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Aerson

Any ichnofossil specialist in there? Ichnofossil from Brazil Jurassic ID

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Aerson

Hello everyone.
I'm a geologist/stratigraphist and I've been studying Missão Velha Formation (Araripe Basin, Brazil Jurassic-Cretaceous) for a couple of years.
We found some structures that seem to be trace fossils, but as geologists, we assume ourselves to be slightly ignorant in ecologic behavior of species.
The MV Formation are corsed sandstones, well stratified, with few purple siltic-sandstone levels with ped structures.
These trace fossils I'll be presenting next resemble the top of one of these siltic-sandstone levels.
They are tridimensional and cilindric, with an spheric edge on the bottom and the top is not well seen. It have sort of a stratification, like it was many piled up rings.

2015-11-17 15.05.40.jpg

2015-11-17 15.06.11.jpg

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DPS Ammonite

Welcome to the Forum.

 

I see the red cylinders that are deposited in the purplish underlayer. Exactly what are the compositions of the red and purple rocks? In what environment were they deposited: lake, stream, ocean etc? Is there any evidence that the red rocks are root or stem casts? In other words, have you seen any plant material that would suggest that the purplish rocks were the top of a soil surface with plants growing in it?

 

 

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doushantuo

Welcome here!

They look more or less like infilled pot/gutter casts to me,like those found in the Triassic of Germany

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DPS Ammonite
2 minutes ago, doushantuo said:

They looks mor or less like infilled pot/gutter casts to me,like those found in the Triassic of Germany

Pothole fillings are a possibility. The environment of deposition will help determine if potholes are likely as opposed  to plant casts or burrows.

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doushantuo

The paleo-environments are those that are usually encountered in a rift-to-drift sequence.The Missao has fluvial deposits

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abyssunder
Aerson
On 26/09/2018 at 1:03 AM, DPS Ammonite said:

Welcome to the Forum.

 

I see the red cylinders that are deposited in the purplish underlayer. Exactly what are the compositions of the red and purple rocks? In what environment were they deposited: lake, stream, ocean etc? Is there any evidence that the red rocks are root or stem casts? In other words, have you seen any plant material that would suggest that the purplish rocks were the top of a soil surface with plants growing in it?

 

 

Thanks mate!

The purple color within this strata is believed to be post-diagenetic Mn influence (manganese oxide or concretion are relatively common in Araripe Basin).
The red layers are possibly ped clay structures holding leached Fe 3+. There is no chemical analysis yet (nor simple nor XRD). I am actually working on it in the next months!

The Missao Velha Fm consists in braided-river deposits, coarse, well-stratified sandstones (100 m thick aprox.), with this purple strata (2 m thick max), described in the literature as a paleosol, medium to fine sandstones, eroded in the top by the channel deposits. Sedimentary structures are hard to identify, part of my work will be microfacies analysis of the purple strata.

The Missao Velha Fm also carries big size silicified conifer trunks, but it is still believed to be alloctonous, because none have been found in life positions and these trunks are common in Jurassic-Neocomian deposits in Brazil Northeast and Africa West (+8 basins containts it).

In another outcrop root strucutures are present, but it is hard to know if it is syn-depositional or Holocenic, because the current vegetation in the cliffs really mess the outcrops.

I hope I have answered it all! Thank you for the help!

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Aerson
On 26/09/2018 at 1:13 AM, doushantuo said:

Welcome here!

They look more or less like infilled pot/gutter casts to me,like those found in the Triassic of Germany

Hello friend! Would you send me a reference paper, please?

Thank you for the help!

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Aerson
On 26/09/2018 at 6:21 PM, abyssunder said:

Thanks! The Missao Velha Fm has root structures in another outcrop, but they urge for a study still. The structure in my picture resemble a sediment filling, not mineral replacement. Leastwise it is what I think by "eye-analysis". Petrography is needed! I hope I will be making it soon. Thank you for the comment!

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Walt

I cannot help in this ID, but if you have time later, could you go to the attached thread and fill us in on the latest situation at the National Museum?

I think we would all love to hear any information you may have about its current state.

Welcome to the forum! :)

 

 

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abyssunder

My first impression was Diplocraterion, but I wasn't fairly convinced of that.
Try to search in that direction, see if can be ruled out or not. Longitudinal and transverse sections of the specimens, also the ichnofacies they may belong to (if any), might help in the ID. Diplocraterion, Monocraterion, Ophiomorpha and Skolithos belong to the same ichnofacies, for example.
If doesn't resemble anything known at present time, it could be a new ichnological taxon or a geological feature of the sediments, I think. Paleosols may have a lot of features.

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Aerson
14 hours ago, Walt said:

I cannot help in this ID, but if you have time later, could you go to the attached thread and fill us in on the latest situation at the National Museum?

I think we would all love to hear any information you may have about its current state.

Welcome to the forum! :)

 

 

For sure, friend!

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Aerson
14 hours ago, abyssunder said:

My first impression was Diplocraterion, but I wasn't fairly convinced of that.
Try to search in that direction, see if can be ruled out or not. Longitudinal and transverse sections of the specimens, also the ichnofacies they may belong to (if any), might help in the ID. Diplocraterion, Monocraterion, Ophiomorpha and Skolithos belong to the same ichnofacies, for example.
If doesn't resemble anything known at present time, it could be a new ichnological taxon or a geological feature of the sediments, I think. Paleosols may have a lot of features.

The difference is that the structures in Missao Velha paleosol are tridimentional and very cylindrical, "sausage-shaped", not "tongue-shaped" as Diplocraterion.

In the following picture, an overview in a horizontal cut within the strucuture (natural, due to erosion of the top of the bed). Some "walls" are broken and fallen in the center of the structure, but is seen that the structure is an almost regular cylindric shape.

2015-11-17 15.06.38.jpg

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abyssunder

Thank you for the new data.

If we remain in the ichnology segment, there are vertical, cylindrical, circular or  subcircular in cross section, non branching burrows, with funnel structure (e.g. Monocraterion, Rosselia), which may look close to your specimens.
Ichnogenus Rosselia is nicely described in R. Hofmann et al. 2012. Paleoecologic and Biostratigraphic Significance of Trace Fossils from Shallow- to Marginal-Marine Environments from the Middle Cambrian (Stage 5) of Jordan. Journal of Paleontology, 86(6): 931-955.

 

" Vertical to oblique full relief burrows with concentric infill around an off-centered cylindrical shaft (Fig. 5.4, 5.5). These burrows commonly display a pillar-like morphology (Fig. 5.4). Diameter of the burrow slightly and gradually varies along the axis resulting in a faint, bulbous morphology. More rarely, an uppermost funnel-shape or calyx-like structure is visible (Fig. 5.3). On bedding-plane views (Fig. 5.5), cross section is subcircular to slightly elliptical. Burrow length is up to 270 mm but commonly is 100 to 150 mm. Burrow width is 16 to 24 mm. Concentric infill is formed by an alternation of sandstone and mudstone laminae but sandstone laminae tend to be thicker producing a sandstone-dominated infill. The thickness of concentric laminae is 2 to 6 mm, typically increasing from interior to exterior of the structure. "

 

5bb69905be46a_Figure5.thumb.jpg.734c660fe26aeb7deb9c3bcc4bfec49b.jpg

 

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Aerson
On 04/10/2018 at 7:50 PM, abyssunder said:

Thank you for the new data.

If we remain in the ichnology segment, there are vertical, cylindrical, circular or  subcircular in cross section, non branching burrows, with funnel structure (e.g. Monocraterion, Rosselia), which may look close to your specimens.
Ichnogenus Rosselia is nicely described in R. Hofmann et al. 2012. Paleoecologic and Biostratigraphic Significance of Trace Fossils from Shallow- to Marginal-Marine Environments from the Middle Cambrian (Stage 5) of Jordan. Journal of Paleontology, 86(6): 931-955.

 

" Vertical to oblique full relief burrows with concentric infill around an off-centered cylindrical shaft (Fig. 5.4, 5.5). These burrows commonly display a pillar-like morphology (Fig. 5.4). Diameter of the burrow slightly and gradually varies along the axis resulting in a faint, bulbous morphology. More rarely, an uppermost funnel-shape or calyx-like structure is visible (Fig. 5.3). On bedding-plane views (Fig. 5.5), cross section is subcircular to slightly elliptical. Burrow length is up to 270 mm but commonly is 100 to 150 mm. Burrow width is 16 to 24 mm. Concentric infill is formed by an alternation of sandstone and mudstone laminae but sandstone laminae tend to be thicker producing a sandstone-dominated infill. The thickness of concentric laminae is 2 to 6 mm, typically increasing from interior to exterior of the structure. "

 

5bb69905be46a_Figure5.thumb.jpg.734c660fe26aeb7deb9c3bcc4bfec49b.jpg

 

The structures I am reporting happen to be in a continental fluvial context, in a endorheic basin.

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abyssunder

The Rosselia ichnofabric from the Early Devonian deposits of ‘Transition Beds’ (Western Gondwana Paraná Basin, southern Brazil) was described in R. G. Netto et al. 2014. Crowded Rosselia ichnofabric in the Early Devonian of Brazil: An example of strategic behavior. Palaeogeography, Palaeoclimatology, Palaeoecology 395: 107-113.

 

Here's an excerpt from the document, showing nice examples of Rosselia.

 

5bb930c82168a_Fig.4.thumb.jpg.a589b376d546ee39baeff4a7bc937edb.jpg

 

" Rosselia has been described from a range of shallow-marine settings affected by storms and fluvial discharge (e.g., Nara, 1995, 1997, 2002; Uchman and Krenmayr, 1995; Pemberton et al., 2001; Bann et al., 2004; MacEachern et al., 2005; Frieling, 2007; Howell et al., 2007; Miller and Aalto, 2008; Desjardins et al., 2010; Hofmann et al., 2012; Mangano et al., 2013; Netto et al., 2014). The link between Rosselia and sedimentation rate was first put forward by Nara (1997, 2002), who described Pleistocene funnel- and spindle-shaped specimens that are vertically stacked, reflecting upward migration to avoid burial due to event sedimentation in a storm-dominated shallow-marine setting. Also, in similar storm-dominated settings, Pemberton et al. (2001) and Howell et al. (2007) discussed Cretaceous stacked Rosselia reflecting burrow readjustments after storms, whereas Netto et al. (2014) analyzed in detail a Devonian occurrence. Stacked Rosselia have been used to analyze multiple, short-time, depositional events (months to years) in Cretaceous wave-dominated shoreface deposits (Campbell et al., 2014). In addition, Pleistocene stacked specimens of Rosselia occur in oceanic-flood deposits from an adjacent river system, reflecting the ability of terebellid polychaetes to survive under conditions of very high sedimentation rate (Campbell et al., 2006). Stacked Rosselia specimens were also described from Miocene shallowmarine deposits characterized by high sedimentation rates (Miller and Aalto, 2008). The Rosselia ichnofabric from the Castro Formation resembles that described from oceanic flood deposits by Campbell et al. (2006), rather than those from wave-influenced settings, which seem to be more common in the stratigraphic record. Similar to the case of the Ordovician Rosselia, a Permian Rosselia ichnofabric from southeastern Australia occurs in a volcaniclastic setting, but reflecting penetration from a colonization surface at the top of the bed (Buatois and Mangano, 2011). " - as it is stated in Buatois et al., 2016 .

 

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abyssunder

OK. Here's what I have, and I'll sustain Carl's idea about the lungfish burrow. He could be correct.

 

dipnóico ----- lungfish

keywords: dipnoi, dipnoico, dipnoic fish, dipnoiformes

 

5bb94f7e8f539_Fig.2.thumb.jpg.68836e2df822b0b6ad6c87959113f2a5.jpg

excerpt from  Fernandes & Carvalho, 2002

 

reference:

C. Eduardo et al. 2005. Occurrences of the fossil Dipnoiformes in Brazil and its stratigraphic and chronological distributions.  Revista Brasileira de Paleontologia 8(1): 47-56

A. S. Fernandes & I. S. Carvalho. 2002. Uma provável escavação de dipnóico na Formação Ponta Grossa, Devoniano da Bacia do Paraná. Arquivos do Museu Nacional 60(3): 207-211

 

For a better understanding of what we have in question, better close-up pictures are needed of at least one specimen extracted from the sediments.

 

 

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Aerson
3 hours ago, abyssunder said:

OK. Here's what I have, and I'll sustain Carl's idea about the lungfish burrow. He could be correct.

 

dipnóico ----- lungfish

keywords: dipnoi, dipnoico, dipnoic fish, dipnoiformes

 

5bb94f7e8f539_Fig.2.thumb.jpg.68836e2df822b0b6ad6c87959113f2a5.jpg

excerpt from  Fernandes & Carvalho, 2002

 

reference:

C. Eduardo et al. 2005. Occurrences of the fossil Dipnoiformes in Brazil and its stratigraphic and chronological distributions.  Revista Brasileira de Paleontologia 8(1): 47-56

A. S. Fernandes & I. S. Carvalho. 2002. Uma provável escavação de dipnóico na Formação Ponta Grossa, Devoniano da Bacia do Paraná. Arquivos do Museu Nacional 60(3): 207-211

 

For a better understanding of what we have in question, better close-up pictures are needed of at least one specimen extracted from the sediments.

 

 

I think it is a very interesting sugestion, but the assembly I'm presenting do not exceed 8 cm height.
I have a fieldtrip planned in November. The locality is 600 km distant from the town I live so it's a bit hard to schedule a date to go. I intend to colect at least 2 burrows this time.

Thanks!

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