Gymnosperms from the Early Cretaceous Crato Formation (Brazil). II. Cheirolepidiaceae

Abstract

Conifers are common in the Early Cretaceous Crato flora. Sterile foliage shoots of several morphotypes occur. Good preservation of several of these specimens allows detailed morphological and anatomical studies. Based on these characters, two taxa of Cheirolepidiaceae, Tomaxellia biforme and Frenelopsis sp., are identified. The palaeogeographic distribution of the genus Tomaxellia currently extends from southern South America northwards to the palaeoequatorial region. The morphological and anatomical characters of both taxa might be interpreted as adaptations to a warm and temporarily dry palaeoclimate, however their habitat can not be reconstructed yet, due to scarcity of the remains.

Cheirolepidiacean foliage and pollen from Cretaceous high-latitudes of southeastern Australia

“…However, more prominent papillae on the abaxial surface and the fringe of elongate apical cells, distinguish the Victorian species. The foliar variation from basally appressed and imbricate on a branch to apically spreading, has similarities to, but is less pronounced than in Tomaxellia Archangelsky, 1963, which has distinct heterophylly, a character not recognized in other South American Early Cretaceous conifers (Kunzmann et al, 2006). Material examined: Nine specimens examined (all apart from the holotype are paratypes: see Tosolini, 2001).…”

“…The Gippsland specimens are, therefore, more like Frenelopsis (Watson, 1988;Gomez et al, 2002b). Gondwanan examples of Frenelopsis are known from the Crato Formation of Brazil, South America, but those specimens are too poorly preserved to yield anatomical details within the stomata and the Florin ring is non-papillate (Kunzmann et al, 2006).…”

“…8) include Tomaxellia (Archangelsky, 1963(Archangelsky, , 1968Kunzmann et al, 2006), Frenelopsis (Kunzmann et al, 2006) and Otwayia (Pole, 2000;McLoughlin et al, 2002). However, a range of other mid-Mesozoic austral awl-and scaleleafed conifers may belong to this family in the absence of definitive reproductive or cuticular details, including various species of Pagiophyllum (McLoughlin et al, 2000;McLoughlin and Pott, 2009) and Brachyphyllum (Baldoni, 1980;Gould, 1980;Gomez et al, 2002a,c;Rees and Cleal, 2004) and even Araucaria-like forms (McLoughlin, 1996;McLoughlin and Hill, 1996;McLoughlin and McNamara, 2001).…”

“…Although features such as diminutive leaf size, leaf imbrication and thick cuticles with papillate protection of stomata, evident in Otwayia and related dispersed cuticle, are normally linked to dry, saline or windy sites, we hypothesize that such features in Mass extinction (collapse of corystosperm dominance) Spike in cheirolepid pollen (C. torosa Zone; Reiser and Williams, 1969;Helby et al, 1987) Cheirolepid pollen common in Western Australia, locally common in Eastern Australia (de Jersey, 1963;Filatoff, 1975) Numerous Australian awl-or scale-leafed conifers of possible cheirolepid affinity (Walkom, 1921;Gould, 1980;McLoughlin and Pott, 2009) Moderate diversity and abundance of Otwayia and Classopollis in SE Australia (Dettmann, 1986;Pole, 2000;McLoughlin et al, 2002;this study) Decline of Classopollis abundance in Australia (Helby et al, 1987;Dettmann et al, 1992) Otwayia in Chatham Islands, minor Classopollis extends into Turonian (Mays, 2011) Mass extinction or mass vegetation dieback in Southern Hemisphere (Vajda et al, 2001;Vajda & McLoughlin, 2004) Final extinction of cheirolepids following a Classopollis pulse in the immediate wake of K-Pg crisis (Patagonia: Barreda et al, 2012) Earliest southern Gondwanan (Antarctic) Classopollis (Shu et al, 2000) Pseudohirmerella cones, U.S.A. (Axsmith et al, 2004b) Oldest Gondwanan cheirolepidiacean seed cone, Patagonia (Escapa et al, 2012) Tomaxellia and several cheirolepidiacean ovulate cones, Patagonia (Archangelsky, 1963;Villar de Seone, 1998;del Fueyo et al, 2008) Argentina Abundant Classopollis in Eromanga Basin, Australia (Burger, 1973) Scattered examples of reworked (or possibly relictual) Classopollis in southern Gondwana (Contreras et al, 2013) PALEOGENE (Watson, 1983;Kunzmann et al, 2006) Earliest Northern Hemisphere cheirolepid foliage (Ash, 1973) Broad climatic trends in southeastern Gondwana: red = warm...…”

“…Frenelopsids have predominantly a whorled phyllotaxis and the representative genera (e.g., Frenelopsis and Pseudofrenelopsis) are found mainly in Laurasia (Alvin et al, 1981;Alvin, 1982;Francis, 1983;Watson, 1988;Clement-Westerhof and van Konijnenburg-van Cittert, 1991;Zhou, 1995;Guignard et al, 1998;Watson and Alvin, 1999;Daviero et al, 2001;Gomez et al, 2002b;Axsmith, 2006;Yang et al, 2006;Mendes et al, 2010;Bartiromo et al, 2012), but a few are also known from Gondwana (Watson, 1983;Kunzmann et al, 2006;Sucerquia et al, 2008). The non-frenelopsids have leaves borne in a spiral arrangement and include representatives of genera such as Brachyphyllum (Watson, 1988;Du et al, 2013) and Watsoniocladus (Srinivasan, 1995) from Laurasia, and Tomaxellia and Tarphyderma (Archangelsky, 1963(Archangelsky, , 1966(Archangelsky, , 1968Taylor, 1986, 1991;Villar de Seoane, 1998;Kunzmann et al, 2006) from Gondwana. Microsporangiate and ovuliferous cones attached to shoots or associated with leaves of both groups (Alvin et al, , 1994Kvaček, 2000;Axsmith et al, 2004b;Rothwell et al, 2007;del Fueyo et al, 2008;Escapa et al, 2012Escapa et al, , 2013, contain Classopollis pollen (synonyms: Corollina, Circulina, Gliscopollis; Traverse, 2004).…”