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Research Interests: Botany, Evolutionary Biology, Plant Biology, Biology, Ecology, and 6 moreMedicine, fERN, Sterilization, Rhizome, Sporangium, and Lamina
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Research Interests: Botany, Evolutionary Biology, Paleontology, Plant Ecology, Plant Biology, and 14 moreBiology, Patagonia, Fossil, Cretaceous, fERN, Plant Systematics and Evolution, Genus, Paleontología, Sporangium, Enseñanza - Aprendizaje Ciencias Naturales Y Exactas, Reticulate, Macrofossil Analysis, Marsileaceae, and Taxon
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A new late paleozoic taphoflora from the Mojon de Hierro Fonnation at Arroyo Ganido (Chubut province) is described. The fossil plants were found in two sections stratigraphically about 500 m aparto In the lower section (pS 1)the folIowing... more
A new late paleozoic taphoflora from the Mojon de Hierro Fonnation at Arroyo Ganido (Chubut province) is described. The fossil plants were found in two sections stratigraphically about 500 m aparto In the lower section (pS 1)the folIowing taxa were identified: Bumbudendron sp.,Paracalamites austra lis ,Botrychiopsis sp., Nothorhacopteris majar nov. sp., Eusphenoteris cf. obtusiloba and Calymmatotheca sp. In the upper plant-bearing section (PS 11)Asterotheca piatnitzkyi, A. sp. Pecopteris sp., Sphenopteris sp., Glossopteris wilsonii, Eucerospermum cf. nitens and Cordaites sp. are described. Taphocenosis from PS 11es clearly linked to the Lubeckense flora al the Rio Genoa Formation, and is included in the Ferugliocladus Superzone of a regional Lubeckian age (early Permian), On this base, and taking into account compositional and stratigraphic aspects, a pre-Lubeckian (i.e. late Carboniferous) age is suggested for the taphocenosis of the PS 1. This new finding improves the late Palaeozoic floristic record in Patagonia.
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11 Permian and Triassic high latitude paleoclimates: evidence from fossil biotas EDITH L. TAYLOR, THOMAS N. TAYLOR, AND N. RUBEN CUNEO ABSTRACT ... a nearly horizontal bench near the peak of Mount Achernar (84... more
11 Permian and Triassic high latitude paleoclimates: evidence from fossil biotas EDITH L. TAYLOR, THOMAS N. TAYLOR, AND N. RUBEN CUNEO ABSTRACT ... a nearly horizontal bench near the peak of Mount Achernar (84 22'23" S, 164 37'56" E)(Buckley Island Quadrangle ...
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Abstract The structure and taphonomy of araucarian stumps and logs from the Jurassic of Patagonia are analyzed. Density measurements of these trees indicate that they were organized into woodlands that occupied extensive paleosurfaces... more
Abstract The structure and taphonomy of araucarian stumps and logs from the Jurassic of Patagonia are analyzed. Density measurements of these trees indicate that they were organized into woodlands that occupied extensive paleosurfaces affected by repetitive volcanism from nearby areas. At least two episodes of araucarian woodlands were identified, both terminated by explosive volcanism. As a result, fallen trees and stumps were immediately covered by massive ash falls that favored rapid silicification. The abundance of Araucaria mirabilis seedcones in the surroundings suggests that araucarian woodlands produced this type of cone. Paleoecological, sedimentological, and paleoclimatical data are used to better understand the life history of one of the best well preserved examples of Jurassic tree vegetation. The continuous association of araucarian trees with cheirolepidaceous conifers during most of the Jurassic and Early Cretaceous suggests that the Patagonian landscape was covered by open woodlands or closer forests as the dominant plant formation.
Research Interests: Geology, Geophysics, Paleontology, Paleoecology, Taphonomy, and 3 moreCretaceous, Volcanism, and Woodland
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Plant remains from the Piedra Shotel and Nueva Lubecka Formations, at Estancia La Casilda, Chubut Province, are described and/or figured. They are: Cordaites casildensis n. sp., C. cf. hislopi (Bunbury) Seward & Leslie, Glossopteris... more
Plant remains from the Piedra Shotel and Nueva Lubecka Formations, at Estancia La Casilda, Chubut Province, are described and/or figured. They are: Cordaites casildensis n. sp., C. cf. hislopi (Bunbury) Seward & Leslie, Glossopteris wilsonii (Seward) status nov., Gangamopteris obooata (Carr.) D. White and a Glossopteridean fructification. It is suggested that several references of Glossopteris indica in Argentina may well belong to the newly established species, Glossopteris wilsonii, that was based on poorly preserved specimens from Antarctica presented as a variety of indica by Seward. The revision of the type specimen of Clossopteris indica clearly shows a different venation pattem, with many anastomosing veins, a character seldom found in G. wilsonii. An early Permian age is assigned to these fossils.
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New specimens of Asterotheca golondrinensis Herbst found in the type area (Bajo de La Leona, Santa Cruz province) and in the Tepuel-Genoa Basin (Chubut province), allow a new definition of pinnular characters (margins are shown to be... more
New specimens of Asterotheca golondrinensis Herbst found in the type area (Bajo de La Leona, Santa Cruz province) and in the Tepuel-Genoa Basin (Chubut province), allow a new definition of pinnular characters (margins are shown to be toothed). This type of morphology resembles Nemejcopteris pinnules, but the fructification is more similar to Asterotheca . The Patagonian specimens resemble African (Zimbabwe) material determined as Pecopteris arcuata Halle. The stratigraphic distribution of A. golondrinensis is Early Permian in Chubut and Late Permian in Santa Cruz. KEY WORDS. Permian. Argentina. Patagonia. Ferns.
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Abstract. BAQUERÓ GROUP STRATIGRAPHY, PATAGONIA (SANTA CRUZ PROVINCE, ARGENTINA). The stratigraphy of early Cretaceous strata in the central area of Santa Cruz Province has been a matter of study since the time when EW Berry published his... more
Abstract. BAQUERÓ GROUP STRATIGRAPHY, PATAGONIA (SANTA CRUZ PROVINCE, ARGENTINA). The stratigraphy of early Cretaceous strata in the central area of Santa Cruz Province has been a matter of study since the time when EW Berry published his first ...
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SPHENOPHYLLALES DEL PERMICO INFERIOR DE CHUBUT, ARGENTINA. Se describen cinco morfotipos del genero Sphenophyllum Koenig provenientes del Permico inferior de la provincia de Chubut, Argentina, los que representan el registro mas antiguo... more
SPHENOPHYLLALES DEL PERMICO INFERIOR DE CHUBUT, ARGENTINA. Se describen cinco morfotipos del genero Sphenophyllum Koenig provenientes del Permico inferior de la provincia de Chubut, Argentina, los que representan el registro mas antiguo del genero en el hemisferio austral. En ellos se incluyen: Sphenophyllum patagonicum nov. sp., S. chubutianum nov. sp., S. sp. cf. S. speciosum (Royle) Zeiller, S. sp. I y S. sp. II. Las dos especies nuevas poseen ejes carenados con verticilos foliares de seis hojas, margen distal inciso y dientes agudos. Sphenophyllum patagonicum posee hojas con una fuerte incision central, mientras que S. chubutianum muestra hojas con incisiones uniformes en los margenes distales. Los organos reproductivos asociados (en un caso conectado organicamente a S. patagonicum), son tambien verticilados y consisten de bracteas distalmente curvadas hacia arriba, cada una llevando dos esporangioforos con tres a cinco esporangios. S. sp. cf. S. speciosum Royle, una especie comun del Permico medio-superior gondwanico, fue reconocida sobre la base de material fragmentado. S. sp. I se caracteriza por tener verticilos foliares escasamente incisos y dientes distales redondeados mientras que S. sp. II posee hojas profundamente incisas pero con dientes distales obtusos. La mayoria de los morfotipos descriptos es semejante a formas euramericanas, tanto en sus caracteristicas vegetativas como reproductivas. Estas plantas formaron parte de paleocomunidades que crecieron en planicies deltaicas, e integraron el estrato arbustivo bajo en ambientes de alta humedad. Su frecuencia en las tafocenosis eopermicas de Patagonia, sugiere que las Sphenophyllales estaban bien desarrolladas en la region, como consecuencia de condiciones climaticas calidas y humedas. Esta es una nueva evidencia que concuerda con la hipotesis de una localizacion paleogeografica de Patagonia en latitudes mas bajas que las usualmente sugeridas para el Permico.
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PremiseUndoubtedly, fossils are critical for understanding evolutionary transformations in deep time. Here, we reinvestigate the microspores and megaspores of Paleoazolla patagonica, a water fern found in Late Cretaceous sediments of the... more
PremiseUndoubtedly, fossils are critical for understanding evolutionary transformations in deep time. Here, we reinvestigate the microspores and megaspores of Paleoazolla patagonica, a water fern found in Late Cretaceous sediments of the Chubut Province, Patagonia, Argentina, which provides novel evidence on the past history of the water fern clade. The study was based on recently collected specimens and additional observations of the original material.MethodsMost specimens analyzed herein were obtained from new palynological samples collected at the Cerro Bosta and Cañadón del Irupé localities, La Colonia Formation. Samples were mechanically disaggregated and treated with hydrofluoric and hydrochloric acid. Spores were studied using standard light microscopy and scanning electron microscopy. We also reexamined the original materials.ResultsThe newly described characters of Paleoazolla include the presence of heterosporangiate sori composed of one ellipsoidal megasporangium surrounded by three to four oval microsporangia, megasporangium containing one hairy massula that encloses two trilete megaspores (rarely one or three), and microsporangia containing numerous microspore massulae with non‐septate multibarbed glochidia and one trilete microspore per massula.ConclusionsThe reinterpretation has revealed a novel set of characters for understanding the evolution of heterosporous water ferns. The presence of two megaspores in the megasporangium of Paleoazolla exposes serious gaps in the current knowledge on the evolution of monomegaspory in heterosporous water ferns, a fact that emphasizes the need of including fossils within phylogenies to elucidate patterns of character acquisition among water ferns.
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... may show a conspicuous inner oval body (Plate Localities: Cerro La Trampa and Betancourt; VI, 24 A, 28 ... Nueva Lubecka, Chubut province, Argentina. ... POLYSPERMOPHYLLUM, A NEWPERMIAN GYMNOSPER~x 123 PLATE III I 124 S, ARCHANGELSKY... more
... may show a conspicuous inner oval body (Plate Localities: Cerro La Trampa and Betancourt; VI, 24 A, 28 ... Nueva Lubecka, Chubut province, Argentina. ... POLYSPERMOPHYLLUM, A NEWPERMIAN GYMNOSPER~x 123 PLATE III I 124 S, ARCHANGELSKY AND R. CI'JNEO Fig. ...
Research Interests: Geology, Paleontology, Biology, Mesozoic, Gondwana, and 5 moreCarboniferous, Permian, Paleozoic, Gymnosperm, and ovule
Premise of the StudyThe fossil record of Agathis historically has been restricted to Australasia. Recently described fossils from the Eocene of Patagonian Argentina showed a broader distribution than found previously, which is reinforced... more
Premise of the StudyThe fossil record of Agathis historically has been restricted to Australasia. Recently described fossils from the Eocene of Patagonian Argentina showed a broader distribution than found previously, which is reinforced here with a new early Paleocene Agathis species from Patagonia. No previous phylogenetic analyses have included fossil Agathis species.MethodsWe describe macrofossils from Patagonia of Agathis vegetative and reproductive organs from the early Danian, as well as leaves with Agathis affinities from the latest Maastrichtian. A total evidence phylogenetic analysis is performed, including the new Danian species together with other fossil species having agathioid affinities.Key ResultsEarly Danian Agathis immortalis sp. nov. is the oldest definite occurrence of Agathis and one of the most complete Agathis species in the fossil record. Leafy twigs, leaves, pollen cones, pollen, ovuliferous complexes, and seeds show features that are extremely similar to the living genus. Dilwynites pollen grains, associated today with both Wollemia and Agathis and known since the Turonian, were found in situ within the pollen cones.ConclusionsAgathis was present in Patagonia ca. 2 million years after the K‐Pg boundary, and the putative latest Cretaceous fossils suggest that the genus survived the K–Pg extinction. Agathis immortalis sp nov. is recovered in a stem position for the genus, while A. zamunerae (Eocene, Patagonia) is recovered as part of the crown. A Mesozoic divergence for the Araucariaceae crown group, previously challenged by molecular divergence estimates, is supported by the combined phylogenetic analyses including the fossil taxa.
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... culminating in mucro nate, cuspldate, apex 0 5 mm long; body sur rounded ... b, 12005ab, CIRGEO Pb 540 Type locahty Puesto Alambre, Rio Genoa, Chubut Province, Argentina. ... the Rio Genoa Group, Ferughocladus superzone, Lu beckense... more
... culminating in mucro nate, cuspldate, apex 0 5 mm long; body sur rounded ... b, 12005ab, CIRGEO Pb 540 Type locahty Puesto Alambre, Rio Genoa, Chubut Province, Argentina. ... the Rio Genoa Group, Ferughocladus superzone, Lu beckense Stage, early Permian Material studed ...
Research Interests: Botany, Geology, Paleontology, Biology, Gondwana, and 4 morePollen, Permian, SISTEM INTEGUMENT, and ovule
Abstract We describe megaspore apparatuses and microspore massulae of Azolla coloniensis sp. nov., a heterosporous water fern of the family Salviniaceae. The megaspore apparatus is composed of the megaspore body and three tiers of floats... more
Abstract We describe megaspore apparatuses and microspore massulae of Azolla coloniensis sp. nov., a heterosporous water fern of the family Salviniaceae. The megaspore apparatus is composed of the megaspore body and three tiers of floats covered by a dense filosum, while its wall consists of an exine and a two-layered perine, with a spongy endoperine and large, clavate exoperine. Microspore massulae are variable in size and shape and bear aseptate glochidia with anchor-shaped tips. The new species increases the scarce record of Salviniaceae megaspores in the Southern Hemisphere and significantly extends our knowledge of the variability of morphological characters of the genus. Fossils indicate a freshwater depositional environment and are interpreted as being preserved in situ due to their excellent preservation and the frequent attachment of microspore massulae to megaspores. This contribution supports the hypotheses of the rapid geographic dispersal and diversification of the genus, in both hemispheres, during the Late Cretaceous.
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Premise of research. The Río Genoa Formation of Argentine Patagonia hosts Early Permian fossil assemblages that document levels of plant diversity rare among coeval floras. Ongoing work to exhaustively characterize the diversity of these... more
Premise of research. The Río Genoa Formation of Argentine Patagonia hosts Early Permian fossil assemblages that document levels of plant diversity rare among coeval floras. Ongoing work to exhaustively characterize the diversity of these assemblages is key to understanding Permian vegetation and plant evolution. A new fern type identified in the Río Genoa Formation exhibits a novel combination of characters that required taxonomic assessment. Methodology. Observations and measurements of vegetative and reproductive morphology of compression fossils were used in a comparative framework to address the taxonomic placement of the fossils. Pivotal results. The new fern, Floratheca apokalyptika gen. et sp. nov., is characterized by small pinnules with a free base, weakly lobed margin, highly decurrent midvein, and rarely branched lateral veins, as well as radially symmetrical synangia with stellate dehiscence, consisting of six spindle-shaped sporangia. This unique combination of characters distinguishes Floratheca from the more than 25 Permo-Carboniferous marattialean genera known from compressions. Floratheca exhibits variable synangium morphology during development and variation in pinnule base morphology due to a combination of adaxial-abaxial asymmetry of ultimate rachises and taphonomic effects. Conclusions. Floratheca is one of only three late Paleozoic bona fide marattialean compression genera endemic to Gondwana and the second late Paleozoic endemic South American marattialean with preserved fertile structures. Floratheca adds to an increasing diversity of fossils that diminish the disparity between the Southern and Northern Hemispheres, in terms of the extent and intensity of exploration of the plant fossil record, currently skewed taxonomically toward Northern Hemisphere taxa. Variability of synangium and pinnule base morphology in Floratheca cautions against potential taxonomic inflation produced by establishment of new taxa based on small numbers of specimens and incomplete understanding of development and taphonomy.
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Equisetum is the sole living representative of Sphenopsida, a clade with impressive species richness, a long fossil history dating back to the Devonian, and obscure relationships with other living pteridophytes. Based on molecular data,... more
Equisetum is the sole living representative of Sphenopsida, a clade with impressive species richness, a long fossil history dating back to the Devonian, and obscure relationships with other living pteridophytes. Based on molecular data, the crown group age of Equisetum is mid-Paleogene, although fossils with possible crown synapomorphies appear in the Triassic. The most widely circulated hypothesis states that the lineage of Equisetum derives from calamitaceans, but no comprehensive phylogenetic studies support the claim. Using a combined approach, we provide a comprehensive phylogenetic analysis of Equisetales, with special emphasis on the origin of genus Equisetum. We performed parsimony phylogenetic analyses to address relationships of 43 equisetalean species (15 extant, 28 extinct) using a combination of morphological and molecular characters. We recovered Equisetaceae + Neocalamites as sister to Calamitaceae + a clade of Angaran and Gondwanan horsetails, with the four groups forming a clade that is sister to Archaeocalamitaceae. The estimated age for the Equisetum crown group is mid-Mesozoic. Modern horsetails are not nested within calamitaceans; instead, both groups have explored independent evolutionary trajectories since the Carboniferous. Diverse fossil taxon sampling helps to shed light on the position and relationships of equisetalean lineages, of which only a tiny remnant is present within the extant flora. Understanding these relationships and early character configurations of ancient plant clades as Equisetales provide useful tests of hypotheses about overall phylogenetic relationships of euphyllophytes and foundations for future tests of molecular dates with paleontological data.
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"Fertile specimens of Asterotheca [renguenii Archangelsky and de la Sota nov. combo are described. The material is found in Lower Perrnian strata of the Rio Genoa Forrnation, Tepuel-Genoa Basin, vvest of Chubut Province. The original... more
"Fertile specimens of Asterotheca [renguenii Archangelsky and de la Sota nov. combo are described. The material is found in Lower Perrnian strata of the Rio Genoa Forrnation, Tepuel-Genoa Basin, vvest of Chubut Province. The original specimens have been previously assigned to Pecopteris (Asterotheca?) frenguellii Archangelsky and de la Sota. New and better preserved fertile specimens were recentlv tound gri1nting their assignation to the genus Asterotheca, in the sense of Stubblefield here adopted."
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Se describe e ilustra la megaspora Sublagenicula brasiliensis (Dijkstra) Dibova-Jachowicz el al., hallada en la Formacion Rio Genoa, Permico de la provincia de Chubut. Se trata del primer hallazgo de megasporas para esta unidad. El rasgo... more
Se describe e ilustra la megaspora Sublagenicula brasiliensis (Dijkstra) Dibova-Jachowicz el al., hallada en la Formacion Rio Genoa, Permico de la provincia de Chubut. Se trata del primer hallazgo de megasporas para esta unidad. El rasgo mas saliente es la subgula que se desarrolla en el polo proximal de la espora. La escultura es muy reducida y solamente se puede observar con grandes aumentos; suele concentrarse en la region subecuatorial y en la cara distal en forma de microgranulos que pueden estar libres o fusionados. Los cortes realizados permiten observar que la ultraestructura de la esporopolenina que compone las paredes de la megaspora ha sufrido modificaciones sustanciales durante el proceso de fosilizacion, lo cual esta de acuerdo con el alto grado de carbonizacion que se evidencia por las fracturas de la exina. Se efectuan comentarios sobre la amplia distribucion geografica y estratigrafica de esta especie.
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Se describen ejemplares estériles y fértiles de helechos que se refieren a una nueva especie de Oligocarpia, O. patagónica Cesari, Cúneo y Archangelsky. El material fue hallado en estratos del Pérmico Inferior, Formación Río Genoa, Cuenca... more
Se describen ejemplares estériles y fértiles de helechos que se refieren a una nueva especie de Oligocarpia, O. patagónica Cesari, Cúneo y Archangelsky. El material fue hallado en estratos del Pérmico Inferior, Formación Río Genoa, Cuenca Tepuel-Genoa, al oeste de la provincia de Chubut, Argentina. Determinaciones previas de algunas piezas sugerían relaciones con otros géneros con pínnulas esfenopterídeas y eusporangiados. Sin embargo, el hallazgo de nuevo material fértil mejor conservado permitió reconocer esporangios con anillo, y, por lo tanto, asignarlo a Oligocarpia, género que no es conocido en el Gondwana pero que tiene frecuentes representantes en el Neopaleozoico del Hemisferio Norte. La escasa fragmentación del material (la fronde es hasta tripinnada), sugiere condiciones hipoautóctonas en la formación de las tafocenosis portadoras de Oligocarpia. Esta planta se hallaba asociada a otros helechos, tanto leptosporangiados como eusporangiados, en conjuntos tafonómicos que der...
Research Interests: Geography and Humanities
Leaves are the most abundant and visible plant organ, both in the modern world and the fossil record. Identifying foliage to the correct plant family based on leaf architecture is a fundamental botanical skill that is also critical for... more
Leaves are the most abundant and visible plant organ, both in the modern world and the fossil record. Identifying foliage to the correct plant family based on leaf architecture is a fundamental botanical skill that is also critical for isolated fossil leaves, which often, especially in the Cenozoic, represent extinct genera and species from extant families. Resources focused on leaf identification are remarkably scarce; however, the situation has improved due to the recent proliferation of digitized herbarium material, live-plant identification applications, and online collections of cleared and fossil leaf images. Nevertheless, the need remains for a specialized image dataset for comparative leaf architecture. We address this gap by assembling an open-access database of 30,252 images of vouchered leaf specimens vetted to family level, primarily of angiosperms, including 26,176 images of cleared and x-rayed leaves representing 354 families and 4,076 of fossil leaves from 48 families...
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The flip-leaved podocarp Retrophyllum has a disjunct extant distribution in South American and Australasian tropical rainforests and a Gondwanic fossil record since the Eocene. Evolutionary, biogeographic, and paleoecological insights... more
The flip-leaved podocarp Retrophyllum has a disjunct extant distribution in South American and Australasian tropical rainforests and a Gondwanic fossil record since the Eocene. Evolutionary, biogeographic, and paleoecological insights from previously described fossils are limited because they preserve little foliar variation and no reproductive structures. We investigated new Retrophyllum material from the terminal Cretaceous Lefipán, the early Eocene Laguna del Hunco, and the early/middle Eocene Río Pichileufú floras of Patagonian Argentina. We also reviewed type material of historical Eocene fossils from southern Chile. Cretaceous Retrophyllum superstes sp. nov. is described from a leafy twig, while Eocene R. spiralifolium sp. nov. includes several foliage forms and a peduncle with 13 pollen cones. Both species preserve extensive damage from sap-feeding insects associated with foliar transfusion tissue. The Eocene species exhibits a suite of characters linking it to both Neotropic...
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Upper Maastrichtian to lower Paleocene, coarse‐grained deposits of the Lefipán Formation in Chubut Province, (Patagonia, Argentina) provide an opportunity to study environmental changes across the Cretaceous–Palaeogene (K–Pg) boundary in... more
Upper Maastrichtian to lower Paleocene, coarse‐grained deposits of the Lefipán Formation in Chubut Province, (Patagonia, Argentina) provide an opportunity to study environmental changes across the Cretaceous–Palaeogene (K–Pg) boundary in a shallow marine depositional environment. Marine palynological and organic geochemical analyses were performed on the K–Pg boundary interval of the Lefipán Formation at the San Ramón section. The palynological and organic geochemical records from the San Ramón K–Pg boundary section are characteristic of a highly dynamic, nearshore setting. High abundances of terrestrial palynomorphs, high BIT‐index values and the occasional presence of plant fossils are indicative of a large input of terrestrial organic material. The organic‐walled dinoflagellate cyst (dinocyst) assemblage is generally dominated by Senegalinium and other peridinioid dinocyst taxa, indicative of high‐nutrient conditions and decreased salinities, probably associated with a large fluv...
Research Interests: Evolutionary Biology, Geology, Paleontology, Climate Change, Palynology, and 14 moreArgentina, Ecology, Climate, Sea Level, Palaeontology, Palynofacies, Cretaceous, Ecological Succession, Paleogene, Palaeogene, Marine transgression, Enseñanza - Aprendizaje Ciencias Naturales Y Exactas, Wiley, and Dinocysts
The Southern Hemisphere may have provided biodiversity refugia after the Cretaceous/Palaeogene (K/Pg) mass extinction. However, few extinction and recovery studies have been conducted in the terrestrial realm using well-dated macrofossil... more
The Southern Hemisphere may have provided biodiversity refugia after the Cretaceous/Palaeogene (K/Pg) mass extinction. However, few extinction and recovery studies have been conducted in the terrestrial realm using well-dated macrofossil sites that span the latest Cretaceous (late Maastrichtian) and early Palaeocene (Danian) outside western interior North America (WINA). Here, we analyse insect-feeding damage on 3,646 fossil leaves from the latest Maastrichtian and three time slices of the Danian in Chubut, Patagonia, Argentina (palaeolatitude approximately 50° S). We test the southern refugial hypothesis and the broader hypothesis that the extinction and recovery of insect herbivores, a central component of terrestrial food webs, differed substantially from WINA at locations far south of the Chicxulub impact structure in Mexico. We find greater insect-damage diversity in Patagonia than in WINA during both the Maastrichtian and Danian, indicating a previously unknown insect richness. As in WINA, the total diversity of Patagonian insect damage decreased from the Cretaceous to the Palaeocene, but recovery to pre-extinction levels occurred within approximately 4 Myr compared with approximately 9 Myr in WINA. As for WINA, there is no convincing evidence for survival of any of the diverse Cretaceous leaf miners in Patagonia, indicating a severe K/Pg extinction of host-specialized insects and no refugium. However, a striking difference from WINA is that diverse, novel leaf mines are present at all Danian sites, demonstrating a considerably more rapid recovery of specialized herbivores and terrestrial food webs. Our results support the emerging idea of large-scale geographic heterogeneity in extinction and recovery from the end-Cretaceous catastrophe.
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Abstract We compiled the fossil record of the heterosporous water ferns (Salviniales) including macro- and microfossils from South America and the Antarctic Peninsula. Both extant families, Marsileaceae and Salviniaceae, are well... more
Abstract We compiled the fossil record of the heterosporous water ferns (Salviniales) including macro- and microfossils from South America and the Antarctic Peninsula. Both extant families, Marsileaceae and Salviniaceae, are well represented and several fossil spore genera that cannot be placed within the extant families are included as Incertae sedis. Marsileaceae is first recorded in the Middle to Late Jurassic. Incertae sedis genera are recorded for first time in the Early Cretaceous while Salviniaceae in the Late Cretaceous. Two diversity spikes are recognized: one spanned the Aptian–Albian (Early Cretaceous) and is linked to an increase in species diversity within Marsileaceae; and the other occurred during the Campanian–Maastrichtian (Late Cretaceous) and it is associated with the diversification at generic level of the entire Salviniales. Two decreases in diversity are recognized: one during the Cenomanian–Santonian and affected Marsileaceae at specific level but not its generic diversity, and the second is related to the Cretaceous–Paleogene mass extinction and affected all Salviniales at generic and specific levels. From the Paleocene onwards there is a steady decline in the fossil record of the group, with most remains belonging to the extant genera. This study suggests that Southern Hemisphere aquatic ferns underwent a sharp radiation during the Late Cretaceous and a deep decline in the Paleocene that parallels that occurred in the Northern Hemisphere. Probably, the temporal co-occurrence of geological and climate events and the availability of suitable lineages promoted the evolutionary changes of the water ferns in the studied area, including the high diversification and distribution in the Cretaceous and the subsequent post-Maastrichtian decline.
Research Interests: Geography, Geology, Paleontology, Cretaceous, Cenomanian, and 3 moreAptian, Paleogene, and Incertae sedis
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PALAEOECOLOGY OF PLANTIFEROUS MICROSECUENCES OF THE RiO GENOA GROUP, PERMIAN OF CHUBUT, ARGENTINA. - One stratigraphical section was measured at Estancia La Casilda, Chubut Province, and 10 plantiferous sections (PS) were recognized.... more
PALAEOECOLOGY OF PLANTIFEROUS MICROSECUENCES OF THE RiO GENOA GROUP, PERMIAN OF CHUBUT, ARGENTINA. - One stratigraphical section was measured at Estancia La Casilda, Chubut Province, and 10 plantiferous sections (PS) were recognized. Quantitative palaeoecological data from four sedimentary microsequences bearing PS are statistically analyzed PS I, II and V occur in the Piedra Shotel Formation and PS VIII in the overlying Nueva Lubecka Formation, both of the Rio Genoa Group. PS I, II and V probably developed in a fluvial floodplain colonized by conifers, glossopterids and cordaitales. Restricted subenvironments were dominated by sphenophylls and arborescent lycopods, Ferns are usually present as secondary elements. PS VIII was also deposited in a fluvial environment, although in this case the floodplain reached the sea. High humidity environmental conclitions are infered from the petrographical analysis of coals. The age of the sequence is considered to be early Permian (Lubeckense A) with typical species of the Glossopteris flora and mixed northern elements. Intercalated marine beds with invertebrates of the Cancrinella Zone also suggest a Permian age.
Research Interests:
"The phytopalaeoecological analysis carried out on ecofacies of the Rio Genoa Formation at Lomas Chatas, has allowed to distinguish four palaeocommunities in a fluvio-deltaic alluvian plain environment. a) Hidro-higrophylous... more
"The phytopalaeoecological analysis carried out on ecofacies of the Rio Genoa Formation at Lomas Chatas, has allowed to distinguish four palaeocommunities in a fluvio-deltaic alluvian plain environment. a) Hidro-higrophylous community, composed mainly by Articulates (Equisetales and Sphenophyllales) occupying swampy areas with the water table near the surface of the alluvial plain; b) Higro-mesophylous communities, two kinds have been recognized: one with Glossopteridales, ferns and Progymnosperms and another with Conifers and ferns; both grew on a less restricted environment in the floodplain with a deeper water table, and e) Mesophylous community: consisting of Glossopteridales and Conifers that inhabited higher areas of the alluvial plain. Probably neat boundaries between palaeocornmunities did not exist and therefore gradational and ecotonal areas developed. Comparisons with palaeocommunities from nearly fossiliferous loealities show the persistence of higro-mesophylous and mesophylous communities while taxonomic changes have been noted in hidro-higrophylous communities."