Ascocerid cephalopods from the Hirnantian?-Llandovery stages of the southern Paraná Basin (Paraguay, South America): First record from high paleolatitudes

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Ascocerid cephalopods are described for the first time from high paleolatitudes of Gondwana. Studied material was collected from the Hirnantian?-Llandovery strata of the Eusebio Ayala and Vargas Peña formations, Paraná Basin, southeastern Paraguay. The specimens are poorly preserved and were questio...

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Autores principales: Cichowolski, M., Uriz, N.J., Alfaro, M.B., Galeano Inchausti, J.C.
Formato: JOUR
Materias:
cephalopod
Gondwana
immigration
intracratonic basin
micromorphology
new record
paleolatitude
paleontology
Postglacial
transgression
type specimen
Brazil
Paraguay
Parana [Brazil]
Vargas
Venezuela
Cephalopoda
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00223360_v93_n1_p37_Cichowolski
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_00223360_v93_n1_p37_Cichowolski
record_format dspace
spelling todo:paper_00223360_v93_n1_p37_Cichowolski2023-10-03T14:31:45Z Ascocerid cephalopods from the Hirnantian?-Llandovery stages of the southern Paraná Basin (Paraguay, South America): First record from high paleolatitudes Cichowolski, M. Uriz, N.J. Alfaro, M.B. Galeano Inchausti, J.C. cephalopod Gondwana immigration intracratonic basin micromorphology new record paleolatitude paleontology Postglacial transgression type specimen Brazil Paraguay Parana [Brazil] Vargas Venezuela Cephalopoda Ascocerid cephalopods are described for the first time from high paleolatitudes of Gondwana. Studied material was collected from the Hirnantian?-Llandovery strata of the Eusebio Ayala and Vargas Peña formations, Paraná Basin, southeastern Paraguay. The specimens are poorly preserved and were questionably assigned to the subfamily Probillingsitinae Flower, 1941, being undetermined at genus and species rank because diagnostic characters are not visible. A particular feature seen in our material is the presence of both parts of the ascocerid conch (the juvenile or cyrtocone and the mature or brevicone) joined together, which is a very rare condition in the known paleontological record. The specimens are interpreted as at a subadult stage of development because fully grown ascocerids would have lost the juvenile shell. A planktonic vertical migrant mode of life with a subvertical attitude is proposed for the juvenile, and a horizontal demersal nektonic mode for the adult form, as has been previously suggested. A subvertical orientation near the bottom is proposed for the subadult stage. We suggest that the immigration of ascocerids to southwestern Gondwana was possible through ocean currents that would carry the planktonic juveniles from low to high latitudes during the end-Ordovician postglacial transgression that flooded the intracratonic basins of the region. © 2018, The Paleontological Society. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00223360_v93_n1_p37_Cichowolski
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic cephalopod
Gondwana
immigration
intracratonic basin
micromorphology
new record
paleolatitude
paleontology
Postglacial
transgression
type specimen
Brazil
Paraguay
Parana [Brazil]
Vargas
Venezuela
Cephalopoda
spellingShingle cephalopod
Gondwana
immigration
intracratonic basin
micromorphology
new record
paleolatitude
paleontology
Postglacial
transgression
type specimen
Brazil
Paraguay
Parana [Brazil]
Vargas
Venezuela
Cephalopoda
Cichowolski, M.
Uriz, N.J.
Alfaro, M.B.
Galeano Inchausti, J.C.
Ascocerid cephalopods from the Hirnantian?-Llandovery stages of the southern Paraná Basin (Paraguay, South America): First record from high paleolatitudes
topic_facet cephalopod
Gondwana
immigration
intracratonic basin
micromorphology
new record
paleolatitude
paleontology
Postglacial
transgression
type specimen
Brazil
Paraguay
Parana [Brazil]
Vargas
Venezuela
Cephalopoda
description Ascocerid cephalopods are described for the first time from high paleolatitudes of Gondwana. Studied material was collected from the Hirnantian?-Llandovery strata of the Eusebio Ayala and Vargas Peña formations, Paraná Basin, southeastern Paraguay. The specimens are poorly preserved and were questionably assigned to the subfamily Probillingsitinae Flower, 1941, being undetermined at genus and species rank because diagnostic characters are not visible. A particular feature seen in our material is the presence of both parts of the ascocerid conch (the juvenile or cyrtocone and the mature or brevicone) joined together, which is a very rare condition in the known paleontological record. The specimens are interpreted as at a subadult stage of development because fully grown ascocerids would have lost the juvenile shell. A planktonic vertical migrant mode of life with a subvertical attitude is proposed for the juvenile, and a horizontal demersal nektonic mode for the adult form, as has been previously suggested. A subvertical orientation near the bottom is proposed for the subadult stage. We suggest that the immigration of ascocerids to southwestern Gondwana was possible through ocean currents that would carry the planktonic juveniles from low to high latitudes during the end-Ordovician postglacial transgression that flooded the intracratonic basins of the region. © 2018, The Paleontological Society.
format JOUR
author Cichowolski, M.
Uriz, N.J.
Alfaro, M.B.
Galeano Inchausti, J.C.
author_facet Cichowolski, M.
Uriz, N.J.
Alfaro, M.B.
Galeano Inchausti, J.C.
author_sort Cichowolski, M.
title Ascocerid cephalopods from the Hirnantian?-Llandovery stages of the southern Paraná Basin (Paraguay, South America): First record from high paleolatitudes
title_short Ascocerid cephalopods from the Hirnantian?-Llandovery stages of the southern Paraná Basin (Paraguay, South America): First record from high paleolatitudes
title_full Ascocerid cephalopods from the Hirnantian?-Llandovery stages of the southern Paraná Basin (Paraguay, South America): First record from high paleolatitudes
title_fullStr Ascocerid cephalopods from the Hirnantian?-Llandovery stages of the southern Paraná Basin (Paraguay, South America): First record from high paleolatitudes
title_full_unstemmed Ascocerid cephalopods from the Hirnantian?-Llandovery stages of the southern Paraná Basin (Paraguay, South America): First record from high paleolatitudes
title_sort ascocerid cephalopods from the hirnantian?-llandovery stages of the southern paraná basin (paraguay, south america): first record from high paleolatitudes
url http://hdl.handle.net/20.500.12110/paper_00223360_v93_n1_p37_Cichowolski
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AT uriznj ascoceridcephalopodsfromthehirnantianllandoverystagesofthesouthernparanabasinparaguaysouthamericafirstrecordfromhighpaleolatitudes
AT alfaromb ascoceridcephalopodsfromthehirnantianllandoverystagesofthesouthernparanabasinparaguaysouthamericafirstrecordfromhighpaleolatitudes
AT galeanoinchaustijc ascoceridcephalopodsfromthehirnantianllandoverystagesofthesouthernparanabasinparaguaysouthamericafirstrecordfromhighpaleolatitudes
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