An earliest Givetian ''Lilliput Effect'' at Sítio Wolff and São Bento in the Paraná Basin occurred after an extinction event, possibly related to the latest Eifelian KAČ Á K 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 Sítio 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'' Á Earliest Givetian Á KAČ Á K Event Á Malvinokaffric fauna Á Paraná Basin Kurzfassung Im Gebiet von Sítio Wolff und São Bento des Paraná-Beckens tritt im frühesten Givetium ein ,,Liliput-ffekt'' auf, der einem Aussterbeereignis folgt, das möglicherweise Bezug zum KAČ Á K-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 Sítio 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).Schlü sselwörter ,,Liliput-Effekt'' Á frühestes Givetium Á KAČ Á K-Event Á Malvinokaffrische Fauna Á Paraná-Becken
-Two species of Ostracoda are described for the first time from the parastratotype-section of Vila Maria Formation; this section is 30 m thick, located on the northern border of the Paraná Basin. The Vila Maria Formation records the Upper Ordovician-Lower Silurian boundary of the Paraná Basin in Bom Jardim de Goiás, State of Goiás, central Brazil. The new species represents the earliest Ostracoda occurrence from Brazilian strata. Delicate internal and external molds of isolated valves are abundant in the basal portion of the parastratotype-section of Vila Maria Formation. This interval comprises black shales that record post-glacial marine transgression, overlapping the Upper Ordovician glacial sequence of the Iapó Formation. The paleogeographic reconstruction indicates that deposition of the basal portion of the Vila Maria Formation took place in high-latitude, cool water conditions at the margin of Gondwana, under similar environmental conditions to the Djeffara Formation in the Ghadames Basin and the Tichitt Group in the Taoudeni Basin, both in the Northern Africa.Key words: Ostracoda, Ordovician, Paraná Basin.RESUMO -Duas espécies de Ostracoda têm ocorrências inéditas descritas a partir da seção-tipo suplementar da Formação Vila Maria, seção que tem 30 m de espessura, localizada na borda norte da Bacia do Paraná. A Formação Vila Maria está posicionada no limite Ordoviciano Superior-Siluriano inferior da Bacia do Paraná na região de Bom Jardim de Goiás, Estado de Goiás, Brasil central. As novas espécies descritas representam a ocorrência mais antiga de Ostracoda de estratos brasileiros. Moldes internos e externos de valvas isoladas são abundantes na porção basal da seção-tipo suplementar da Formação Vila Maria. Este intervalo é constituído por folhelhos pretos representando a transgressão marinha pós-glacial, sobrepostos aos diamictitos da Formação Iapó, que representa a sequência glacial do Neordoviciano na Bacia do Paraná. A reconstrução paleogeográfica indica que a deposição da porção basal da Formação Vila Maria ocorreu sob condições de altas latitudes e águas frias na margem de Gondwana, onde atualmente se localiza a América do Sul, sob condições semelhantes àquelas das Formações Djeffara na Bacia de Ghadames e Tichitt Group na Bacia do Taoudeni onde atualmente se localiza a porção norte da África.Palavras-chave: Ostracoda, Ordoviciano, Bacia do Paraná.
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