Early permian (Sakmarian)brachiopods from southeastern Oman

EARLY PERMIAN (SAKMARIAN) BRACHIOPODS FROM

SOUTHEASTERN OMAN

LUCIA ANGIOLINI , HUGO B U C H E R , ALAm PILLEVUIT, JEAN-PIERRE PLATEL, JACK R O G E R , JEAN B R O U T I N , AYMON BAUD, JEAN MARCOUX & HAROUB AL H A S H M I

ANGIOLINI L., BUCHER H., PILLEVUIT A., PLATEL J-P., ROGER J., BROUTIN J., BAUD A., MARCOUX J. & AL HASHMI H. 1997. Early Permian (Sakmarian) brachiopods from southeastern Oman. [Brachiopodes du Permien infSrieur (Sakmarien) du Sud-Est de l'Oman]. GEOBIOS, 30, 3: 379-405. Villeurbanne, le 30.06.1997.

Manuscrit d~pos5 le 22.12.1995; accept4 d~finitivement le 01.06.1996.

ABSTRACT - The Lower Permian succession of the Huqf area (Sultanate of Oman) represents the uppermost part of a mega-sequence which includes the Late Carboniferous to ?Sakmarian tillites of the A1 K_hlata Fm. and the overlying transgressive marine Saiwan Fro. of Early Permian age. The Saiwan yields a rich brachiopod fauna associated with bivalves, gastropods, crinoids, conularids, cephalopods and bryozoans. The brachiopod fauna of the Saiwan includes Derbyia haroubi nov. sp., Arctitreta c£ bioni (REED), Reedoconcha permixta (REED), Neospirifer aff. hardmani (FOORD), Neospirifer sp., Trigonotreta sp., ?Cyrtella aff. nagmargensis (BION), Subansiria sp., Punctocyrtella spi- n o s a PLODOWSKI, Punctospirifer sp., Callispirina sp., Fletcherithyris sp., ?Gilledia sp. This brachiopod assemblage indicates a Late Sakmarian age. Application of the Unitary Association method (Guex 1991) to the brachiopod data of the Saiwan leads to establish a local biochronological sequence of three faunal associations.

KEYWORDS: OMAN, SAIWAN FORMATION, BRACHIOPODS, SAKMARIAN, BIOSTRATIGRAPHY.

R]~SUMt~ - La succession des s~diments du Permien infgrieur dans la r5gion du Huqf (Sultanat d'Oman) repr~sen- te le terme ultime d'une m6gasdquence qui d4bute par les tillites de la Formation A1 Khlata (CarboniFere sup~rieur- ?Sakmarien) et qui se poursuit par les d~p6ts marins trangressifs de la Formation Saiwan d'fige sakmarien. Cette derni~re unitg contient une trgs riche faune de brachiopodes associ4e h des bivalves, gast~ropodes, crinoides, conu- larides, c6phalopodes et bryozoaires. La faune de brachiopodes de la Formation Saiwan contient Derbyia haroubi nov. sp., Arctitreta cf. bioni (REED), Reedoconcha permixta (REED), Neospirifer aff. hardmani (FooRD), Neospirifer sp., Trigonotreta sp., ?Cyrtella nagmargensis (BION), Subansiria sp., Punctocyrtella spinosa PLODOWSKI, Punctospirifer sp., Callispirina sp., Fletcherithyris sp., ?Gilledia sp. L'fige de cette faune est Sakmarien sup~rieur. Le traitement de ces donnfies biostratigraphiques par la m~thode des associations unitaires (Guex 1991) permet d'~tablir une succession chronologique locale comprenant trois associations.

MOTS-CL]~S: OMAN, FORMATION DE SAIWAN, BRACHIOPODES, SAKMARIEN, BIOSTRATIGRAPHIE.

INTRODUCTION

This pa pe r deals wi th the uppe r S a k m a r i a n brachiopod f a u n a of the Sa iwan Forma t ion from the H u q f a rea in sou th -ea s t e rn Oman. L imi ted collec- t ions f rom the H u q f a rea were made by A. Pi l levui t in 1991. In 1995, two sections (Saiwan and Wadi Haush i ) were t ho rough ly sampled by an i n t e rna t i ona l t e a m of the Pe r i t e thys Project (L. Angiolini, A. Baud, J. Brout in , H. Bncher, H. A1 Hashmi , J. Marcoux, J.P. Platel , J. Roger).

Brachiopods f rom s o u t h e a s t e r n Oman (Haush i and Wadi Lusaba , 21°02.3'N and 57°36.2'E) were

f i rs t descr ibed by H u d s o n & S u d b u r y (1959). These au thors recognized two faunas : t he H a u s h i f a u n a from the H a u s h i Fm. (= Sa iwan Fm. in Brou t in et al. 1995) and the L u s a b a f a u n a f rom the Lusaba Fm. (= K h u f f Fm. in B ro u t i n et al. 1995). Most of the species descr ibed in the p r e s e n t cont r ibut ion can be r e f e r r ed to the H a u s h i f a u n a of Hudson & S u d b u ry (1959). However , a few t axa were r epor t ed by these au th o r s to occur bo th in the Sa iwan and the Khuff, b u t our own in tens ive sampl ing of the K h u f f Fm. (Angiolini et al. in prep.) does not suppor t the occur rence of such long rang ing taxa .

380

G E O L O G I C A L S E T T I N G

The Huqf area is located on the southeastern margin of the Arabian Plate, in the Sultanate of Oman (Fig. 1). Late Paleozoic rocks are well expo- sed along the western border of the area, along a North-South oriented cuesta bordered by sab- khas. The northwestern par t of this outcrop belt displays the most comprehensive sections of rocks of Permian age.

The oldest marine rocks overlying the tillites of the A1 Khlata Fm. were previously designated as the marine basal member of the essentially non marine Gharif Formation (Hughes-Clarke 1988). Subsequent mapping led to erect these marine beds at the formation rank and they were designated as the Saiwan Formation by Dubreuilh et al. (1992). The Saiwan Fm. with its age-diagnostic marine faunas is thus intercalated between poorly-dated, non marine formations: the underlying A1 Khla ta Fm. of Upper Carboniferous to ?Sakmarian age and the overlying Gharif Fm. (Dubreuilh et al. 1992; Roger et al. 1992; Broutin et el. 1995).

The type-section of the Saiwan Fm. is located near the Saiwan 1 oil well (Dubreuilh et el. 1992), where the Saiwan is about 60 m thick (Figs. 2,3). The formation comprises a terrigenous lower

member and a carbonate upper member which both yielded rich and diversified marine assemblages composed of brachiopods, bivalves, gastropods, crinoids, conularids, cephalopods and bryozoans. The fossils are generally well preserved at the base of the section, whereas they are fre- quently fragmented in the upper member. The age of the Saiwan Fm. is Late Sakmarian, as indicated by the brachiopod and bivalve assemblages (bivalves currently studied by J.M. Dickins).

As composed of a sequence of deltaic terrigenous facies followed by prograding tidal sand bar facies, the Saiwan Fm. can be interpreted as a t ransgress ive-regress ive cycle ending wi th a sharp transition to the terrigenous fluvial deposits of the Permian Gharif Fro.

C O M P O S I T I O N OF THE B R A C H I O P O D F A U N A

The brachiopods described in this contribution were obtained from the Saiwan Fm. type section located close to the Saiwan 1 oil well (20°52'00" N - 57°36'30"E) and from a section located on the left bank of wadi Haushi (21°01'00 " N-57°37'30"E) (Figs. 1,3). Two additional faunules (Huqf 3: 20°59'00 " N-57°38'00"E; H u q f 4 : 2 0 ° 5 6 ' 3 0 " N -

FIGURE 1 - Geological sketch map of the Huqf area, southern Oman, with location of sections and isolated localities. Carte gdologique simplifide de la rdgion du Huqf, Omen mgridional, avec situation des coupes et des localitgs isoldes.

Heushi left Huqf 3 Huqf 4

'~, ~"~SAUDI ARABIA ~

' ~ Fars Group (Miocene-Pliocene) and Quaternary

~ Dhofar Group (Oligocene-Miocene)

~ Hadhramaut Group (Paleocene-Eocene)

Aruma Group

TERTIARY

l END- CRETACEOUS

I

Triassic - Late Cretaceous I IARABIAN Akhdar Group I PLATFORM (Late Permian) I Haushi Group J (Late Palaeozoic) P RE-LATE Haima Group and PERMIAN Thumaylah Formation ! BASEMENT (Early Palaeozoic) I Huqf Group (Latest Proterozoic to Cambrian)

J CRYSTALLINE AI Jobsh Granodiorita I BASEMENT

381

F I G U R E 2 - T y p e s e c t i o n o f t h e S a i w a n F m . a t S a i w a n . Coupe type de la Formation Saiwan ~t Saiwan.

AGES !

Z

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Lithology

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Claystone/Shale

Sandstone

Diamictite

Fauna / Samples Flora

T ~ , OL 18 Y~Z~

V{}~ Z~ OL 17

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Crinoids t, Bryozoan

Nautiloids ~ " Silicified trunk

~' Orthocones ~:~ Cross-bedding

57°37'40"E) were collected in the same area, (see Fig. 1).

The type section provides a good il lustration of the succession of the different faunal assemblages known from the Saiwan (Figs. 2,3). The lowest fos-

siliferous bed of the Saiwan (OL14) occurs near the base of the formation and yields ?Cyrtella aff. nagmargensis (BIoN). Art iculated shells occur locally in this bed and seem to have been preserved in life position with the dorsal valve up.

382

FIGURE 3 - De ta i l ed ske t ch m a p of the S a i w a n section. Carte de ddtail de la coupe de Saiwan.

I I Aeolian sand cover and wadi deposits

~ S a n d dunes

~ Cretaceous formations

, , , ~ , ~ Jurassic formations

~ Khuff formations

~ Ghariff Formation

] I Saiwan Formation

~ AI Khlata Formation

fault

~ trail

small benches ' fossil location

-'~ bedding attitude

Exclusively disarticulated valves occur laterally in coarse sandstone, thus suggesting deposition in a higher energy nearshore setting. The OL14 bed is characterized by a monospecific assemblage and a high biomass, suggesting colonization of newly open shallow water environments in a transgressive phase.

The next fossiliferous levels (OL15-OL17) show higher taxonomic diversity and yield Derbyia haroubi nov. sp., Arctitreta cf bioni (REED), Reedo- concha permixta (REED), Neospirifer aff. hardmani (FOORD), Trigonotreta sp., Subansiria sp., Puncto- cyrtella spinosa PLODOWSKI, Punctospirifer sp., Callispirina sp., Fletcherithyris sp., ?Gilledia sp. Other abundant components include crinoids, conularids, bivalves, cephalopods, and gastropods. The shells are disarticulated, abraded and fragmented, indicating a high energy environment. Both high diversity and taphonomic evidence suggest a mid-shelf biofacies of a siliciclastic platform.

The uppermost coquinoid layer of the Saiwan (OL18) occurs 10 m below the top of the formation and is characterized by abundant specimens of Neospirifer aff. hardmani associated with bivalves. Decreasing taxonomic diversity as well as intense abrasion and fragmentation of shells suggest deposition in a high energy nearshore environment.

The Saiwan brachiopod fauna consists of 1) genera of worldwide distribution such as Derbyia,

Neospirifer, Punctospirifer and Dielasma; 2) antitropical genera (in the sense of Hubbs 1952, i.e. genera ranging from palaeotemperate to palaeopolar zones of both hemispheres) such as Arctitreta, Cyrtella and Callispirina; 3) Cimme- rian genera (in the sense of Archbold 1983) such as Reedoconcha, Punctocyrtella and Subansiria; 4) endemic Gondwanan genera (in the sense of Shi et al. 1995) such as Trigonotreta, Fletche- rithyris and ?Gilledia.

The Saiwan fauna is a mixed fauna characterized by moderate diversity, predominance of cosmopolitan genera, and occurrence of both Cimmerian and Gondwanan genera. The southern Oman fauna is labelled as transit ional with respect to Gondwanan fauna s.s. and Tethyan fauna s.s. by Shi et al. (1995). The Saiwan fauna shows affini- ties with faunas of Central Afghanistan (Termier et al. 1974), the Himalayas (Reed 1932; Singh & Archbold 1993), Peninsular India (Dickins & Shah 1979), and to a lesser degree with the Sakmarian faunas of the Westral ian Province (Western Australia).

The brachiopod faunas described by Yanagida & Pillevuit (1994) from the Jebel Qamar south, Saih Hata t and Batain melange (Oman Mountains) differ from the Saiwan fauna by their Late Permian age.

383

FIGURE 4 - Local range charts of brachiopods in the two sections and two isolated localities of the Huqf area. Output of Biograph 2.02 program, Savary & Guex 1990. Distributions biostratigraphiques locales des brachiopodes dans les deux coupes et deux localitgs isolges de la r~gion du Huqf. Output de Biograph 2.02, Savary & Guex.

LOCAL RANGE CHART

~ = ~.

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slll,,;li,i, l 23, 2 7 Section HAUSHI_LB 1 1 . . . . . . . . . . .

Section SAIWAN

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Section HUQF3 Section HUQF4

B I O S T R A T I G R A P H Y

Based on the U n i t a r y Associat ion me thod of Guex (1991) t h r e e u n i t a r y associat ions are es tab l i shed in the Sa iwan Fm. (Figs. 4,5). The oldest un i t (U.A.1) is cha rac te r i zed by ?C. aff. nagmargensis; t he i n t e r m e d i a t e un i t (U.A.2) by Punctospiri fer sp., Trigonotreta sp. and Callispirina sp.; the younges t un i t (U.A.3)byA. bioni and ?Gilledia sp.

The reproducib i l i ty of the U.A. 1 is 2; t h a t of U.A.2 is 1, whe r e a s the reproducib i l i ty of U.A.3 is 3. The respec t ive superpos i t ion of U.A.1 and U.A.2 is unknown , bu t bo th are known to occur below U.A.3. However , t he composi t ion of U.A.2 shows aff in i ty wi th t h a t of U.A.3 and ?C. aff. nagmargensis , t he cha rac te r i s t i c species of U.A.1, is known to occur s t r a t ig raph ica l ly below R. permixta (see Archbold & Gup ta 1986), which occurs in bo th U.A.2 and U.A.3. Hence, i t can be r ea sonab ly in fe r r ed t h a t U.A.2 is younge r t h a n U.A.1.

We can thus ex t rac t two biochronozones and one U.A. (U.A.2), the l a t t e r being not chronological ly mean ingfu l hav ing a l a t e ra l reproduc ib i l i ty of 1. F rom top to bot tom, these are: - Zone B corresponding to U.A.3; - U . A . 2 ; - Zone A corresponding to U.A. 1.

The age of Zone A is ea r ly La te S a k m a r i a n , whereas U.A. 2 and Zone B are p robab ly la te La te S a k m a r i a n in age on the basis of the following considerat ions: - The genera Reedoconcha and Punctocyrtel la are of La te S a k m a r i a n age in the H i m a l a y a s and Cen t ra l Afghan i s t an (Plodowski 1968; Te rmie r et al. 1974; Archbold & Gaetani , 1993). - According to Archbold & Gup ta (1986) and Singh & Archbold (1993), the Cyrtel la-Subansiria f auna may s t raddle the Ear ly -La te S a k m a r i a n boundary. - Subans i r ia is an endemic C i m m e r i a n genus of the La te S a k m a r i a n of P en in su l a r Ind ia and the

384

A

1 2 3

_.

- - - t H H 4 t - - I H

m

m

?Cyrtella aff. nagmargensis (BION, 1928) Derbia haribi nov. sp. Neospirifer aft. hardmani (FOORD,1890) Trigonotreta sp. Punctospififer sp. Callispirina sp. Reedochoncha permixta (REED, 1932) Subansiria sp. Punctocyrtella spinosa PLODOWSKI, 1968 Fletcherithyris sp. Arctitreta cf. A. bioni (REED, 1932) ? Gilledia sp.

REPRODUCIBILITY OF THE UA

133 J

. m

UAn o~ T-r T

2 1 | 1 2 4 1

c

CORRELATION TABLE 9 horizons

Section HAUSHI LB Section SAIWAN Section HUQF3 Section HUQF4

~ 2 : 3-3 % 5: 1-3 / 1 : 1 - 1 1 : 2- 2 2: 3- 3 4: 2 - 3 3 : 3- 3 ~ 1: 3- 3

1:1-1 FIGURE 5 - Output of the Biograph program 2.02 (Savary & Guex 1991). 5A) Sorted Uni ta ry Associations. 5B) Reproducibility of the Uni ta ry Associations. 5C) Correlation table. Output du Biograph 2.02 (Savary & Guex 1991). 5A) Associations unitaires suc- cessives. 5B) Table de reproductibilitg des Associations Unitaires. 5C) Table de correlations.

Himalayas (Sahni & Srivastava 1956; Singh & Archbold 1993). - N e o s p i r i f e r h a r d m a n i occurs in the late Sakmarian of Central Afghanistan and in the Late Sakmar ian and Art inskian of Western Aust ra l ia (Termier et al. 1974; Archbold & Thomas 1986). - In the Saiwan, representat ives of T r i g o n o t r e t a show some affinity with T. o r i e n t a l i s SI~GH & ARCHBOLD, 1993 of the Late Sakmarian from the Himalayas. - F l e t c h e r i t h y r i s occurs in the Late Sakmarian of Badhaura (Dickins & Shah 1979) and is known to span the late Sakmarian to Midian time interval in Australia.

Associated bivalves also indicate a Late Sakmarian age (J.M. Dickins pers. comm. 1995).

SYSTEMATIC DESCRIPTIONS (L. Angiolini)

All the described specimens are housed in the Geological Museum of Lausanne, Switzerland (MGL numbers ) and in the Paleontological Museum of the Universi ty of Milan, Italy (MPUM

numbers). Field numbers of single fossiliferous beds (OL prefixed) are reported along with catalogue numbers.

The systematic s tudy follows the classifications of Williams & Brunton (1993) for the orthotetidines, Brunton et al. (1995) for the productids, Carter et al. (1994) for the spiriferids and of the Treatise (Williams et al. 1965) for the terebratulids.

The brachiopods described here have been collected in the following sections and isolated localities; Saiwan type-section: OL14, OL15, OL16, OL17, OL18, Left bank ofWadi Haushi section: OL10, O L l l , Isolated locality Huqf 3, Isolated locality Huqf 4, Isolated locality OL70.

In the systematic descriptions, catalogue numbers are given for figured specimens only. For each species, the amount of available specimens is given in brackets following each bed number. For example, OL15 (4, 6, -) means that four articulated shells, six ventral valves and no dorsal valves are available from bed OL15.

Order STROPHOMENIDA Opik, 1934 Suborder ORTHOTETIDINA Waagen, 1884

Superfamily ORTHOTETOIDEA Waagen, 1884 Family DERBYIIDAE Stehli, 1954

Subfamily DERBYIINAE Stehli, 1954 Genus D e r b y i a WAAGEN, 1884

Type species - Derbyia regularis WAAGEN, 1884. Remarks - Distinctive characters of the genus Derbyia are the strong ventral median septum and the long, divergent and extending forward socket plates including the muscle field as pointed out by Thomas (1958), Grant (1976) and Grant (1993). Termier et al. (1974) introduced the genus Wardakia with D. grandis W~GEN from the Permian of Timor as the type species. In fact Wardakia is very closely similar to Derbyia and is considered as a junior synonym of the latter (Grant 1993). Derbyia is a Permo-Carboniferous cosmopolitan genus which is know from Australia, Asia, and America.

Derbyia haroubi nov. sp. Fig. 8.1-4; Table 1

Etymology - Species named for Dr. Haroub A1 Hashmi, Ministry of Petroleum and Minerals of Oman.

Holotype - MPUM7917 (0L15-65), ventral valve.

Type locality and age - Southern Oman, Saiwan Fro., Saiwan section, bed OL15. Late Sakmarian.

Figured material - 2 ventral valves: MPUM7917 (0L15-65), MPUM7918 (0L15-84); 2 dorsal valves: MPUM7919 (OL15- 114), MPUM7920 (OL15-116).

Occurrence and age - Saiwan section: OL15 (6, 23, 18), OL17 (-, -, 1); HUQFa: (-, -, 6); HUQF4: (5, 3, 2). Saiwan Fro. Late Sakmarian.

D i a g n o s i s - R e p r e s e n t a t i v e of Derbyia wi th a s emic i r cu la r outl ine, a c o m p a r a t i v e l y low v e n t r a l i n t e r a r e a , a long v e n t r a l m e d i a n s ep t um , and an o r n a m e n t a t i o n composed of subequal , t h in and n u m e r o u s costellae.

D e s c r i p t i o n - La rge - s i zed shell, convex-p lana r to convex -concave , w i t h s e m i c i r c u l a r ou t l ine . M a x i m u m w i d t h an t e r i o r to h inge line. Ca rd ina l e x t r e m i t i e s r o u n d e d to obtuse. Shell subs t ance p s e u d o p u n c t a t e . Ven t ra l va lve f l a t t ened or sl ight- ly concave, w i t h s emic i r cu l a r outl ine. Ven t ra l u m b o s t r a igh t , pointed, not v e r y high. I n t e r a r e a fiat, abou t 3 to 4 t imes wider t h a n high, horizon- t a l ly s t r i a ted , incl ined b a c k w a r d s fo rming a v e r y low ang le w i th c o m m i s s u r a l p lane . D e l t h y r i u m t r i angu la r , covered by a convex pseudode l t id ium; n a r r o w p a r a d e l t i d i a l a r eas p resen t . Dorsa l va lve r e g u l a r l y convex, w i t h semic i r cu la r out l ine and f l a t t e n e d ears . U m b o smal l , recurved . I n t e r a r e a v e r y narrow. M a t u r e dorsa l va lves showing an a n t e r o m e d i a n depress ion .

O r n a m e n t a t i o n cons is t ing of th in sub-equa l costel]ae, i n c r e a s i n g in n u m b e r by in t e rca la t ion up to 8-9 cos te l lae eve ry 5 m m at the an t e r io r m a rg in . I n t e r c o s t a l t r o u g h s equa l or s l ight ly wider t h a n

385

the costel lae and d i sp lay ing n u m e r o u s g row th lines. G r o w t h l ame l l ae ve ry dense a t t he ml~Ho~ marg in . Low r u g a e r a r e l y p r e s e n t on v e n t r a l valve.

Ven t ra l va lve in te r io r w i t h long den t a l p la tes , m e r g i n g a t the apex wi th a m e d i a n s e p t u m , ex tend ing to h a l f l eng th of the valve; t e e t h s t rong and s tout , dorsa l ly recurved . Muscle field wide, r ad ia l ly s t r i a t ed and showing a lobed and r a i sed an t e r io r m a r g i n a l r idge. Dorsa l va lve in te r io r w i th v e r y long, dorsa l ly recurved , b i lobed ca rd ina l process, each lobe b e a r i n g a deep d iduc tor musc le groove. Socket p l a t e s s t rong, un i t i ng w i t h cardi- na l process and bo rde red by i nne r socket r idges. Cru ra l p l a t e s s u p p o r t e d by a p a i r of s t rong ly d ive rgen t and long p la tes , e x t e n d i n g forwe_rd a long the floor of t he va lve and s u r r o u n d i n g the r ad ia l ly s t r i a t ed musc le field.

Dimensions - see Fig.6 and Tabl. 1 of appendix.

D i s c u s s i o n - Derbyia haroubi nov. sp. is v e r y s imi l a r to Derbyia buriensis REED, 1944 f rom the A m b Fro. of the Sal t Range. However , m i n o r differences a re the o r n a m e n t a t i o n composed of subequal costel lae w i th n a r r o w e r i n t e r s p a c e s and the backwards , low angle inc l ina t ion of t he i n t e r a r e a . I t also differs f rom Derbyia diversa REED, 1944 by the absence of r u g a e and by the s t r u c t u r e of the longer v e n t r a l s e p t u m which is not composed of two convergen t pla tes . The new species also shows aff ini t ies wi th Derbyia baroghi lensis REED, 1925 f rom the S a k m a r i a n of K a r a k o r u m , bu t differs by

80

¢ , -

75 70 65 60 55 50 45 40 35 30 25 20 15 10-

5-

N • •

•

0~) ,5 1'0 1'5 2'0 2'5 3'0 3'5 4'0 4'5 5~0 5'5 6'0 6'5 7'0 75 80 Length (ram)

FIGURE 6 - Scatter diagram comparing length and width of D. haroubi nov. sp. Squares: ventral valves; crosses: dorsal valves. Distribution des longueurs et @aisseurs de D. haroubi nov. sp. Carrgs: valves ventrales; croix: valves dorsales.

80

75 70- 65- 60 55-

.-. 50- E

E 451 I . 40

-o 3 5 +

3o 25. 20 15- lO-

5-

o o 1'o 1'5 2'0 a'o 4'0 5o is 6'0 6'5 is 80

Length (mm) FIGURE 7 - Scatter diagram comparing length and width of R. permixta (REED). Squares: ventral valves; crosses: dorsal valves. Distribution des longeurs et dpaisseurs de R. permixta (REED). Carrgs: valves ventrales; croix: valves dorsales.

its f iner o rnamenta t ion . Fur the rmore , the costellae of D. h a r o u b i nov. sp. do not swell into small kno ts as in D. b a r o g h i l e n s i s .

The spec imen described as S t r e p t o r h y n c h u s aff. h a l l i a n u s ? DERBY, 1874 by Reed (1932, p. 23, pl. 6, fig. 10) f rom the Agglomera t ic Slate of Kashmi r seems to be closely allied to D. h a r o u b i nov. sp.

Fami ly STREPTORHYNCHIDAE Stehli, 1954 Subfami ly STREPTORHYNCHINAE Stehli, 1954

Genus A r c t i t r e t a WHITFIELD, 1908

Type species - Arctitreta pearyi WHITFIELD, ]908.

R e m a r k s - A r c t i t r e t a WHITFIELD differs f rom S t r e p t o r h y n c h u s KING by the presence of dental plates in the ven t ra l valve and by shorter, recur-

386

ved crural plates, la rger dimensions, and coarser o rnamenta t ion . A r c t i t r e t a is ve ry common in the Arctic Permian, bu t it occurs also in the P e r m i a n of Austra l ia , Asia and N America. I t shows antitropical d is t r ibut ion in the sense of Hubbs (1952).

A r c t i t r e t a cf. b i o n i (REED, 1932) Fig. 8.5,6; Table 2

Figured material - 2 articulated shells: MPUM7925 (OL15- 87), MPUM7926 (OL70-2).

Occurrence and age - Saiwan section: OL15 (5, -, -), OL16 (1, -, -); Haushi left bank section: OLll (-, 3, 1); OL70 (2, -, -). Saiwan Fm. Late Sakmarian.

D e s c r i p t i o n - Shell conical wi th m a x i m u m wid th an te r io r to the s t r a igh t h inge line. Card ina l extremit ies rounded. Shell subs t ance coarse ly extropunctate .

Ventral valve conical, resupina te , wi th h igh and s t ra igh t umbo. Ventra l i n t e r a r e a v e r y high, inclined backwards at h igh angle to the commissura l p lane and t r ansve r sa l ly s t r ia ted; pseudode l t id ium very high and convex, l a te ra l ly bounded by deltidial grooves. Dorsal valve s l ight ly convex wi th semicircular outline.

Radial o rnamen ta t i on composed of fine, rounded costellae, wi th na r row interspaces , inc reas ing in n u m b e r by in terca la t ion up to 10-12 costellae every 5 m m at the an te r ior margin . Low i r regu la r rugae occur on both valves.

Ventral valve inter ior wi th long denta l p la tes rea- ching the floor of the valve in the th ickened umbonal region. Dorsal valve in ter ior w i th shor t and recurved crura l p la tes and shor t m e d i a n septum.

Dimensions - see Tabl. 2 of appendix.

D i s c u s s i o n - The specimens f rom O m a n look similar to A r c t i t r e t a b i o n i (REED, 1932) f rom the Agglomerat ic Slates of Kashmir . However, the small n u m b e r of specimens and the poor preser- va t ion preclude ident i f icat ion at the species level.

FIGURE 8 - 1-4. Derbyia haroubi nov. sp. 1. ventral valve, holotype, MPUM7917 (OL15-65). 2. interior of ventral valve showing spondylium, median septum and muscle scars, MPUM7918 (OL15-84). 3. dorsal valve in postero-dorsal view, MPUM7919 (OL15- 114). 4. interior of dorsal valve showing cardinal process, MPUM7920 (OL15-116). 5-6. Arctitreta cf. bioni (REED). 5. dorsal view of an articulated shell, MPUM7925 (OL15-87). 6. ventral view of an articulated shell, MPUM7926 (OL70-2). 7-14. Reedoconcha permixta (REED). 7,8,10. dorsal valves showing cardinal process, MPUM7930 (OL10-33) (7), MPUM7931 (OL10-37) (8), MPUM7932 (OL10-35) (10). 9. lateral view of ventral valve, MPUM7933 (OL16-28). 11-13. ventral valves, MPUM7934 (OL16-21) (11), MPUM7935 (OL16-22) (12), MPUM7936 (OL16-20) (13). 14. ventral valve anterior margin bearing spines, MPUM7941 (OL16-23). 15-16. Reedoconcha permixta (REED). 15. dorsal view of an articulated shell, MPUM7938 (OL16-46). 16. ventral valve, MPUM7937 (OL16-27). (All figures natural size). 1-4. Derbyia haroubi nov. sp. 1. valve ventrale, holotype, MPUM7917 (0L15-65). 2. intdrieur de la valve ventrale montrant le spondylium, le septum rngdian et les empreintes musculaires, MPUM7918 (0L15-84). 3. vue postdro- dorsale de la valve dorsale, MPUM7919 (0L15-114). 4. intdrieur de la valve dorsale montrant le processus cardinal, MPUM7920 (0L15-116). 5-6. Arctitreta cf. bioni (REED). 5. vue dorsale d'un spdcimen complet, MPUM7925 (0L15-87). 6. rue ventrale d'un spdcimen complet, MPUM7926 (0L70-2). 7-14. Reedoconcha permixta (REED). 7~8~10. valve dorsale montrant le processus cardinal, MPUM7930 (0L10-33) (7), MPUM7931 (0L10-37) (8), MPUM7932 (0L10-35) (10). 9. valve ventrale en rue latdrale, MPUM7933 (0L16-28). 11-13. valves ventrales, MPUM7934 (0L16-21) (11), MPUM7935 (0L16-22) (12), MPUM7936 (0L16-20) (13). 14. bord antdrieur de valve ventrale portant des dpines, MPUM7941 (0L16-23). 15-16. Reedoconcha permixta (REED). 15. rue dorsale d'un spgcimen complet, MPUM7938 (0L16-46). 16. valve ventrale, MPLTM7937 (0L16-27).

387

13

7

8

3

4

5

15

388

The specimen described as Streptorhynchus bioni by Termier et al. (1974, p. 79, P1. 10, fig. 6) from the Asselian of Wardak (Central Afghanistan) is an internal mould of a ventral valve which do dot permit identification of the species.

Other o c c u r r e n c e s - A. bioni (REED) is known from the Agglomeratic Slates of Sakmarian age in Kashmir (Reed 1932).

Order PRODUCTIDA Sarytcheva & Sokolskaya, 1959

Suborder STROPHALOSIIDINA Waagen, 1883 Superfamily AULOSTEGOIDEA Muir-Wood &

Cooper, 1960 Family AULOSTEGIDAE Muir-Wood & Cooper, 1960

Subfamily AULOSTEGINAE Muir-Wood & CoopeI, 1960

Genus Reedoconcha KOTLYAR, 1964

Type species -Productus (Taeniothaerus)permixtus REED, 1932.

D i a g n o s i s - Large-sized shell with low interarea. Ornamentat ion composed of very long, regularly spaced ridges provided with numerous prostrate and suberected spines; thick brushes of erected spines projected backwards on ears and flanks. Cardinal process trifid with elongated shaft, strongly projecting into the ventral umbo.

D i s c u s s i o n - Reedoconcha KOTLYAR differs from Taeniothaerus WHITEHOUSE by its spine ridges and cardinal process. The lateral lobes of the cardinal process of Reedoconcha are not completely fused posteriorly to a massive ]ophidium as in Taenio- thaerus. The larger cardinal process pit of Reedo- concha is an additional difference. Reedoconcha shows some resemblance with Ramavectus STEHLI, 1954 but differs by the following characters: ornamentation of long ridges bearing prostrate spines of one size only; spines clustered on the ears and on the lateral and anterior margin, but not on the cardinal margin; absence of lateral ridges and of diverging buttress plates in the dorsal valve; presence of lophidium; long shafted, trifid cardinal process highly projecting ventrally and with more prominent median lobe; dorsal adductor scars located far anterior to the base of the shaft.

O c c u r r e n c e a n d age - The genus Reedoconcha is apparent ly widely distributed in the Early Permian of the Peri-Gondwanan margin from Oman to Centra l Afghanistan, Sou theas te rn Pamir and the Himalayas. It is also present in Iran and Irian Jaya. It is regarded as a Cimme- rian genus, in the sense of Archbold (1983).

1932

Reedoconcha permixta (REED, 1932) Fig. 8.7-16; Table 3

Productus (Taeniotherus)permixtus REED, p. 12, pl. 1, figs. 1-4; pI. 2, figs. 1-3; pl. 4, fig. 1.

1932 P. (Taeniotherus) brenensis REED, p. 14, pl. 3, figs. 1-3.

1932 P. (Buxtonia) hashmiricus REED, p. 15, pI. 2, figs. 5-8; pl. 3, figs 4-6; pl. 4 figs. 6-10.

1959 Taeniothaerus sp. cf. Buxtonia ? punjabensis REED: Hudson & Sudbury, p. 32, pl. 2, figs. 4a-c.

1974 Taeniothaerus permixtus REED: Termier et al., p. 96, pl. 11, figs. 1-8.

F i g u r e d m a t e r i a l - 1 articulated shell: MPUM7938 (OL16- 46); 6 ventral valves: MPUM7933 (OL16-28), MPUM7934 (OL16-21), MPUM7935 (OL16-22), MPUM7936 (OL16-20), MPUM7937 (OL16-27), MPUM7941 (OL16-23); 3 dorsal valves: MPUM7930 (OL10-33), MPUM7931 (OL10-37), MPUM7932 (0L10-35).

O c c u r r e n c e a n d age - Saiwan section: OL15 (5, 3, 1), OL16 (2, 45, -); Haushi left bank section: OL10 (-, -, 6). Saiwan Fm. Late Sakmarian.

D e s c r i p t i o n - Large-sized, concavo-convex shell, longer than wide, oval in outline. Maximum width near anterior margin. Ears poorly differentiated.

Ventral valve very convex and arched. Umbo large, swollen, recurved, nearly as wide as the hinge line. Interarea low, triangular. Median sulcus present, with variable depth, but usual ly shallow.

Dorsal valve flat with a steeply geniculated anterior margin.

Ornamentat ion of ventral valve with very long, quincunxially arranged spine ridges bearing pros- t rate to suberect spines; erected and posterolate- rally recurved spines occur in thick brushes on ears and on lateral margins. Spine ridges up to 15 mm in length and up to 1.3 mm in width; diameter of prostrate spines near anterior margin of about 0.9-1.2 ram. Finer spines of about 0.5-0.7 mm in diameter on ears and lateral margins. Growth lines visible on entire valve surface. Ornamentat ion of dorsal valve with numerous, fine, short spine ridges, radial ly distr ibuted; spines prostrate to suberected, increasing in size anteriorly.

Dorsal valve interior with trifid, long shafted cardinal process with large cardinal process pit. Cardinal process notably projecting posteriorly and ventrally into the ventral umbo. Presence of a dorsal t r iangular lophidium. Cardinal process bearing widely spreaded myophore ridges with prominent median lobe; some specimens showing lateral lobes closely united to the median lobe. Shaft of cardinal process with deep furrows and bases extending anteriorly and surrounding the posterior terminat ion of the median septum; bases of shaft merging with the median septum in mature specimens. Median septum about three- fourths of the valve length, dividing the dendritic adductor scars. Median septum very thick posteriorly, getting narrower anteriorly.

389

Depth of ventral sulcus and length/width ratio (Fig. 7) displaying high intraspecific variation.

Dimens ions - see Fig. 7 and Tabl.3 of appendix

D i s c u s s i o n - The available material matches the description of Productus (Taeniotherus) permixtus REED, 1932 from the Agglomeratic Slates of Kashmir. Reed op. cit. also introduced P. (T) brenensis and Productus (Buxtonia) kashmiricus. He suggested that the first could be a variety ofP. (T) permixtus, being represented by two internal moulds of ventral valves showing a finer ornamentation, whereas P. (B.) kashmiricus is represented by more transverse, subquadrate shells.

Termier et a1..~(1974, p. 97) suggested that P. (B.) kashmiricus could represent juvenile forms of the larger T. permixtus.

P. (B.) kashmiricus was next reported as Reedo- concha kashmirica (REED, 1932) by Archbold & Gaetani (1993), who suggested that it could represent juvenile and submature specimens of the two larger species R. permixta (REED, 1932) and R. brenensis (REED, 1932).

The population of Oman includes elongate specimens in which the length is only slightly greater than the width and few specimens in which the length is about 10 mm greater than the width. So they seem to represent intermediate forms between R. kashmirica and R. permixta, leading to the conclusion that R. kashmirica could belong to the same species as R. permixta.

However the specimens described as R. kashmir# ca by Archbold & Gaetani (1993) show a coarser ornamentat ion with more erect spines with respect to R. permixta.

The specimens described as T permixtus by Termier et al. (1974) clearly belong to the same species as those from Oman. R. rustica (GRuNT, 1973) from the southeastern Pamir and R. aifa- mensis (A~cHBOLD, 1991) from Irian Jaya show finer ornamentat ion than R. permixta. The same holds true for the specimens from Iran described as T cf. permixtus and T iranicus FANTINI SESTINI, 1966 by Fantini Sestini (1966).

O t h e r o c c u r r e n c e s - R. permixta (R~ED) occurs in the Sakmarian Agglomeratic Slates of Kashmir (Reed 1932) and in the Late Sakmarian of Afghanistan (Termier et al. 1974).

Order SPIRIFERIDA Waagen, 1883 Suborder SPIRIFERIDINA Waagen, 1883 Superfamily SPIRIFEROIDEA King, 1846

Family TRIGONOTRETIDAE Schuchert, 1893 Subfamily TRIGONOTRETINAE Schuchert, 1893

Genus Trigonotreta KIENIG, 1825

T y p e s p e c i e s - Trigonotreta stokesi KOENIG, 1825.

R e m a r k s - The genus Trigonotreta KOENIG, 1825 has been described and discussed by Armstrong (1968a), Clarke (1979), Archbold & Thomas (1984, 1986), ClarKe (1990), Archbold (1991) and Angiolini (1995). Archbold & Thomas (1984, 1986) fully discussed the relationship between Trigonotreta and Neospirifer FREDERICKS, 1924. Trigonotreta seems to be characterized by coarse bundles of unequal ribs, with the primary costa coarser than the seconda- ries. Furthermore, branching of costellae appear later in the ontogeny of Trigonotreta than in that of Neospirifer. The delthyrial structures are also different in the two genera, Trigonotreta being characterized by a bulbous apical callosity. Archbold & Thomas (1984) and Clarke (1990) have pointed out the strong similarity between Brachythyrinella WATERHOUSE & GUPTA, 1977 and Trigonotreta. Archbold (1991) regarded Brachythyrinella as a junior synonym of Trigonotreta. The genus Trigono- treta occurs in the Early Permian of Australia, Peninsular India, Himalaya, Karakorum, South- eastern Pamir, Central Afghanistan, N. Iran and Oman. It is a widespread and diagnostic Gondwa- nan genus.

Trigonotreta sp. Fig. 15.12

F i g u r e d m a t e r i a l - 1 ventral valve: MPUM7944 (OL10-23).

O c c u r r e n c e a n d a g e - Haushi left bank section: OL10 (-, 3, 1). Saiwan Fm. Late Sakmarian.

D e s c r i p t i o n - Biconvex shell transverse in outline. Maximum width at the hinge. Maximum width = 36.4 ram; corresponding estimated length >14 mm. Ventral valve with recurved umbo overhanging a concave interarea. Median sulcus V-shaped, widening and deepening anteriorly. Dorsal valve with moderately high fastigium with acute section.

Ornamentat ion consisting of sub-angular costel~ lae branching at about 6-7 mm from the umbo, forming 4 bundles of 3 costae on each flank of the valve. Pr imary costa of bundles always more pro~ minent than costellae. Growth lines and lamellae well visible.

D i s c u s s i o n - Poor preservation of this material precludes identif ication at the species level. However, the mater ia l is ve ry close to Trigonotreta orientensis SmGH & ARCHBOLD, 1993 which is known from the Late Sakmar ian Garu Fro. of eastern Himalaya.

Subfamily NEOSPIRIFERINAE Waterhouse, 1968 Genus Neospiri fer FREDERICKS, 1924

Type-species - Spirifer fasciger von KEYSERHNG, 1846.

Remarks - The relationships of Neospirifer with other genera are fully discussed by Archbold & Thomas (1984 & 1986).

390

Neospirifer is a cosmopolitan genus, widespread in the Permian of Australia, Asia and America.

Neospirifer aff. hardmani (FooRD, 1890) Fig. 15.4-10; Table 4

1959 Neospirifer aff. moosakhailensis (DAVIDSON): Hudson & Sudbury, p. 49, pl. 6, figs. 2-5.

1959 Neospirifer hardmani (FooRD): Hudson & Sudbury, p. 49, pl. 6, fig. 1.

Figured material - 5 ventral valves MPUM7947 (OL18-17), MPUM7948 (OL18-16), MGL74114 (OLll-2), MPUM7951 (OL18-7), MPUM7952 (OL18-1); 2 dorsal valves MPUM7949 (OL18-34), MPUM7950 (OL17-7).

Occur rence and age - Saiwan section: OL15 (-, 10, 2), OL16 (-, 3, -), OL17 (-, 1, -), OL18 (-, 54, 6); Haushi left bank section: OLl l (-, 7, -); HUQF3 (-, -, 1); HUQF4 (2, 1, -). Saiwan Fro. Late Sakmarian.

D e s c r i p t i o n - Biconvex shell, subtriangular- transverse to subrectangular in outline, varying from transverse to subrectangular or subquadrate with growth; maximum width anterior to hinge line, located at mid-lenght at maturity. Anterior commissure uniplicate.

Ventral valve with high, concave, transversally striated interarea, overhang by a small and recurved umbo. Median sulcus shallow, originating at the umbo and widening anteriorly, U-shaped in cross section. Sulcal tongue long. Four moderate lateral plications on each lateral slope. The inner pairs of plications are part of the sulcal flanks. Ornamentat ion of fine equidimensional costellae and growth lamellae imparting a tegulate pattern. Ornamentat ion relatively stouter in imma- ture specimens. Costellae branching at the umbo and anteriorly, resulting in bundles of 8 costellae along the anterior margin of the valve. The width of the costellae at the anterior margin is about 1 mm. Dorsal valve with low but distinct interarea. Dorsal fastigium acute, with high anterior fold. Lateral plications and ornamentation as in yen- tral valve.

Ventral valve interior with stout dental plates and adminicula apically included in shell thicke- ning. Mature individuals provided with a small delthyrial plate. Ventral muscle field elongated oval to circular in outline; adductor scars striated. Dorsal valve interior with stout socket plates and deep sockets.

D i m e n s i o n s - see Tabl. 4 of appendix.

D i s c u s s i o n - Specimens collected in the Saiwan Fm. agree with the description of Neospirifer hardmani (FooRD, 1890) as described by Archbold & Thomas (1986). However, the specimens from Oman show a shallower sulcus in comparison with the Austral ian specimens.

The specimens described by Hudson & Sudbury (1959) as Neospirifer aff. moosakhailensis (DAvID- SON, 1862) fall in the range of variation of N. hardmani although they exhibit sligthly stronger plications. The specimens from Oman differ from Neospirifer foordi ARCHBOLD • THOMAS, 1986 from the Callytharra Fro. (Carnarvon Basin) and from the Nura Nura Member (Canning Basin) in having a shallower sulcus and weaker lateral plications.

According to Archbold & Thomas (1986), the Sak- marian specimens from Wardak (Central Afgha- nistan) described as Aperispirifer undatus (REED, 1944) by Termier et al. (1974) are closely related to N. hardmani. Examination of the material of Afghanistan, housed at the Office National des Collections Fossiles, Lyon, confirms tha t the specimens described by Termier et al. (1974) as A. undatus from Wardak have the diagnostic characters of N. hardmani. Furthermore the specimens from Afghanistan differ from the true A. undatus (REED) from the Salt Range by their coarser and fewer costae, and more acute dorsal fastigium. The specimen described by Termier et al. (1974) as N. trimuensis REED, 1944 may belong to N. hardmani. In fact the original N. trimuensis from the Amb Fm. of the Salt Range shows finer costae and greatest width at hinge line.

Finally Reed (1932) recorded N. hardmani from the Agglomeratic Slates of Kashmir, but his specimens are too f ragmentary to ascertain the specific determination.

O t h e r o c c u r r e n c e s - N. hardmani is known from the Sakmarian Callytharra Fro. (Carnarvon Basin) and Fossil Cliff Mb. (Perth Basin) of Western Australia. A few specimens have been recorded in the J imba Jimba Calcarenite (Early Artinskian) of Carnarvon Basin (Archbold & Thomas 1986) and from the Sakmar i an of Wardak, Afghanistan (Termier et al. 1974).

Neospirifer sp. Fig. 15.11

Figured material - i ventral valve: MPUM7958 (OLll-8).

O c c u r r e n c e a n d age - Haushi left bank section: O L l l (-, 1, -). Saiwan Fm., Late Sakmarian.

D e s c r i p t i o n a n d d i s c u s s i o n - This unique ventral valve of Neospirifer differs from the specimens of N. aff. hardmani by stronger plications and by deeper vent ra l sulcus. It somewhat resembles Neospirifer foordi ARCHBOLD & THOMAS, 1986 from the Callytharra Fro. (Carnarvon Basin) and from the Nura Nura Member (Canning Basin).

Order SPIRIFERINIDA Ivanova, 1972 Suborder SPIRIFERINIDINA Ivanova, 1972

Superfamily SYRINGOTHYRIDOIDEA Fredericks, 1926

Family SYRINGOTHYRIDIDAE Fredericks, 1926 Subfamily PERMASYRINXINAE Waterhouse, 1986

R e m a r k s - In their preliminary classification of the spiriferid brachiopods for the revision of the Treatise, Car ter et al. (1994) included in the family Syringothyrididae Fredericks, 1926 all the punc- rate, strophic, biconvex spiriferids with numerous simple ribs, medianly smooth fold and sulcus, high to very high ventral interarea and provided with perideltidial areas. Based on the presence or the absence of the syrinx and the ventral median septum, they distinguished three subfamilies within the Syringothyrididae. They included Subansiria SAHNI & SRIVASTAVA, 1956 in the subfamily Syringothyridinae Fredericks, 1926 characterized by the occurrence of the syrinx, while Cyrtella FREDERICKS, 1924 and its junior synonym Punctocyrtella PLODOWSKI, 1968 were assigned to the subfamily Permasyrinxinae Waterhouse, 1986 on the basis of the absence of syrinx. As discussed below, Subansiria lacking a true syrinx it must be placed within the subfamily Permasyrinxinae, whereas Cyrtella and Punctocyrtella must be regarded as distinct and separate genera.

Genus Cyrtella FREDERICKS, 1924

Type species - Cyrtia kulikiana FREDERICKS, 1916.

D i a g n o s i s - Syringothyridinid resembling Pseudo- syrinx WELLER but with longitudinal grooved fold; ornamentation consisting of simple costae; micrornamentat ion made of small pustules. Ventral interarea flat or slightly concave, nearly orthocline. Interior of ventral valve with considerable apical callosity, delthyrial plate, dental plates and adminicula. Dorsal cardinalia massive, recurved socket plates with prominent crural plates on their inner sides, absence of supporting septum.

D i s c u s s i o n - The relationships of Cyrtella with other genera have been fully discussed by Thomas (1971) and Archbold (1990).

The genus was considered to be a senior synonym of Punctocyrtella PLODOWSKY, 1968 by Thomas (1971), Waterhouse (1987), Archbold (1990), Singh & Archbold (1993) and Archbold & Gaetani (1993) because both genera are punctate. Thomas (1971, p. 149) found punctae on a topotype specimen of C. kulikiana (FREDERICKS, 1916), demonstrating tha t Cyrtella is puncta te . However, Archbold & Gaetani (1993, p. 35) made the point tha t detailed study of the shell structure is required for a more objective generic ass ignment of the various Gondwanan species.

391

In the present paper Punctocyrtella spinosa PLODOWSKI, 1968 from Afghanistan is not t reated as synonym of Cyrtella, from which it differs by its very transverse outline (width/length ratio of about 2.5-3.5), lower and apsacline ventral interarea instead of high and orthocline one, shorter ventral adiminicula, smaller del thyrial plate, greater number of costae and spinose micrornamentation. In conclusion, the two genera seem to be different, but detailed s tudy of the ultrastruc- ture and micrornamentation of P. spinosa from Afghanistan is necessary in order to confirm this generic assignment.

Cyrtella is herein t reated as a senior synonym of Asyrinx HUDSON • SUDBURY, 1959 from the Metalegoceras Limestone and Lusaba Limestone in Oman. Hudson & Sudbury (1959) stated tha t Asyrinx has no syrinx as well as no delthyrial plate and tha t it shows "a kind of roll round the edge of each dental plate which largely fills the central delthyrial cavity". Personal examination of a cast of the holotype of Asirinx haushiensis HUDSON & SUDBURY, 1959 (specimen BB20181) kindly provided by C.H.C. Brunton (Natural History Museum of London) does not confirm the description given by Hudson & Sudbury (1959). The holotype actually shows the delthyrial plate and is similar to the specimens under study. Furthermore the genus Asyrinx is based on two specimens which are not congeneric: in fact the paratype BB 20182 (Hudson & Sudbury 1959, pl. V, fig. 3, text-fig. 11) belongs to the genus Subansiria.

O c c u r r e n c e a n d age - Cyrtella is a typical antitropical genus, ranging from pa]aeotemperate to palaeopolar regions in both hemispheres during Early Permian times. Large-sized representatives of Cyrtella occur in Gondwanan and Cimmerian faunas of Early Permian age. They are know from Oman to Tasmania as indicated by Archbold (1987) and Archbold & Gaetani (1993) .

?Cyrtella aff. nagmargensis (BIoN, 1928) Fig. 11.1-6; Table 5

1959 Asyrinx haushiensis HUDSON 8z SUDBURY, p. 46-47, pl. 5, fig. 2.

1959 Pseudosyrinx sp.: Hudson & Sudbury, p. 46, pl. 5, figs. la-b.

1990 Cyrtella nagmargensis (BION): Gaetani et al., p. 115, fig. 5.3.

1993 Cyrtella nagmargensis (BION): Archbold & Gaetani, p. 35, pl. 4, figs. 4-8; pl. 5, figs. 1 & 6.

F i g u r e d m a t e r i a l - 4 articulated shells: MPUM7959 (OL141- 23), MPUM7960 (OL141-28), MPUM7961 (OL143-19), MPUM7962 (OL143-3); 3 ventral valves: MPUM7963 (OL144- 17), MGL67119, MGL67121; 1 dorsal valve MPUM7964 (OL144-13).

392

O c c u r r e n c e a n d age - Saiwan section: OL14 (38, 19, 45); HUQF 3 (-, 17, 10). Saiwan Fm., Late Sakmarian.

D e s c r i p t i o n - Medium to large-sized biconvex shell with maximum width at hinge line. Cardinal extremities t runcated on adult shells. Shell substance punctate; punctae are of about 8-11 ~m in diameter (Fig. 13). Micropunctae also present.

Ventral valve almost flat, trigonal in outline. Interarea high, flat to slightly concave, at a very low angle with the commissural plane (almost orthocline), and with t runcated extremities; perideltidial areas not well demarcated owing to par- tial decortication of the shell. At comparable size, height of interarea and outline of the shell may vary from low interarea and transverse outline to high interarea and trigonal outline. Delthyrium closed by apical and lower stegidial plates in the sense of Legrand-Blain (1985); hypodeltidial and deltidial furrows separated by deltidial ridge (Fig. 9). Shallow and smooth ventral sulcus arising at umbo, widening anteriorly and protruding as a long tongue anteriorly. Ornamentat ion of simple costae, rounded to flat-topped. Flanks with 12-14 costae separated by narrow intercostal troughs. Costae widening anteriorly from 0.6-0.7 mm wide at 0.5 cm from the umbo, to about 3-4.5 mm in width on the anterior margin of larger specimens. Growth lamellae present. Micrornamentation of minute pustules. Dorsal valve transverse in outline, strongly arched near the anterior margin. In terarea distinct, t ransversal ly str iated with open notothyrium. Fastigium not very high, sho-

- :L -JA /~"-~_.:- ~. . .....--....i~.~

FIGURE 9 - Dorsa l view of t he i n t e r a r e a of ?C. aff. nagmargensis (BIoN) s h o w i n g t he s teg id ia l p la tes , t h e hypode l t id ia l an d del t idial furrows, t he del t id ia l r idge a n d t h e de l thy r i a l p la te (modified from Leg rand -B la in , 1985). The v e n t r a l i n t e r a r e a is f ia t and a lmos t orthocline. Vue dorsale de l'interarea de ?C. aff. n a g m a r g e n s i s (BION) montrant les plaques st@idiales, le sillon hypodeltidial, le sillon deltidial, la cr~te deltidiale et la plaque delthyriale ( d'apr~s Legrand-Blain, 1985, modifid). L'interarea ventrale est aplatie et presque orthocline.

wing steep flanks at the anterior margin only and bearing a deep median furrow which widens anteriorly. Ornamentat ion of 12-14 simple rounded costae on each side of the fold with narrower intervals. Costae widen anteriorly, from about 0.6- 0.9 mm wide at a distance of 0.5 cm from the umbo, to 3-3.8 mm wide at the anterior margin. Growth lamellae occurring throughout entire valve and becoming denser anteriorly.

2 3 4

FIGURE 10 - Ser ia l sec t ions of ?C. aff. nagmargensis (BION),(al l x 2.8). 1-8: Sec t ions of s p e c i m e n M G L 6 7 1 2 1 r e s p e c t i v e l y a t 2.8 m m , 4 m m , 7.7 m m , 9.7 m m , 11.1 m m , 12.9 m m a n d 15.3 m m from t h e umbo . Sections s~ri~es de ?C. n a g m a r g e n s i s (BSON), (toutes x 2.8). 1-8: Sections du spdcimen MGL67121 & 2.8 mm, 4 ram, 7.7 ram, 9.7 ram, 11.1 ram, 12.9 mm and 15.3 mm de l'umbo.

5 6

7 8

393

Ventral valve interior with large and concave delthyrial plate, showing a concave margin towards the hinge line. In rare specimens (e.g. MGL67119) the delthyrial plate sinks anteriorly in its middle part, thus forming two rolls on each side of the delthyrium. Umbonal callus apically embedding dental plates and adminicula and filling the central cavity below delthyrial plate (Fig. 10); anterior par t of apical callus deeply pitted by gonad markings. Dental flanges high, merging with adminicula and concave towards lateral margins. Adminicula surrounding the posterior par t of the muscle field. Teeth stout and coarse. Muscle field large, depressed, dendritic on posterior part and longitudinally striated on anterior part. Muscle field divided by a myophragm (e.g. OL143-3). Dorsal valve interior with a broad, sessil cardinal process bearing numerous lamellae; socket plates and crural plates fused to the cardinal process by a callus which is very large in mature specimens. Specimens MGL67102, OL143-13,-10 showing crural plates embedded in the callus. Spiralia laterally directed. Depressed adductor sears with a thin median myophragm.

D i m e n s i o n s - s ee Tabl . 5 of a p p e n d i x .

O n t o g e n e t i c v a r i a t i o n - Earliest stages transverse with low ventral interarea; at about 50-62 mm in length, negative allometry of shell width imparts a more equidimensional shell shape, with a long sulcal tongue; at length greater that 62 mm, allometry of shell width becomes positive, thus result ing in a change into a t ransverse outline (Fig. 12). Height of ventral interarea to width ratio of higher values in mature specimens than in juveniles. Juveniles stages with angular cardinal extremities, becoming truncated at maturity.

D i s c u s s i o n - Specimens from the Saiwan Fm. fall within the range of variation of Cyrtella nagmargensis as described from the Agglomeratic Slate of Kashmir (Bion 1928; Reed 1932). However, truncated cardinal extremities, the inclination of the interarea and a shallower sulcus appear as dis- t inct ive fea tures of the specimens from the Saiwan Fm.

The Oman specimens differ from Cyrtella austra- lis THOMAS, 1971 from the Lyons Group and the Callytharra Fm. of the Carnarvon Basin (Western Austral ia ) in having longer ventral adminicula, a higher ventral interarea and a deeper and larger furrow on the fold.

The holotype of Asyrinx haushiensis HUDSON & SUDBUR¥, 1959 from the Metalegoceras Lmst. and the Lusaba Lmst. is very similar to ?C. aff. nagmargensis. No differences are detected both in external and internal characters of the two species.

The specimens from the Sakmarian of South- eastern Pamir described by Grunt & Dmitriev (1973) as Punctocyrtella spinosa PLODOWSKI, 1968 are probably conspecific with C. nagmargensis. Allowing for minor differences such as a shallower furrow on the fastigium, the specimens described as C. cf. nagmargensis from the Sakmarian of Karakorum (Angiolini 1995) and from the Late Sakmarian Garu Fm. of Eastern Himalaya (Singh & Archbold 1993) are probably conspecific with C. nagmargensis, too.

According to Archbold (1990), the specimens from Tibet described as C. nagmargensis by Hu (1983) belong to a different species, being characterized by finer, sharper and denser costae.

O t h e r o c c u r r e n c e s - C. nagmargensis is known from the Sakmar ian Agglomerat ic Slate of Kashmir (Bion 1928, Reed 1932) and from the Late Sakmarian of Wardak, Central Afghanistan (Termier et al. 1974). It probably occurs in the Sakmarian-?Ear ly Art inskian of sou theas te rn Pamir (Grunt & Dmitriev 1973, Grunt & Novikov 1994), in the Chumik Fm. of Zanskar, northwestern Himalaya (Archbold & Gaetani 1993), in the Late Sakmarian Garu Fm. of eastern Himalaya (Singh & Archbold 1993) and in the Sakmar ian of Karakorum (Angiolini 1995).

Genus Subansir ia SAHNI & SRIVASTAVA, 1956

Type species - Subansiria ranganensis SAHNI & SmVASTAVA, 1956.

D i a g n o s i s - Biconvex, t ransverse shell with high and very concave, apsacline ventral interarea, with perideltidial areas. Ornamentat ion of simple costae; micrornamentat ion of radial striae and elongated pustules (twill pattern). Internal characters of the ventral valve consisting of long dental plates and long adminicula, deeply sunken delthyrial plate and a cylindrical callus above the floor of the valve. Shell substance finely punctate.

D i s c u s s i o n - The genus Subansiria was erected by Sahni & Srivastava (1956) for impunctate syringothyrids with a "structure similar in outline to the syrinx but s i tuated close to ventral sinus". Singh (1978) revised the genus, introducing a new species. Armstrong (1968b) described the ultra- structure of the shell of Subansiria sp. from the Permian Peawaddy Fm. (Bowen Basin, Queens- land), recognizing the presence of punctae as thin, slightly sinuous pores, around which the secondary layer fibres were deflected towards the exterior. Waterhouse (1987) stated that he revised the types of Subansiria and that he counted 10-13 punctae for 1 mm in a dorsal valve. Fur thermore he checked the occurrence of a calcite rod lying above the adductor impressions. The ul trastructu-

394

ral analyses performed by the present author in two specimens of Subansiria sp. (Fig. 13) from southern Oman, confirm the occurrence of outward deflection of secondary layer fibres around punctae about 6-9 ~m in diameter in the postero- lateral par t of the ventral valve.

The genus Subansiria differs from Cyrtella by its strongly concave and apsacline ventral interarea, longer ventral adminicula, occurrence of a cylindrical callus above the floor of the ventral valve, strongly divergent socket plates.

O c c u r r e n c e a n d age - Subansiria is a Cimme- rian endemic genus occurring in the Late Sakma- rian of Himalaya and Oman. Its possible a ccur- rence in Australia is still debatable.

Subansiria sp. Fig. 11.7-9

1959 Asyrinx haushiensis HUDSON & SUDBURY, p. 46-47, pl. 5, figs. 3, text-fig. 11.

F i g u r e d m a t e r i a l - 3 ventral valves: MPUM7976 (OL 10-1), MPUM7978 (OL 10-A), MPUM7979 (OLl1-12); 1 dorsal valve: MPUM7977 (OL10-18).

O c c u r r e n c e a n d age - Saiwan section: OL15 (-, 7, 2), OL16 (1, -, -), OL17 (-, 5, 1); Haushi left bank section: OL10 (-, 17, 4), O L l l (-, 7, -). Saiwan Fm. Late Sakmarian.

Desc r i p t i on - Shell biconvex, transverse in outline. Maximum width at hinge line. Cardinal extremities alate. Anterior commissure uniplicate. Shell substance with fine punctae (6-9 ~m in diameter) and micropunctae (Fig. 13). Ventral valve very convex, flattening near cardinal extremities. Umbo strongly recurved on the high, very concave, and apsacline interarea; perideltidial areas present. Two grooves along the delthyrium (hypodeltidial and deltidial furrows) may have accommodated stegidial plates. Ventral sulcus smooth, deep, '~V" shaped, deepening and widening anteriorly. Dorsal valve convex with very low, poorly defined interarea and wide notothyrium. Fastigium low, with a shallow median furrow.

Ornamentat ion of 12-14 rounded costae on each flank. The width of the costae is about 0.9-1 mm at 1 cm from the umbo and 1.6-1.9 mm at the anterior margin. Growth lamellae are also present. Micrornamentation of radial striae and elongated, ra ther closely spaced, and i r regular ly arranged pustules, giving a twill pa t te rn (Fig. 14).

Ventral valve interior with long dental flanges and adminicula, showing a concave anterior margin. A deeply sunken delthyrial plate joins the dental plates. The cavity below this plate is filled by a cylindrical callus, extending anteriorly above the floor of the valve. A callus may also fill the lateral cavities. Muscle field wide, longitudinally striated. Gonadal pits occur in the postero-lateral region. Dorsal valve interior with very broad, laminated cardinal process. Socket plates concave, strongly diverging, almost parallel to hinge line. A low median septum is present anteriorly to the cardinal process. Elongated grooves are radially arranged on the floor of the lateral flanks of the valve.

D i s c u s s i o n The available specimens of Subansiria may belong to the species S. ananti SINGH, 1978, which exhibits finer costae than those of S. ranganensis.

The material of Oman is similar to Subansiria sp. described by Singh & Archbold (1993) from the Sterl i tamakian of Eastern Austral ia and interpreted as submature specimens of S. ananti. However the specimens under examination are characterized by a massive umbonal callosity, which has not been observed in the Himalayan

Genus Punctocyrtel la PLODOWSKI, 1968

Type spec ies - Punctocyrtella spinosa PLODOWSKI, 1968.

D i a g n o s i s - Very t ransverse shell (W/L > 2.5), with smooth and deep sulcus and variably sulcate fold; ornamentation of simple costae; micrornamentation of radial striae and elongated, hollow

FIGURE 11 - 1-6. ?Cyrtella aff. nagmargensis (BIoN). 1. dorsal view of an articulated shell, MPUM7959 (OL141-23). 2. ventral view of an articulated shell, MPUM7960 (0L141-28). 3. ventral valve in dorsal view showing hypodeltidial and deltidial furrows, delthyrial plate and muscle field, MPUM7963 (0L144-17). 4. postero-dersal view of an articulated shell, MPUM7961 (OL143-19). 5. interior of an articulated shell showing teeth, dental plates and adminicula, muscle scars, apical callus, median septum in the ventral valve and socket plates ankylosed to cardinal process in the dorsal valve, MPUM7962 (OL143-3). 6. dorsal valve in ventral view showing cardinal process and socket plates, MPUM7964 (OL144-13). 7-9. Subansir ia sp. 7-8. ventral (7) and dorsal (8) view of ventral valve showing hypodeltidial and deltidial furrows, delthyrial plate, dental plates and adminicula, cylindrical callus, MPUM7976 (OL 10-1). 9. interior of dorsal valve showing cardinal process and socket plates, MPUM7977 (OL10-18). (All figures natural size). 1-6 ?Cyrtella aff. nagmargensis (BraN). 1. rue dorsale d'un spgcimen complet, MPUM7959 (0L141-23). 2. rue dorsale d 'un spdcimen complet, MPUM7960 (0L141-28). 3. rue dorsale d'une valve ventrale montrant les sillons hypodeltidial et deltidial, la plaque delthyriale et l'insertion musculaire, MPUM7963 (0L144-17). 4. rue postdro-dorsale d'un spgcimen complet, MPUM7961 (0L143-19). 5. intdrieur d'un specimen articuld montrant les dents, les plaques dentales et l 'adminicula, les empreintes musculaires, le cal apical, le septum mddian ventral et les plaques des fossettes dentales souddes au processus cardinal, MPUM7962 (0L143-3). 6. Vue ventrale d'une valve dorsale montrant le processus cardinal et les plaques alvdolaires, MPUM7964 (0L144-13). 7-9. Subansiria sp. 7-8. rues ventrale (7) et dorsale (8) d'un valve ventrale montrant les siUons hypodeltidial et deltidial, la plaque delthyriale, les plaques dentales et l 'adminicula, le cal cylindrique, MPUM7976 (OL 10-1). 9. intdrieur d'une valve dorsale montrant le processus cardinal et les plaques des fossettes dentales, MPUM7977 (0L10-18).

395

2

4

3

6

9

396

80- 75- 70 65- 60 55

._, 50 E 45 g

40 -o 35

30 25 20 15 10

5

+ • . ; , L .

+ •

0 5 1'0 1'5 2'0 2'5 3'0 3'5 40 4'5 5'0 5'5 6'0 6'5 7'0 7'5 80 Length (ram)

FIGURE 12 - Scatter diagram comparing length and width of ?C. aff. nagmargensis (BIoN). Early juvenile individuals have a transverse outline; at about 50-60 mm in length, they change into a equidimensional outline; finally, at length greater than 60 ram, adult change back to a transverse outline. Distribution des longueurs et largeurs de ?C. aff. nagmargensis (BIoN). Les juveniles pr~coces ont une forme transverse; & des longueurs de 50-60 rnm, les juveniles deviennent dquidimensionnels; & des longueurs de 60 mm et plus, les adultes poss~dent & nouveau une forme transverse.

pustules quincuncial ly arranged; inter ior of ven- t ra l valve wi th short de l thyr ia l plate, apical callus, long and divergent denta l plates and short adminicula . Shell substance wi th very fine and i r regular ly a r ranged punctae.

D i s c u s s i o n - As discussed above, Punctocyrtella PLODOWS~ was considered a junior synonym of Cyrtella by most authors. Other authors, such as Grunt & Dmitriev (1973) and Waterhouse (1978), use the generic name Punctocyrtella for those species similar to Cyrtella but with punctate shell substance. Termier et al. referred Punctocyrtella spinosa PLoDows~, 1968 to the genus Licharewia EINOR, 1939 and considered Permospirifer (?) wardakensis LEGRAND-BLAIN, 1968 as its junior synonym. Fur- thermore Termier et al. (1974) stated tha t the species spinosa PLODOWSKI from Afghanis tan was impunctate. In fact Plodowski (1968) described the shell substance ofP. spinosa as perforate, but, according to Termier et al. (1974, p. 101), these perfora- tions are due to the spongy nature of the primary layer. The SEM analyses of the shell of P. spinosa from southern Oman pointed out tha t the secondary layer is punctate (Fig. 14), as previously suggested by Thomas (1971, p. 150), who detected punctae on Plodowski's specimens of Punctocyrtella.

The differences be tween the genera Cyrtella and Punctocyrtella are l is ted above, in the discussion of the former genus. Punctocyrtella differs from Subansiria by its more t ransverse shape, lower vent ra l in te rarea , shor ter ven t ra l adminicula , absence of a cylindrical callus.

Termier et al. (1974) raised the problem of the relationship of Punctocyrtella with the similar genera Permospirifer KULIKOV, 1950 and Licharewia EINOR, 1939. Permospirifer has been considered a junior synonym of Licharewia by Ivanova (1960), P i t ra t (in Treatise, 1965) and Termier et al. (1974}. Grigorieva & Kotlyar (1966) and Waterhouse (1968) dist inguished Permospirifer from Licharewia by their respective micrornamenta t ion characterized by pustules in the former and by radial str iae in the latter. According to Legrand-Blain (1968} Permo- spirifer differs from Licharewia by lower ventral interarea and th inner dental plates. Another transverse genus is Orulgania SOLOMINA & TSCHERN~A~, 1966 and it is characterized by a higher ventral interarea, longer dental plates and adminicula, larger delthyria] plate and micrornamenta t ion of elongated tubercles. Kotlyar (1995, pers. comm.) saw the specimens from southern Oman and considered them different from the type-species of Permospirifer. Fur thermore Permospirifer, Lichare- wia and Orulgania lack perideltidial areas (Carter et al. 1994), which occur in Punctocyrtella.

In conclusion in the p resen t paper the generic name Punctocyrtella is res t r ic ted to very t ranver- se species (Width/Length > 2.5) wi th per idel t idial areas, short vent ra l adiminicula, smal l de l thyr ia l plate, numerous costae (> 20 for each flank), mic ro rnamenta t ion of radia l s t r iae and elongated pustules, shell substance puncta te .

O c c u r r e n c e a n d a g e - Punctocyrtella is a Cim- mer ian genus, occurring in the Ear ly Pe rmian of Centra l Afghanis tan and Oman.

Punctocyrtella spinosa PLODOWSKI, 1968 Fig. 15.1-3; Table 6

1959 Spirifer latus (McCoY): Hudson & Sudbury, p. 47, pl. 5, fig. 9.

1968 Punctocyrtella spinosa PLODOWSK1, p. 253, pl. 1, fig. 10. 1968 Permospirifer (?) wardakensis L~G~D-BtaIN, p. 205,

pl. 1, fig. 5; pl. 4, fig. 1-2; text-figs. 5-6.

1970 Punctocyrtella spinosa: Plodowski, p. 43, pl. 7, fig. 1-8.

Figured material - 1 articulated shell: MPUM7987 (OL15- 32); 4 ventral valves: MPUM7988 (OL15-A), MPUM7989 (OL15-B), MPUM7990 (OL15-A), MPUM7986 (OL15-30).

O c c u r r e n c e a n d a g e - Sa iwan section: OL15 (1, 30, 3); Haush i left bank section: OL10 (-, 2, -); HUQF4 (-, 2, -). Sa iwan Fm. La te Sakmar ian .

397

FIGURE 13 - A: transverse section of a ventral valve of ?CyrteUa aff. nagmargensis (BIoN) (MGL67119) showing secondary layer fibres. B: transverse section of a ventral valve of ?Cyrtella aff. nagmargensis (BION) (MGL67121) showing punctae. C: transverse section of a ventral valve of Punctocyrtella spinosa PLODOWSKI [MPUM7988 (OL15-A)] showing regular keel and saddle profile of the secondary layer fibres. D: longitudinal section of ventral valve ofSubansiria sp. [MPUM7978 (OL 10-A)] showing thick fibres and punctae of the secondary layer..4" section transversale d'une valve ventrale de ?Cyrtella aff. nagmargensis (BIoN) (MGL67119) montrant les fibres de la couche secondaire. B: section transversale d'une valve ventrale de ?Cyrtella aff. nagmargensis (BloN) (MGL67121) montrant les punctae. C: section transversale d'une valve ventrale de Punctocyrtella spinosa PLODOWS~ [MPUM7988 (OL15-A)] montrant la morphologie rdguli~re en car~nes et selles des fibres de la couche secondaire D: section longitudinale d' une valve ventrale de Subansiria sp. [MPUM7978 (OL IO-A)] montrant les fibres et punctae gpaisses de la couche secondaire.

398

FIGURE 14 - A" longitudinal section of a ventral valve ofPunctocyrteUa spinosa PLODOWSKI [MPUM7989 (OL15-B)] showing punctae. B-C: surface of a ventral valve (anterior margin top right) of Punctocyrtella spinosa PLODOWSKI [MPUM7990 (OL15-A)] showing micrornamentation of elongated pustules in quincux between radial striae. D- surface of a ventral valve (anterior margin top right) of Subansir ia sp. [MPUM7979 (OL11-12)] showing micrornamentation of irregularly arranged, elongated pustules between radial striae. A: section longitudinale d'une valve ventrale de Punctocyrtella spinosa PLODOWSKI (MPUM7989 (OL15-B)] montrant les punctae. B-C: surface d" une valve ventrale (marge antdrieure, en haut ~t droite) de Punctocyrtella spinosa PLoDOWSKl [MPUM7990 (OL15-A)] montrant une micro-ornementation faite de pustules alIong~es en quinconce entre les stries radiales. D: surface d'une valve ventraIe (marge antdrieure, en haut & droite) de Subansiria sp. [MPUM7979 (0Ll1-12)] montrant une micro-ornementation faite de pustules allongdes et disposdes irrgguli~rement entre les stries radiales.

399

D e s c r i p t i o n - Shell biconvex very t ransverse in outline. Maximum width at hinge line; cardinal extremities angular. Anterior commissure uniplicate. Shell substance punctate and micropuncta- re. Punctae are irregularly arranged and very fine (6-7 l~m in diameter) as shown in Figs. 13 & 14. Ventral valve elongate alate, with angular cardinal extremities. Interarea moderately high, sligh- ty concave, with large perideltidial areas. Median sulcus bald, deep and narrow with subparabolic cross section. Sulcus widening and deepening anteriorly. Long sulcal tongue. Ornamentat ion of flat rounded costae wi th nar row intercostal troughs and growth lamellae, crowded anteriorly. The maximum width of the costae at the anterior margin is 1.6-1.8 mm and they number about 24- 30 on each flank of the valve. The width of the costae decreases from the sulcus to the lateral margins. Micrornamentat ion of radial striae and elongated hollow pustules, widely spaced and quin- cuncially arranged (Fig. 14). Dorsal valve arched, very t ransverse in outline. Interarea low, striated. Fastigium narrow with high fold. Two thin costae and a median furrow may be present in the anterior par t of the fold. Ornamentat ion of the flanks as in the ventral valve.

Ventral valve interior with very short ventral adminicula and longer, anteriorly free dental flanges bearing a stout recurved tooth. Delthyrium closed under umbo by a small, flat delthyrial plate and by an apical callus. Muscle field depressed, broad and striated. Gonadal pits extend in the postero-lateral region of the shell, surrounding the muscle field. The gonadal pits cause the secondary layer fibres to be deflected outward around a central nucleus of irregular accretions, about 5-6 ~m in diameter (MacKinnon, 1974). Dorsal valve interior with laminated cardinal process and with thin socket and crural plates. Laterally directed, very long spiralia.


D i s c u s s i o n - The specimens from Oman are very similar to Punctocyrtella spinosa PLODOWSKI, 1968 from the Early Permian of Central Afghanistan.

Termier et al. (1974) considered Permospirifer (?) wardakensis LEaRAND-BLAIN (1968, p. 205, pl. 1, fig. 5a-c; pl. 4, fig. 2a-c; text-fig. 5, 6a-b) a junior synonym of Punctocyrtella spinosa PLODOWSKI, 1968 and described in detail the internal characters of the ventral valve as consisting of dental plates and adminicula and dendritic diductor scars. In the original description of the species Permospirifer (?) wardakensis, Legrand-Blain (1968, p. 207) s tated that the dental plates were lacking. In fact the ventral adminicula are very reduced, whereas the dental flanges are present, as also testified by her serial section (Legrand- Blain 1968, p. 207, fig. 5-6).

However Termier et al. (1974) failed in detecting punctae in the shell ofP. spinosa and they described a spongy, perforate pr imary layer and an impunctate secondary layer.

O t h e r o c c u r r e n c e s - In the Late Sakmarian of Wardak (Afghanistan), Punctocyrtella spinosa has been recorded to occur a few meters below the PseudofusuIina ambigua zone (Legrand-Blain 1968, Termier et al. 1974).

Superfamily PENNOSPIRIFERINOIDEA Dagis, 1972 Family PUNCTOSPIRIFERIDAE Waterhouse, 1975

Subfamily PUNCTOSPIRIFERINAE Waterhouse, 1975

Genus Punctospirifer NORTH, 1920

T y p e spec i e s - Punctospirifer scabricosta NORTH, 1920.

R e m a r k s - The genus Punctospirifer has been introduced by North (1920) for those septate and punctate spiriferids, showing high ventral interarea and large, rounded ventral sulcus and dorsal fold. Punctospirifer differs from Spiriferellina FREDERICKS, 1924 by a greater number of lateral costae, larger ventral sulcus and dorsal fold. Moreover the ventral interarea is sharply differen- t ia ted from the lateral flanks of the valve. Punctospirifer can be distinguished from Call# spirina IVANOVA, 1975 by the absence of spines, higher interarea, more numerous costae and higher median septum in the ventral valve interior. Fur thermore the in terarea of the genus Punctospirifer is normal to the commissural plane. Punctospirifer is a word-widely distributed genus.

Punctospirifer sp. Fig. 15.6-18

1959 SpirifereUina ? bilotensis var. curta REED: Hudson & Sudbury, p. 41, pl. 5, fig. 4, text-fig. 9.

F i g u r e d m a t e r i a l - 1 articulated shell: MPUM7994 (OL10-29).

O c c u r r e n c e a n d age - Haushi left bank section: OL10 (1, -, -). Saiwan Fm. Late Sakmarian.

D e s c r i p t i o n - Small sized, biconvex shell, with transverse outline. Maximum width at hinge line. Maximum width = 17.3 mm; corresponding length = 11.3 mm and height of in terarea = 4.2 mm. Car- dinal extremities acute. Anterior commissure uniplicate. Shell substance densely punctate. Ventral valve with blunt umbo. Ventral interarea high, concave, transversally striated, inclined at right angle to the commissural plane. Delthyrium open. Median sulcus deep, "U" shaped, widening anteriorly. Dorsal valve with rounded fastigium and high fold.

Ornamentat ion of simple rounded costae numbering 5 on each flank. Growth lamellae evident.

D i s c u s s i o n - The unique available specimen and that of Hudson & Sudbury (1959) differ from Spiriferellina bilotensis var. curta REED, 1944 by the natuy~e~of the interarea, larger sulcus, less incurved umbo. It differs from Punctospirifer a f g h a n u s TERMIER, TERMIER, LAPPARENT & MARIN, 1974 by its smaller dimensions, finer costae and more transverse shape.

Family PARASPIRIFERINIDAE Cooper & Grant, 1976

Genus Callispirina COOPER • MUIR-WOOD, 1951

Type spec ies - Spiriferina ornata Waagen, 1883.

R e m a r k s - Callispirina COOPER & MUIR-WOOD, 1951 is similar to Paraspiriferina REED, 1944 dif- fering from it by means of its sharper and less numerous costae; dorsal fold only slightly higher than lateral costae; high, inwardly bended crural plates fused to unusually high adminicula; larger cardinal process. Furthermore according to Cooper & Grant (1976, p. 2743) the micrornamentation of the genus Callispirina consists of irregularly spaced growth lamellae, whereas according to Grant (1976, p. 231) the growth lamellae of Callispirina are regularly spaced and those of Paraspiriferina are irregular in strenght and spacing. Judging from the illustrations reported in both papers, Callispirina show more regular growth lamellae with respect to Paraspiriferina. Callispirina differs from similar genera of the family Reticulariinidae by means of the absence of coarse hollow spines. Callispirina seems to be an antitropical genus, occurring both in the Boreal and Gondwanan Realms.

CaUispirina sp. Fig. 15.13-15; Table 7

1959 Callispirina ornata (WAAGEN, 1883): Hudson & Sudbury, p. 42, pl. 5, fig. 6.

400

F i g u r e d m a t e r i a l - 3 ventral valves: MPUM7995 (OL10-24), MPUM7996 (0L10-25,-31).

O c c u r r e n c e and age - Haushi left bank section: OL10 (-, 4, -). Saiwan Fm. Late Sakmarian.

D e s c r i p t i o n - Ventral valve convex, sub-elliptical in outline. Shell substance densely punctate. Maximum width at hinge line. Umbo pointed and recurved; interarea high and concave, transversally striated, with truncated margins. Delthy- rium open, apically closed by a small detthyrial plate. A groove occurs along each edge of the delthyrium (deltidial furrows). Ventral median sulcus deep and narrow, with fiat bottom.

Ornamentation of large and sharp costae, decreasing in size laterally and numbering 3-4 on each flank. Micrornamentation of growth lamellae, which are very dense and regular in strength and spacing. Fine capillae occur on the lamellae.

Ventral valve interior with long dental plates apically fused to short, divergent ventral adminicula; a thin median septum is also present.


D i s c u s s i o n - The available specimens differ from C. ornata (WAAGEN, 1884) by means of their truncated cardinal extremities, more transverse outline, less angular and deep ventral sulcus.

Order TEREBRATULIDA Waagen, 1883 Suborder TEREBRATULIDINA Waagen, 1883

Superfamily DIELASMATACEA Schuchert, 1913 Family DIELASMATIDAE Schuchert, 1913 Genus Fletcherithyris CAMPBELL, 1965

Type spec ies - Terebratula amygdala DANA, 1847.

R e m a r k s - The genus Fletcherithyris is characterized by the presence of a median septum supporting the cardinal plate. Fletcherithyris is a Gondwanan

FIGURE 15 - 1-3. Punctocyrtella spinosa PLODOWSKI. 1-2. ventral (6) and dorsal (7) view of a ventral valve, MPUM7986 (0L15-30). 3. dorsal view of an articulated shell, MPUM7987 (0L15-32). 4-10. Neospirifer aff. hardmani (FooRD). 4-6. ventral view of ventral valves, (4) MPUM7947 (OL18-17), (5) MPUM7948 (OL18-16), (3) 6GL74114 (OLll-2). 7-8. dorsal view of dorsal valves, (7) MPUM7949 (OL18-34) and (8) MPUM7950 (OL17-7). 9-10. interior of ventral valves, (9) MPUM7951 (OL18-7) and (10) MPUM7952 (OL18-1). 11. Neospirifer sp. Internal mould of ventral valve, MPUM7958 (0Lll-8) . 12. Trigonotreta sp. Ventral valve, MPUM7944 (OL10-23). 13-15. Callispirina sp. 13: ventral view of a ventral valve, MPUM7995 (OL10-25). 14: interior of a ventral valve, MPUM7996 (OL10-24). 15: ventral view of a ventral valve, MPUM7995 (0L10-31). 16-18. Punctospirifer sp. Dorsal (16), ventral (18) and anterior (17) view of an articulated shell, MPUM7994 (OL10-29). 19. Gilledia sp. Ventral valve, MPUM8001 (OL16- 6). 20-22. FIetcherithyris sp. 20. interior of dorsal valve, MPUM7997 (0L10-38). 21. ventral view of an articulated shell, MPUM7998 (OL15-124). 22. dorsal view of an articulated shell, MGL67162. (All figures natural size). 1-3. Punctocyrtella spinosa PLODOWSKI. 1-2. rues ventrale (6) et dorsale (7) d'une valve ventrale, MPUM7986 (0L15-30). 3. vue dorsale d'un spdcirnen complet, MPUM7987 (0L15-32). 4-10. Neospirifer aft. hardmani (FooRD). 4-6. rues ventrales de valves ventrales, (4) MPUM7947 (0L18-17), (5) MPUM7948 (0L18-16), (3) 6GL74114 (0Lll-2). 7-8. vues dorsales de valves dorsales, (7) MPUM7949 (0L18-34) et (8) MPUM7950 (0L17-7). 9-16. intdrieur de valves ventrales, (9) MPUM7951 (0L18-7) et (10) MPUM7952 (0L18-1). 11. Neospirifer sp: Moule interne de valve ventrale, MPUM7958 (0Lll-8). 12. Trigonotreta sp. Valve ventrale, MPUM7944 (0L10-23). 13-15. Callispirina sp. 13. vue ventrale d'une valve ventrale, MPUM7995 (0L10-25). 14. intgrieur de valve ventrale, MPUM7996 (0L10-24). 15. vue ventrale de valve ventrale, MPUM7995 (0L10-31). 16-18. Punctospirifer sp. Vues dorsale (16), ventrale (18) et antdrieure (17) d'un spdeimen complet, MPUM7994 (0L10-29). 19. Gilledia sp. Valve ventrale, MPUMBO01 (0L16-6). 20-22. Fletcherithyris sp. 20. intdrieure de valve dorsale, MPUM7997 (0L10-38). 21. vue ventrale d'un spdcimen complet, MPUM7998 (0L15-124). 22. rue dorsale d'un spdcimen complet, MGL67162.

401

3

..... ~ 10

11

16

7

12

2 0

13 14

19 21

/

402

genus and it is p resen t from the Late S a k m a r i a n to Midian of Aus t ra l i a and in the Late S a k m a r i a n of Badhaura , Pen insu la r India (Dickins & Shah 1979).

Fletcherithyris sp. Fig. 15.20-22; Table 8

F i g u r e d m a t e r i a l - 2 articulated shells: MPUM7998 (OL15- 124), MGL67162; 1 dorsal valve: MPUM7997 (OL10-38).

O c c u r r e n c e a n d a g e - S a i w a n section: OL15 (1, 3, -); H a u s h i left b a n k section: OL10 (1, -, 1); H U Q F 4 (3, -, 1). S a i w a n Fm. La t e S a k m a r i a n .

D e s c r i p t i o n - Biconvex shell, e longate oval to s u b - p e n t a g o n a l in out l ine. M a x i m u m wid th an te - r ior to mid- lenght . An te r io r c o m m i s s u r e s l ight ly unipl ica te . Ven t ra l va lve more a rched t h a n the dorsa l valve. Ven t ra l u m b o h igh and r ecu rved w i t h a l a rge apical f o r amen . Both va lves unfolded.

O r n a m e n t a t i o n of s t rong g rowth lamel lae .

Ven t r a l va lve in te r io r w i th low den ta l p la tes . Dorsa l va lve in te r io r w i t h h igh m e d i a n s e p t u m s u p p o r t i n g the ca rd ina l p la te .


D i s c u s s i o n - The s t a t e of p r e s e r v a t i o n p r e v e n t s a n y specific a s s i g n m e n t .

Genus Gi l l ed ia STEHLI, 1961

Type s p e c i e s - Terebratula cymbaeformis MORRIS, 1845.

?Gilledia sp. Fig. 15.19

F i g u r e d m a t e r i a l - 1 articulated shells: MPUM8001 (OL16-6).

O c c u r r e n c e a n d a g e - Sa iwan section: OL16 (1, - , -); H U Q F 4 (1, -, -). Sa iwan Fm. La te Sakmar i an .

D e s c r i p t i o n a n d d i s c u s s i o n - Shell biconvex, oval in outline. O r n a m e n t a t i o n of wavy rad ia l carinae. Spec imen MGL67164 is 15.5 m m long, 12.1 m m wide and 6.7 m m thick. Al though the avai lable spec imens are poorly p re se rved , they are questio- nab ly ass igned to the genus Gilledia on the basis of the i r o r n a m e n t a t i o n of wavy rad ia l carinae.

A k n o w l e d g m e n t - Field work in Oman was supported by the Peritethys Project. We are deeply indebted to P.R. Racheboeuf for his suggestions and assistance during the preparation of the final version of the manuscript. M. Legrand-Blain, H.C.H. Brunton and M. Gaetani made useful comments on an earlier version of the manuscript.

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A P P E N D I X

specimens n. Width Length W. int. H. int.

MGL67150 6.3 67.4 44.6 19 MGL67154 5.8 37 MGL67160 5.7 53 43.3 16.5 MGL67156 5.7 47.6 MGL67136 3.7 28 MGL67142 4.6 40.6 MGL67151 3 28 0L15-104 5.3 42 39.6 14.2 0L15-65-Holotype 4.5 34.9 0L15-69 6.3 39.7 13 0L15-88 >9 47.5 0L15-105 3.2 28.2

TABLEAU 1 - Derbyia haroubi nov. sp. W int.: width of interarea. H. int.: height of interarea.

specimens n. Width Length W. int. H. int.

OL15-77 >47 31 18 0L15-87 25.2 31 20.1 12.8 OL70-2 55.9 >50 35 19

TABLEAU 2 -Acti t re ta cf. bioni. W. int.: width of in terarea . H. int.: heigth of interarea.

specimens n. Width Length

0L15-23 48.7 50 0L16-46 37.7 41.5 0L16-8 42.3 47.3 OL16-21 39 47 OL16-27 43.8 46.9 OL16-25 42.2 51.9 OL16-32 35 39.9

TABLEAU 3 - Reedoconcha permixta.

specimens n. Width Length Thickness

MGL67143 52.3 33.3 18.9 MGL67144 60 27 22.3 OL18-1 50.9 35.4 OL18-2 40 27.7 OL18-17 >60 >37

TABLEAU 4 - Neospirifer aff. hardmani.

specimens n. Width Length H. int.

MGL67104 54.5 >34.4 >22 MGL67110 55.5 >23 MGL67112 54.7 >34 25.5 MGL67115 45.6 >31 18 MGL67119 57.7 >37.5 22.7 MGL67120 62.9 >28.4 MGL67121 62 >46.2 28.7 MGL67102 43.9 30.6 MGL67107 52.2 >27 MGL67109 51.5 >29.3 0L141-9 56.1 42 0L141-12 26.4 0L141-23 71.4 65.9 0L141-24 63.8 60.7 0L141-25 68.8 64.3 0L141-28 67.5 65.2 0L141-29 68.5 67

0L141-30 81.3 >57 0L141-31 70.9 62.2

0L141-32 64.7 62.7

0L141-34 57.7 52 0L141-35 73.9 64.3

0L141-36 75.2 64.9

0L141-37 63.7 >51

0L141-38 73.9 >58

0L142-II 45.8 30

0L142-12 45.8 36.1

9L142-13 48.6 40.2 0L142-15 48.3 40.2

0L142-17 36.4 30.6

01142-19 72.6 63.8 0L142-21 74 69.4

0L143-4 64.4 48

0L143-15 66.2 58.7

9L143-17 61.2 45.3 0L143-19 66.7 61.1

0L143-20 67.6 64

OLI41-1 61 26.7

0L141-13 79.5 29.6

0L141-14 63.5 24.1

0L141-16 62.2 26.5

0L141-17 61.7 24.1 0L141-41 64.1 27.3 0L142-6 79.9 30 0L142-8 70.7 27.5

0L143-I 70.6 27.7 0L144-17 72.2 31.7 0L144-18 79 36.4

0L144-19 70.3 32.7 0L144-20 67 28.9

0L144-21 89 39.2

0L142-I 66.4 40.9 0L142-2 71.1 41.6 0L143-5 58.5 44.6

tABLEAU 5 - ?Cyrtella aff. nagmargensis.

4 0 5

specimens n. Width Length

0L15-30 >104 30 0L15-32 >42.7 20.9 OL15-42 >63.5 25.9 0L15-60 >57.5 19.8

TABLEAU 6*PunctocyrteUa spinosa.

specimens n. Width Leng th H. int

0L10-24 16.9 13.3 5.7 0L10-25 16.3 12

TABLEAU 7 - Callispirina sp.

specimens n. Width Leng th Thickness

OL15-124 14.1 19.2 OL15-125 11.7 17.3 MGL67161 16.9 24.3 10.3 MGL67162 14.6 20.3 8.5 MGL67165 10.3 14.4 6.6

TABLEAU 8 - Fletcherithyris sp.