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Fossil vertebrates of the early-middle Miocene Cerro Boleadoras Formation, northwestern Santa Cruz Province, Patagonia, Argentina

Publication ,  Journal Article
Vizcaíno, SF; Bargo, MS; Pérez, ME; Aramendía, I; Cuitiño, JI; Monsalvo, ES; Vlachos, E; Noriega, JI; Kay, RF
Published in: Andean Geology
September 1, 2022

The early-middle Miocene continental Cerro Boleadoras Formation (CBF) crops out in the area of Cerro Boleadoras and Cerro Plomo on the western slope of the Meseta del Lago Buenos Aires, northwestern Santa Cruz Province, Argentina. The lower levels of the CBF consist of laterally extensive medium to pebbly sandstone beds with trough cross-bedding, interpreted as fluvial channel deposits, interbedded with tabular fine-grained floodplain deposits. Recent fieldwork provided fossil vertebrates from these levels with an estimated age between ~16.5 Ma and 15.1 Ma (late Burdigalian-early Langhian). The studied section temporally overlaps with the middle or upper sections of the Santa Cruz Formation (SCF) in the Austral-Magallanes Basin of southern Patagonia, the Río Frías Formation in Chile, and the lower Collón Curá Formation of northern Patagonia. We compile an integrated faunal list for this locality, including specimens from previous collections, and discuss its chronological and paleoenvironmental implications. The taxa list includes most of the groups recorded in the SCF: one anuran, three birds, and at least 33 mammals (metatherians, xenarthrans, litopterns, notoungulate typotheres and caviomorph rodents), indicating a Santacrucian age sensu lato. We also recorded a testudine, which constitutes the southernmost record of tortoises in South America and worldwide. Faunal dissimilarities between the vertebrate fossil content of the CBF and the mentioned sections of the Santa Cruz, Río Frías and Collón Curá formations may reflect ecologic, climatic and geographic differences rather than temporal ones. The co-occurrence of arboreal or semiarboreal, browsing, frugivorous, and grazing mammals suggests the presence of both forested and open environments for the area occupied by the CBF rocks. However, it is not possible to discern whether these two environments coexisted or alternated, and whether one environment predominated over the other. Marker taxa, such as the chinchillid rodents Prolagostomus and Pliolagostomus, and the typothere Pachyrukhos indicate a trend to aridification during the Miocene in southern Patagonia, as previously reported for the upper part of the SCF along the Río Santa Cruz and south to the Río Coyle, along the Atlantic coast and the Río Gallegos.

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Published In

Andean Geology

DOI

EISSN

0718-7106

ISSN

0718-7092

Publication Date

September 1, 2022

Volume

49

Issue

3

Start / End Page

382 / 422

Related Subject Headings

  • Geology
  • 3705 Geology
  • 0403 Geology
 

Citation

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ICMJE
MLA
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Vizcaíno, S. F., Bargo, M. S., Pérez, M. E., Aramendía, I., Cuitiño, J. I., Monsalvo, E. S., … Kay, R. F. (2022). Fossil vertebrates of the early-middle Miocene Cerro Boleadoras Formation, northwestern Santa Cruz Province, Patagonia, Argentina. Andean Geology, 49(3), 382–422. https://doi.org/10.5027/andgeoV49n3-3425
Vizcaíno, S. F., M. S. Bargo, M. E. Pérez, I. Aramendía, J. I. Cuitiño, E. S. Monsalvo, E. Vlachos, J. I. Noriega, and R. F. Kay. “Fossil vertebrates of the early-middle Miocene Cerro Boleadoras Formation, northwestern Santa Cruz Province, Patagonia, Argentina.” Andean Geology 49, no. 3 (September 1, 2022): 382–422. https://doi.org/10.5027/andgeoV49n3-3425.
Vizcaíno SF, Bargo MS, Pérez ME, Aramendía I, Cuitiño JI, Monsalvo ES, et al. Fossil vertebrates of the early-middle Miocene Cerro Boleadoras Formation, northwestern Santa Cruz Province, Patagonia, Argentina. Andean Geology. 2022 Sep 1;49(3):382–422.
Vizcaíno, S. F., et al. “Fossil vertebrates of the early-middle Miocene Cerro Boleadoras Formation, northwestern Santa Cruz Province, Patagonia, Argentina.” Andean Geology, vol. 49, no. 3, Sept. 2022, pp. 382–422. Scopus, doi:10.5027/andgeoV49n3-3425.
Vizcaíno SF, Bargo MS, Pérez ME, Aramendía I, Cuitiño JI, Monsalvo ES, Vlachos E, Noriega JI, Kay RF. Fossil vertebrates of the early-middle Miocene Cerro Boleadoras Formation, northwestern Santa Cruz Province, Patagonia, Argentina. Andean Geology. 2022 Sep 1;49(3):382–422.

Published In

Andean Geology

DOI

EISSN

0718-7106

ISSN

0718-7092

Publication Date

September 1, 2022

Volume

49

Issue

3

Start / End Page

382 / 422

Related Subject Headings

  • Geology
  • 3705 Geology
  • 0403 Geology