Rio Claro municipality: Artinskian, Brazil
List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
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Mesosauridae
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| 9 individuals | ||||||||||
| UFRGS PV0245P to PV0251P, PV0252P*, PV0253P to PV0256P, PV0258P, PV0259P, PV0263P; RI-1*, RI-2, RI-3*, RI-4*, RI-5*, RI-6*, RI-7*, RI-8*, RI-9*; asterisks mark partially articulated skeletons | ||||||||||
| 10 individuals | ||||||||||
| UFRGS PV0170P to PV0172P, PV0174P to PV0176P, PV0180P, PV0181P, PV0345P; DGM542-R | ||||||||||
| 2 individuals | ||||||||||
| UFRGS PV0267P; DGM 539-R | ||||||||||
| see common names | ||||||||||
Geography
| Country: | Brazil | State/province: | São Paulo | County: | Rio Claro |
| Coordinates: | 22.5° South, 47.6° West (view map) | ||||
| Paleocoordinates: | 45.4° South, 26.1° West (Wright 2013) | ||||
| Basis of coordinate: | based on nearby landmark | ||||
| Geographic resolution: | outcrop |
Time
| Period: | Permian | Epoch: | Cisuralian |
| Stage: | Artinskian | 10 m.y. bin: | Permian 2 |
| Key time interval: | Artinskian | ||
| Age range of interval: | 290.1 - 283.3 m.y. ago |
Stratigraphy
| Geological group: | Passa Dois | Formation: | Irati | Member: | Assistencia |
| Stratigraphic resolution: | group of beds | ||||
| Stratigraphy comments: Soares (2003) states that the fossils come from the Irati Formation but only gives "Permian" as the most precise age specification. However, in a quite recent publication it is stated that the Irati Formation is Artinskian in age, based on absolute ages obtained from zircons from a bentonite layer (Santos et al., 2006, Gondwana Res. 9). Presence of dolomites within the succession (see lithology description) suggests that the fossils comes from the Assistência Member of the Irati Fm. (see Santos et al., 2009, J. S. Am. Earth Sci., Article in Press, doi:10.1016/j.jsames.2008.12.002). | |||||
Lithology and environment
| Primary lithology: | dolomitic "limestone" | ||
| Secondary lithology: | tabular "mixed carbonate-siliciclastic" | ||
| Includes fossils? | Y | ||
| Includes fossils? | Y | ||
| Lithology description: A thick dolomite bed occurs at the base of the sequence, which consists mainly of laminated dolomitic calcilutites with undulated lamination. Interleaved with the calcilutites there are dolomitic calcarenite horizons rich in bioclasts (mesosaur bones, crustacean shells, ostracodes, foraminifera and stromatolite clasts). This carbonate facies assemblage (the so-called “dolomitic bank”) is overlain by dark-grey and bituminous black shales interbedded with limestones and dolomites (“rhythmic zone”; Fig. 5). Crustacean shell-beds also occur in this facies. According to Lavina (1991) this rhythmic facies, with recurrently associated carbonates and shales, are distal tempestites linked to deposition from turbulent currents induced by storms and deposited below the baselevel of the storm wave action. Most of the articulated mesosaur specimens (Class I) have been collected from the top of the lower dolomitic bed, close to its boundary with the overlying rhythmic facies. Semi-articulated (Class II) and disarticulated (Classes IIIA and IIIB) bone-bed materials occur both at this level and in the rhythmically stratified deposits." (Soares, 2003). | |||
| Environment: | carbonate indet. | Tectonic setting: | cratonic basin |
Taphonomy
| Size of fossils: | macrofossils |
| Preservation of anatomical detail: | good |
| Articulated whole bodies: | none |
| Associated major elements: | many |
| Disassociated major elements: | many |
| Temporal resolution: | time-averaged |
Collection methods and comments
| Collection excludes: | some macrofossils,some microfossils |
| Collection methods: | survey of museum collection |
| Reason for describing collection: | taxonomic analysis |
| Collection method comments: UFRGS PV = vertebrate palaeontoloogy collections of the Universidade Federal do Rio Grande do Sul, Porto Alegre
DGM = Divisão de Geologia e Mineralogia, Departamento Nacional de Produção Mineral PI = specimens in private collections | |
| Taxonomic list comments:Soares (2003) gives no specific assignment of the mesosaurs. Since all mesosaur genera are considerd monotypic the Stereosternum specimens listed by Soares (2003) are referred to as Stereosternum tumidum and the Brazilosaurus specimens are referred to as Brazilosaurus sanpauloensis in the taxonomic list. | |
Metadata
| Also known as: | Paraná Basin | ||
| Database number: | 90429 | ||
| Authorizer: | J. Mueller | Enterer: | T. Liebrecht | Research group: | vertebrate |
| Collections that are a subset of this one: | |||
| Created: | 2009-07-20 07:46:44 | Last modified: | 2025-02-22 15:12:02 |
| Access level: | authorizer only | Released: | 2012-07-20 07:46:44 |
| Creative Commons license: | CC0 | ||
Reference information
Primary reference:
| 30368. | M. B. Soares. 2003. A taphonomic model for the Mesosauridae assemblage of the Irati Formation (Paraná Basin, Brazil). Geologica Acta 1(4):349-361 [J. Mueller/T. Liebrecht] |