Taxonomy of the bivalve Ptychomya in the Lower Cretaceous of the Neuquén basin (west-central Argentina)

In the Lower Cretaceous Agrio Formation, Neuquén Basin (west-central Argentina), the highly variable genus Ptychomya Agassiz has challenged traditional taxonomists for over a century. Here we apply a previously outlined quantitative protocol in order to settle the taxonomy of the genus based on spec...

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Autores principales: Milla Carmona, P.S., Lazo, D.G., Soto, I.M.
Formato: JOUR
Materias:
Agrio Formation
closed outlines
Lower Cretaceous
open outlines
Ptychomya
taxonomy
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_20562802_v3_n2_p219_MillaCarmona
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_20562802_v3_n2_p219_MillaCarmona
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spelling todo:paper_20562802_v3_n2_p219_MillaCarmona2023-10-03T16:39:05Z Taxonomy of the bivalve Ptychomya in the Lower Cretaceous of the Neuquén basin (west-central Argentina) Milla Carmona, P.S. Lazo, D.G. Soto, I.M. Agrio Formation closed outlines Lower Cretaceous open outlines Ptychomya taxonomy In the Lower Cretaceous Agrio Formation, Neuquén Basin (west-central Argentina), the highly variable genus Ptychomya Agassiz has challenged traditional taxonomists for over a century. Here we apply a previously outlined quantitative protocol in order to settle the taxonomy of the genus based on specimens recorded from the base to the top of the Agrio Formation. The shell outline and ribbing pattern, two prominent external features of the valves, were quantified using geometric morphometric measurements of closed and open outlines, respectively. Morphological groupings were identified using model-based clustering, and the presence of significant morphological gaps between them was statistically tested. Our results show that the variation historically attributed to a single species, namely Ptychomya koeneni Behrendsen, corresponds to intra- and interspecific variability of at least four species, one of which was previously unknown (Ptychomya esbelta sp. nov.) whereas another was regarded as a subspecies of P. koeneni, namely Ptychomya windhauseni Weaver. We were also able to confirm the specific rank of Ptychomya coihuicoensis Weaver and the presence of P. koeneni in the upper Hauterivian of the Agrio Formation. This study represents a significant improvement over the previous state of knowledge of the genus Ptychomya in the Andes of Argentina, enhancing its biostratigraphical usefulness and palaeobiogeographical significance, and may serve as a model for the study of other poorly known bivalve faunas from other Andean basins of South America. © The Palaeontological Association Fil:Lazo, D.G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Soto, I.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_20562802_v3_n2_p219_MillaCarmona
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Agrio Formation
closed outlines
Lower Cretaceous
open outlines
Ptychomya
taxonomy
spellingShingle Agrio Formation
closed outlines
Lower Cretaceous
open outlines
Ptychomya
taxonomy
Milla Carmona, P.S.
Lazo, D.G.
Soto, I.M.
Taxonomy of the bivalve Ptychomya in the Lower Cretaceous of the Neuquén basin (west-central Argentina)
topic_facet Agrio Formation
closed outlines
Lower Cretaceous
open outlines
Ptychomya
taxonomy
description In the Lower Cretaceous Agrio Formation, Neuquén Basin (west-central Argentina), the highly variable genus Ptychomya Agassiz has challenged traditional taxonomists for over a century. Here we apply a previously outlined quantitative protocol in order to settle the taxonomy of the genus based on specimens recorded from the base to the top of the Agrio Formation. The shell outline and ribbing pattern, two prominent external features of the valves, were quantified using geometric morphometric measurements of closed and open outlines, respectively. Morphological groupings were identified using model-based clustering, and the presence of significant morphological gaps between them was statistically tested. Our results show that the variation historically attributed to a single species, namely Ptychomya koeneni Behrendsen, corresponds to intra- and interspecific variability of at least four species, one of which was previously unknown (Ptychomya esbelta sp. nov.) whereas another was regarded as a subspecies of P. koeneni, namely Ptychomya windhauseni Weaver. We were also able to confirm the specific rank of Ptychomya coihuicoensis Weaver and the presence of P. koeneni in the upper Hauterivian of the Agrio Formation. This study represents a significant improvement over the previous state of knowledge of the genus Ptychomya in the Andes of Argentina, enhancing its biostratigraphical usefulness and palaeobiogeographical significance, and may serve as a model for the study of other poorly known bivalve faunas from other Andean basins of South America. © The Palaeontological Association
format JOUR
author Milla Carmona, P.S.
Lazo, D.G.
Soto, I.M.
author_facet Milla Carmona, P.S.
Lazo, D.G.
Soto, I.M.
author_sort Milla Carmona, P.S.
title Taxonomy of the bivalve Ptychomya in the Lower Cretaceous of the Neuquén basin (west-central Argentina)
title_short Taxonomy of the bivalve Ptychomya in the Lower Cretaceous of the Neuquén basin (west-central Argentina)
title_full Taxonomy of the bivalve Ptychomya in the Lower Cretaceous of the Neuquén basin (west-central Argentina)
title_fullStr Taxonomy of the bivalve Ptychomya in the Lower Cretaceous of the Neuquén basin (west-central Argentina)
title_full_unstemmed Taxonomy of the bivalve Ptychomya in the Lower Cretaceous of the Neuquén basin (west-central Argentina)
title_sort taxonomy of the bivalve ptychomya in the lower cretaceous of the neuquén basin (west-central argentina)
url http://hdl.handle.net/20.500.12110/paper_20562802_v3_n2_p219_MillaCarmona
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AT lazodg taxonomyofthebivalveptychomyainthelowercretaceousoftheneuquenbasinwestcentralargentina
AT sotoim taxonomyofthebivalveptychomyainthelowercretaceousoftheneuquenbasinwestcentralargentina
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