Plant–arthropod interaction in the Early Cretaceous (Berriasian) of the Araripe Basin, Brazil Etiene Fabbrin Pires a, * , Margot Guerra Sommer b,1 a CNPq/PPG-GEO, Departamento de Paleontologia e Estratigrafia, Instituto de Geociências, Universidade Federal do Rio Grande do Sul – 91501-970 Porto Alegre, RS, Brazil b CNPq, Departamento de Paleontologia e Estratigrafia, Instituto de Geociências, Universidade Federal do Rio Grande do Sul – 91501-970 Porto Alegre, RS, Brazil article info Article history: Received 15 January 2008 Accepted 8 September 2008 Keywords: Wood boring Isoptera Equatorial belt Early Cretaceous Araripe Basin – Brazil abstract Plant–arthropod interactions provide the first relevant data for addressing evidence of phytophagy for an assemblage of coniferous silicified woods from the pre-rift phase in the Araripe Basin, Brazil. A complex system of borings, sometimes filled with small, oval to hexagonal coprolites, allow inferences to be made about the activities of termites (Isoptera). Previous dendrological data indicated that the climate during the Early Cretaceous on the landmasses of the northern Afro-Brazilian Depression was dry and savanna like, where termite borings were common. Features of wood preservation demonstrate that the damage was probably caused by herbivores, not detritivores. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction In the northeastern Brazilian interior basins, sedimentary re- cords of the pre-rift sequence occur in scattered exposures about 8° S latitude (Fig. 1a–c). These deposits represent the remains of what once was a regional great shallow basin, the Afro-Brazilian Depression (ABD; Ponte, 1972). The equatorial region of the South American–African landmass formed part of the hot tropical equa- torial arid belt (Chumakov, 1995). This zone lacks evidence of suf- ficient moisture that supported forests. Nevertheless, growth ring analyses (Fig. 2a and c–e) in silicified coniferous woods from the Missão Velha Formation (Berriasian), Araripe Basin, conducted by Pires and Guerra-Sommer (unpublished data) have yielded impor- tant information about periodicity of wood production in this southern equatorial belt. Despite warm temperatures, dendrolog- ical data indicate that the climate was characterized by cyclical alternation of dry and rainy periods influenced by periodic pre- cipitation. These growth rings patterns are consistent with a trop- ical savanna climate condition during a greenhouse climate phase. Evidence of arthropod attack is visually observable on the exter- nal surface of the vascular cylinder and also in cross-sections of coniferous silicified wood from Missão Velha Formation (Fig. 2b and c). Despite the large abundance and diversity of insects pre- served in the Santana Formation, which overlies the Missão Velha Formation and represents an important Fossil-Lagerstätten for the Aptian (Labandeira and Eble, in press), absence of plant–arthropod interactions is surprising, making this occurrence a matter of great significance. Wood borers are known in various groups among living arthropods. Beetles and termites probably are the most common, but mites, ants, sawflies, bees, wasps, moths, and mayflies may also take part in wood boring (Eaton and Hale, 1993; Grimaldi and Engel, 2004; Francis and Harland, 2006). Borers provide fre- quent evidence of damage in fossil woods because highly ligni- fied tissues of stems and branches tend to be very well preserved in the fossil record. Different patterns of boring have been reported in woods from the Late Carboniferous to Tertiary age. Boucot (1990), Scott et al. (1992) and Labandeira et al. (1997) reviewed the literature and summarized the fossil record of wood borings. In this study, evidence of a previously unknown plant–arthropod relation in Brazilian pre-rift phase is described with the principal focus to: (1) to record the patterns of plant damage on fossil woods, and (2) to obtain palaeocological information from the wood borings. 2. Geological setting The Araripe Basin is the most extensive of the northeastern Brazilian interior basins, with an area of approximately 0895-9811/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jsames.2008.09.004 * Corresponding author. Present address: Rua Alberto Torres, 223/106 Porto Alegre, RS 91050-080 Brazil, Tel.: +55 51 33467412; fax: +55 51 33086340. E-mail address: tinadefel@yahoo.com.br (E.F. Pires). 1 Present address: Margot Guerra Sommer- Rua Comendador Caminha, 128/701 Porto Alegre, RS 90430-030 Brazil. Journal of South American Earth Sciences 27 (2009) 50–59 Contents lists available at ScienceDirect Journal of South American Earth Sciences journal homepage: www.elsevier.com/locate/jsames