Morphological evolution of the bivalve Ptychomya through the Lower Cretaceous of Argentina

The complex morphological evolution of the bivalve Ptychomya throughout the well-studied Agrio Formation in the Neuquén Basin (west-central Argentina, lower/upper Valanginian-lowest Barremian) constitutes an ideal opportunity to study evolutionary patterns and processes occurring at geological times...

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Autores principales: Carmona, P.S.M., Lazo, D.G., Soto, I.M.
Formato: JOUR
Materias:
ammonite
biostratigraphy
bivalve
Cretaceous
morphology
morphometry
shell
taxonomy
time series analysis
Argentina
Neuquen Basin
Bivalvia
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00948373_v44_n1_p101_Carmona
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_00948373_v44_n1_p101_Carmona
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spelling todo:paper_00948373_v44_n1_p101_Carmona2023-10-03T14:56:35Z Morphological evolution of the bivalve Ptychomya through the Lower Cretaceous of Argentina Carmona, P.S.M. Lazo, D.G. Soto, I.M. ammonite biostratigraphy bivalve Cretaceous morphology morphometry shell taxonomy time series analysis Argentina Neuquen Basin Bivalvia The complex morphological evolution of the bivalve Ptychomya throughout the well-studied Agrio Formation in the Neuquén Basin (west-central Argentina, lower/upper Valanginian-lowest Barremian) constitutes an ideal opportunity to study evolutionary patterns and processes occurring at geological timescales. Ptychomya is represented in this unit by four species, the morphological variation of which needs to be temporally assessed to obtain a thorough picture of the evolution of the group. Here we use geometric morphometrics to measure variation in shell outline, ribbing pattern, and shell size in these species. We bracket the ages of our samples using a combination of ammonoid biostratigraphy and absolute ages and study the anagenetic pattern of evolution of each trait by means of paleontological time-series analysis and change tracking. We find that evolution in Ptychomya is mostly speciational, as the majority of traits show stasis, with the exceptions of shell size in P. coihuicoensis and shell outline in P. windhauseni, which seem to evolve directionally toward larger and higher shells, respectively. Ptychomya displays changes in its average morphology and disparity, which are the result of amixture of taxonomic turnover and mosaic evolution of traits. Pulses of speciation would have been triggered by ecological opportunity, as they occur during the recovery of shallow-burrowing bivalve faunas after dysoxic events affecting the basin. On the other hand, the presence of directional patterns of evolution in P. coihuicoensis and P. windhauseni seems to be the result of a general shallowing-upward trend observed in the basin during the upper Hauterivian-lowest Barremian, as opposed to the cyclical paleoenvironmental stability inferred for the early/late Valanginian-early Hauterivian, which would have prompted stasis in P. koeneni and P. esbelta. © 2017 The Paleontological Society. All rights reserved. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00948373_v44_n1_p101_Carmona
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic ammonite
biostratigraphy
bivalve
Cretaceous
morphology
morphometry
shell
taxonomy
time series analysis
Argentina
Neuquen Basin
Bivalvia
spellingShingle ammonite
biostratigraphy
bivalve
Cretaceous
morphology
morphometry
shell
taxonomy
time series analysis
Argentina
Neuquen Basin
Bivalvia
Carmona, P.S.M.
Lazo, D.G.
Soto, I.M.
Morphological evolution of the bivalve Ptychomya through the Lower Cretaceous of Argentina
topic_facet ammonite
biostratigraphy
bivalve
Cretaceous
morphology
morphometry
shell
taxonomy
time series analysis
Argentina
Neuquen Basin
Bivalvia
description The complex morphological evolution of the bivalve Ptychomya throughout the well-studied Agrio Formation in the Neuquén Basin (west-central Argentina, lower/upper Valanginian-lowest Barremian) constitutes an ideal opportunity to study evolutionary patterns and processes occurring at geological timescales. Ptychomya is represented in this unit by four species, the morphological variation of which needs to be temporally assessed to obtain a thorough picture of the evolution of the group. Here we use geometric morphometrics to measure variation in shell outline, ribbing pattern, and shell size in these species. We bracket the ages of our samples using a combination of ammonoid biostratigraphy and absolute ages and study the anagenetic pattern of evolution of each trait by means of paleontological time-series analysis and change tracking. We find that evolution in Ptychomya is mostly speciational, as the majority of traits show stasis, with the exceptions of shell size in P. coihuicoensis and shell outline in P. windhauseni, which seem to evolve directionally toward larger and higher shells, respectively. Ptychomya displays changes in its average morphology and disparity, which are the result of amixture of taxonomic turnover and mosaic evolution of traits. Pulses of speciation would have been triggered by ecological opportunity, as they occur during the recovery of shallow-burrowing bivalve faunas after dysoxic events affecting the basin. On the other hand, the presence of directional patterns of evolution in P. coihuicoensis and P. windhauseni seems to be the result of a general shallowing-upward trend observed in the basin during the upper Hauterivian-lowest Barremian, as opposed to the cyclical paleoenvironmental stability inferred for the early/late Valanginian-early Hauterivian, which would have prompted stasis in P. koeneni and P. esbelta. © 2017 The Paleontological Society. All rights reserved.
format JOUR
author Carmona, P.S.M.
Lazo, D.G.
Soto, I.M.
author_facet Carmona, P.S.M.
Lazo, D.G.
Soto, I.M.
author_sort Carmona, P.S.M.
title Morphological evolution of the bivalve Ptychomya through the Lower Cretaceous of Argentina
title_short Morphological evolution of the bivalve Ptychomya through the Lower Cretaceous of Argentina
title_full Morphological evolution of the bivalve Ptychomya through the Lower Cretaceous of Argentina
title_fullStr Morphological evolution of the bivalve Ptychomya through the Lower Cretaceous of Argentina
title_full_unstemmed Morphological evolution of the bivalve Ptychomya through the Lower Cretaceous of Argentina
title_sort morphological evolution of the bivalve ptychomya through the lower cretaceous of argentina
url http://hdl.handle.net/20.500.12110/paper_00948373_v44_n1_p101_Carmona
work_keys_str_mv AT carmonapsm morphologicalevolutionofthebivalveptychomyathroughthelowercretaceousofargentina
AT lazodg morphologicalevolutionofthebivalveptychomyathroughthelowercretaceousofargentina
AT sotoim morphologicalevolutionofthebivalveptychomyathroughthelowercretaceousofargentina
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