The Cemitério Paleolake, Catalão, Goiás, is a lacustrine deposit that is rich in spicules of continental sponges. These spicules, which are present in three sections (1-3), were analyzed for the taxonomic identification of the species in order to reconstruct the late Quaternary palaeoenvironment. An indigenous assemblage of lentic sponges was found, consisting of Metania spinata (Carter 1881), Dosilia pydanieli Volkmer-Ribeiro (1992), Radiospongilla amazonensis Volkmer- Ribeiro and Maciel (1983), Trochospongilla variabilis Bonetto and Ezcurra de Drago (1973), Corvomeyenia thumi (Traxler 1895), Heterorotula fistula VolkmerRibeiro and Motta (1995), plus Corvoheteromeyenia australis (Bonetto and Ezcurra de Drago 1966), which here has its first record in an assemblage formed by biosiliceous deposits. Furthermore, at the base of the sections, spicules of sponges from lotic environments were detected, including Corvospongilla seckti Bonetto and Ezcurra de Drago (1966), Oncosclera navicella (Carter 1881) and Eunapius fragilis (Leidy 1851), which suggests a contribution from flowing water. We identified 25 spongofacies horizons caused by sponge assemblages typical of a lentic environment, dated from at least 39,700 years BP., and currently occurring in lakes typical of the Cerrado Biome.

Surveys for freshwater sponges were performed at several water bodies at sandy environments along a north-south direction of particularly the Brazilian coastal line. The results allowed for the distinction of four different species-specific environments along this coastal border. The main fact considered was the dominant or the sole recurrent occurrence of a single sponge species at one particular habitat. The first one is that of the lagoonal mesohaline habitats at the tropical and subtropical realms, indicated by Spongilla alba Carter, 1849. The second one refers to shallow ponds among dunes at the tropical area indicated by Corvoheteromeyenia heterosclera (Ezcurra de Drago, 1974). The third one is that of also shallow ponds close to the dune belt at the temperate region indicated by Racekiela sheilae (Volkmer-Ribeiro, De Rosa-Barbosa & Tavares, 1988). The fourth one is that of organically enriched environments, at the marginal areas of lagoons and mouth of small rivers, evolving towards freshwater muddy ponds and coastal swamps, not far from the ocean border: Ephydatia facunda Weltner, 1895 is the species to occupy this habitat with almost exclusiveness. The above species are thus proposed as indicators of such habitats and have their descriptions improved and that of their environments summarized. A taxonomic key based on the spicules of the four species is proposed. The results presented aim to contribute to the identification of spicules of these sponges in sediment columns recovered at the Brazilian and South American coastal area. Determination of paleo ocean borders are a present issue of upmost importance in what respects projections of timing and fluctuations of ascending/regressing sea levels.

-Entire structures of freshwater sponges are rare in the paleontological record and no register existed for the Pleistocene. A previous study of the spicules of such sponges composing pleistocenic strata of the Cemitério Paleolake, Brazil, led to the discovery of several in situ preserved gemmules. The present research aimed to identify the sponge species which produced these gemmules, their relationship to the already described spicules found in the lake strata and enter a taphonomic enquiry towards the factors which would have led to this remarkable preservation. The materials were mounted for analysis at SEM. The gemmules pertain to the extant species Corvoheteromeyenia australis, Dosilia pydanieli, Radiospongilla amazonensis and Corvomeyenia thumi. Young gemmules of Heterorotula fi stula, a sponge known only from loose spicules in spongillite deposits were also detected and are for the fi rst time fi gured, confi rming the species status. Two factors would have favored this exceptional gemmular preservation. The abundance of young gemmules indicates short immersion periods, which led to the incipient development of pneumatic coats, impairing their buoyancy and accelerating deposition in the lake bottom. Algal blooms, formed next with probable heat and desiccation, would have provided an elastic but consistent crust over the recently deposited gemmules, preventing their dismantling. Radiocarbon dating of the basal-most layer indicated an age of more than 53,780 14 C years BP.Key words: freshwater sponges, taphonomy, lacustrine deposit, carbonatite complex, Brazil.RESUMO -Estruturas inteiras de esponjas continentais são raras no registro paleontológico e nenhum para o Pleistoceno. Um estudo anterior de espículas dessas esponjas contidas em depósitos pleistocênicos do Paleolago Cemitério, Catalão, Goiás, Brasil, levou à descoberta de diversas gêmulas preservadas in situ. Este trabalho visa identifi car as esponjas que produziram essas gêmulas e a sua relação com as espículas já descritas para os mesmos estratos do lago, além de abordar os processos tafonômicos que induziram essa excepcional preservação. Os materiais foram montados para análise ao MEV. As gêmulas pertencem às espécies atuais Corvoheteromeyenia australis, Dosilia pydanieli, Radiospongilla amazonensis e Corvomeyenia thumi. Gêmulas jovens, inteiras de Heterorotula fi stula, uma esponja conhecida só por espículas soltas em depósitos de espongilitos, foram também detectadas e pela primeira vez ilustradas, confi rmando o status da espécie. Dois fatores teriam favorecido essa rara preservação de gêmulas. A abundância de gêmulas jovens aponta para períodos curtos de imersão, responsáveis pelo desenvolvimento precário das camadas pneumáticas, prejudicando a fl utuação dessas gêmulas e acelerando seu depósito no fundo do lago. Uma provável cobertura por uma capa de algas, formada em seguida, devido ao calor e a dessecação, forneceu uma crosta elástica, mas consistente, que cobriu as gêmulas recentemente depositadas, impedindo sua desagregação. Da...

The Cemitério Palaeolake deposit in Catalão, Goiás State, Brazil, comprises a single, complete lacustrine sequence, dated from less than 27,500 ± 4000 yr B.P. to more than 51,780 ± 400 14 C yr B.P. The unprecedented presence of spongillite and diatomite layers in this deposit was investigated using spicules of continental sponges as proxy data for environmental and climate reconstruction, which was relatively extensive for the ages examined. From the analysis of the sedimentary features and the associations of spicules preserved in the deposit, it was possible to reconstruct the evolution of the limnic system. Five developmental stages were thus identified, corresponding to the installation (lotic and erosion phase), establishment and development of the lake and its colmatation, the latter correlating to the Last Glacial Maximum (LGM). Moreover, based on the ecological requirements of the sponge species identified in the deposit, it was possible to infer the likely weather patterns related to respective phases of the lake. The presence of the sponge species Corvoheteromeyenia australis, presently recorded only from southern South America, indicated that polar incursions originating from the Antarctic were frequent during the last glacial period and might have played a notable role in what is now central Brazil. However, for a short time, drier and hotter weather conditions might have predominated, as suggested by the presence of the species Corvomeyenia thumi.

The freshwater sponges Trochospongilla variabilis Bonetto & Ezcurra de Drago (1973), Radiospongilla crateriformis (Potts, 1882), Spongilla cenota Penney & Racek (1968) and Corvoheteromeyenia heterosclera (Ezcurra de Drago, 1974) compose with the sphaerid bivalve Eupera cubensis (Prime, 1865) and several Phylactolaemata bryozoans a benthic filter feeding community living in seasonal lentic and lotic habitats with high Particulate Organic Carbon (POC), low conductivity and acid pH within the Costa Rica Dry Forest biome. The sponge specimens gathered led to the re-description of the four species.