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Article: Evaluation of the ontogeny and sexual dimorphism in a new species of Middle Triassic Darwinulocopina (Crustacea, Ostracoda) from Argentina

Papers in Palaeontology - Volume 7 Issue 1 - Cover
Publication: Papers in Palaeontology
Volume: 7
Part: 3
Publication Date: August 2021
Page(s): 1233 1259
Author(s): Ana P. Carignano, Javier Echevarría, and Ana M. Zavattieri
DOI: 10.1002/spp2.1340
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How to Cite

CARIGNANO, A.P., ECHEVARRíA, J., ZAVATTIERI, A.M. 2021. . Papers in Palaeontology, 7, 3, 1233-1259. DOI: /doi/10.1002/spp2.1340

Author Information

  • Ana P. Carignano - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
  • Ana P. Carignano - División Paleozoología Invertebrados, Museo de La Plata Facultad de Ciencias Naturales y Museo Universidad Nacional de La Plata Paseo del Bosque s/n F1900BWA La Plata Buenos Aires, Argentina
  • Javier Echevarría - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
  • Javier Echevarría - División Paleozoología Invertebrados, Museo de La Plata Facultad de Ciencias Naturales y Museo Universidad Nacional de La Plata Paseo del Bosque s/n F1900BWA La Plata Buenos Aires, Argentina
  • Ana M. Zavattieri - Departamento de Paleontología Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA) CCT-CONICET Mendoza Av. Adrián Ruiz Leal s/n., Parque General San Martín Casilla de Correo 330 M5002IRA Mendoza Argentina

Publication History

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    Abstract

    Darwinulocopina is an interesting group of ostracods that includes some of the first invaders of freshwater habitats during the late Palaeozoic. The Permian–Triassic extinction greatly reduced their diversity, culminating in a single extant family. The darwinulids are regarded as ‘ancient asexuals’ given that a parthenogenetic mode of reproduction is assumed for all post-Triassic members of the group. However, the high diversity achieved during the late Palaeozoic is often associated with sexual reproduction. Here we studied a monospecific assemblage of ostracods from the Middle Triassic of the Cuyo Basin, Province of Mendoza, Argentina, recognizing a new species of Darwinulocopina, Prasuchonella? huarpe sp. nov. We discuss the traditional length/height and length/width graphical method for identifying ontogeny/sexual dimorphism in fossil ostracod assemblages. A geometric morphometric analysis was performed on both lateral and dorsal views of almost 170 carapaces, to evaluate the ontogeny and sexual dimorphism of the species. The best results were obtained from the analysis in dorsal view, discriminating four ontogenetic stages. This revealed a main ontogenetic trend related to the development of the brooding chamber. Although subtle in difference, female carapaces are wider not only at the brooding chamber, but also along the whole length, compared with the presumptive males. We provide full systematic descriptions and discussions, attempting to unify descriptive criteria for recent and fossil darwinulocopine carapaces, and suggest closeness to species previously described from the upper Permian of Russia. As a result, we recommend a review of Mesozoic records of Darwinulocopina, particularly those from the Triassic.

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