Paläontol Z
DOI 10.1007/s12542-010-0075-8
RESEARCH PAPER
An earliest Givetian ‘‘Lilliput Effect’’ in the Paraná Basin,
and the collapse of the Malvinokaffric shelly fauna
Elvio Pinto Bosetti • Yngve Grahn • Rodrigo Scalise Horodyski
Paula Mendlowicz Mauller • Pierre Breuer •
Carolina Zabini
•
Received: 22 December 2009 / Accepted: 16 June 2010
Ó Springer-Verlag 2010
Abstract An earliest Givetian ‘‘Lilliput Effect’’ at Sı́tio
Wolff and São Bento in the Paraná Basin occurred after an
extinction event, possibly related to the latest Eifelian
KAČÁK Event. The Malvinokaffric fauna was reduced
from 65 genera before the extinction event to eight genera
after the event. However, the abundance of the individual
taxa is high. The size reduction of the surviving taxa was
up to 90%. The palynomorphs during the extinction and
post-extinction (‘‘Lilliput Effect’’) events are scarce. Normal palynomorph abundance and diversity is restored later
in the early Givetian immediately after the post-extinction
event. The relictual fauna in the beds with the ‘‘Lilliput
Effect’’ at Sı́tio Wolff and São Bento constitute the last
survivors of the classical Malvinokaffric shelly fauna in the
Paraná Basin, and are at these sites mixed with immigrants
and alien elements (e.g. orthoconic nautiloids).
Keywords ‘‘Lilliput Effect’’ Earliest Givetian KAČÁK Event Malvinokaffric fauna Paraná Basin
E. P. Bosetti
Laboratório de Paleontologia, Universidade Estadual de Ponta
Grossa, Rua Otaviano Macedo Ribas 164, Ponta Grossa,
PR 84070-540, Brazil
e-mail: [email protected]
Y. Grahn (&) P. Mendlowicz Mauller
Faculdade de Geologia, Universidade do Estado do Rio de
Janeiro, Bloco A, Sala 4001, Rua São Francisco Xavier 524,
Rio de Janeiro, RJ 20550-013, Brazil
e-mail: [email protected]
P. Mendlowicz Mauller
e-mail: [email protected]
R. S. Horodyski C. Zabini
Programa de Pós-Graduação em Geociências,
Universidade Federal do Rio Grande do Sul, Av. Bento
Gonçalves 9500, BL L Prédio 43113, Campus do Vale,
Porto Alegre, RS 91509-900, Brazil
e-mail: [email protected]
C. Zabini
e-mail: [email protected]
P. Breuer
Saudi Aramco, Geological Technical Services Division,
Dhahran 31311, Saudi Arabia
e-mail: [email protected]
Kurzfassung Im Gebiet von Sı́tio Wolff und São Bento
des Paraná-Beckens tritt im frühesten Givetium ein ,,Liliput-ffekt’’ auf, der einem Aussterbeereignis folgt, das
möglicherweise Bezug zum KAČÁK-Event des späten
Eifeliums hat. Die Malvinokaffrische Fauna wurde von 65
Gattungen vor dem Aussterbeereignis auf acht Gattungen
danach reduziert. Dennoch bleibt die Häufigkeit individueller Taxa hoch. Die Größenreduktion überlebender Taxa
erreicht 90%. Weiterhin sind Palynomorphen während des
Aussterbeereignisses und des ,,Liliput-Effekts’’ selten.
Normale Häufigkeit und Diversität erreichen die Palynomorphen erst später im frühen Givetium, unmittelbar
nach dem Auftreten des ,,Liliput-Effekts’’. Die Reliktfauna
aus den Lagen mit ,,Liliput-Effekt’’ im Gebiet von Sı́tio
Wolff und São Bento beinhaltet die letzten Rudimente
der klassischen Malvinokaffrischen Schalen-Fauna im
Paraná-Becken. Sie vermischt sich hier mit eingewanderten
Formen und exotischen Elementen (z. B. orthoconen
Nautiloiden).
Schlüsselwörter ,,Liliput-Effekt’’ frühestes Givetium KAČÁK-Event Malvinokaffrische Fauna Paraná-Becken
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E. P. Bosetti et al.
Introduction
The term ‘‘Lilliput Effect’’ was introduced by Urbanek
(1993) to describe the size changes of faunas in extinction
events. In the aftermath of biotic crises, the organisms tend
to be much smaller than before the crises. According to
Twitchett (2006), this effect is one of the most widespread
evolutionary phenomena, but is virtually unstudied. Body
size is a key element in animal evolution, and many
paleontologists have observed that organisms that survived
mass extinctions often have a much smaller body size than
their predecessors. There are many reason why organisms
shrink, including drastic environmental changes (e.g.
effects of volcanic activity, increasing competition). By
definition, size reduction of individual taxa from preextinction to immediate post-extinction is the ‘‘Lilliput
Effect’’ sensu stricto of Urbanek (personal communication
to E.P.B. 2009). A drastic reduction of body size was
observed in all megafossil taxa from the earliest Givetian
part of the São Domingos Formation. This interval generally contains few body fossils, and all of them are reduced
in size. The fossils are represented by conulariids, trilobites, nautiloids, and brachiopods (rhynchonellids, discinids, and lingulids). Additionally, ostracods, plant
fragments, and ichnofossils are preserved. Palynomorphs
are scarce, which is unusual for Middle Devonian strata in
Western Gondwana. The scarcity of acritarchs and chitinozoans is probably because of the geochemical annexation
of carbon and nutrients such as nitrogen and phosphorus
during the black shale formation that characterized the
KAČÁK Event (cf. Riegel 2008), thus tending to deprive
the marine palynomorphs of essential food sources. Given
the normal progressive reduction in quantities of terrestrial
spores transported seawards from the shoreline, their rarity
in the investigated (distal shoreface) strata is not unexpected. In comparison with the dimensions of a typical
Malvinokaffric fauna, the sizes of the post-extinction fossils are reduced by up to 90%. One taphonomic aspect that
may affect the size of the fossils in an assemblage is
hydrodynamic sorting. This is probably not the case
because of the low degree of fragmentation. Small ichnofossils are also present, corroborating the in situ size
reduction. The specimens here described are adult organisms, and their preservation indicates autochthony or parautochthony conditions (Kidwell and Bosence 1991).
Fig. 1 a Map showing the localities discussed or investigated in this
study. b Detail of the area studied. The dotted line shows the
administrative city limits of Tibagi. c Sample points in the Barreiro
section (localities 1–3) and at São Bento (locality 4)
Estadual de Ponta Grossa (Paleontology Laboratory of the
Geosciences Department). Approximately 700 samples
were analyzed, each sample displaying one or more fossils.
The megafossils were processed by means of fine brushes
and needles. The microfossils were processed with Petrobras standard methods (Quadros and Melo 1987). The
palynomorph material is housed in the collections of the
Biostratigraphy and Paleoecology Management of Petrobras Research Center, Petrobras/Cenpes/Pdexp/Bpa, Ilha
do Fundão, Rio de Janeiro, RJ, Brazil (BPA).
Materials and methods
Geologic setting
The paleontological material was collected from the São
Domingos Formation at Sı́tio Ari, Sı́tio Wolff, São Bento,
and Casa de Pedra (Fig. 1). The material (DEGEO/MPI3230 to DEGEO/MPI-3930) is deposited at Universidade
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The Paraná Basin (Fig. 1a) is classified as a polycyclic
intracratonic and intercontinental basin. In Brazil it is
represented by two sedimentary depocenters, i.e. the
Earliest Givetian ‘‘Lilliput Effect’’ in the Paraná Basin
northern Alto Garças and southern Apucarana Sub-basins.
The total extent of the Paraná Basin is ca. 1,600,000 km2
and includes parts of southern Brazil, eastern Paraguay,
central Uruguay, and northeastern Argentina. Lange and
Petri (1967) formalized the Devonian lithostratigraphic
succession based on the geology of the Apucarana Subbasin. Their proposition was, in ascending order, Furnas
Formation and the tripartite division of the Ponta Grossa
Formation, viz., the Jaguariaı́va, Tibagi, and São Domingos Members. More recently, Grahn (1992), Gaugris
and Grahn (2006), and Grahn et al. (2000, 2002, 2010)
subdivided the Devonian of the Apucarana Sub-basin into
three formations, in ascending order, Furnas, Ponta
Grossa (including the Tibagi Member), and São Domingos. This nomenclature will be adhered to in this paper.
The São Domingos Formation is dated as latest Emsian—
late early Frasnian with miospores (Loboziak et al. 1988;
Melo and Loboziak 2003; Mendlowicz Mauller 2008) and
chitinozoans (Grahn et al. 2000, 2002, 2010; Gaugris and
Grahn 2006; Mendlowicz Mauller et al. 2009). The
‘‘Lilliput Effect’’ occurs at Sı́tio Wolff and São Bento
(Fig. 1b–c) close to the top of the outcropping part of the
São Domingos Formation, which is dated as early Givetian at the Casa de Pedra locality (Fig. 1b–c). It is preceded by the rocks at Sı́tio Ari (Fig. 1b–c), dated as no
older than latest Eifelian and near the Eifelian/Givetian
boundary from acritarch evidence. The Barreiro region,
situated in the São Domingos district, Tibagi (Fig. 1b–c),
is the type–area of the São Domingos Formation (Bodziak
and Maack 1946). With the exception of Petri (1948),
Lange and Petri (1967), Melo (1985), Bosetti (2004), and
Bosetti et al. (2009), the references to the type-area are
rarely based on field data from the region. However, the
São Domingos shales reach their maximum surface
thickness, ca. 90 m, in the type-area itself (Bodziak and
Maack 1946; Lange and Petri 1967). According to Melo
(1985), these shales overlap the Tibagi Member sensu
stricto in virtually all its extent. The total thickness of the
São Domingos Formation is estimated at ca. 350 m (Melo
1988; Grahn et al. 2010).
Outcrops in the region vary in thickness between 1 and
25 m, and are commonly penetrated by diabase dikes.
This makes continuous stratigraphic sampling over geographic distances difficult. However, similar lithologies
are exposed along the Tibagi–Telêmaco Borba highway
PR-340 (Bergamaschi 1999; Grahn et al. 2000, 2002), and
in a road-cut at km 424 on highway BR-376 in the Imbaú
region (Bergamaschi and Pereira 2001); these enable
correlation of facies with the Barreiro section. Furthermore, a section with a ‘‘Lilliput’’ fauna followed by a
normal-sized fauna dated as earliest Givetian is known
from São Bento at km 280 along highway PR-340 (see
below).
Localities
Sı́tio Ari (24°310 21.7300 S,50°280 10.1700 W)
Sı́tio Ari is situated in the Barreiro region, São Domingos
district, Tibagi (Fig. 1b–c). This outcrop is located in the
basal part of the Barreiro section (Fig. 2) and in the São
Domingos Formation. The exposed thickness is ca. 10 m.
At the base occur cm-thick lenses of very fine to finegrained sandstone, and in the uppermost part siltstones with
lingulids. These siltstones also contain rare palynomorphs
(listed in Appendix 2). Of these, Chomotriletes vedugensis
indicates an age not older than latest Eifelian.
Sı́tio Wolff (24°330 4200 S,50°310 0000 W)
Sı́tio Wolff is situated in the Barreiro region near Salto Santa
Rosa waterfall, São Domingos district, Tibagi (Fig. 1b–c).
The locality corresponds to the middle part of the Barreiro
section (Fig. 2) and is within the São Domingos Formation.
The exposed thickness is 20.5 m (Figs. 2 and 3). At this site
bioclasts that represent the Malvinocaffric Realm with subnormal phenotypes are found (Bosetti et al. 2009). The Sı́tio
Wolff outcrop is stratigraphically above the medium to
coarse-grained fossiliferous sandstones at Sı́tio Ari referred
to interval D3 by Lange (1967), corresponding to latest
Emsian–Eifelian strata in the Apucarana Sub-basin. The silty
shales, ca. 5–7 m below the top of the section, contain (in
decreasing abundance order) ichnofossils (Phycosiphon),
Spongiophyton fragments and other unidentified plant
remains, conulariid fragments, discinid brachiopods,
calmoniid trilobites, rhynchonellid brachiopods, ostracods,
orthoconic nautiloids, lingulid brachiopods, and bivalves.
The siltstones in the uppermost 5 m of the section contain
(also in order of decreasing abundance) ichnofossils (Phycosiphon), Spongiophyton fragments and other unidentified
plant remains, orthoconic nautiloids, calmoniid trilobites,
discinid brachiopods, conulariid fragments, ostracods, and
lingulid brachiopods (Fig. 3).
A distinct feature of all bioclasts found in these beds is
their small dimensions when compared with the same taxa
in other facies of the Devonian sequences. Despite their
reduced size, all taxa collected are in an advanced ontogenetic stage, and therefore represent adult forms. As they
are not randomly distributed in the section (Figs. 2 and 3),
the vertical distribution of the bioclasts is controlled by
lithologic variation. The identified fossils are listed in
Appendices 1 and 2.
São Bento (24°280 11.2100 S, 50°320 08.4600 W)
São Bento is situated at km 280 along highway PR-340
(Fig. 1b–c). The lower 30 m of this road-cut section
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E. P. Bosetti et al.
Fig. 2 Barreiro section with
taxonomic and taphonomic
distributions
contain a ‘‘lilliput fauna’’ (mainly conulariids) mixed with
normal-sized fossils in the upper part of the interval. The
uppermost 10 m of the section feature normal-sized
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brachiopods and trilobites, and ‘‘lilliput’’ bioclasts are less
common. The total exposed thickness is ca. 40 m (Fig. 4).
A siltstone sample, ca. 21.5 m above the base of the
Earliest Givetian ‘‘Lilliput Effect’’ in the Paraná Basin
medium to coarse-grained siltstone with intercalated
sandstone lenses showing distinct hummocky cross stratification. The sandstones seem to contain pebbles of the
same type as in the basal siltstones. Towards the top are
claystones and siltstones. The contact with the Pennsylvanian beds is discordant. The palynomorphs (listed in
Appendix 2) are characteristic of the early Givetian and
display a normal abundance and diversity. Normal–sized
Lingulida spp., Pennaia pauliana and ichnofossils occur at
the locality.
The Malvinokaffric realm
Fig. 3 a Occurrence and distribution of bioclasts in the different
lithologies of the Sı́tio Wolff outcrop. b Relative abundance of the
bioclasts in the Sı́tio Wolff outcrop
section, yielded a characteristic earliest Givetian palynomorph assemblage. This indicates that the postextinction event with the ‘‘Lilliput Effect’’ was short-lived
and related to the initial Givetian transgression in the Paraná Basin. The identified palynomorphs are listed in
Appendix 2.
Casa de Pedra (24°340 0000 S, 50°300 5500 W)
Casa de Pedra (Fig. 1b–c) is located in the São Domingos
Formation at the top of the Barreiro section (Fig. 2). The
exposed thickness is ca. 7.5 m. The base consists of ca.
1 m of dark gray, very fine-grained siltstone, with angular
multi–faceted pebbles. These are overlain by 4.5 m of
The term ‘‘Malvinokaffric’’ was introduced by Richter
(1941) to replace the inappropriate term ‘‘austral’’ of
Clarke (1913). The term ‘‘austral’’, which defined the
Devonian forms in South America, became inadequate
because it implied that all Southern Hemisphere Devonian
faunas had an exclusively austral paleobiogeographic
character. This is not the case, and the morphological
characteristics of the euro-asiatic (boreal) faunas of New
Zealand and Australia were already known.
Clarke (1913) considered not only the trilobites but
also a faunistic set that characterized a vast Southern
Hemisphere region, and included different brachiopods
and other invertebrate groups. The derivation of the term
(Malvinocaffrische) came about with the reunion of two
regions of occurrence of Clarke’s (1913) austral fauna:
the Falkland (Malvinas) Islands and Cape Province (South
Africa). Richter and Richter (1942) concluded that the
Malvinokaffric Realm constituted one faunistic unit, as
Clarke (1913) had already mentioned. However, they
stressed through comparisons with the Northern Hemisphere fauna that this paleobiogeographic realm had been
established during the Devonian, under constant migratory
exchanges between the Malvinokaffric austral and boreal
seas. Clarke (1913) conceived that the two isolated faunas
experienced a parallel development since the Silurian
(Bosetti 2004).
The Paraná Basin is a center of the Malvinokaffric
Realm in South America. This realm developed essentially in the Southern Hemisphere (South America, Antarctica, South Africa, and Ghana) during the Early
Devonian and Eifelian. In contrast with the contemporaneous zoogeographical entities that dominated the shallow
seas with warmer water in the Northern Hemisphere and
Oceania, the Malvinokaffric was characterized by a low
faunistic diversity, with few taxa represented by numerous
individuals having extensive regional distribution (Shirley
1965).
The Early Devonian–Eifelian strata in the Paraná Basin
are characterized by the Malvinokaffric fauna. The entry of
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E. P. Bosetti et al.
Fig. 4 São Bento section with
taxonomic and taphonomic
distributions
the extra-Malvinokaffric articulate brachiopod Tropidoleptus, in regions previously dominated by Malvinokaffric
forms, is considered by most geologists to represent the
irreversible decline of the faunistic realm defined by the
Malvinokaffric shelly fauna.
The Malvinokaffric extinction
The causes of the extinction of the Malvinokaffric shelly
fauna in Western Gondwana is a controversial matter
involving geochronology and physical environmental factors. Copper (1977) stated that the mass extinction of the
fauna occurred at the Frasnian–Famennian boundary. This
assertion was founded on the hypothesis that an extremely
cold climate would have caused recifal and peri-recifal
faunal extinction. Isaacson (1978) agreed with Copper that
the extinction resulted from a major marine regression at
the end of the Devonian. According to Melo (1985), there
were no records of Malvinokaffric forms in the upper
part of the São Domingos Formation, but he conceded a
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temporal expansion of the fauna (particularly trilobites,
albeit uncommonly) into the Givetian. Assine and Petri
(1996) confirmed that the transgression at the Eifelian–
Givetian transition led to a drastic ecological change that
was responsible for the disappearance of the Malvinokaffric Realm. This conclusion is corroborated by this study
and is discussed below.
Although the magnitude of Devonian extinctions is
widely accepted, the duration, number, and causes of these
events remain controversial: in particular, whether an event
should be considered as a prolonged extinction, or two
separate events, or a series of events.
Most geologists now regard the Frasnian–Famennian
extinction as being the most significant during the Devonian. However, House (2002) stressed that some other
Devonian crises were at least comparable with the F/F
Event, and he pointed out that the Eifelian–Givetian
(KAČÁK) Event might have been the most striking
extinction.
Most of these events are diagnosed by lithofacies
and, according to House (2002), the 20 middle Paleozoic
Earliest Givetian ‘‘Lilliput Effect’’ in the Paraná Basin
extinction events share many common characteristics.
They are usually characterized by dark-colored sedimentary facies (indicative of dysoxia or anoxia), hosting a
depauperate or no benthic fauna, and are frequently under
and overlain by regressive facies.
Many of these sediments are associated with faunal
extinction. The primary cause of dysoxia or anoxia is still
much debated, but this phenomenon has a clear short-term
effect on contemporary sea beds. According to House
(2002), many events show complex and progressive
changes in oxygenated conditions during the Devonian,
following a common pattern and probably also having a
common cause. These changes may have been induced by
climatic and consequential cycles of erosion or fluctuations
in sea level (eustatic or epeirogenic). Related cyclic climate
changes forced by orbital cycles (e.g. Milankovitch) may
also be implicated.
Most of the extinction events recorded in the Devonian
are associated with a transgression followed by a regressive
phase (House 2002 and references therein). These events
are usually manifested globally, but local or regional
variations of this pattern cannot be disregarded.
It is unclear if the event represented in the São Domingos Formation was a consequence of one of these
global events. However, the studied sequence does show
sedimentary characteristics in accordance with the general
regression/transgression model whereby shallow water
ecosystems would be quickly replaced by anoxic deep
water ecosystems. The black shales characterizing parts of
the São Domingos Formation are accepted as maximum
flooding surfaces (Lange and Petri 1967; Melo 1985, 1988;
Assine and Petri 1996; Assine 1996; Bergamaschi 1999;
Bergamaschi and Pereira 2001; Bosetti 2004), thus indicating dysoxic/anoxic conditions during the maximum
marine inundation of the basin.
Bosetti (2004) used a high resolution collecting
taphonomic method and described in some detail part of
the São Domingos Formation in the Barreiro region
(Tibagi), and new finds of calmoniid trilobites, conulariids, and rhynchonellid brachiopods (Schuchertella, Australocelia, and Derbyina). All of these were supposedly
extinct at this time of deposition. Bosetti (2004) also
indicated that the Malvinokaffric fauna extended beyond
the Eifelian–Givetian boundary, reaching into the Givetian, and without apparent modifications in its paleobiodiversity. However, later finds by Bosetti et al. (2009)
in the same region demonstrated that only a few Malvinokaffric taxa transgressed this boundary and that these
taxa are represented by phenotypes of subnormal
dimensions compared with the typical representatives of
the Malvinokaffric fauna. Therefore, this São Domingos
shale fauna can be regarded as a relictual Malvinokaffric
assemblage.
It is generally believed that the Paraná Basin exposures
of late Middle–Late Devonian strata are poorly fossiliferous, and that the major proportion of the invertebrates
(especially cnidarians, trilobites, and articulate brachiopods) occurring in the Ponta Grossa Formation sensu
stricto had become extinct before the early Givetian.
However, this alone does not explain the absence of the
paleofauna, because even in the lower sequences there are
records of other trangressive peaks of equal intensity, and
with an abundance of invertebrates. In the early Givetian,
after the collapse of the classic Malvinokaffric shelly
fauna, the effect of warm water faunas with an Appalachian affinity is obvious in the Amazonas Basin (Melo
1988; previously noted by Rathbun 1874). The situation is
somewhat different in the Paraná Basin, where a calmoniid
trilobite (i.e. Pennaia pauliana) ranges into the early Givetian after the collapse of the classic Malvinokaffric
shelly fauna.
Relictual assemblage in the São Domingos formation
The appearance of relictual fossil assemblages is common
in global paleontological records, especially during
immediate post-extinction events (e.g. latest Ordovician
Event; Ireviken Event, Silurian of Sweden, Erlfeldt 2006;
Trangrediens Event, Siluro—Devonian boundary in Eastern Europe, Urbanek 1993; Late Devonian (Frasnian/
Famennian) Event and Permo—Triassic Event, Twitchett
2007; Late Triassic Event; K/T Event, etc.). Urbanek
(1970) defined relictual assemblages as sets of low-diversity species or monospecific occurrences that survived
environmental disturbances in a given area. It is the
immediate effect of the extinction, associated with each
biotic crisis that leads to a drastic reduction of the number
of species as a result of ecological change. Such changes
open possibilities for new species to occupy the affected
area via speciation or immigration. Once the dispersion of
the species has been established, the local area is rapidly
recolonized (Krebs 1986).
Urbanek (1993) stated that in some cases the relictual
assemblages exhibit attributes of post-event syndrome, for
example extremely low diversity, high abundance of individuals, and subnormal phenotype like reduction in size.
They represent a brief delay in the evolutionary changes of
a specific fauna, before adaption to new environmental
conditions.
The fossil assemblages studied here can be regarded as
representatives of a relictual assemblage because, as typical Malvinokaffric fauna, they show low taxonomic
diversity and great abundance in the Sı́tio Wolff and São
Bento outcrops. The distinctive factor of this new assemblage is that the diversity is even lower than that
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E. P. Bosetti et al.
characterizing the typical Malvinokaffric endemic fauna,
and the abundance levels of each taxon are high. The fact
that the fossil adult forms found in these localities are
much smaller than normal, and that alien elements (orthoconic nautiloids) are present in these beds (as likely
immigrants) suggest that the conditions inferred by Urbanek (1970, 1993) were established at these localities
during the Eifelian–Givetian transition. In the post-crisis
phase two lines of development in the relictual assemblages are envisaged:
1.
2.
A great numerical abundance creates favourable
conditions for generating a sufficient variation (‘‘raw
material’’ later used in adaptive radiation), and some
expansion of the niche is also involved, because of
both the abundance and increased variation of the
relictual species (Urbanek 1993). These factors
obstruct, at least in part, the invasion of empty habitats
by immigrants, thus facilitating rapid local speciation
of native elements. In a relatively short time, the main
niches available are inhabited again by new settlers,
hindering the possibility of entry of alien forms. These
latter are thus restricted but not necessarily absent
(Urbanek 1993).
When a delay of the evolutionary response of the
indigenous relictual species does not show distinct
post-event syndrome, and, especially, no sign of a
population explosion, the habitats remain sufficiently
empty to eventually be colonized by immigrants. The
delayed response to ecological change could create an
opportunity for rapid habitation by immigrants (Urbanek 1993).
In the São Domingos Formation, the faunal composition, distribution, and abundance indicate the first situation,
where the relictual assemblage itself occupies a substantial
part of the benthic niches; and the only alien element of the
assemblage, the immigrant orthoconic nautiloids, occupy
the newly created pelagic niches.
The lithologic variation observed in the study area
was produced by pronounced eustatic variations, considering the modest lithologic variation in major parts of
the Ponta Grossa and São Domingos formations. These
strata signify a succession of paleoenvironments; i.e. a
pattern of coarse sediments, at shoreface, to fine offshore
sediments, according to Walker and Plint (1992) and
Reading and Collinson (1996). The paleoenvironments
progress from proximal shoreface to distal offshore. The
base is represented by a coarse regressive phase with the
occurrence of conglomeratic (quartzite and quartz pebbles, maximum diameter ca. 1 cm), very coarse-grained
unfossiliferous sandstones (6 m thick at Sı́tio Wolff)
suggestive of a proximal shoreface environment. Above
this facies is a succession of fine-grained sandstone to
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medium-grained siltstone (2 m thick at Sı́tio Wolff) with
ichnofossils (Phycosiphon) and fragmented plants (mm to
cm-sized, parallel to the bedding planes); this culminates
with an argillaceous dark shale (5 m thick at Sı́tio Wolff)
lacking benthic fossils and indicating a distal offshore,
retrogradational environment, below storm wave base
(SWB). Towards the top a conglomeratic sandstone bed
(maximum thickness 0.5 m at Sı́tio Wolff), similar to the
basal one represents a sudden recurrence of the shore
facies (proximal shoreface). Above this sequence, silty
shales (2 m at Sı́tio Wolff) are covered by coarse to finegrained siltstones with wavy stratification (5 m at Sı́tio
Wolff), similar to distal shoreface environments near fair
weather wave base (FWWB). These latter two facies are
abundantly fossiliferous, and contain subnormal-size
phenotypes. The distribution and abundance of the fossils
in the section are not random; they are linked to the
depositional tracts recognized by the sedimentary facies
analysis.
At Sı́tio Wolff at least three main bathymetric changes are recognizable, reflecting changes in temperature
and oxygenation. The base of the section represents
the shore facies and the absence of bioclasts can be
explained taphonomically, whereby the preservation of
fossils in conglomeratic coarse-grained sandstones is
less probable. The middle part represents a brief interval
of maximum flooding; i.e. at the extreme peak of the
local transgression. The fact that no megafossils or
ichnofossils occur in this facies is evidently a consequence of anoxia or extremely low oxygenation of the
sea floor.
The post-event syndrome would be expected in the
upper part of the section (distal shoreface environment)
where the bioclasts represent a phenotypic reaction to
conditions unfavourable for growth of individuals (conulariids, brachiopods, and molluscs) and the natural selection of specimens and species of smaller size (ichnofossils
produced by small organisms, ostracods, and trilobites).
The conditions envisaged by Urbanek (1970, 1993) are
exemplified by these facies of the São Domingos
Formation.
To conclude, the stratigraphic intervals investigated here
are considered to have been deposited during the collapse
of the Malvinokaffric shelly biota, and the fauna can
therefore be considered as relictual with subnormal-size
phenotypes. This distinctive fauna clearly exemplifies the
post-event syndrome. Brayard et al. (2010) studied Early
Triassic gastropods in the aftermath of the Permian–Triassic mass extinction. They found that large specimens had
already developed some 1–2 Ma following the mass
extinction, and concluded either that the lilliput effect was
an artifact (or not particularly significant), or that the postextinction recovery in the marine realm was rapid, in the
Earliest Givetian ‘‘Lilliput Effect’’ in the Paraná Basin
Fig. 5 Conulariids (a–g) and brachiopods (h–j) from Sı́tio Wolff. a
Conularia quı´chua. MPI 3697. b Paraconularia ulrichana. MPI 3654.
c Paraconularia ulrichana with plant fragments. MPI 3751. d
Paraconularia ulrichana. MPI 3772. e Paraconularia ulrichana. MPI
3401. f Paraconularia ulrichana with plant fragments. MPI 5678. g
Paraconularia ulrichana. MPI 3707. h Schuchetella agassizi. MPI
3664. i Australocoelia palmata. MPI 5679. j Australocoelia palmata.
MPI 3599
order of 1–2 Ma. Our results suggest that the recovery after
the KAČÁK Event was indeed rapid and probably less than
1 Ma.
2.
Taphonomic considerations
The taphonomic analysis aimed primarily at determining
the following attributes:
1.
the degree of valve fragmentation;
3.
4.
5.
6.
7.
the degree of disarticulation of valves and component
parts;
the position of valves and parts in relation to bedding
planes;
the effects of bioerosion;
the effects of abrasion;
the degree of packing; and
distribution and abundance levels (Appendix 1).
The conulariids are very fragmented, whereas brachiopods and molluscs are intact, with the exception of one,
123
E. P. Bosetti et al.
Fig. 6 Bivalves (a) and trilobites (b–e) from Sı́tio Wolff. a Nuculana? viator. MPI 3535. b Thorax of Pennaia pauliana. MPI 3818 c Pygidium
of Pennaia pauliana. MPI 3662. d Cephalon of Pennaia pauliana. MPI 3748–B. e Pennaia pauliana. MPI 3367–A
partly fragmented specimen of Schuchertella agassizi Hartt
1874. Trilobites are mostly articulate (entire specimens and
articulated thorax/pygidium), isolated pygidia and cephala
being incommon.
123
Apart from Spongiophyton, the plant fragments are
difficult to classify. There are no bioclasts with evidence of
bioerosion and abrasion, and the bioclasts are poorly
packed and matrix-supported.
Earliest Givetian ‘‘Lilliput Effect’’ in the Paraná Basin
Fig. 7 Brachiopods (a–d), nautiloids (e–f), and ichnofossils (g–h)
from Sı́tio Wolff. a Orbiculoidea baini, Brachial valve uncompressed.
MPI 3669. b Orbiculoidea excentrica (1– ventral valve; 2– brachial
valve). MPI 3663. c Lingulid indet in ‘‘scissor’’–position. MPI 3582.
d Lingulid indet. MPI 3769–B. e ?Ctenoceras sp. MPI 5680. f
?Ctenoceras sp. MPI 5681. g Phycosiphon isp. MPI 3666. h
Phycosiphon isp. MPI 5682
123
E. P. Bosetti et al.
Morphological variations and apparently subnormal size
phenotypes must be carefully analyzed, because the fossilization processes, especially diagenetic factors, can
affect the original morphology of the bioclasts. Lucas
(2001) introduced the term ‘‘taphotaxa’’, referring to taxa
based on morphological characters produced by the fossilization processes. The identification of invalid taxa in the
Ponta Grossa Formation (conulariids and trilobites) by
Simões et al. (2003) and Soares et al. (2008), demonstrates
that diagenetic and weathering alterations can modify the
original structure of fossils, thus leading to erroneous taxonomic assignments.
The subnormal-sized phenotypes have been described
above and compared with those of normal size that occur in
other facies; and taphotaxa have not been found in the
analyzed concentration, because morphological alterations
linked to taphonomic characteristics have not been
observed. Moreover, all the fossils display growth lines,
striae, and morphological features of the carapaces and
exuviae indicative of advanced ontogenetic growth.
Twitchett (2007) stressed that, in relation to body size
of specimens, some preservational aspects can affect the
totality of the fossils in an assemblage, and the hydrodynamic selection of bioclasts (by some kind of water flux) is
one of the factors to be considered in search of taphonomic
bias.
In this study, entire fossils and fragments of variable
size occur in the same sample and on the same bedding
plane. Fragile plant fragments are intimately associated
with entire trilobite carapaces and minute orbiculoid
valves, all of them of different sizes and densities, but
occurring side by side. This suggests that, if transportation
of bioclasts had occurred, it was insufficient to cause
selection by size or density.
Taphonomic classes linked to paleobathymetry and to
autochthony/parautochthony/allochthony factors were proposed by Rodrigues et al. (2003) based on conulariids, and
by Simões et al. (2009) based on homalonotid trilobites.
The conulariids (Fig. 5) are represented at Sı́tio Wolff by
isolated, horizontally oriented and incomplete specimens
without apertural parts and are attributable to taphonomic
class 3-IV of Rodrigues et al. (2003). They occur in bioturbated siltstones (bioturbation index 3 of Miller and
Smail 1997) at the FWWB. The taphonomy of the conulariids indicates that the taphocoenosis is parautochthonous
to allochthonous.
In relation to the degrees of disarticulation and fragmentation, the basic, distinctive morphologies of the
diverse taxonomic groups was considered. All rhynchonellids and bivalves (Figs. 5, 6) are disarticulated and
concordant with the bedding planes, thus suggesting a
time interval between death and ultimate burial of the
bioclasts, but without hydrodynamic selection. Regarding
123
the trilobites (Fig. 6), three situations are evident (in
descending frequency):
1.
2.
3.
the predominant occurrence of complete exuviae
(extended skeleton);
the occurrence of articulated thorax/pygidium; and
subordinate occurrence of isolated pygidia, and more
rarely isolated cephala.
Overall, this points to autochthony/parautochthony
(Fig. 6).
Discinid brachiopods (Fig. 7) are abundant and represented exclusively by the genus Orbiculoidea. The typical
dorso-ventral flattening of the brachial valve was not
observed.
Dorsal and ventral valves normally occur disarticulated,
but very close to each other and, in some cases, they belong
to the same individual. Lingulids (Fig. 7), are normally
concordant with the bedding planes, complete or with the
valves in scissor position, demonstrating that there was no
significant transport of these specimens; hence they are
regarded as autochthonous to parautochthonous.
Nautiloids (Fig. 7) are relatively rare in the Paraná Basin,
and only two genera are known (Orthoceras and Spyroceras). Orthoconic nautiloids, here referred questionably to
?Ctenoceras Noetling 1884, are abundant in the studied area
and are recorded for the first time in the São Domingos
Formation. These bioclasts are found complete or without
the apical extremity, concordant with the bedding planes,
and without preferred orientation, thus indicating the
absence of paleocurrents or occurrence in the nearshore
swash zone (Grahn 1986). The cyrtoconic shell of the
orthoceratids is strongly curved, and when fragmented
can be confused with the shells of tentaculitds of the genus
Fig. 8 Selected acritarchs (a–b), miospores (c–o), and chitinozoans c
(p–t) from the Barreiro section and São Bento. The scale bar
represents 20 lm. a Chomotriletes vedugensis. Sı́tio Ari, sample 2,
BPA 200912041, G67/3. b Lunulidia micropunctata, Sı́tio Wolff,
sample 7, BPA 200912046, O45/3. c Grandispora mammillata, Casa
de Pedra, BPA 200904539, D43. d Craspedispora paranaensis, Casa
de Pedra, BPA 200904539, D54. e Grandispora pseudoreticulata,
Casa de Pedra, BPA 200904539, J61. f Chelinospora ligurata, Casa
de Pedra, BPA 200904539, G51/2. g Zonotriletes armillatus, Casa de
Pedra, BPA 200904539, K41/4. h Leiotriletes balapucensis, Casa de
Pedra, BPA 200904539, O54. i Cristatisporites sp.1, Casa de Pedra,
BPA 200904539, R50. j Archaeozonotriletes variabilis, Casa de
Pedra, BPA 200904539, S40. k Dibolisporites turriculatus, Casa de
Pedra, BPA 200904539, U40/3. l Grandispora douglastownense, São
Bento, BPA 200913384, L39/1. m Verrucosisporites premnus, São
Bento, BPA 200913384, V58/4. n Grandispora permulta, São Bento,
BPA 200913384, W61/4. o Chelinospora timanica, São Bento, BPA
200913384, M52. p Alpenachitina matogrossensis?, São Bento, BPA
200913384, D65c. q Alpenachitina petrovinensis, São Bento, BPA
200913384, E42c. r Ancyrochitina sp. cf. A. cornigera, São Bento,
BPA 200913384, L38/1. s Ramochitina aff. R. boliviensis, Casa de
Pedra, BPA 200904539, Q38/4. t Ramochitina ramosi. Casa de Pedra,
BPA 200904539, Q55
Earliest Givetian ‘‘Lilliput Effect’’ in the Paraná Basin
123
E. P. Bosetti et al.
Homoctenus Ljaschenko 1955, which was recorded by
Ciguel (1989) in strata dated as Givetian. Despite the similarities, the specimens studied are clearly chambered, longer
than tentaculitids and the curvature is located near the midline of the shell, rather than in the apical region. Because of
the characteristic morphology of the shell it was decided to
use the genus ?Ctenoceras to define this group; however,
taxonomic studies are clearly necessary.
Ichnofossils (Fig. 7) belonging to the ichnogenus Phycosiphon (ichnofacies Zoophycos) occur as U–shaped
loops, frequently ramified, and when in great numbers they
form large systems parallel or oblique to the bedding
planes. These structures are recorded for the first time in
the Paraná Basin, and the animal that originated them was
probably a small (possibly mm-sized) vermiform organism.
This ichnofossil has been recorded in the Devonian of the
Parnaı́ba Basin, and is likely to represent another migratory
element in the assemblages here analyzed.
Palynomorphs (Fig. 8) are scarce immediately before
the extinction event (Sı́tio Ari) and during the post–
extinction ‘‘Lilliput Effect’’ (Sı́tio Wolff and São Bento),
but become common subsequently (Casa de Pedra). The
siltstones above the basal sandstones at Sı́tio Ari contain,
inter alia, Chomotriletes vedugensis, an acritarch that first
occurs in latest Eifelian strata near the Eifelian–Givetian
boundary (Le Hérissé, personal communication 2009) in
Bolivia (base of Los Monos Formation). Lunulidia micropunctata, an ecological phenotype of Navifusa bacilla, that
occurs at Sı́tio Wolff and has been recorded in stressed
environments of latest Emsian–Frasnian age in the Paraná
Basin. Thus, its presence at Sı́tio Wolff likewise signifies a
stressed environment. Miospores and chitinozoans from
São Bento and Casa de Pedra are diversified and abundant
(Appendix 2), and indicative of earliest and early Givetian
age, respectively (the miospore index species Chelinospora
ligurata is present at Casa de Pedra). The section at São
Bento also contains chitinozoans restricted to the earliest
Givetian (i.e. Alpenachitina matogrossensis? and Alpenachitina petrovinensis).
On the basis of all the data obtained from this taphonomic analysis, it can be concluded that the taphocoenose
is parautochthonous being preserved essentially in a near
life position with little or no evidence of transportation.
(Figs. 1 and 2) have been investigated. They demonstrate
a pre-extinction Malvinokaffric sequence at Sı́tio Ari;
followed at Sı́tio Wolff and São Bento, by an extinction
event possibly related to the latest Eifelian KAČÁK
Event, and an earliest Givetian post-extinction event
characterized by the ‘‘Lilliput Effect’’. The extinction
event reduced the Malvinokaffric genera from 65 to
eight in the post-extinction event. The individual taxa
from the surviving genera are notably abundant and, as a
manifestation of the ‘‘Lilliput Effect’’, they display a size
reduction of up to 90%. Palynomorphs are scarce during
the extinction and post-extinction events. The Malvinokaffric relictual fauna at Sı́tio Wolff and São Bento
represents the last survivors of the distinctive Malvinokaffric fauna in the Paraná Basin. They are here mixed
with immigrants and alien elements (e.g. orthoconic
nautiloids). At Casa de Pedra, the São Domingos Formation is stratigraphically immediately above the postextinction beds and yields an early Givetian warmer
water assemblage with Malvinokaffric survivors (e.g.
Pennaia pauliana).
Acknowledgments Elvio Pinto Bosetti acknowledges Conselho
Nacional de Desenvolvimento Cientifico e Tecnológico (CNPq, PQ
480427/2007-0), Rafael Costa da Silva CPRM-RJ, for improving
ichnofossil taxonomy, Juliana de Morais Leme (Universidade de
São Paulo—USP), for improving conulariid taxonomy, and Dmitry
A. Ruban (Rostov-na-Donu, Russia), for valuable suggestions.
Yngve Grahn thanks the Faculty of Geology at Universidade do
Estado do Rio de Janeiro (UERJ) and Dr C. S. Valladares, head of
the post-graduate program at the Faculty of Geology, for access to
the facilities, and the Conselho Nacional de Desenvolvimento Cientifico e Tecnológico (CNPq, PQ 309751/2007-1) which made his
work possible through grants. Rodrigo Scalise Horodyski thanks
CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nı́vel
Superior), Paula Mendlowicz Mauller CAPES (Coordenação de
Aperfeiçoamento de Pessoal de Nı́vel Superior, BEX 4515/05-6),
and Carolina Zabini the Conselho Nacional de Desenvolvimento
Cientifico e Tecnológico (CNPq, 140659/2007-2) for grants. Pierre
Breuer acknowledges the Saudi Arabian Oil company (Saudi
Aramco) for granting permission to work on this published material. Prof. emer. Art Boucot (Corvallis, Oregon) and Prof. emer.
Adam Urbanek (Warsaw, Poland) read the manuscript, and their
comments were most useful. The comments and linguistic correction by the two reviewers, Prof. emer. Art Boucot (Corvallis,
Oregon) and Prof. emer. Geoffrey Playford (Brisbane, Australia)
greatly improved the content of the manuscript. Dr Thomas Heuse
(Jena, Germany) made the German translations. Willian Mikio Kurita
Matsumura (UEPG, Ponta Grossa) is acknowledged for help in field and
improvement of the illustrations. Our sincere thanks to all.
Concluding remarks
Three sections (Sı́tio Ari, Sı́tio Wolff, and Casa de Pedra) in the lower part of the São Domingos Formation in
its type area near Tibagi and at a locality at São Bento
123
Appendix 1
See Table 1.
Earliest Givetian ‘‘Lilliput Effect’’ in the Paraná Basin
Sample 2
Table 1 Fossils and taphonomic data from Sı́tio Wolf
Taxon
Fragmentation
Articulation
Position
VF
X
OB
VF
X
OB
Conulatae
Conularia quı´chua
Ulrich 1890
Paraconularia
ulrichana Clarke 1913
Lingulida
Acritarchs: Chomotriletes vedugensis Naumova 1953,
?Navifusa sp, and Tasmanites spp.
Sı́tio Wolf
Sample 3
Orbiculoidea baini
Sharpe 1856
NF
D
OB
Orbicoloidea
excentrica
Lange 1943
Lingulids indet
NF
D
OB
NF
D
OB
Sample 4
Derbyina whitiorum
Clarke 1913
NF
D
OB
Spores: Spore gen. sp. indet
Australocoelia
palmata
NF
D
OB
Sample 5
F
D
OB
Acritarchs: cf. Dactylofusa sp., Acritarcha gen. sp. indet.
Chitinozoans: Ancyrochitina? spp.
Spores: Spore gen. sp. indet.
Rhynchonellida
(Morris and Sharpe 1846)
Schuchertella agassizi
Hartt 1874
Barren
Sample 6
Bivalvia
Nuculana? viator
Reed 1925
NF
D
OB
LF
X
OB
Nautiloida
?Ctenoceras sp.
Noetling 1884
Trilobita
Pennaia pauliana
Clarke 1913
Barren
Sample 7
Acritarchs: Lunulidia micropunctata Pöthe de Baldis 1979
X
D–A
OB
Sample 8
Crustacea
Ostracoda indet.
NF
A
OB
Barren
X
X
OB
Sample 9
F
X
OB
Barren
Zoophycos
Phycosiphon isp
Spongiophytaceae
Spongiophyton spp.
Kräusel 1954
São Bento
Algae
Algae indet.
VF
X
OB
F fragmented, VF very fragmented, LF little fragmented, NF not
fragmented, D disarticulated, A articulated, OB on the bedding plane,
X not considered
Sample 1
Barren
Sample 2
Appendix 2: Palynomorphs from Sı́tio Ari, Sı́tio Wolf,
São Bento, and Casa de Pedra
Sı́tio Ari
Sample 1
Acritarchs: Leiosphaeridia spp.
Acritarchs: Navifusa bacilla (Deunff) Playford 1977 and
other unidentified acritarchs.
Chitinozoans: Alpenachitina matogrossensis? Burjack &
Paris 1989, Alpenachitina petrovinensis Burjack & Paris
1989, Ancyrochitina langei Sommer & Boekel 1964, Ancyrochitina sp. cf. A. cornigera Collinson & Scott 1958,
Ancyrochitina spp., Fungochitina pilosa Collinson & Scott
1958, and Ramochitina sp.
123
E. P. Bosetti et al.
Spores: cf. Acinosporites lindlarensis Riegel 1968, Chelinospora timanica (Naumova) Loboziak & Streel 1989,
Grandispora douglastownense McGregor 1973, cf. Grandispora douglastownense McGregor 1973, Grandispora libyensis Moreau–Benoit 1980, Grandispora permulta (Daemon)
Loboziak, Streel & Melo 1999, cf. Grandispora sp., Muraticavea sp., Verrucosisporites premnus Richardson 1965.
Casa de Pedra
Acritarchs: Gorgonisphaeridium spp., Leiosphaeridia spp.,
Navifusa bacilla (Deunff) Playford 1977, and other
unidentified acritarchs.
Chitinozoans: Ancyrochitina spp., Ancyrochitina langei
Sommer & Boekel 1964, Ramochitina aff. R. boliviensis
Grahn 2002, R. ramosi Sommer & Boekel 1964, Sphaerochitina? spp., and Chitinozoa gen. et sp. indet.
Spores: Acinosporites acanthomammillatus Richardson
1965, A. lindlarensis Riegel 1968, A. macrospinosus
Richardson 1965, Apiculiretusispora spp., Archaeozonotriletes variabilis (Naumova) Allen 1965, Auroraspora
minuta Richardson 1965, Camarozonotriletes? concavus
Loboziak & Streel 1989, Chelinospora ligurata Allen
1965, C. timanica (Naumova) Loboziak & Streel 1989,
Craspedispora paranaensis Loboziak, Streel & Burjack
1988, Cristatisporites sp.1, Diatomozonotriletes franklinii
McGregor & Camfield 1982, Dibolisporites turriculatus
Balme 1988, Emphanisporites mcgregorii Cramer 1966, E.
rotatus McGregor 1961, Geminospora svalbardiae (Vigran) Allen 1965, Grandispora incognita (Kedo) McGregor & Camfield 1976, G. libyensis Moreau–Benoit 1980,
G. mammillata Owens 1971, G. permulta (Daemon) Loboziak, Streel & Melo 1999, G. pseudoreticulata (Menéndez
& Pöthe de Baldis) Ottone 1996, Leiotriletes balapucensis
di Pasquo 2007, Retusotriletes paraguayensis Menéndez &
Pöthe de Baldis 1967, Retusotriletes spp., Samarisporites
spp., Verrucosisporites scurrus (Naumova) McGregor and
Camfield 1982, Verrucosisporites spp., and Zonotriletes
armillatus Breuer et al. 2007.
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