Help with Brazilian Permian Fossils

[Julio Campos]

Hello

I've got these for some time now and was wondering if it's possible to get close to any ID on them.
They came from São Paulo state countryside, Brazil, from a calcareous mine at a Permian geological formation know as "Passa Dois".

The 1 and 2  images display two separate fossils

The 3 and 4 (detail of 3) two fossils at a same rock.

The 5 is the same rock sample from 3 and 4 but on the opposite side of it. the rock is about 10cm thick bu I don't know if this image is from a upper layer or a lower layer in relation to pics 3 and 4. It seem to be a vegetal shape of sort?

The ruler is in cm.

I enhanced the color to male them more visible.

 

anyway, thank you in advance for any considerations.

 

Julio Campos

[Fossildude19]

Welcome to the Forum.  

 

I believe the Passo Dois Group consists of 4 different formations: The Irati Formation, the Serra Alta Formation, the Terrasina Formation, and the Rio do Rasto Formation.

I don't know what formation the mine is in, but the Irati Formation is known for it's Mesosaurus fossils. 

I could be wrong, but the image with 2 fossils looks like ribs and vertebrae to me.  

 

 

Maybe messaging a paleontologist from the University of Sao Paulo would be in order?

Regards,

[Max-fossils]

Hi Julio, and welcome to TFF! 

 

Those are some amazing fossils!

I can't help much, but this is all I can say.

#2 makes me think of a vertebrate animal, those things kinda look like ribs. Yet it looks a lot like #1, which is in no way a vertebrate fossil. Plus, their 'flatness' excludes that possibility.

#3 and #4 are most probably the same species as #1 and #2.

 

Best regards,

 

Max

[abyssunder]

Those are excellent finds! Tim is right with the ID.

 

" Three genera are currently recognized in the family Mesosauridae: Mesosaurus tenuidens Gervais, 1864, Stereosternum tumidum Cope, 1886, and Brazilosaurus sanpauloensis Shikama and Ozaki, 1966. " - as stated in Pretto, F.A., Cabreira, S.F., and Schultz, C.L. 2014. Tooth microstructure of the Early Permian aquatic predator Stereosternum tumidum. Acta Palaeontologica Polonica 59 (1): 125–133.

 

Also here is SEAN PATRICK MODESTO†. 2010. THE POSTCRANIAL SKELETON OF THE AQUATIC PARAREPTILE MESOSAURUS TENUIDENS FROM THE GONDWANAN PERMIAN. Journal of Vertebrate Paleontology, 30(5):1378-1395.- for reference.

 

[Julio Campos]

Hi.

thank you for the tips.

 

sorry for the poor quality of the images.

they're all vertebrate and do have the ribs altought 1 and 2 have only the negative of the vertebrae.

will check at university.

 

any idea about the #5?

thank you

Julio

 

[abyssunder]

The sample from the last picture (5) looks more like it has septarian propagation cracks rather than fossil plant material. Maybe this document helps : L. Alessandretti et al. 2015. Septarian carbonate concretions in the Permian Rio do Rasto Formation: Birth, growth and implications for the early diagenetic history of southwestern Gondwana succession. Sedimentary Geology 326, p1–15.

 

" The concretions are often cut by one or more generations of fractures also known as septarian cracks/fractures. These fractures are completely or partially filled by carbonate cements and secondary minerals such as silica, phosphates and sulfates. They typically range in shape: subvertical lenses, concentric sheets, radial or crosscutting fractures. The processes involved in the formation of septarian cracking have been explained by the following:
(i) shrinkage (brittle fracturing) induced by the dehydration of clay minerals or organic matter (Raiswell, 1971);
(ii) compaction and overpressure of pore waters (Astin, 1986);
(iii) gas generation due to bacterial decay of organic compounds (Irwin et al., 1977); and

(iv) syn-depositional earthquake-induced ground motion (Pratt, 2001).
Due to the post-depositional origin of the concretions, they have been used as key features for understanding the diagenetic evolution of the sedimentary rocks (Irwin et al., 1977).  (...)

 

The presence of Permian-aged carbonate concretions in the Paraná Basin (Fig. 1), particularly in the Rio do Rasto Formation, has been acknowledged for many years, although few studies have been published. On the basis of sedimentological and paleontological evidence (Schneider et al., 1974; Gama Jr., 1979; Rohn, 1994; Warren et al., 2008; Holz et al., 2010), it is impossible to definitively determine if these concretions were formed in a freshwater lacustrine or a marine depositional environment. "

 

[Fossildude19]

Septarian structure was my thought on that, as well. 

Regards,

[Julio Campos]

thank you

Julio