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1.
PeerJ ; 10: e13186, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35855906

RESUMO

Vicariance is the simplest explanation for divergence between sister lineages separated by a potential barrier, and the northern Andes would seem to provide an ideal example of a vicariant driver of divergence. We evaluated the potential role of the uplift of the Eastern Cordillera (EC) of the Colombian Andes and the Mérida Andes (MA) of Venezuela as drivers of vicariance between lowland populations co-distributed on both flanks. We synthesized published geological data and provided a new reconstruction showing that the EC-MA grew from north to south, reaching significant heights and separating drainages and changing sediment composition by 38-33 million years ago (Ma). A few lowland passes across the EC-MA may have reached their current heights (~1,900 m a.s.l.) at 3-5 Ma. We created a comparative phylogeographic data set for 37 lineages of lowland tetrapods. Based on molecular phylogenetic analyses, most divergences between sister populations or species across the EC-MA occurred during Pliocene and the Quaternary and a few during the latest Miocene, and coalescent simulations rejected synchronous divergence for most groups. Divergence times were on average slightly but significantly more recent in homeotherms relative to poikilotherms. Because divergence ages are mostly too recent relative to the geological history and too asynchronous relative to each other, divergence across the northern Andes may be better explained by organism-environment interactions concomitant with climate oscillations during the Pleistocene, and/or dispersal across portals through the Andes.


Assuntos
Clima , Filogeografia , Filogenia , Colômbia , Venezuela
2.
Data Brief ; 25: 104398, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31516931

RESUMO

This contribution contains a GPlates digital reconstruction of the northern Andes and southern Caribbean margin for the last 90 Ma. It is built using different strain datasets fully described in "Continental Margin Response to Multiple Arc-Continent Collisions: the Northern Andes-Caribbean Margin" [1]. Two digital reconstructions are included here: one is a rigid block reconstruction, and the other is a continuously closing polygon reconstruction digitized every one -million years. We placed the South and North American plates at the root of the reconstruction tree, so that the Andean blocks move with respect to the former, and the Caribbean Plate, and related intra-oceanic arcs with respect to the latter. These reconstructions can be used as templates to place in palinspastic space any dataset that can be represented by lines or points.

3.
Sci Adv ; 3(6): e1602321, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28630903

RESUMO

A review and reanalysis of geological, molecular, and paleontological data led O'Dea et al. (1) to propose (i) that reports by Montes et al. (2) and Bacon et al. (3) regarding a middle Miocene closure of the Central American Seaway (CAS) are unsupported, and (ii) a new age of the formation of the Isthmus at 2.8 million years ago (Ma). Here, we reject both of these conclusions.


Assuntos
Fósseis , Paleontologia , Geologia , Panamá
4.
PLoS One ; 12(5): e0176010, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28489866

RESUMO

Volcanic rocks along the Panama Canal present a world-class opportunity to examine the relationship between arc magmatism, tectonic forcing, wet and dry magmas, and volcanic structures. Major and trace element geochemistry of Canal volcanic rocks indicate a significant petrologic transition at 21-25 Ma. Oligocene Bas Obispo Fm. rocks have large negative Nb-Ta anomalies, low HREE, fluid mobile element enrichments, a THI of 0.88, and a H2Ocalc of >3 wt. %. In contrast, the Miocene Pedro Miguel and Late Basalt Fm. exhibit reduced Nb-Ta anomalies, flattened REE curves, depleted fluid mobile elements, a THI of 1.45, a H2Ocalc of <1 wt. %, and plot in mid-ocean ridge/back-arc basin fields. Geochemical modeling of Miocene rocks indicates 0.5-0.1 kbar crystallization depths of hot (1100-1190°C) magmas in which most compositional diversity can be explained by fractional crystallization (F = 0.5). However, the most silicic lavas (Las Cascadas Fm.) require an additional mechanism, and assimilation-fractional-crystallization can reproduce observed compositions at reasonable melt fractions. The Canal volcanic rocks, therefore, change from hydrous basaltic pyroclastic deposits typical of mantle-wedge-derived magmas, to hot, dry bi-modal magmatism at the Oligocene-Miocene boundary. We suggest the primary reason for the change is onset of arc perpendicular extension localized to central Panama. High-resolution mapping along the Panama Canal has revealed a sequence of inward dipping maar-diatreme pyroclastic pipes, large basaltic sills, and bedded silicic ignimbrites and tuff deposits. These volcanic bodies intrude into the sedimentary Canal Basin and are cut by normal and subsequently strike-slip faults. Such pyroclastic pipes and basaltic sills are most common in extensional arc and large igneous province environments. Overall, the change in volcanic edifice form and geochemistry are related to onset of arc perpendicular extension, and are consistent with the idea that Panama arc crust fractured during collision with South America forming the observed Canal extensional zone.


Assuntos
Geologia , Erupções Vulcânicas , Panamá
5.
Nature ; 533(7602): 243-6, 2016 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-27096364

RESUMO

New World monkeys (platyrrhines) are a diverse part of modern tropical ecosystems in North and South America, yet their early evolutionary history in the tropics is largely unknown. Molecular divergence estimates suggest that primates arrived in tropical Central America, the southern-most extent of the North American landmass, with several dispersals from South America starting with the emergence of the Isthmus of Panama 3-4 million years ago (Ma). The complete absence of primate fossils from Central America has, however, limited our understanding of their history in the New World. Here we present the first description of a fossil monkey recovered from the North American landmass, the oldest known crown platyrrhine, from a precisely dated 20.9-Ma layer in the Las Cascadas Formation in the Panama Canal Basin, Panama. This discovery suggests that family-level diversification of extant New World monkeys occurred in the tropics, with new divergence estimates for Cebidae between 22 and 25 Ma, and provides the oldest fossil evidence for mammalian interchange between South and North America. The timing is consistent with recent tectonic reconstructions of a relatively narrow Central American Seaway in the early Miocene epoch, coincident with over-water dispersals inferred for many other groups of animals and plants. Discovery of an early Miocene primate in Panama provides evidence for a circum-Caribbean tropical distribution of New World monkeys by this time, with ocean barriers not wholly restricting their northward movements, requiring a complex set of ecological factors to explain their absence in well-sampled similarly aged localities at higher latitudes of North America.


Assuntos
Migração Animal , Fósseis , Platirrinos , Clima Tropical , Animais , Região do Caribe , Cebidae , Florestas , História Antiga , América do Norte , Oceanos e Mares , Panamá , Filogenia , Platirrinos/anatomia & histologia , Platirrinos/classificação
6.
Science ; 330(6006): 957-61, 2010 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-21071667

RESUMO

Temperatures in tropical regions are estimated to have increased by 3° to 5°C, compared with Late Paleocene values, during the Paleocene-Eocene Thermal Maximum (PETM, 56.3 million years ago) event. We investigated the tropical forest response to this rapid warming by evaluating the palynological record of three stratigraphic sections in eastern Colombia and western Venezuela. We observed a rapid and distinct increase in plant diversity and origination rates, with a set of new taxa, mostly angiosperms, added to the existing stock of low-diversity Paleocene flora. There is no evidence for enhanced aridity in the northern Neotropics. The tropical rainforest was able to persist under elevated temperatures and high levels of atmospheric carbon dioxide, in contrast to speculations that tropical ecosystems were severely compromised by heat stress.


Assuntos
Ecossistema , Aquecimento Global , Plantas , Árvores , Clima Tropical , Atmosfera , Biodiversidade , Dióxido de Carbono , Colômbia , Extinção Biológica , Magnoliopsida , Pólen , Esporos , Temperatura , Tempo , Venezuela
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