The Frasnian–Famennian brachiopod extinction events: a preliminary review. Acta Palaeontologica Polonica 43: 395–411

The Frasnian-Fam ennian brachiopod prelim inary A review event s: GRZEGORZ ext inct ion RACKI Racki, G. 1998. The Frasnian-Famennian brachiopod ext inct ion event s: A preliminary review . - Act a P alaeont ologica P olonica 43, f , 39 5411. Preliminary review of t axonomy of t he brachiopod order AĘpida and it s st rat igraphic dist ribut ion in t he lat e Frasnian Kellwasser Crisis of several regions of Laurussia, west em Siberia and Sout h China point t o t heir moderat e diversit y and st epdown but irregular ext inct ion pat t ern. The dist inct ive charact er of t he lat e Frasnian at rypid fauna is emphasised by several relict genera, marked by recurrent and possibly aberrant charact ers (mainly in ornament at ion t ypes), t endency t o size reduct ion and homeomorphy in some t axa. The t ransgressive/ hypoxic Lower Kellwasser Event and preceding eust at ic changes during t he Palmat olepis rhenanaZone had only a regional dest ruct ive effect , and were linked rat hęr t o an enhanced dispersal of t he last generic set of aĘpids. The VariaĘpinae, Spinat rypinae and I owat ryp,a-group seem t o belong t o t he lat est surviving at rypids. The final demise of t he remaining at rypids (and some ot her art iculat e brachiopods, e.g., gypidulids) coincided wit h t he fransgressive/ hypoxic Upper Kellwasser Event , followed by cat ast rophic eust at ic fall during t he lat e Palmat olepis linguiformisZone (F-F Event ). This was probably exacerbat ed by accelerat ed submarine volcano-hydrot hermalact ivĘ, and consequent progressive regional eut rophicat ion, and climat ic dest abilizat ion. The level-bot t om rĘnchonellid-inart ioulat e biofacies crosses t he fat al F-F boundary horizon wit hout maj or changes. No reliable dat a exist for t he presence of aĘpids in t he Famennian survival and recovery biot a, even for t he smoot h lissaĘpid Perat os. Sust ained competition from radiating and diversiffing productid-cyrtospirifrid-athyrid faunas may have provide an additional biotic factor in the collapse of the Frasnian shelly benthos at the time of sfress, as well as in a post-extinction offshore repopulation from inner shelf habitats. Key w ords: Brachiopoda, AĘ pida, Pent am erida,biosf f at igraphy,palaeoecology, biogeography, mass ext inct ion, Kellwasser Crisis, Frasnian, Famennian, Devonian. Grzegorz Racki [ racki@us.edu.pl] , Kat edra Paleont ologii i St rat ygrafii, Uniwersyt et Ślqski, ut . Będzińska 60, 41-200 Sosnowiec, Poland. I nt roduct ion Since t he classicw orksof Copper ( 1966,1973,1986b)t,hebrachiopodorderAt rypida, a prominentbenthic componęntof Middle Palaeozoic shelf ecosystems(AĘpid4ypidulid Biofacies of Racki et aI . 1993), is commonly cited as a prime victim of the 396 Brachiopod ext inct ion event s: RACKI mid-Late Devonian (Frasnian-Famennian;F-F) mass extinction. This was one of thę severest global bio-crises in the Phanerozoic, termed by Schindler (1990) thę Kellwasser (KW) Crisis (see Racki 1998). This biotic turnover coffesponds to the late Frasnian to earliest Famenniansęriesof extinction pulses,manifestedprimarily during the late Frasnian in the two eustatic/ trypoxicKellwasser events, culminating in the ecosystemcollapsenear the F-F transition(seesummaryin McGhee 1996and Walliser 1996).Atangled combinationof causalfactors,especially profoundoceanographicand climatic changes,probably brought aboutthe bio-crisis (Joachimski & Buggischl996; Copper 1998;Racki in press) . Atrypid catastrophiccollapse was examined at the family, subfamily and generic level by Copper (1986b). For other brachiopods,similar detailed data,but only on a regional scale, were gatheredfor gypidulid pentamerids(Godefroid & Racki 1991), anothergroup that becametotally extinct at the close of the Frasnian age. The last (late Frasnian) phasein the aĘpid history has been only in a preliminary manner studied until now, as emphasizedby Copper (1986b).A major constrainthas always been the limits of stratigraphicresolution, with precise referenceto conodont zones available for few F-F brachiopod successions(seeMcGhee 1996),as exemplified by Baliński ( 1979' | 995a, 1996) and Cooper & Dut ro ( 1982) .Nonet heless,t he resulting revised genericrange chart in the substageframework exhibits the stepdown characterof atrypid demise during the Frasnian time (Copper 1986b, 1998). The resultsof the intemationalcollaborationresearchproject,funded in part by the State Committee for Scientific Research (Project no. 6P201 019 05), and presentedin the presentissue, enablea more detailed discussion of this problem, including refined datafrom widely separatedregions (Fig. 1). Taxonomic and evolut ionary framew ork I n a provisional genericand subgeneńcrangechart,Copper (1986b:fie.2) showedthe occrilrence of five generain the late Frasnian interval (startingfrom the Upper Palmat olepisgigasZone = Lat e Palmat olepisrhenanaZonesensuZiegler& Sandberg1990) . Copper (1998:fig. 1) recentlyshowedthepersistenceof 15 generalsubgenera duringthis timespan.However, someof the datastill requireconfirmation due to imprecisebiosffatigraphic dating (e.g.,Kyrtatrypa in WesternAustralia) and/ orambiguoustaxonomy.For example, the genus DevonaĘpa (synonymisedwith Neatrypa by Copper 1967, and Rzhonsnitskaya 1975)' and the representationof Peratos (_ at least in part rĘnchonellid juveniles in Late Devonian; Godefroid & Helsen 1998),needreexamination. Undoubtedly,the Frasnian continued a phase of decline which cofirmencedin the Givet ian.As discussedby Copper ( 1998) ,st rongext inct ionpulses,combinedw it h low to zero origination rates, killed off the Frasnian aĘpids. New taxonomic data, presentedby Balińsla (1997) and in this volume, partly refine the extinction pattern. The late Frasnian occuffenceof five atrypid subfamilies,all assignableto two families, is documentedherein. Of these,the Pseudogruenewaldtiinae(= the Frasnian member of I nvertininae; Copper & Chen 1994) are particularly typical for the KW Crisis interval. The stratigraphicrestrictionto this timespanmay be assumedfor at least four generaand subgenera:Pseudogruenewaldtia,Gibberosatrypa,Spinatrypa(Plicspinat- ACTA PALAEONTOLOGTCA POLOMCA (43) (2) 397 rypą) andWaiotrypa.Conversely,Copper (1998) has notfound any distinctive species group ońginated in the late Frasnian, but the diversity analysis is still hamperedby limited consistency in the taxonomy of the declining aĘpids, in particular for the Russian faunasstudiedby Rzhonsnitskayaet al. (1998). The atrypid dominancepatternvaries from region to region, even within the same epicontinentalsea, and was apparentlycontrolled by facies. The available data enable only a tentativesynthesisat the species level. An increasing number of species are recognized in the stratigraphicallyyoungest Pseudogruenewaldtiinae,SpinaĘpinae and Variat rypinae( e.9.,Godefroid & Helsen 1998;Rzhonsnit skayaet aL.1998) . Morphologic tendencies. - Among the Frasnian atrypids, especially among speciesduńng the KW Crisis, severalfeafures(re)appearedor culminated: ( 1) Copper ( 1973)est ablishedt w o mainly middle-lat eFrasnianspecies-groups, t he origin of which appearedto be enigmatic due to a re-appearanceof a rib structure typical of older, mostly Middle Devonian genera.I owatrypa andPseudogruenewaldtia exhibit a tightly imbricated,Atrypa-like shell surface,whilst Costatrypaclosely resemblesAtrypariainits undulose,shallow ribbing. On the other hand, someVariatrypinae, in particular Radiatrypa,lost growth lamellae and frills, exhibiting extremely simple, tubularrib sffucture;this tendencyis known also in Spinatrypina(Exatrypa) (seeRacki & Bat iński 1998) ( 2) Copper ( 1978: p.299) not ed a t rend t ow ardsrib disappearanceas t ypical of Frasnian Spinatrypa species.This characteris most perfectly expressedby late Frasnian speciesfrom I owa and New Mexico, such as Spinatrypa obsolescensCooper & Dutro, 1982. Otherwise, a rapid transition from simple and coarse ribbing in the posteriorpart into bifurcatedand thinner ribes in the anteriorpart is noticeablein some speciesof Costatrypa, e.g., C. vańcostata (Stunbrook, 1945)' Waiotrypa,I owatrypa and Spinat rypa( seeexamplesin Baliński L997; Racki & Baliński 1998; Rzhonsnit sk ay aet aL. 1 9 9 8 ) . (3) BalińsŁ,J(1997) has found that shell carination, manifestedin an elevated rib pair forming a median keel on the pedicle valve and a coffespondingnarrow sinus on the brachial valve, is a diagnosticfeatureof the genus Waiotrypa,which is limited to the late Frasnian. A similar tendency is known among many other affypids, but is mostly limited to the juvenile stages.Several more or less distinctive exceptionsare 'Atrypa'svinordi-gtoup, Spinatknown in the middle-lateFrasnian taxa, as shown by (Cher(Exatrypa) relicta Racki Baliński and Spinatrypa bifidaeformls & ,1998, rypina nyschev, 1887), as well as by Gibberosatrypa and the problematic carinanitid describedby Yudina in Rzhonsnit skayaet ą l. ( 1998) . (4) The above features,combined with reduced shell size (typically less than 2.5 cm), strongly suggestthe possible dwarfism and/ orpaedomorphosisin the late phase of aĘpid evolution in severallineages. At least someof thesecharactersmay be seenas aberrantor recurent, even if others may be merely a random adaptationto peculiar niches. Likewise, homeomorphywith older taxa seems to have been widespread among the stressedFrasnian aĘpids, as exemplifiedby Spinat rypina,I ow at rypaandWaiot rypa ( e.g.,Baliński 1997;Rzhonsnit skayaet a\ .1998) , as w ell as by Gibberosat rypa,Carinnt ina( ?) nd some Spinat rypina (Exatrypa). Likewise, a similarity even to orthids is sometimes observable 398 Brachiopod ext inct ion event s: RACKI (Baliński 1997), which is conspicuousI y expressedby ,Atrypa, svinordi Venyukov, 1885, originally assignedto Orthis (seeNalivkin 1941;Lyashenko 1959). Regional pat t erns of dist ribut ion The distribution pattern of late Frasnian aĘpids is summarized below for the four main Devonian continents(Fig. 1), with detaileddocumentationpresentedfor threeof them in papersin this volume: Laurussia (majority of analyses),southwesternSiberia and South China. The eust at iccyclicit y pat t ernof Johnsonet al. ( 1985) ,improvedby Sandberget al. (1988, 199f), presentsa convenientbasis for 'natural'chronostratigraphy. The middle Frasnian coincides with the transgressive-regressive (T-R) Cycle I I c, while the late Frasnian is a gross equivalent of the complex T-R Cycle trd (but notably beginning from the Palmątolepis semichatovaetransgressionin the Early Palmątolepis rhenana Zone, following Ziegler & Sandberg1997).The latest Frasnian correspondsto the key time interval following the second transgressive/ trypoxic pulse within the Devonian eustatichighstand(= Upper Kellwasser Event), in the Palmatolepis linguifurmisZone. Laurussia Sout h Polish-Moravian shelf. - The lat e Frasnian brachiopod fauna of t he Holy Cross Mount ains is st ill only part ially known, but st udies of t he gypidulids (Godefroid & Racki 1990), biernat ellids (Baliński 1995b) and ot her at hyridids (Grunt & Racki 1998), rhynchonellids (Sart enaer et al, 1998), and at rypids (Baliński 1997; Racki & Baliński 1998) form a basis for evaluat ing ext inct ions in t he shallow-wat er AĘpid_Gypidulid Biofacies (Racki et al. | 993). The occulTence of 15 t axa of At rypinae (Cost at rypa), Spinat rypnae lSpirut rypa, Spinat rypina (Spinat rypina), Spinat rypina (Exat rypa)1, Pseudogruenewaldt linae (I owat rypa,Waiot rypa) and Variat rypinae (Radiat rypa, Desquamat ia), is est ablished, including t wo new species (Baliński 1997; Racki & Baliński 1998). Adiverse at rypid-gypidulid associat ion, wit h Spinat rypina (Exat rypa),Variat rypa, Desquarnat ia (Serat rypa) and.Met abolipa as t he main component , is richly represent ed in t he earliest middle Frasnian Kadzielnia-t ype,localized sfromat oporoid-calcimicrobial bioherms developed on t he gent le slope of t he Dyminy Reef; similar faunas occur in variet y of ot her reef margin t o foreslope set t ings, especially in paraut ocht onous pocket s near renalcid-dominat ed lat e Frasnian buildups (Rackt et al. 1993). During t he Palmat olepis rhenanaZone, aĘpids were t he dominant element of very diverse brachiopod assemblages (more t han 40 belonging t o at least 25 genera; most ly rĘnchonellids, spiriferids and at hyridids), t hriving in declining perireefal habit at s (see Racki et al.1993; Grunt & Racki 1998). The t axonomic composit ion of t he associat ion remained generally similar, and in t he 'reef-cap' phase (sensu Krebs 1974) t hrived Cost at rypa varicost at a (St ainbrook, 1945), in part icular t he morphoĘpe ext ensa of Cooper & Dut ro (I 98f), and a larger-sized variet y of lowat rypa(?). A relat ively large-sized Desquamat ia(?) is also an end-member of t he at rypid succession of fore-reef sequences' and persist ed up t o t he F-F boundary. Biernat (1970) not ed some aĘpids in t he early Famennian of Kadziet nia, but cert ainly t hey have been derived from t he underlying Frasnian members in t his localit y. Middle Frasnian deeper-wat er (1eve1-bot t om)faunas are marked by Pseudoat rypa or minut e Carinat rypa(?) and Spinat rypa. The st at igraphically younger mid- t o downslope faunas include abundant lowat rypa, SpinaĘpina (Exat rypa), Cost at rypa, WaioĄpa and Desqunmarla. Thus, rapid lat e Frasnian eust at ic changes, especially during t he Palmat olepis semichat ovae t ransgression in t he Early P rhenana Zone (see Sandberg et al. I 99f), were linked wit h a significant brachiopod immigrat ion wave, and also wit h t he evolut ionary fransit ion from Met abolipa t o Neomet abolipa ACTA PALAEONTOLOGTCA POLONTCA (43) (2) [ Tł T: il Deepocean W Landm ass ffi Mount ains 399 Act ive su bdu ct ion zon e Fig. 1. Locat ions of st udied and discussedbrachiopod faunasagainst t he Lat e Devonian palaeogeography (court esyof J. Golonka, adapt ed). am ong gypidulids ( Godef roid & Racki 1990: f ig. 9) . The Low er KW Event w as w it hout cat ast rophic consequences for t he brachiopod faunas here. [ n cont rast , a regional ext inct ion phase of at least downslope assemblagesis linked wit h expanding anoxic condit ions duńng t he Upper KW deepening pulse in t he lat e Palmat olepis linguiformis Zone. The ult imat e ext inct ion of deeper-wat er aĘpids coincided wit h a severe eust at ic fall (Event 6 in Sandberg et al. 1988: p.296), recorded in episodic calcareous deposit ion of t he F- F passagebeds ( Racki & Baliński 1998) . The dominant aĘpids in t he shallow-wat er, post -reef crest brachiopod-crinoid assemblageswere progressively replaced duńng t he lat er phase of t he KW Cńsis by impoveńshed (up t o eight genera) faunas, comprising product ids, cyrt ospiriferids, at hyńdids (Grunt & Racki 1998)' including t he last biernat ellids( Baliński 1995b) ' as w ellas ort hids, m ainly Schizophoria ( see Racki & Baliński 1998) . Est ablishment of far more diverse shelly faunas, wit h t ypical Famennian species, is indicat ed in t he Palmat olepis crepida Zone (see review in Biemat 1988), as part of t he sust ained shelf ecosyst em recovery. I n general t erms, cont inuit y of t he deeper-wat errhynchonellid-inart iculat e biofacies across t he F-F boundary is well expressed in t he marly successions (Racki et al. 1993). This is well exemplified by t he t ransit ion wit hin aut ocht onous monospecific assemblages from Ryocańynchus t umidus (Kayser, 1871) t o Orbiculat isinurost rum laeve (Gi.irich, 1903) in t he east ern Holy Cross Mount ains, in agreement wit h t he rhynchonellid succession in t he Cracow area (Baliński 1995a). Coeval brachiopod faunas are well-known from t he more sout hern (proximal) fragment of t he Polish shelf (Dębnik near Cracow; B aliński L9] 9 , I 995a). Persist ence of t he cyrt ospiriferid- at hyridid assemblage across t he ext inct ion level is not ewort hy, t erminat ing in a conspicuous brachiopod acme in t he P. crepida Zone (Baliński 1996). Single middle Frasnian at rypid species of Cost at rypa were succeeded by a species pair in t he Palmat olepis j amieae-Early P. rhenana zonal int erval. This includes species of low at rypa, probably I . am ericana ( St ainbrook, 1945) , and Desquam at ia ( Desquamat ia) alt icolifurmis Rzhonsnit skaya, 1975, t he lat t er possibly ranging even int o t he Palmat olepis linguifurmis Zone. Due t o poor out crops, t he brachiopod succession is not adequat ely document ed across t he F-F boundary. only disart iculat ed at rypid mat erial has been found duńng t he preliminar ycollect in gfrom t he F-F sect ions of t he Moravian shelf near Brno (Śumbera on Hadv Hill and Lesni Lom)' which 400 Brachiopod ext inct ion event s: RACKI represent shallow-wat er det rit al successions ((Fig. f; see Hladil & Kalvoda 1993). This includes represent at ives of t wo subfamilies t ypical of t he fore-reef facies, Variat rypinae and Spinat rypinae. Only t he former sect ion has been available for det ailed sampling, and t he presence of t wo assemblages is est ablished in t he Lat e P rhenana-P linguiformis zones (St reit ova 1994). The older assemblage is composed of small-sized Radiat rypa(?) and Desqunmat ia(?), whilst medium-sized spinat rypinids predominat e in t he succeeding assemblage. I n addit ion, a product ellid level occurs in an int ervening posit ion, whilst t he basal Famennian beds are composed of int raclast ic brachiopod-naut iloid-crinoid coquinas, wit h product ellids (Praewaagenoconchn) predominant and schizophoriids, cyrt ospiriferids and large cost at e rhynchonelllds (Ripidiońynchus) also present . Ardenne-Rhenish shelf. - I n t he Dinant Synclinorium, pent amerids and at rypids become ext inct well below (ca. 50 m) t he F-F boundary but above t he highest reef level of t he Neuville Format ion (Godefroid & Racki 1990; Godefroid & Helsen 1998). I n t his region t heir ext inct ion coincides more or less wit h t he appearance of shale facies of t he Mat agne Format ion, dat ed by conodont s as being in t he Early P rhenanaZone. Even if t his facies t urnover was correlat ed wit h t he Upper Kellwasser Event as proposed by Johnson et aI . (1985) and Sandberg et al. (1992), t he current conodont dat ings document a more complex, diachronous regional facies change. hence, t hey also record earlier t ransgressive-hypoxic event s during t he KW Crisis. From t he t hirt een aĘpid t axa described by Godef roid & Helsen ( 1998) ' only Cost at rypa vańabills ( Godef roid, 1970) andWaiot rypa(?) pluviaGodefroid & Helsen, 1998 occur above t he basal boundary of t he greenish argillaceous suit e. These t wo species are rare from t hat point up t o t he appearanceof t he blackish shales. Not ably, t he frilled and abundant C. variabills was adapt ed t o t he non-reef muddy and part ly oxygen-deplet ed habit at s, t ypical of t he int erval (F2i) bet weent wo last Frasnian reef levels (F2handF2j ). Several ot her species, belonging t o Spinat rypina, I owat rypa, and Desquamat ia werc apparent ly ext erminat ed during t he deepening-hypoxic pulse, even t hough t hese most ly small-sized forms preferred t he shales and limest ones deposit ed in t he vicinĘ of t he reef mounds. An alleged smoot h species of At rypida, Glassia drevermanni Maillieux, 1936 (see Copper 1986a), described from t he lat est Frasnian Mat agne Format ion, is now found (Godefroid & Helsen 1998) t o represent immat ure specimens of t he rhynchonellid Ryocarhynchys t umidus (Kayser, l81f). The lissat rypid genus Perat os is known 'reef-cap' (I berg) from t he Frasnian facies in Germany (Copper 1998). The Belgian lat e Frasnian bioherm (F-fj ) at ypid associat ion, which included Spinat rypa t umuli Godefroid & Helsen, 1998, and Desquamat ia (Serat rypa) derelict a Godefroid & Helsen, 1998, st ill recalls in generic t erms t he early Frasnian reef (F2d; Arche Member) fauna, wit h D. (5.) frasnensls Godefroid, 1970 t he dominant species. I n summary, t he Ardenne aĘpid-gypidulid faunas, dominat ed by Cost at rypa, Desquamat ia (t hree species), I owat rypa (t wo species), Spinat rypa, and Neomet aboĘa, arc a good example of a regional ext inct ion most ly in earlier phases of t he KW Crisis, aft er t he deat h of t he last impoverished reefs. I n t he Frasnian of t he Boulonnais region (NW France), only early-middle Frasnian aĘpids are described by Godefroid (1988), belonging t o Desquamat ia (t hree species), Spinat rypina (t hree species), Spinat rypa (t wo species) and post at rypa (one species). The st rat igraphically youngest aĘpid-bearing argillaceous sfoat a(Lat e Palmat olepis hąssi Zone) has t wo species of Spinat rypa. From t he Rhenish Shelf, Copper (1966,1967,1973) ment ioned a unique lat e Frasnian (F2h-F3) aĘ p id associat ion in t h eAach en ar ea' ca. 50k m NWof t h eEif el, g en er ally g r ou p ed ast h e, cu b oid es, fauna. This is marked by an abundance of Cost at rypa, Spinat rypa and lowat rypa (of I . t imanicat ype) , w it h t he last t axon lim it ed t o t he lat est Frasnian ( F3; Cgpper 1973: p.495) . How ever, t his assemblage st illawait s a more refined sfudy as does anot her spinaĘpid localit y in Germany, in t he Wildenfels Mount ains of Saxony (Becker et aI . I 99I ). Scht iller (1949) placed his nodular'At rypaKalk' (wit h presumed spinat rypinid 'At rypa aspera') in t he basal Famennian (Cheiloceras St ufe), but Schreiber (1985) referred t his fossiliferous pyrit e-rich limest one-shaly complex (39 m t hick) t o an int ermediat e level bet ween t he diabase series and t he Upper KW Limest one, dat ed as t he P gigas Zone. AĘpids report ed from t he Famennian .Langenaubucher Tuffbrekzie' by Drevermann (1901) are reworked late Frasnian faunas (Copper 1967). ACTA PALAEONTOLOGTCA POLOMC A (43) (Z) z Ż r Yl ń .3 (r) SUI \ UMBERA-1 10 f fEsś " .N dE 9 S' S d" , 'sF 8 luctidProducti athyridid Assemblage +- 7 z z ot i\ L > .> .ś 401 -- Spinatrypinae productellids Variatrypinae (f genera) v) 9 5 4 ffiilsff* '* : (!) F.l \\ żt / ) coquinas z [ l' [ f] l'l uiosparites biomicrites& l!fiffi l: : : : : : : : : : : : : : : : : l ! ig5pą fi 1ęg I ffi uo-i"rit", Fig. 2. Lithologic succession (after Streitovd 1994) and brachiopod faunas of the F-F boundary beds at Śumbera, Moravia. Note the occtlrTenceof atrypid- and productellid-ńch levels. East ern European Plat form. - Nalivkin (\ 94l)document ed t he absence of at rypids in t he lat e Frasnian shallowing basin of t he Main Devonian Field (NW East ern European Plat form). The t ypical Frasnian genus Anat rypa was originally described from t his area (for t ype species see Copper 1978), and remains essent ially unknown from ot her regions. I n a geographically broader st udy, Lyashenko (1959) recorded lat e Frasnian species. Decreasing diversit y t oward t he end of t he Frasnian is shown by t he presence of 10 species (Pseudoat rypa?, Desquamat ia, Variat rypa, Spit nt rypina, I owat rypa) in t he early Frasnian Sargaevo suit e (in t he present sense; see Rńonsnit skaya 1988)' reduced t o seven (Pseudoat rypa?, Spinat rypa, Spinat rypina) in t he middle Frasnian Semiluki srit e (Palmat olepis punct at a-P j amieaeZones; Menner & Ovnat anova 1996). However, t he generic posit ion of several species erect ed by Lyashenko remains doubt ful (Copper 1967,1973). No more t han t wo species are report ed from each of t he lat er Frasnian carbonat e-argillaceousunit s, most ly represent ing Spinat rypina and problemat ical Pseudoat rypa f'At rypa' symmet rica Lyashenko, 19591 and Desqunmat i.a ,At rypa' | ,At rypa, polj anica Lyashenko' 1959] . The st rat igraphically youngest f= ?Pseudoat rypą; (in p. Copper 1973: 4921 t anaica Nalivkin, 1950 Sarycheva & Sokolskaya 1950) is not ed as a commonly occurring species in t he cent ral part s of t he East European Plat form from t he Evlanovo suit e, i.e., I -at eP rhenanaZone. The impoverished brachiopod faunas are marked by t he widespread, locally rock-forming spiriferid. Theodossla, schuchert ellids, product ellids and cyrt ospiriferids. The slight ly more diverse Evlanovo bent hic faunas were probably linked wit h more marine condit ions, possibly during t he t ransgressive Lower KW Event . The lat est Frasnian fauna st ill cont ains rare undescribed at rypids and gypidulids (Lyashenko 1959: p. 200), and also t he last Theodossia. The unconformably overĘing Famennian sfoata are marked by an abundance of costate rhynchonellids, product ids, cyrt ospiriferids, and chonet ids. 402 Brachiopod ext inct ion event s: RACKI I n the NE part of the East European Platform (Timan-Petchora Province), the cunent study by Yudina (1996 1997; n Rzhonsnit skaya et al. 1998) revealed t hat Desquamat ia, Spinat rypa and SpinaĘpina persisted throughout the Frasnian, but never played a significant role. As a result of the Early P rhenana Zone sea-level fall (Veimarn et aI . 1997). a sffong differentiation of facies and brachiopod assemblages was established. The enĘ of CostaĘpavetlasjanica (Yudina, 1997) :rirtheshallow-shelf facies (Ukhta suite) and I owatrypa in deeper-watermarly facies (Lyaiol suite) coincides with this turnover. Surprisingly, an acme of aĘpids is report'edfrom the latest P rhenana_P linguifurmis zonalintervalin the same facies framework. The Ukhta cańonate sheĘ grading upwmd into evaporite deposits, is typified by an impoverished Theodossia ischmensis assemblage, which commonly contains an endemic species, Splnatrypina (S.) sosnovkeł zslsYudina, 1998 (in Rńonsnitskaya et al. 1998). [ n addition, the sftomatoporoid-calcimicrobial reefs were dwelled by a rare Hypothyridina-Gypidula association, with subordinate small-sized aĘpids: Desquamnt in(Desquamat ia) alt icolifurmisRzhonsnit skayą 19] 5, Radiflt ryparnn7nit ica Q.{ alivkin,| 947) andsporadic minut e endemic Cańnat ina(?) biohermica Yudina, 1998. I n confrast ' coeval basin argillaceous sediments (Lyaiol suite) were populated by abundant brachiopod communities (Biernntella timanica assemblage), dominated by diverse but mostĘ endemic aĘpid species: Pseudogruenewaldtia tschemyschevri Rzhonsnitskaya, 1964,I owatrypa(?) nebulosa Yudina, 1998, and diminut ive WaioĘpa(?) sp. A. Urals. - Rich and diverse Frasnian brachiopod faunas from t he Urals have been described in several st udies( e.g.,Nalivkin 1951; Lyashenko 1973; Markovskii 1989; Rńonsnit skayaet at .1998) , The st rat igraphic dist ribut ion of at rypids was recent ly summarized by St epan ova et al. (1985) for t he east slope of t he Sout h Urals (Magnit ogorsk Synclinorium), corresponding t o an act ive margin zone, and by Rzhonsnit skaya & Markovskii (ln Rzhonsnit skaya et al. 1998) for t he west slope of t he area. As shown by St epanova (in St epanova et al. 1985: fig. 4), t he at rypid associat ion is invariably composed of four t o five species in all t he Frasnian subst ages, but geneńc assignment is most ly uncert ain (Desquamafla sensu lat o, probably Spinat rypina, I owat rypa and Cost at rypa). However, lat e Frasnian reefal (Kolt uban suit e; st udied by Nalivkin 1951), volcanogenic and siliciclast ic-carbonat e deposit s cont ain more diverse fauna (10 species list ed in St epanova et ąl. 1985: p. 126) of Radiat rypa, Cost at rypa, Spinat rypina and lowat rypa. Only At rypa (= Cost at rypa?) post uralica is rest rict ed t o t his suit e (it s middle kiklin horizon). Diminishing species diversit y t o t he end of t he Frasnian is shown in faunal list s of t he succeeding hońzons (ńne, five and t hree species' respect ively), and only long-ranging species have been quot ed from t he highest Ust 'kolpak horizon: 'Desquam at ia' cf . alt icola ( Frech, 1901) , Spinat rypina t ubaecost at a( Paeckelm an, 1913) and,Spinat rypa I = Spinat rypina (Exat rypa)l bifurcat a (Markovskii, 1955 in Mikryukov 1955). Refinement of t he lat e Frasnian (Early P. rhenana t o P linguifoimis) nt ewal by Rzhonsnit skaya & Markovskii (in Rzhonsnit skaya et al. 1998) reveals t he presence of eight species, referred t o pseudoat rypa, Gibberosat rypa, Desquamat ia (Desqunmat ia), RadiaĘpa, I owat rypa and Spinat rypina.This t imespan is marked by t he development of massive limest one facies wit h numerous brachiopod coquinas and nest s. The appearance of six biogeographically new species was linked t o t he growt h of | f m t hick reefs of t he Askyn horizon, perhaps relat ed t o an immigrat ion wave induced by t he P semichąt ovae t ansgt ession, even t hough an overall shallowing t rend is not ed for t he lat e Frasnian of t his domain (Veimarn et al. 1997). Some of t he species might be endemic, e.g. Gibberosat rypa gibberosa (Markovskii, 1989), I owat rypa nalivkini Rzhonsnit skaya & Sokiran, 1998 (in Rńonsnit skaya et al. 1998), in t he Hypot hyridinn'cuboides'-D. (D.) alt icoliformis associat ion. St epanova et al. (1985) ascribed t he t wo highest aĘpid-bearing unit s t o t he Famennian P t riangularis Zone, but t heir correlat ion wit h t he Askyn hońzon (t able 1 t herein) clearly argues for a Frasnian age. I n brachiopod limest ones of t he earliest P. t ńangulańs Zone (bot t om part of t he Barma format ion), t he assemblage is dominat ed by rhynchonellids, at hyridids, product ellids (Mesop li ca) and cyrt ospiriferids. Cent ral and West ern Nort h America' -Lat er Frasnian aĘpids from Nort h America were st udied by Fent on & Fent on ( 1924) , St ainbrook ( 1945) , Copper ( 1978) , Cooper & Dut ro ( 1982) and Day & Copper (1998), and t heir dist ribut ion was summarizedby Day (1998). East ern American and largely Canadian faunas await t axonomic revision or descript ion, but it is known t hat t he New York F r Eg 6 ?o - * J! ' + F ggęł Hgf $* * H [ ĘFiią$=iEĘE! gś Ff Eę F E. r y g FF o Palnatolepis rhenana g$ł ia EĘ ś gęg F. Eigę 1E$$$ś fil[ BiiB,ui ,aĘ{ = $.* e T t J'fiffi^ Ft 6FĘ $EE f f ilFEiif lgEś $t E$HfgBBątg.69+ ErIsEiFą$EE' i . e ; . ^ s $K: EL L * ^ - f * = , "( l \ w , Fł ts P HĘ " " J..f f il$..ł PP 2B d> - uesquamaila - Spinatrypina - Costatrypa Ó 3 3 ' ? g s H x E 3 L s * # t rb , 9 : E Ę . {Br P FeEFsĘ t . * i$6t gBE; [$$EĘ $$* l g : g ' sĘ8 .# = ; a E g ĘE 3 H. d g g p s* 35 EB - . E& Ę Ei l H FE t - 3i }EĘFE $ " - E, f r EFE ilr Eą iŁ7ł: [,. t ś ĆilĘH. I ia HĘ ł E [ 3= F$sĘ 9B$sE[i:*i; [gŁ E. Ę F gĘ " g { a sEŁs* Bę 3iEl* *. ?t ' ?g Ę $ i sE 1- 5 ' i 5 Bg Yf i [ sf i g F* 1 $ * " g Ł= ti E.Ęr;ręę t; g ł xś i EiĘ P iI E $E i - H ś E* ś i 3 $ " Nf H lowatrypa = e : E. sf f F. ś f r ?= E1: ' H3gsE Śaę . [ g2Ę $; .H* ł $ ET ś F+ 38 Eg 3 # sE* ś $ * * r ee o Spinatrypina lowatrypa Spinatrypina _pęgquąrnątia - lowatrypa z j o I o U) U> {U' t- 7 o m z. z m cl) Spinatrypa- Waioatrypa z o E = 5 U, U, t J (.| ) c u : @: Spinatrypa _ JW p = J _ Spinatrypina - D""qyŁs!:yt,vy TI -{ z lgntąlrypą DAT A U) G' Scn Uesł layla:ayp" No rU) = :) )r = ł z Costatrypa - jseuclatrypa Ę+ EąE p $*N FE; Ę g e fgl3ĘFł* J* o o*' g=]i Oe c) Pseudoatrypa, 1igĘ 5g$irsa; ę E5 Ę 5[ .$ Ę ; aE # EYE ś a9 E EE Esę x e1 x E * T aE i$ E< m x ?Pseudoat rypa ?Cost at rypa iH. ś i= : * s: Fg t : Tx : f i. E. t E: Ę Er T . Tl Waiotrypa Costatrypa Desquamatia = o -{ = c) -{ Spinatrypa- Radiatrypa F ts k6 Palmatolepi s linguiformi s Lat e Early tI L - s Pi n a t u ł a i?lowat-'rypauost F at.-rypa | c) z 5 UJ 404 Brachiopod ext inct ion event s: RACKI only six species crossed t he F-F ext inct ion horizon in New Mexico (Cooper & Dut ro I 98f). I ncreasingly diverse rĘnchonellids, spiriferids and product ellids charact erizedt he Famennian bent hos ( e.g., Cyrt ospirif er sulcif t r Assem blageZone of Duf ro 1981; see also Duf f o 1986) . I n addit ion, Savage & Baxt er (1995) described lat e Frasnian(P. rhenanaZone) brachiopod fauna from SE Alaska (Alexander t errane). The deeper, offshorę assemblage combines most ly endemic element s of ambocoeliid' gypidulid and rĘnchonellid associat ions (and many corals; N.M. Savage 1998, let t er communicat ion), but only t wo aĘpid t axa, I . owenensis and Spinat rypa cf. S. t rulla (St ainbrook,1945). Also t he Famennian at hyńdid-rĘnchonellid-spiriferid fauna is unusually provincial in view of t he cosmopolit an nat ure of brachiopod faunas elsewhere at t his age (Savage et al. 1978). Thus, Lat e Devonian Alaskan t errane faunas were not in good communicat ion wit h coeval Nort h American crat onic biot a t o t he east , and t he paleogeographic cont ext remains equivocal (Savage & Baxt er 1995). Other continents Sibeńa and adj acent microcont inent s. - Frasnian aĘpid faunas from t he act ive sout hern margin of t he Siberian cont inent were st udied by Alekseeva (1962), Bublichenko (1974) and Rzhonsńt skaya (1975, in Rńonsnit skaya et al. 1998). I n geneńc t erms, t wo st rat igraphic assemblages are dist inct ive in t he NW and W part of t he Kuznet sk Basin (Ko1yn'-Tomsk geosynclinal zone), and early Frasnian faunas cont ain Spinat rypina (Exat rypa), Desquamat ia, At rypa and Sibirat rypa. Lat er Frasnian t ime is marked by a more diverse at rypid assemblage, but t he basal sandst one-mudst one seńes (Teryokhino suit e) is wit hout aĘpids. The t ypicallat e Frasnian assemblage' from clayey and carbonat e (Kurlyaki) and overlying limest one (Glubokaya) suit es, consist s of abundant P post uralica and D{ D.) alt icolifurmls, accompanied by lowat rypa(?) kadzielnioides (Rzhonsnit skaya, I 915) and Spinat rypa cf. planosulcat a (Webst er, 1887). The lat e Frasnian mixed siliciclast ic-carbonat e succession (Solomino horizon), probably coffesponding t o t he KW t imespan (Yolkin et al. 1997), exhibit s t wo different brachiopod assemblages. Only minut e (st unt ed?) at rypids appear close t o t he F-F boundary wit hin t he more rest rict ed marine Anat hyrella monst rum-Cyrt ospirifer ussovi Assemblage from t he N and NE part s of t he Kuznet sk Basin. I n cont rast , t he more open marine Anat hyrella fauna from t he NW of Kuzbass cont ains a five poorly preserved at rypid species, including common t axa from t he undeĄing members, as wellas some limit ed t o t his int erval, e.g. Spinat rypa (Plicspinat rypa) plicat a (Rńonsnit skaya, 1975) and S. (Exat rypa) cf. bifurcara. Of t hem, t he lat t er species and L(?) kadzielnioides persist ed int o t he F-F t ransit ion. Afirypids, pent amerids and Anat hyrella vanished at t he crit ical level, alt hough Yolkin er al. (1997) ment ioned a single at rypid species crossing t he F-F boundary. Succeeding faunas are marked by an abundance of productellids (with index Mesoplica), cyrtospffierids and aĘridids (see also Bublichenko 1914). The recent st udy by Aleekseva & Komarov (in Aleekseva et al. 1996) supplied dat a on Frasnian aĘpid faunas from East Yakut ia and t he Magadan disfrict , corresponding t o t he Kolyma-omolon microplat e. The early Frasnian associat ion includes Pseudoat rypa, Spinat rypina, Desquamat ia and Variat rypa. Varint rypa nalivkini (Lyashenko, 1959) is an index species of t he middle Frasnian brachiopod zone (ranging up t o t he P. gigas Zone),'in which five t axa of t he same geneńc set , supplement edby Spinat rypa,have been found. Alat e Frasnian fauna of t heTheodossiaZone (Trogov suit e) is marked by t he presence of D. (Serat rypa) mayselae t ompoensis Aleksseva, 1996, Spinat rypina (S.) sp., Spinat rypina (Exat rypa) orient alis Alekseeva & Komarov,1996 and Pseudogruenewaldt ia elongat a Alekseeva, 1996. The endemic assemblage remains ambiguously dat ed by conodont s (Aleekseeva & Sidj achęnko in Alekseeva et al. 1996: p. 28)' but undoubt ed Famennian associat ions consist of numerous diverse cyrt ospiriferids (wit h guide species), associat ed wit h product ids (Nigerinoplic a), at hyidids and rhynchonellids. China. - The Sout h China shelf has been regarded as a pot ent ial refuge area for t he at rypids (Jia et al. 1988; Ji 1990). Hou et al. (1992) cit ed t he disappearance of t he last at ypids (Radiat rypa?) in t he Lat e P. rhenana Zone of Guangxi, below t he Upper KW Event . HoweveĘ t hey remarked t hat ACTA PALAEONTOLOGI CA POLONI CA (43) (2) 405 aĘpid ext inct ions were not synchronous in t he different iat ed epeiric sea, and t hat t wo or t hree genera persist ed even int o t he earliest Famennian (Early Palmat olepis t riangularis Zone) in t he nearby more shallow-wat er (upslope) habit at s, while more diverse aĘpids (| ke Anat rypa, = ?I owat rya; P. Copper 1997,let t et communicat ion) have been found in t he lat est Frasnian in cent ral Hunan. The quest ion of supposed Famennian at rypids in t he Guangxi sect ions was clarified by Ma (1998). These brachiopod occurs in a light grey, massive, coarse grainst one bed of Famennian age (Middle P. t riangularis Zone) yielding very abundant brachiopods which may represent a coquina bank deposit . However, t he shelly mat erial is inferred t o be reworked. The reasons for t his conclusion are t he following: (1) t he brachiopods are a t ransport ed assemblage, indicat ed by t he lit hology and t he shell fragment at ion and abrasion, nd (2) t here are associat ed Frasnian conodont s, and below t his bed t hey are very abundant (Bai et al. I 994; t ig.7 -7).I n anot her localit y, t he Frasnian specimens from t he Baqi sect ion occur in similar grainst one which was slumped in t he Famennian in t he EaĄ Palmat olepis rhomboidea Zone (Bai et al. 1994: figs 7-10), or alt ernat ively t he sediment and associat ed Frasnian conodont s were reworked. I n a preliminary account , Ma (1998) document ed nine aĘpid t axa from t he P linguiformisZone of cenfral Hunan and Guangxi. They were collect ed from marly and limest one facies, wit h abundant corals and brachiopods. Among represent at ives of Spinat rypa (t hree species), Spinat rypina (one species), Cost at rypa (one species),I owat rypa(?) (one new species), Desquamat ia (t wo species) and Radiat rypa (one species), t he highest records (ca. 1 m below t he F-F boundary) revęal Desquamat ia shet ienchiaoensis( Tien, 1938) and Ra^ diat rypa m aanshanensis Yang & Chen, 1988, and perhaps Spinat rypa sp.B. The earliest Famennian faunas comprise numerous cyrt ospiriferids, product ellids (Product ella lachrymosa var. asiat ica Tien, 1938) and rĘnchonellids (Yunannelina). Gondwana and adj oining nort hern microcont inent s. - AĘpids remain essent ially unknown from most Gondwana sequences(e.g.,from Morocco; R.T. Becker let t er communicat ion 1996), wit h only t he conspicuous except ion of t he low-lat it ude reef-complexes of West ern Aust ralia. Grey (1978) present ed a descript ion of t he dist inct ive low-diversit y associat ion (five species, mainly of Spinat rypina), marked by t he relict appearance of At rypa (Kyrt at rypa) and Desquamat ia (Synat rypa); t he lat t er subgenus also occurs in t he lat est Frasnian of China (Mao 1998), and possibly in Nort h Viet nam. Nevert heless, det ails of t he st rat igraphic ranges remain unclear. The at rypid-bearing reefal and perireefal (most ly Pillara and Sadler) format ions from t he Canning Basin comprise most of t he Frasnian sequences (Becker et al. 1993). Only one species, Spinat rypina prideri nurungunia Grey, 1978, is cit ed by Becker et al. (1991) as st ill occurring in t he P. I inguiformis Zone. The lat est Frasnian fauna also comprises ot herundescribed species, including larger-sized and frilled VariaĘpinae (R.T. Becker I 996,I et t er communicat ion). Recent observat ions conflrmt he conclusion of Grey (1978), t hat t here is no Famennian record of aĘpids in West ern Aust ralia. Farsan (1986) showed t hat only t he genera Rhipidiorhynchus, Product ella and Cyrt ospirifer cross t he F-F boundary unchanged in Sout h-Cenfral Asia (I ran and Afghanist an). The only at rypid recorded t his area t s Spinat rypa(?),bat t his is rest rict ed t o t he middle Frasnian of Afghanist an. From microplat es locat ed bet ween Gondwana and Laurussia, Garcia-Alcalde (1990) cit ed aĘpids in several lat e Frasnian faunas of t he Cant abrian Mount ains. Some det ails are given only for t he more dist al and deeper-wat er Palent ine Domain, where black shales around t he F-F boundary (Cardano Format ion) have yielded many int emal moulds of small biconvex, round-out lined and smoot h-shelled specimens very close t o t he glassiid genus Perat os, possibly ext ending int o t he P crepida Zone. Apart from t his, Schindler (1990: pl. 5; fig. 13) also ment ioned t he glassiid genus Perat os from t he P. crepida Zone of Morocco. The dat a need t axonomic and biost rat igraphical confirmat ion (see below). Rich at rypid faunas occur in t he Armońcan Massif but t hey are most Ę limit ed t o t he Early and Middle Devonian ( Copper & Racheboeuf 1985) . Several cosm opolit an t axa, including Pseudoat rypa, Cost at rypa and Spirut rypina appeaned here during t he earĘ Frasnian. By mid-Frasnian t ime, however, at rypids disappeared from t he aręa, wit h t he except ion of undet ermined coarsely ribbed species of Cost aĘpa. 406 Brachiopod ext inct ion event s: RACKI Conclusions (1) Late Frasnian atrypids remain diverse and dominant among perireefal shelly faunasin the Palmntolepis rhenana7-one,and at least 15 genera/ subgenera and at least 50 speciespersistedin the early interval of the KW Cńsis. [ n general,this diversity is also similar to faunasfrom the older Frasnian levels, although distinctly less than in the Givetian; in fact, the main collapse in atrypid history is associated with the Early-Middle Devonian boundary,as summarizedbyCopper ( 1998:figs 1, 2) . As for the threegeneraof gypidulids (Godefroid & Racki 1990)'the decline phaseof aĘpids is charactenzedby a distinctive set of genera and species, possibly including four genera limited in range to the KW Crisis. Thus, the pre-extinction assemblagesare more diverse, especially among Spinatrypinaeand Pseudogruenewaldtiinae, than previously thought.The atrypid speciesattaina richnessof at least 15 taxa in someregions (Holy Cross Mountains, Urals). However, middle Frasnian brachiopodfaunasremain relatively poorly documentedin some areas.Thus, thereis still agap in the knowledge of evolutionary lineagestracedfrom the early Frasnian. (2) The atrypid crisis fauna seemsto be identified by distinctive trendsin ornamentation types, an overall tendencyto size reduction(..Liliput effect''; Baliński 1996) and homeomorphy,also to some orthids. This suggestspossible paedomorphosislate in atrypid evolution, which is a common species response to large-scaleperturbation (Harries et aI . 1996). As discussed for the end-Permian brachiopod extinction by Carlson (1991),changesin the relative frequency of setsof characters(both homologous and non-homologous)must be evaluated.Morever, it seemsthat some environmental restriction and a tendencytoward stenotopycharacterizedthe last aĘpids. For example,atrypidswere common in Middle Devonian black shalesand limestones(e.g., Copper 1965; Baliński & Racki 1981),but ratherrare in widespreadFrasnian oxygendepleted(dark grey-black shale) facies and positioned upslope relative to low-diverist y'leiorhynchid'faunas( RhynchonellidBiofacies of Racki et al.1993; Racki L989; J. Day 1998,,lettercommunication).The regional aĘpid demise, at least in Europe, was probably associatedwith pronouncedventilation changes and/ or related factors during the late Frasńan deepeningpulses(Godefroid & Helsen 1998;Racki & Baliński 1998) ,but t he mechanismremainsdebat able( Copper 1998) . (3) A stepdownextinctionpattern,proposedby Copper (1986b),hasbeen confirmed in some detail. The hypoxic/ nansgressivepulse of the Lower Kellwasser Event and the preceding eustaticchangesduring the Palmatolepis rhenaną Zone had only a regional destructiveeffect (see Day 1998, Godefroid & Helsęn 1998).The eventswere linked ratherto an eńanced dispersalof thelast genericset of aĘpids (e.g.I owatrypafrom the Timan-Uralian domain) as a result of interconnectionsestablished between hitherto semi-isolatedepeiricseas(Copper L973).Thefinal demiseandreductionto ca.20 species (and 8-10 generaand subgenera)was related to the Upper KW Event and catasffophic eustaticfall duringthe latePalmatolepislinguiformisZone (Sandberget al. 1988,1992). Joachimski& Buggisch ( I 996) emphasizedrepeated,possibly autocycliccmccurrences of sea-level oscillations, anoxic conditions and climatic changes(probably toward a global cooling; Copper 1986b' 1998) during the KW Cńsis. The stressmay have been enhanced by at least regionally accelerated submarine volcano-hydrothermalactivity (Veimarn et al. 1997), and consequentprogressive eutrophication and thermal pulses ACTA PALAEONTOLOGTCA POLONTCA (43) (2) 4U acmed in the F-F Event (Racki in press). The factors were certainly detrimentalto the reef ecosystems,aSaSlow-latitudeand perhapsnutńent-limitedsfromatoporoid-coral sumedby Wood (1993). AĘpid associationswere closely linked with reefs since the Silurian (seeRacki et aI . L993) and possibly include speciesthat were either symbiotic with the major reef builders' or were highly specialised,occupying Very nź [ Towecological niches (Copper L9l3). However, Frasnian brachiopodsnot show any specific adaptationin responseto the worldwide reef expansion(Copper 1998). (4) An irregular spatial pattern of the exterminationis evident from study of the vanishedreef complexes, and different generaand speciespersistedwithin the intermittently drowned shelves (Fig. 3). Thus, it is difficult to envisage a global event scenariofor the atrypid collapse. [ n general,the atrypid speciesthat survived longest in the perireefalhabitatsbelong to Variatrypinae,I owatrypa andSpinatrypina,whereas in the stressedlevel-bottom(e.g.nearshore)environmentsit was speciesof Spinatrypa that were best able to cope with the conditions. Among Frasnian gypidulids, a three -stepgeneric sequence,recognisedin Belgian and Polish partsof the Laurussian shelf ( Godefroid & Racki 1990),awaitsconfirmation in other areas. (5) Literaturedataon FamennianaĘpid occurrencesare essentiallynot confirmed during this study (seereview in Copper 1986b).Chinese occrurencesare re-interpreted by Ma (1998) as reworked faunas, including those deńved from slumped Frasnian blocks within the Famennian sequence.Also Uralian and Siberian aĘpid-bearing strata, placed previously in the P. triangularis Zone, are now more or less firmly correlatedwith the late Frasnian units (Alekseeva et ąl. 1996; Rzhonsnitskayaet ąl. 1998), with a questionableexception in the Kuznetsk Basin (Yolkin et aI . 1997). Smooth aĘpid shells,reportedas the lissaĘpid genusPeratos fromFamennian sffata (Garcia-Alcalde 1990; Schindler 1990),may representjuvenile rhynchonellids(Gode.t ypical'ribbed froid & Helsen 1998) .So, at least speciesof AĘ pida ( aĘ pids sensu stricto; Copper 1973) vanished as a biomass during the catastrophicregressionnear the F-F boundaryeven in thepotentialrefuges.This late Frasnian stepdownbrachiopod crisis and a final extinction in the F-F Event is more or less evidencednot only among gypidulids (Godefroid & Racki 1990), but also e.g. in the common spiriferids Theodossia and the plicathyridines in the Russian successions (Lyashenko 1959; Rzhonsnit skaya& Modzalevskaya1996;Rzhonsnit skayaet al. 1998) . (6) Despite generic losses (e.g.,Pammegetheńynchlzs;Sartenaeret al. 1998), the apparentcontinuity of the deeper-waterhypoxic rhynchonellid-inarticulatebiofacies across the F-F boundary needsmore strict evaluation in taxonomic and stratigraphic terms, including the relative advantageof inarticulates over articulatesin stressful set t ing( Harrieset al. 1996) .I thasbeen show nby Carlson ( 1991)for t he end-Permian brachiopod record, that it is difficult to assessmagnitude,pattern and ecologic-geographic selectivity, so long as detailedphylogeneticrelationshipsremain uncertainor subjectto arbitrarytaxonomic convention. (7) Regional extinction control may be more relatedto facies andbiotic factors,i.e., accelerated competition of expansive productid-spiriferid-athyridid faunas (Ager 1968;Copper 1986b;Dut ro 1986;Grunt & Racki 1998)( seeFig. f) ,t hanw it h overall biogeographiccircumstances,at least at the generic level (Copper 1973).This agrees well with the concept of ecodemity of atrypids (Copper 1966; Copper & Racheboeuf 1985).A tendencyto endemism is observable,especially within particular reef com- 408 Brachiopod ext inct ion event s: RACKI plexesandbuildups(Grey L978; Rzhonsnitskayaet al. 1998).The distinctivecharacter of the Uralian-Timan, North American and Australian atrypid faunas does not agree with the consensusregarding late Frasnian faunal cosmopolitanism (see summary in Hallam 1996).A similar conclusion is presentedfor Frasnianconodontfaunas(Klapper 1995),and certainly the Frasnian was not a time of cosmopolitanismin all groupseven within tropical domains. Rapidly changing relative sea level during this Devonian tectono-eustatichighstand and increasing plate tectonic activity (Racki in press) establishedcomplex biogeographicand phylogeneticresponsesin epeińc settings(see McGhee et al. 1991) .Such links havebeen show nby Sheehan( L975) for t he end-Ordovican glaciation-inducedbrachiopod turnover, and await a more quantitativeapproach at specieslevel for the KW Crisis. ( 8) Copper ( 1986a, 1998) suggest srepopulat ionof Famennian seas by deepercooler brachiopods, including surviving spiriferid-aĘridid-productid assemblages from high-latitude domains. I n addition, as assumedby Flessa (1973), an offshore recolonization by inner shelf shelly faunas, marked by eurytopic cyrtospiriferids, aĘridids and productellidsin the Frasnian, seemsto be at least of similar significance during the recovery (Racki et al. 1993). Acknow ledgm ent s Collaborat ors of t he research proj ect support ed by t he St at ę Commit t ee of Scient ific Research are grat efully acknowledged. I am also indebt ed t o P. Copper and J. Day for t horough review of t he manuscript and heĘfulcomment s. R.T. Becker and P. Copper kindly supplied many dat a useful for t his synopsis. Special t hanks go t o J. Golonka and A. Feliga for supply palaeogeographic map for use in t his issue. Ref erences Ager, D.V. 1968. The Famennian t akeover.- Palaeont ologicalAssociat ionCircular 54a,23. Alekseeva, R.E. 19ó2. DevonianAt rypids of Kuznet skandMinusinskBasins andEast ernSlope of t he orals [ in Russian] , I -I 9 6. I zdat elst voAkademii Nauk SSSR, Moskva. Aleekseva, R.E., Sidj achenko,A.J. ( sideć enko,A.J.) , BaI anov, V.V., Af anasj eva, G.A', Grunt , T.A., Komarov, V.N., Lazarev, S.S., & Manankov I .N. 1996. 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