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Paradoxides type from ZAGORA


mediterranic

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1 hour ago, mediterranic said:

I would like to post other pics from the back side (with an incomplete unprep specimen) that could help, but the uploading problem still remains.

Miguel

Reducing the size or pixel count of the pictures seems to work for most. Not the most desirable, but better than nothing.

Hopefully the problem will get fixed soon.

Darwin said: " Man sprang from monkeys."

Will Rogers said: " Some of them didn't spring far enough."

 

My Fossil collection - My Mineral collection

My favorite thread on TFF.

 

 

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On 1/28/2018 at 2:56 AM, Tidgy's Dad said:

It looks like what we would call Acanthoparadoxides mureroensis here. 

I understand these have been described from Spain, but not officially from Morocco. 

 

On 1/28/2018 at 11:02 AM, Tidgy's Dad said:

And therefore, that the above specimen could be A. mureroensis? 

 

On 1/28/2018 at 1:00 PM, Tidgy's Dad said:

No, I am quite familiar with A. briareus and A. nobilis , but this doesn't seem to match either, especially the latter which is a bit smaller?  

 

4 hours ago, Tidgy's Dad said:

But both Geyer and Vincent 2015 and Alvaro et al. 2017 agree that Acadoparadoxides nobilis has a notched median indentation to the pygidium which is not present in the OPs well preserved pygidium, though part of the margin may be missing. A. nobilis also exhibits a shorter, very triangular/ trapezoidal shape to the pygidium while A. mureroensis and A. briareus have a much more rounded pygidium as does the specimen here. Also, A. nobilis doesn't get as big as the specimen pictured by the OP

Tentatively,I would suggest it's not A. nobilis. 

 

 

Let me try to help as you seem to be confused on a few points.  First you incorrectly stated that Acadoparadoxides mureroensis was not described from Morocco.  Additionally, A. mureroensis is not a good possibility in any event, it does not reach the giant proportions of A. briareus and A. nobilis.  The photos appear to show a ~12"  example, typically a size range that would be assigned to A. briareus.  If you were familiar with A. briareus and A. nobilis, they certainly should have been part of the discussion as the two largest Moroccan paradoxidid species. 

 

Klug et al. 2015 reports a 16" example of A. nobilis, on par with the upper maximum for A. briareus.  Fletcher et al. 2005 suggested that A. briareus was synonymous with Paradoxides (Hydrocephalus) harlani (see Geyer & Vincent 2015 for rebuttal).  Geyer & Vincent 2015 modified the diagnosis of A. briareus to 17 thoracic segments from 18 segments in Geyer 1993.  These are a couple of reasons for the conservative approach in this instance.  A. briareus Geyer 1993 should probably supersede all others as the largest of the giant Moroccan species.  Until additional comment and rebuttal is available from Geyer and others, for the time being, at least we can all agree it is Acadoparadoxides sp.

 

 

Fletcher, T.P., Theokritoff, G., Lord, G. S., & Zeoli, G. (2005)

The early paradoxidid harlani trilobite fauna of Massachusetts and its correlatives in Newfoundland, Morocco, and Spain.

Journal of Paleontology, 79(2):312-336  PDF LINK

 

Klug, C., De Baets, K., Kröger, B., Bell, M.A., Korn, D., & Payne, J.L. (2015)

Normal giants? Temporal and latitudinal shifts of Palaeozoic marine invertebrate gigantism and global change.

Lethaia, 48(2):267-288  PDF LINK

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5 minutes ago, mediterranic said:

The specimen has 35 x 28,5 cm

 

 

Do I win a prize for close without going over? :P  Next time a proper scale would be best.

 

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  • 2 months later...
On 1/30/2018 at 12:25 PM, piranha said:

 

 

Do I win a prize for close without going over? :P  Next time a proper scale would be best.

 

 

Only if you're standing next to Drew Carey.

 

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  • 10 months later...
On 1/30/2018 at 11:39 AM, piranha said:

...Until additional comment and rebuttal is available from Geyer and others, for the time being, at least we can all agree it is Acadoparadoxides sp.

 

As expected, Geyer et al. have published a rebuttal:

 

Geyer, G., Nowicki, J., Żylińska, A., Landing, E. 2019

Comment on: Álvaro, J. J., Esteve, J. & Zamora, S. 2018. Morphological assessment of the earliest paradoxidid trilobites (Cambrian Series 3) from Morocco and Spain. Geological Magazine, 156(10):1691-1707

 

ABSTRACT


Álvaro et al. (2018) argued that at least six species of Acadoparadoxides described from the lower–middle Cambrian boundary interval successions in the Anti-Atlas of Morocco all belong to Acadoparadoxides mureroensis (Sdzuy, 1958), which was first described from the Iberian Chains, Spain. Their study is based entirely on a morphometric analysis, which ignores the stratigraphic occurrences of particular morphotypes, deformation-related compaction of individual sclerites and their original relief, and thus underestimates some of the earlier described differences between these species. Their synonymization of a number of named Acadoparadoxides species is based on the morphometric approach that they rely on to distinguish between a number of congeneric species. A morphometric approach as applied by Álvaro et al. will lead to an apparent synonymy based on sclerites of similar taxa. Thus, morphometric study must be complemented by an analysis of which morphologically distinctive sclerites (i.e. cranidia and pygidia) are stratigraphically associated, and evaluation of which measurements are more critical to distinguishing sclerites that may represent distinct taxa, and the recognition of related character sets. Apart from demonstrating problems in the conclusion of Álvaro et al., our more inclusive approach of morphologic and stratigraphic analysis works to reassert the diagnostic characters and differences between six earlier named species of Acadoparadoxides. Our conclusions also emphasize the taxonomic problems associated with the identification and morphological variation of A. mureroensis owing to tectonic deformation of its topotype material and to questionable taxonomic assignment of Acadoparadoxides specimens from the Iberian sections.

 

SUMMARY

 

The stratigraphic sequence of the (provisional) Cambrian Stage 4 – Wuliuan boundary beds in the Jbel Ougnate region, eastern Anti-Atlas of Morocco, is interpreted to accurately record the phylogenetic development of trilobite species in this interval, particularly of ellipsocephaline and protolenine species and at least six species of Acadoparadoxides, the older of which were described in detail by Geyer & Vincent (2015). The assumption published by Álvaro et al. (2018) that A. pampalius Geyer & Vincent, 2015, A. levisettii Geyer & Vincent, 2015, A. cf. mureroensis (Sdzuy, 1958), A. ovatopyge Geyer & Vincent, 2015 and A. nobilis Geyer, 1998 are all identical with A. mureroensis (Sdzuy, 1958) described from the Iberian Chains, northern Spain, is shown herein to be incorrect. The study of Álvaro et al. (2018) is based entirely on a morphometric analysis, ignores stratigraphic occurrences, individual deformation-related compaction and the original relief, and underestimates some of the earlier described differences between these species. Their suggested synonymy is based on the inability to detect differences by morphometrics. The conclusion is inappropriate because differences cannot be detected solely by the applied morphometric techniques, and other features such as distinctive character associations and the stratigraphic association of sclerites are distinctive of different paradoxidine species. Emphasis of the diagnostic characters and differences between earlier named species of Acadoparadoxides indicate that their differences are often subtle but coherent with the stratigraphic differences.

 

The emphasis in this and earlier reports on Acadoparadoxides species focuses on distinguishing relatively subtle but consistent morphologic differences between the sclerites of similar species (Geyer, 1998; Geyer & Landing, 2001; Geyer & Vincent, 2015). A comparable focus is now emphasized in neontologic work in which consistent differences in minor morphologic features and the presence of unique features correspond to genomic differences that define distinctive taxa (see review in Westrop et al. 2018). This approach does not necessarily lead to ‘oversplitting’ of existing taxa, but does allow the evaluation of palaeospecies and other taxa that are geographically widespread, purportedly morphologically ‘plastic’ and seem to be particularly ‘useful’ for interregional and interhabitat biostratigraphic correlations.

 

This report also emphasizes and details the currently unresolved problems in the diagnosis, description, formal illustration and, consequently, identification of the purportedly geographically widespread, early paradoxidine species A. mureroensis. This species is regarded as a nomen dubium known from tectonically distorted material from Iberia, which may include the sclerites of more than one species in its topotype series. As a consequence, if a number of Acadoparadoxides species should ultimately prove to be synonymous, A. mureroensis should not be regarded as a senior synonym. Even the identification of A. mureroensis from some of the Iberian sections, such as the Porma and Valdoré sections in the Cantabrian Mountains, should be re-evaluated. Indeed, any well-preserved Acadoparadoxides material from the lower–middle Cambrian boundary interval of West Gondwana should be compared with what we conclude as the better defined species from Morocco.

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