Cretaceous angiosperm pollen from the Kachaike Formation, south-western Santa Cruz Province, Argentina

Abstract

Thirty-three angiosperm pollen species are here reported from mid-Cretaceous deposits of the Kachaike Formation, Austral Basin, southern Argentina. Clavatipollenites is the most abundant angiosperm genus, with six well-defined morphological groups recognised on the basis of their reticulum morphology and sculpture. Pollen of eudicots are scarce, represented by tricolpate (Psilatricolpites spp. and Tricolpites spp.), tricolporoidate and tricolporate morphotypes (Dryadopollis spp.). Increasing complexity in the aperture structure is seen throughout the sequence; tricolpate and tricolporoidate forms are recorded in almost all samples, while tricolporate pollen grains are restricted to the middle and upper levels of the unit. The high species richness and abundance of monocolpate-ulcerate angiosperm related to monocots or magnoliids sensu lato recorded in the unit is comparable to that previously recognised in other assemblages from the early and middle Albian of the southern (e.g. Australia) and northern hemispheres (e.g. Western Portuguese basin, Europe). The recorded increase in the number of angiosperm species towards the middle and upper parts of the Kachaike Formation, with the presence of monocolpate, tricolpate, tricolporoidate and tricolporate pollen, suggests an early-early middle Albian age for these parts of the unit, in agreement with the early Albian age proposed for its basal levels on the basis of dinoflagellates.

How deep is the conflict between molecular and fossil evidence on the age of angiosperms?

“…(), Llorens & Perez Loinaze (), and Perez Loinaze et al . (); Antarctica (James Ross Island, Antarctic Peninsula): Dettmann & Thomson (); Queensland, Australia (Eromanga and Surat Basins): Burger (); Victoria, Australia (Otway Basin): Dettmann (, ) and Korasidis et al . ().…”

“…Aptian, and reticulate tricolpates in the middle or late Albian (Dettmann, 1973(Dettmann, , 1986Burger, 1993;Korasidis et al, 2016). In southern Argentina, Clavatipollenites and other angiosperm monosulcates occur in the Aptian and are joined by tricolpates in the early Albian (Archangelsky et al, 2009;Llorens & Perez Loinaze, 2016;Perez Loinaze et al, 2016). In the Antarctic peninsula, Clavatipollenites appears in the early Albian and tricolpates in the middle Albian-Cenomanian (Dettmann & Thomson, 1987).…”

“…Tricolpate pollen with weakening at the middle of the colpi (tricolporoidate) first occurs in the middle Albian and becomes common in the late Albian, whereas types with more distinct ora appear in the latest Albian and Cenomanian. Many tricolporates show shifts from reticulate sculpture to a smooth tectum and triangular shape (Doyle, 1969;Pacltov a, 1971;Herngreen, 1973;Laing, 1975;Singh, 1975;Doyle & Robbins, 1977;Burger, 1993;Horikx et al, 2016;Perez Loinaze et al, 2016).…”

Carbon Isotopic Signature and Organic Matter Composition of Cenomanian High-Latitude Paleosols of Southern Patagonia

“…These authors found that the Patagonian palynofloras showed different affinities depending on their paleolatitude. Palynofloras from high-latitude areas of Patagonia (MAF, Piedra Clavada/Kachaike formations ( [57,58,[109][110][111][112][113][114][115][116][117]) were related with Antarctica (Whisky Bay; [118,119]) and New Zealand (Tupuangi; [120,121]) palynofloras, based on the presence of widespread taxa, including Classopollis, Podocarpidites, Cyathidites, Microcachryidites, Tricolpites and Clavatipollenites. On the other hand, mid-latitude palynofloras from northern Patagonia (Cañadón Seco and Huincul formations; [122][123][124][125]) had similarities with Australian palynofloras (Toolebuc, Mackunda, Winton, Allaru and Bathurst Island formations; [126][127][128][129]).…”

Análisis palinoflorístico de la Formación Mata Amarilla (Cenomaniano de la provincia de Santa Cruz) con énfasis en el estudio de angiospermas

“…Registros previos. Aptiano-Albiano de Cuenca de San Luis (Prámparo, 1994;Arcucci et al, 2015); Albiano-Cenomaniano de Cuenca Neuquina (Vallati, 2001) y Cuenca Austral (Barreda y Archangelsky, 2006;Archangelsky et al, 2008;Archangelsky et al, 2012;Perez Loinaze et al, 2015); Coniaciano-Santoniano de Antártida (Barreda et al, 1999); Aptiano-Albiano de Cuenca Parnaíba, Brasil (Ferreira et al, 2016); Cretácico Temprano de la Península Ibérica (Friis et al, 2000;Horikx et al, 2016); Albiano-Cenomaniano de Hungría (Juhász y Góczán, 1985).…”