%0 Journal Article %J Geological Magazine %D 2019 %T Comment on: Álvaro, J. J., Esteve, J. & Zamora, S. 2019. Morphological assessment of the earliest paradoxidid trilobites (Cambrian Series 3) from Morocco and Spain %A G. Geyer %A Nowicki, Jakub %A Żylińska, Anna %A E. Landing %K Anti- Atla %K Biostratigraphy %K Iberian Chains %K morphometrics %K trilobite systematics %K West Gondwana %X

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.

%B Geological Magazine %V 156 %P 1691-1707 %8 Apr-03-2019 %G eng %U https://www.cambridge.org/core/product/identifier/S0016756818000961/type/journal_article %N 10 %! Geol. Mag. %R 10.1017/S0016756818000961 %0 Book Section %B Morocco 2006. EdiacaranCambrian Depositional Environments and Stratigraphy of the Western Atlas Regions. Explanatory Description and Field Excursion Guide %D 2006 %T Morocco Field Excursion 2006. Ediacaran-Cambrian Depositional Environments and Stratigraphy of the Western Atlas Regions %A G. Geyer %A E. Landing %E G. Geyer %E E. Landing %K Biostratigraphy %K Cambrian %K Ediacaran %K intercontinental correlation %K lithostratigraphy %K Moroccan Atlas regions %K paleoenvironments %K sequence boundaries %K volcanic ash occurrences %X

This field excursion emphasizes paleoenvironments, litho- and biostratigraphy, sequence boundaries, volcanic ash occurrences, and potential for intercontinental correlation of a number of important Ediacaran and Cambrian sections of the Moroccan Atlas regions. The arrangement of the sections visited during the field excursion from December 2 to 5, 2006, begins on the northern slope of the western Anti-Atlas with the lowest Cambrian at Tiout and the lower part of the trilobite-bearing Cambrian at Tazemmourt. Complete sections through the trilobite-bearing Cambrian in the Lemdad syncline feature the Cambrian in the western High Atlas range. The subsequent drive across the western Anti-Atlas shows aspects of post-Pan-African Proterozoic, siliciclastic facies with archaeocyathan bioherms in the Issafen Syncline, and spectacular slump-folding of the Lie de vin Formation as well as a siliciclastical-dominated Lower and fossiliferous Middle Cambrian in the Tata region. The final day in the field features the Devonian and the siliciclastic Middle Cambrian along the southern flank of the western Anti-Atlas and carbonate-dominated Lower Cambrian at the western rim of the Anti-Atlas.

Information on the stops includes a summary of the lithologic sequence and, if available, a complete list of faunas found at successive levels. The sample numbers with the prefix F refer either to the faunal levels of HUPÉ (1953, 1959) or SDZUY (1978); sample numbers with a comma indicate a precisely measured level above the base of the section or unit; other samples refer to horizons reported by G. GEYER (e.g., 1986, 1988b, 1990c, 1998) or to subsequent collections by the authors and W. HELDMAIER (1997).

%B Morocco 2006. EdiacaranCambrian Depositional Environments and Stratigraphy of the Western Atlas Regions. Explanatory Description and Field Excursion Guide %S Beringeria Special Issue %P 47-112 %G eng %0 Journal Article %J Journal of Paleontology %D 2001 %T Middle Cambrian of Avalonian Massachusetts: Stratigraphy and Correlation of the Braintree Trilobites %A G. Geyer %A E. Landing %K Biostratigraphy %K Braintree Member %K Middle Cambrian %K trilobites %X

Although Middle Cambrian trilobites of the Braintree Member in eastern Massachusetts were among the first published on in North America, re-examination of this fauna has led to wholesale taxonomic and biostratigraphic re-evaluation. This low diversity fauna now includes at least seven species, with the first report of agnostoids (three poorly preserved taxa) and the ellipsocephalid Kingaspis avalonensis new species. Paradoxides (Acadoparadoxides) harlani Green emend., a senior synonym of P. (A.) haywardi Raymond, allows correlation into the lowest Middle Cambrian elsewhere in Avalon. However, all the polymeroid species are endemic, and this precludes a highly resolved correlation into other Cambrian paleocontinents. A breakdown of provincial barriers in the late Early Cambrian as western Gondwana passed from equatorial to the higher south latitudes of Avalon led to faunal exchanges between these continents. Paradoxides (Acadoparadoxides) and Kingaspis of the Braintree fauna are shared with western Gondwana, while Braintreella and “Agraulos quadrangularis are closest to genera known from the Spanish, Moroccan, and Perunican (Bohemian) margins of Gondwana.

%B Journal of Paleontology %V 75 %P 116-135 %G eng %U http://dx.doi.org/10.1666/0022-3360(2001)075<0116:MCOAMS>2.0.CO;2 %R 10.1666/0022-3360(2001)075<0116:MCOAMS>2.0.CO;2