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Santiago del Estero, Argentina

Barreda V.D.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Palazzesi L.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Palazzesi L.,Jodrell Laboratory | Telleria M.C.,Laboratorio Of Sistematica Y Biologia Evolutiva | And 3 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

The Asteraceae (sunflowers and daisies) are the most diverse family of flowering plants. Despite their prominent role in extant terrestrial ecosystems, the early evolutionary history of this family remains poorly understood. Here we report the discovery of a number of fossil pollen grains preserved in dinosaur-bearing deposits from the Late Cretaceous of Antarctica that drastically pushes back the timing of assumed origin of the family. Reliably dated to ∼76-66 Mya, these specimens are about 20 million years older than previously known records for the Asteraceae. Using a phylogenetic approach, we interpreted these fossil specimens as members of an extinct early diverging clade of the family, associated with subfamily Barnadesioideae. Based on a molecular phylogenetic tree calibrated using fossils, including the ones reported here, we estimated that the most recent common ancestor of the family lived at least 80 Mya in Gondwana, well before the thermal and biogeographical isolation of Antarctica. Most of the early diverging lineages of the family originated in a narrow time interval after the K/P boundary, 60-50 Mya, coinciding with a pronounced climatic warming during the Late Paleocene and Early Eocene, and the scene of a dramatic rise in flowering plant diversity. Our age estimates reduce earlier discrepancies between the age of the fossil record and previous molecular estimates for the origin of the family, bearing important implications in the evolution of flowering plants in general. © 2015, National Academy of Sciences. All rights reserved.

Telleria M.C.,Laboratorio Of Sistematica Y Biologia Evolutiva | Telleria M.C.,CONICET | Palazzesi L.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Palazzesi L.,CONICET | And 2 more authors.
Review of Palaeobotany and Palynology | Year: 2015

Barnadesioideae (94 species) is the sister subfamily to the rest of the Asteraceae (23,000 species). Pollen grains in this subfamily are structurally and sculpturally distinctive and diverse. Although pollen morphology has contributed to the taxonomy of the subfamily, there is a gap of knowledge concerning the evolution of the exine structure. This study aims at exploring the systematic and phylogenetic significance of optimizing selected pollen characters of Barnadesioideae on the latest molecular phylogenetic tree. Transmission electron microscope (TEM) observations on pollen of selected species, some of them never explored so far, show that the exine probably evolved from a thin pattern (ca. 1-3 μm), with a well-developed foot layer and solid and free columellae, present in sister family Calyceraceae, towards a thicker (>. 6-11. μm) and a more complex columellate-granulate bilayered exine in Barnadesioideae (with very delicate columellae). The particular exine structure observed in the monotypic Schlechtendalia luzulaefolia, which combines compact and independent columellae (common in more derived Asteraceae) with a granular internal tectum as the inner ectexine layer (as in Barnadesioideae), reinforces its distant phylogenetic position within Barnadesioideae. More derived lineages within Asteraceae (e.g. Mutisioideae) retained some ancestral exine features although evolved an even thicker exine and a columellate trilayered exine (with robust columellae), rare in the angiosperm pollen grains. © 2015 Elsevier B.V.

Palazzesi L.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Barreda V.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Telleria M.C.,Laboratorio Of Sistematica Y Biologia Evolutiva | Telleria M.C.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia
Review of Palaeobotany and Palynology | Year: 2010

A new fossil pollen species (Psilatricolporites protrudens sp. nov) is described from Miocene sedimentary sections of the Chenque and Puerto Madryn formations (Chubut province, Argentina). The fossil pollen grains are characterized by being small, tricolporate, subspheroidal to suboblate in shape; rhombic outline in equatorial view and subtriangular in polar view. The exine is tectate and columellate; the nexine is thickened toward endoapertures resulting in a typical wall protrusion on the external surface. These morphological features point to a possible relationship with Gamocarpha type of the Calyceraceae. Most species of this type grow in high-altitude arid habitats or in coastal locations under extreme climatic condition. The gradual spread of the stress-adapted Calyceraceae as well as other phylogenetically related taxa (e.g. Barnadesioideae, Mutisioideae) during the Miocene in southern South America may have been triggered by the increasing aridity and seasonality caused by Andean uplift. This fossil record represents the first finding of Calyceraceae, the most closely related family of Asteraceae, and provides evidence for the timing of their geographic radiation. © 2009 Elsevier B.V. All rights reserved.

Telleria M.C.,Laboratorio Of Sistematica Y Biologia Evolutiva | Barreda V.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Palazzesi L.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Katinas L.,Museo de La Plata
Plant Systematics and Evolution | Year: 2010

The Late Oligocene Mutisiapollis telleriae, which is the oldest echinate fossil pollen of Asteraceae from Patagonia, was tentatively related to the subfamily Mutisioideae. A detailed comparison of M. telleriae with extant asteraceous pollen indicates strong similarities with both Mutisioideae (in particular the Gongylolepis type) and Carduoideae (some genera of Carduinae) subfamilies. This morphotype, as an example of the exceptional diversity of fossil pollen of Asteraceae found in Patagonia, contributes to the knowledge of the early history of the family. © Springer-Verlag 2010.

Telleria M.C.,Laboratorio Of Sistematica Y Biologia Evolutiva | Sancho G.,Museo de La Plata | Funk V.A.,Smithsonian Institution | Ventosa I.,Institute Ecologia y Sistematica | Roque N.,Federal University of Bahia
Plant Systematics and Evolution | Year: 2013

In the context of recent molecular phylogenies of the basal grades of Compositae, we investigated the utility of pollen morphology within the tribe Gochnatieae. The pollen of 64 species of Anastraphia,Cnicothamnus, Cyclolepis, Gochnatia, Pentaphorus, and Richterago was studied using light microscopy and scanning electron microscopy. In addition, three extra-Gochnatieae genera (Ianthopappus, Leucomeris, and Nouelia) were examined as they were traditionally morphologically related to members of the tribe Gochnatieae. Three of the species of Gochnatieae were examined using transmission electron microscopy. Two pollen types, and two new subtypes, have been recognized on the basis of the pollen shape, size, and exine sculpture. The pollen features of Gochnatia sect. Moquiniastrum and G. cordata are similar and distinctive within the genus and support the recently re-circumscribed section Hedraiophyllum. Within the species with echinate pollen surface, the distinctive spine length of Anastraphia supports its recent resurrection as a genus. The identity of Pentaphorus could not be supported by pollen features as was for other morphological characteristics. The pollen features shared across Cyclolepis,Ianthopappus, Leucomeris, Nouelia and Gochnatia sect. Moquiniastrum, as well as those shared by Richterago and Anastraphia could be a result of parallel evolution. © 2013 Springer-Verlag Wien.

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