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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

First record of lobed trace fossils in Brazil's Upper Cretaceous paleosols: Rhizoliths or evidence of insects and their social behavior?

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Author(s):
do Nascimento, Diego Luciano [1] ; Batezelli, Alessandro [1] ; Bernardes Ladeira, Francisco Sergio [2]
Total Authors: 3
Affiliation:
[1] Univ Estadual Campinas, UNICAMP, Inst Geosci, Dept Geol & Nat Resources, Campinas, SP - Brazil
[2] Univ Estadual Campinas, UNICAMP, Inst Geosci, Dept Geog, Campinas, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Journal of South American Earth Sciences; v. 79, p. 364-376, NOV 2017.
Web of Science Citations: 4
Abstract

This is the first report of trace fossils potentially associated with insect social behavior in sandy and well-drained paleosols of the Upper Cretaceous continental sequence of Brazil. The trace fossils consist of dozens of lobed and vertical structures cemented by CaCO3 and preserved mainly in full relief in paleosols of the Marilia Formation (Bauru Basin) in the state of Minas Gerais. The described ichnofossils are predominantly vertical, up to 2 m long, and are composed of horizontal lobed structures connected by vertical tunnel-like structures that intersect in the center and at the edges. The lobed structures range from 3 to 15 cm long and 2-6 cm thick. Two different hypotheses are analyzed to explain the origin of the trace fossils; the less probable one is that the structures are laminar calcretes associated with rhizoliths and rhizoconcretions. The hypothesis involving social insects was considered because the trace fossils described herein partially resemble a modern ant nest and the ichnofossil Daimoniobarax. The micromorphological analysis of the lobed and tunnel-like structures indicates modifications of the walls, such as the presence of inorganic fluidized linings, dark linings and oriented grains, supporting the hypothesis that they are chambers and shafts. The architecture and size of the reported nests suggest the possibility that social insect colonies existed during the Maastrichtian and are direct evidence of the social behavior and reproductive strategies of the Cretaceous pedofauna. (C) 2017 Elsevier Ltd. All rights reserved. (AU)

FAPESP's process: 15/17632-5 - Sedimentation and pedogenesis in Cretaceous continental sequences of the Bauru, Sanfranciscana, Parecis and Neuquén basins.
Grantee:Alessandro Batezelli
Support Opportunities: Regular Research Grants