yl.4, 06 4pin.e de L~)ph.ostdi/brme. Echelle = 0,1 ram.

Polygonal scales (B53/66) wi th e longate mult i-r ib- bed tuberc les might belong to a pa l aeacan thasp id or acan tho thorac id re la ted to Pi lo l ep i s m a r g a r i t i - /'era TI-tORSTEINSSON (Fig. 2 .1 ) . Chondr i ch thyans include scales comparable wi th those called "Gualepis" sp. by Wang 1992, which do not look like the type. Ohio lep i s type scales are found t l~ 'oughout wi th Ohio lep i s cf. O. n e w b e r r y i (WELLS, 1944) p resen t in the Ems ian (Fig. 2.4). Scales comparable wi th W u x u a n i c h t h y s watk8i WANG 1992 also occur in the Emsian.

Palaeoniscoid scales fi'orn the Ganxi Fo rma t ion belong to cK D i a p i l i n a m a r k a e Mmwn f)om Cana- da and the Lochkov ian-Prag ian Kure ika and Ra- zvedochny Format ions , Kotui basin and Nor i l sk Region, Siber ia (Schultze 1992). L i g u l a l e p i s t o o m b s i SCHULTZE, scales and a small jawbone, en te rs in the mid Emsian . Dist inct ive pla tes and a spine (Figs. 2.3,6) m a y be L o p h o s t e u s s u p e r b u s of Otto (1991, fig. 1B) which he believes migh t not be an os te ich thyan (see C. Burrow, this vo- lume).

386

total sf ' 3 15 l b 8 9 l 9 J 53 43 15 I 7 2 3 9 l l 8 a l 3 I t 19

A [ C h e l m c a m h o i d c s ? x X x x x x x x

A2 C, c o m p t u s x x x x

x x x x x x A3 N ~ l o l ¢ p i s ? spp. x x x

A 4 p o ~ c a m h o d a d x x x A5 Ecmpacamhus? sp. x x x x x x • A6 Q? l i u ) i n g c n s l s x x x? x x x? x ?

A7 W a t s o n a c a a t h u s ? sp. x x A 8 $ o m p h o a e h i d ? x x x x x

A 9 G?. t ~ t h w h o r l x A I 0 A e a n t h o d e $ ? el . d t l h i i n ¢ ~ i s x x x x x x

A I 1 a c a a t h s p i n e n e w x

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P f b u c h a n o s t e i d * t a l e x x x x x? x x x x x x

P2 [ r a l aeoacan th . sca le , x x x x P3 y u r m a n o l © p f d ? x x x x x'! x?

P4 r a d o t i m d ? s ca l e x x P5 cL I h l o f e p i s x x

P6 hish cones x x P7 spiky tube~ le x x x x x

x P8 cf . B r l n d a b e l l ~ p i s x P9 p i a e o d e r m sca les u n d e l x x ' x x x x x x P I 0 r o u n d e d t u b e r c l e x x

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O6 ] o p h ~ t m t o n m x x 0 7 p a l a e o n i s c o i d other x x x x x C I k G u a l e p i s , sp. x x x x x

C2 Ob lo lep i s cf. newbcr ry l x x x x x

C3 O t u o l e p i s ' ! x x x x C4 W u x u a z u c h l h y s sp. x x ?

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s s You : ~ o l e p s ? so. x s a m I I¢ no . 3 6 3 7 3 8 3 9 4 0 41 4 2 4 4 4 7 4 8 5 0 5 3 5 4 $ 5 5 6 5 8 6 3 6 4 6 6 6 7

Table 1 - Lower Devonian taxa in Bailiuping (Samples B31-36), Ganxi (B37-50) and Xiejiawan Formations (B51-68), Longmens- han, China. A, acanthodians ; P, placoderms ; O, osteichthyans, actinopterygians or related forms ; C, chondrichthyans ; S, sarcopterygians. Missing sample numbers denote no fish or indeterminate bone present. Taxa du DEvonien inf~rieur des forma- tions de Bailiuping (Echantillons B31-36), Ganxi (B37-50) et Xiejiawan (B51-68), Longmenshan, Chine. A, Acanthodiens ; P, Placodermes ; O, OstEichthyens, ActinoptErygiens ou formes apparentEes ; C, Chondrichthyens ; S, SarcoptErygiens. Les numdros d'Echantillons manquants correspondent soit ~ l'absence de microrestes soit ~z la presence d'os inddterminEs.

Sarcopterygian scales occur in older horizons. Scales with minute horseshoe pat tern ornament (V'yushkova 1992) are similar to those elsewhere in Lower Devonian marine deposits. One resem- bles a Y o u n g o l e p i s t runk scale (Tong-Dzuy & Janvier 1990 : pl. VIII/5). Onychodont teeth ap- pear at Longmenshan in the lower Emsian. One small toothplate f ragment (Fig. 2.5) might belong to the labial dentit ion of a dipnoan or to an unknown chondrichthyan.

SIGNIFICANCE

The Longmenshan vertebrate microfauna is simi- lar to those from the Lower Devonian of central Guangxi Province, the Bac Bun Suite of northern Vietnam and the Pragian-Emsian of eastern Aus- tralia. The cosmopolitan elements (especially acanthodians) are comparable with those, for ins- tance, of the Telengitian of Salair (V'yushkova 1992). The Xiejiawan Formation fauna mirrors tha t in the Ganxi Formation but with the addi- tion of new acanthodian, placoderm and palaeo- niscoid scales. This late Emsian fauna is close to

tha t typified by Wells (1944). The use of acantho- dians for worldwide correlation is supported, the problem being to identify scales to species level when they show a large range of morphological and even histological variation. Placoderm, chon- drichthyan and palaeoniscoid scales are fur ther useful in refining correlation.

The absence of agnathan microfossils might re- flect small sample size or a similar hia tus in cer- ta in marine limestones of eastern Austral ia and central Europe. Faunal differences in t ime are re- latively minor and might be linked to environ- mental conditions. However, there seems to be a significant changeover of taxa in the early Em- sian.

Acknowledgments - We thank Xiong Jianfei, Ji Qiang, Tian Chuanrong, Qian Yongzhen, Dong Zhizhong, Han Yingiian (Chengdu and Beijing Institutes of Geology) for use of their collections ; Carole Burrow (Univ. Queensland) and the staff of the Queensland Museum gave valuable help.

387

This is a cont r ibut ion to IGCP 328. Palaeozoic Micro- ver tebra tes .

R E F E R E N C E S

BURROW C. in press. - Microver tebra te b ios t r a t ig raphy of Lower Devonian mar ine sed iments (pesavis/sul- catus conodont zones) from cent ra l New South Wa- les, Aus t ra l i a . In The Wal te r Gross Symposium. Modern Geology.

BURROW C. 1995 - A new lophosteiform (Osteichthyes) from the Lower Devonian of Aus t ra l ia . In H. LELI~.- V-RE, S. WENZ, A. BLIECK & R. CLOUTIER (eds.) : Pre- miers Vert6br6s et Vert6br6s inf~rieurs. Geobios, M . S . 19 : 327-333.

OTTO M. 1991 - Zur sys temat i schen S te l lung der Lo- phos te iden (Obersilur, Pisces inc. sedis). Pal~ionto- logische Zeitschrift, 65 : 345-350.

SCHULTZE H-P. 1992. - Ea r ly Devonian act inoptery- g ians (Oste ichthyans , Pisces) from Siberia. Acade- mia, 1, Ta l l inn : 233-242.

THORSTEINSSON R. 1973 - Dermal e lements of a new lower ve r t eb r a t e from Middle S i lu r ian (upper Wen- lockian) rocks of the C a n a d i a n Arctic Archipelago. Palaeontographica, A, 143 : 51-57.

TONG-DZUY T. & JAN~ER Ph. 1990 - Les Vert6br6s du D6vonien inf6r ieur du Bac Bo or ienta l (provinces de Bac Tha~ e t Lang Son, Vi~t Nam). Bulletin du Mu- sdum national d'Histoire naturelle Paris, 4, 12, C, (2) : 143-223.

V'YUSHKOVA L. 1992 - F ish assemblages and facies in the Telengi t ian Suprahor izon of Salair . Academia, 1, Tal l inn : 281-288.

WANG N-Z. 1992 - Microremains of agna thans and fis- hes from Lower Devonian of centra l Guangxi wi th correlat ion of Lower Devonian between cen t ra l Guangxi and eas te rn Yunnan, South China. Acta Palaeontologica Sinica, 31 : 280-303.

WANG S-T. 1988 - Ver tebra te Paleontology. In HOU et al. (eds) : Devonian Stratigraphy, Paleontology and Sedimentary Facies of Longmenshan, Sichuan. Geo- logical Publ i sh ing House, Bei j ing : 96-99, 339-345, 406-410, 466-467. (In chinese, wi th engl ish summa- ry).

WELLS J.W. 1944 - F i sh r ema ins from the Middle De- vonian bone beds of the Cincinnat i Arch. Palaeonto- graphica Americana, 3, (6) : 5-60.

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