Phytogeographic, Stratigraphic, and Paleoclimatic Significance Of
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Review of Palaeobotany and Palynology 222 (2015) 116–128 Contents lists available at ScienceDirect Review of Palaeobotany and Palynology journal homepage: www.elsevier.com/locate/revpalbo Phytogeographic, stratigraphic, and paleoclimatic significance of Pseudofrenelopsis capillata sp. nov. from the Lower Cretaceous Crato Formation, Brazil Paula Andrea Sucerquia a,b,⁎, Mary E.C. Bernardes-de-Oliveira a, Barbara A.R. Mohr c a Instituto de Geociências, Universidade de São Paulo, Rua do Lago 562, Cidade Universitária, CEP 05508–080, São Paulo, SP, Brazil b Departamento de Geologia, Universidade Federal de Pernambuco, Avenida Acadêmico Hélio Ramos s/n, Cidade Universitária, CEP 50740–530, Recife, PE, Brazil c Museum of Natural History, Collections, Invalidenstrasse 43, 10115 Berlin, Germany article info abstract Article history: Coniferales are represented during the Early Cretaceous in northern South America both by macrofossils and Received 9 September 2013 palynomorphs of the families Araucariaceae and Cheirolepidiaceae. Fossils of Cheirolepidiaceae are often abun- Received in revised form 1 July 2015 dant in coastal deposits; plants of this family are considered to have grown under semiarid to arid climate con- Accepted 30 July 2015 ditions because of characteristic anatomical features which include several adaptations to aridity and/or Available online 28 August 2015 salinity. Here histologically preserved specimens of Pseudofrenelopsis from laminated limestones of the Crato For- mation (Araripe Basin, NE Brazil) were studied by light and scanning electron microscopy. A new species Keywords: Pseudofrenelopsis capillata Pseudofrenelopsis capillata sp. nov. is described which seems to have grown exclusively at the Early Cretaceous Cheirolepidiaceae (sub)paleoequatorial area of South America and may be therefore endemic. The new taxon may have grown in Histology a riparian environment along the borders of a large lake as a minor constituent of the surrounding vegetation. Climate sensitivity © 2015 Elsevier B.V. All rights reserved. Crato Formation Early Cretaceous 1. Introduction triradiate scar and a distal cryptopore, where the exine is thinner. The pollen also exhibits a circumpolar ridge or rimula just above the equator During the Early Cretaceous, global vegetation was dominated by towards the distal pole. Around the equator, the exine is thickened, like gymnosperms, which were affected by a rapid evolution of the angio- a belt and is usually ribbed on the inside (Srivastava, 1976; Watson, sperms towards the mid- to Late Cretaceous. Several gymnosperm 1988). Classopollis pollen grains bear diversified external sculptures groups became extinct or were dramatically reduced at the end of this and orbicules in the pollen grain surface, which may be of taxonomic period. The conifer family Cheirolepidiaceae did not surpass the relevance (Reyre, 1970). Cretaceous–Paleogene boundary. The possibly youngest member of Abundant Classopollis in palynological assemblages is considered to Cheirolepidiaceae may be Brachyphyllum patens from the Maastricht represent coastal deposition under arid climatic conditions. Thus it is Formation of SE Netherlands and NE Belgium (van der Ham et al., 2003). used to define floristic regions and arid areas (Vakhrameev, 1970, Cheirolepidiaceae have been traditionally defined by a single 1991). Vegetative parts of several taxa have morphologies supporting character: the morphology of pollen grains of the genus Classopollis the hypothesis that they grew in an arid or at least seasonally dry Pflug (Doludenko, 1978; Watson, 1988), formerly named Corollina habitat (Watson, 1988). Reduced leaves, very thick cuticles, sunken Maljavkina or Circulina Maljavkina (Pocock and Jansonius, 1961; stomata, and fleshy appearance of branches and leaves speak for the Traverse, 2004). According to the pollen record, Cheirolepidaceae xeromorphic nature of Cheirolepidiaceae (Upchurch and Doyle, 1981). range from the Late Triassic to the Late Cretaceous (Reyre, 1973; Maximum abundances are related to stratigraphic intervals and regions Srivastava, 1976), with a cosmopolitan distribution, but minor abun- showing lithologic and paleobotanical evidence of aridity expressed as dance at high latitudes (Vakhrameev, 1970; Brenner, 1976). red beds or evaporites, low diversity of ferns and low diversity of large Classopollis is easily recognizable in sporomorph assemblages. This leaved gymnosperms. Its decline at the end of the Cretaceous period pollen type occurs both as single grains as well as in tetrads. When sin- may be related to less severe weather conditions, when the global cli- gle, the grains have an approximately spherical form, with a proximal mate was overall cooler, and at low latitudes with higher precipitation rates. Although representatives of this family show generally a strong ⁎ Corresponding author. Tel.: +5581998008124. xeromorphic appearance, the vegetative morphology is highly variable, E-mail address: [email protected] (P.A. Sucerquia). with two types of leafy branches, the Brachyphyllum–Pagiophyllum type http://dx.doi.org/10.1016/j.revpalbo.2015.07.012 0034-6667/© 2015 Elsevier B.V. All rights reserved. P.A. Sucerquia et al. / Review of Palaeobotany and Palynology 222 (2015) 116–128 117 with adpressed and fleshy or falcate leaves, in spiral arrangement, and the the families Araucariaceae and Cheirolepidiaceae, including vegetative Frenelopsis–Pseudofrenelopsis type with jointed stems, thick internode cu- and reproductive remains, though not found in organic connection. ticles, sheathing leaf bases, and reduced free leaf tips, also known This paper considers vegetative remains of Pseudofrenelopsis from the informally as frenelopsids (Watson, 1988; Axsmith et al., 2004). Crato Formation. Brachyphyllum–Pagiophyllum type twigs are found almost during the en- tire Mesozoic globally distributed, while the frenelopsids are restricted to 2. Geological setting the Cretaceous of North America and South America, Europe, Africa and Asia, and are frequently used as environmental indicators of tropical to The Crato Formation is an upper Aptian lithologic unit of the subtropical arid climate (Alvin, 1982). Araripe Basin. This basin extends over an area of approximately In South America, frenelopsids are recorded from the Crato and 8000 km2 between 38°30′–40°50′ Wlongitudeand7°05′–7°50′ S Romualdo Formations, Araripe Basin, northeastern Brazil, as Frenelopsis latitude, occupying parts of the States Piauí, Ceará, Pernambuco, sp. (Kunzmann et al., 2006) and Pseudofrenelopsis sp. (Bernardes-de- and Paraiba in a nearly rectangular shape, with a EW longitudinal Oliveira et al., 2013). Records exist also from the Paja and Villeta Forma- axis (Fig. 1). It is formed by Paleozoic and Mesozoic sedimentary tions, Colombia, of the two genera Pseudofrenelopsis and Frenelopsis sequences covering the Precambrian basement. Its origin and evolu- (Moreno-Sánchez et al., 2007), but their preservational state does not tion are related to the tectonic events responsible for the fragmenta- allow a species determination. tion of Gondwana, separating the South American and African plates The ages of these four lithological units range from the Aptian to and the consequent establishment of the South Atlantic Ocean early Albian. They share paleofloras composed of abundant conifers of (Ponte and Ponte-Filho, 1996). Fig. 1. Outcroping area of Crato Formation (after Martill, 2007) and location of limestone quarries between Nova Olinda and Santana do Cariri, State of Ceará, northeast Brazil. 118 P.A. Sucerquia et al. / Review of Palaeobotany and Palynology 222 (2015) 116–128 The Crato Formation is composed of laminated limestones 3. Material and methods interbedded with siltstones deposited in a lacustrine environment. The paleolake, which gave rise to this unit, developed under a tropical–sub- The fossil plants are preserved in light yellow to grayish brown lam- tropical paleoclimatic regime (Neumann et al., 2003). The water body inated limestones, preserved as coalified compressions with cuticles, was permanently stratified with hypersaline and anoxic bottom waters, iron oxides casts with epidermal and anatomical features preserved but well-mixed and productive in the surface waters (Heimhofer and and impressions. Most fossils were presumably found in Pedra Cariri Martill, 2007). Halite pseudomorphs and lack of indicators of benthonic quarries located between the towns of Santana do Cariri and Nova life are interpreted as evidence of a bottom brine in the lacustrine system Olinda in the State of Ceará, Brazil. (Neumann et al., 2003). The studied material is housed in the paleobotanical collection of the The age of the Crato Formation is considered to be late Aptian (Pons Museum für Naturkunde der Humboldt-Universität, Berlin (Mb.Pb. et al., 1990; Heimhofer and Hochuli, 2010), which corresponds to the 2002/1344), in the scientific collection of the Departamento de Geologia Sergipea variverrucata Palynozone (P-270) from the Meso-Alagoas Sedimentar e Ambiental, Instituto de Geociências/Universidade de São Brazilian local stage. This zone also represents the late Aptian (Arai Paulo (GP/3E 9118, GP/3E 9380), and at the scientific collection et al., 2001) and equals the Cytheridea Ostracozone (NRT-011). of the Instituto de Geociências, Universidade Federal de Rio de The fossil assemblage of the Crato Formation contains abundant in- Janeiro (UFRJ Pb 428a). The frenelopsid specimen SM.B.16447 sects, fishes, and plants. Macro- and microfloral remains are diverse (Senckenberg