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Reimold W.U.,Leibniz Institute for Evolution and Biodiversity Science | Reimold W.U.,Humboldt University of Berlin | Koeberl C.,University of Vienna
Journal of African Earth Sciences | Year: 2014

More than 50. years of space and planetary exploration and concomitant studies of terrestrial impact structures have demonstrated that impact cratering has been a fundamental process - an essential part of planetary evolution - ever since the beginning of accretion and has played a major role in planetary evolution throughout the solar system and beyond. This not only pertains to the development of the planets but to evolution of life as well. The terrestrial impact record represents only a small fraction of the bombardment history that Earth experienced throughout its evolution. While remote sensing investigations of planetary surfaces provide essential information about surface evolution and surface processes, they do not provide the information required for understanding the ultra-high strain rate, high-pressure, and high-temperature impact process. Thus, hands-on investigations of rocks from terrestrial impact craters, shock experimentation for pressure and temperature calibration of impact-related deformation of rocks and minerals, as well as parameter studies pertaining to the physics and chemistry of cratering and ejecta formation and emplacement, and laboratory studies of impact-generated lithologies are mandatory tools. These, together with numerical modeling analysis of impact physics, form the backbone of impact cratering studies.Here, we review the current status of knowledge about impact cratering - and provide a detailed account of the African impact record, which has been expanded vastly since a first overview was published in 1994. No less than 19 confirmed impact structures, and one shatter cone occurrence without related impact crater are now known from Africa. In addition, a number of impact glass, tektite and spherule layer occurrences are known. The 49 sites with proposed, but not yet confirmed, possible impact structures contain at least a considerable number of structures that, from available information, hold the promise to be able to expand the African impact record drastically - provided the political conditions for safe ground-truthing will become available. The fact that 28 structures have also been shown to date NOT to be of impact origin further underpins the strong interest in impact in Africa. We hope that this review stimulates the education of students about impact cratering and the fundamental importance of this process for Earth - both for its biological and geological evolution. This work may provide a reference volume for those workers who would like to search for impact craters and their ejecta in Africa. © 2014 Elsevier Ltd.

Bibi F.,Leibniz Institute for Evolution and Biodiversity Science | Kiessling W.,Leibniz Institute for Evolution and Biodiversity Science | Kiessling W.,Friedrich - Alexander - University, Erlangen - Nuremberg
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

Much debate has revolved around the question of whether the mode of evolutionary and ecological turnover in the fossil record of African mammals was continuous or pulsed, and the degree to which faunal turnover tracked changes in global climate. Here, we assembled and analyzed large specimen databases of the fossil record of eastern African Bovidae (antelopes) and Turkana Basin large mammals. Our results indicate that speciation and extinction proceeded continuously throughout the Pliocene and Pleistocene, as did increases in the relative abundance of arid-adapted bovids, and in bovid body mass. Species durations were similar among clades with different ecological attributes. Occupancy patterns were unimodal, with long and nearly symmetrical origination and extinction phases. A single origination pulse may be present at 2.01.75 Ma, but besides this, there is no evidence that evolutionary or ecological changes in the eastern African record tracked rapid, 100,000-y-scale changes in global climate. Rather, eastern African large mammal evolution tracked global or regional climatic trends at long (million year) time scales, while local, basin-scale changes (e.g., tectonic or hydrographic) and biotic interactions ruled at shorter timescales.

Gomez B.,CNRS Geological Laboratory of Lyon: earth, planets and environment | Daviero-Gomez V.,CNRS Geological Laboratory of Lyon: earth, planets and environment | Coiffard C.,Leibniz Institute for Evolution and Biodiversity Science | Martin-Closas C.,University of Barcelona | Dilcher D.L.,Indiana University Bloomington
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

The early diversification of angiosperms in diverse ecological niches is poorly understood. Some have proposed an origin in a darkened forest habitat and others an open aquatic or near aquatic habitat. The research presented here centers on Montsechia vidalii, first recovered from lithographic limestone deposits in the Pyrenees of Spain more than 100 y ago. This fossil material has been poorly understood and misinterpreted in the past. Now, based upon the study of more than 1,000 carefully prepared specimens, a detailed analysis of Montsechia is presented. The morphology and anatomy of the plant, including aspects of its reproduction, suggest that Montsechia is sister to Ceratophyllum (whenever cladistic analyses are made with or without a backbone). Montsechia was an aquatic angiosperm living and reproducing below the surface of the water, similar to Ceratophyllum. Montsechia is Barremian in age, raising questions about the very early divergence of the Ceratophyllum clade compared with its position as sister to eudicots in many cladistic analyses. Lower Cretaceous aquatic angiosperms, such as Archaefructus and Montsechia, open the possibility that aquatic plants were locally common at a very early stage of angiosperm evolution and that aquatic habitats may have played a major role in the diversification of some early angiosperm lineages. © 2015, National Academy of Sciences. All rights reserved.

Wunnemann K.,Leibniz Institute for Evolution and Biodiversity Science | Weiss R.,Virginia Polytechnic Institute and State University
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2015

When a cosmic object strikes the Earth, it most probably falls into an ocean. Depending on the impact energy and the depth of the ocean, a large amount of water is displaced, forming a temporary crater in the water column. Large tsunami-like waves originate from the collapse of the cavity in the water and the ejecta splash. Because of the far-reaching destructive consequences of such waves, an oceanic impact has been suggested to be more severe than a similarsized impact on land; in other words, oceanic impacts may punch over their weight. This review paper summarizes the process of impact-induced wave generation and subsequent propagation, whether the wave characteristic differs from tsunamis generated by other classical mechanisms, and what methods have been applied to quantify the consequences of an oceanic impact. Finally, the impact-induced tsunami hazard will be evaluated by means of the Eltanin impact event. Copyright © 2015 The Author(s) Published by the Royal Society.

Dunlop J.A.,Leibniz Institute for Evolution and Biodiversity Science | De Oliveira Bernardi L.F.,Campus Universitario
Naturwissenschaften | Year: 2014

A fossil opilioacarid mite (Parasitiformes: Opilioacarida) in Burmese amber is described as ?Opilioacarus groehni sp. nov. This ca. 99 Ma record (Upper Cretaceous: Cenomanian) represents only the third fossil example of this putatively basal mite lineage, the others originating from Eocene Baltic amber (ca. 44-49 Ma). Our new record is not only the oldest record of Opilioacarida, but it is also one of the oldest examples of the entire Parasitiformes clade. The presence of Opilioacarida - potentially Opiloacarus - in the Cretaceous of SE Asia suggests that some modern genus groups were formerly more widely distributed across the northern hemisphere, raising questions about previously suggested Gondwanan origins for these mites. © 2014 Springer-Verlag Berlin Heidelberg.

Knaust D.,Statoil | Neumann C.,Leibniz Institute for Evolution and Biodiversity Science
Earth-Science Reviews | Year: 2016

The ichnogenus Asteriacites von Schlotheim, 1820 results from the resting activity of sea stars (Asteroidea) and brittle stars (Ophiuroidea) and is a common cosmopolitan trace fossil recorded from the Cambrian to the Quaternary. Its taxonomic validity has recently been challenged because of the lack of type material, but newly discovered specimens from the von Schlotheim collection in the Natural History Museum (Museum für Naturkunde) of Berlin justify the validity of this ichnotaxon and thus make it the oldest valid ichnogenus name. The ichnofamily Asteriacitidae nov. is established for radial imprints and shallowly excavated pits and contains the ichnogenera Asteriacites (type ichnogenus), Asterichnites Brown and Vokes, 1944, and Ichnocumulus Seilacher, 1956. Basic morphology is regarded as the main ichnotaxobase for distinction of ichnogenera, while overall morphology in combination with morphometry (e.g. length/width ratio of arm imprints) aids the distinction of ichnospecies. Consequently, three Asteriacites ichnospecies can be differentiated, which are (with decreasing length/width ratio of their arm imprints) A. lumbricalis von Schlotheim, 1820; A. stelliformis (Miller and Dyer, 1878) Osgood, 1970; and A. quinquefolius (Quenstedt, 1876) Seilacher, 1953. Moreover, arcuate or hook-shaped imprints occurring isolated or clustered (e.g. trackways) are assigned to the ichnofamily Biformitidae nov., containing Biformites Linck, 1949 (type ichnogenus); Arcichnus Sutcliffe, 1997; and Harpichnus Vallon et al., 2015 (produced by moulting of arthropods). Burrows attributed to asterozoan activity are briefly mentioned. © 2016 Elsevier B.V.

Jepson J.E.,Leibniz Institute for Evolution and Biodiversity Science
Zootaxa | Year: 2015

There are 32 individual specimens of Mantispidae (Insecta: Neuroptera) currently recorded from the fossil record, the oldest of which dates back to the Lower Jurassic. These include 19 described species (in 16 genera), 1 specimen described to genus level and 9 unnamed specimens The specimens have been assigned to the extant subfamilies Drepanicinae (4), Mantispinae (10), Symphrasinae (1), and the extinct subfamily Mesomantispinae (16), with one incertae sedis within Mantispidae. There are currently no known fossil representatives of the subfamily Calomantispinae. Mesithoninae has been removed from Mantispidae and placed back within Berothidae. The species Mesithone carnaria and M. monstruosa, however, are true mantispids and have been removed from Mesithone and placed within a new genus Karataumantispa gen. nov. in the subfamily Mesomantispinae. The current state of knowledge of the fossil record of Mantispidae is reviewed and a key to the genera of Mesomantispinae is provided. Copyright © 2015 Magnolia Press.

Frobisch N.B.,Leibniz Institute for Evolution and Biodiversity Science | Bickelmann C.,Leibniz Institute for Evolution and Biodiversity Science | Olori J.C.,State University of New York at Oswego | Witzmann F.,Leibniz Institute for Evolution and Biodiversity Science | Witzmann F.,Brown University
Nature | Year: 2015

Among extant tetrapods, salamanders are unique in showing a reversed preaxial polarity in patterning of the skeletal elements of the limbs, and in displaying the highest capacity for regeneration, including full limb and tail regeneration. These features are particularly striking as tetrapod limb development has otherwise been shown to be a highly conserved process. It remains elusive whether the capacity to regenerate limbs in salamanders is mechanistically and evolutionarily linked to the aberrant pattern of limb development; both are features classically regarded as unique to urodeles. New molecular data suggest that salamander-specific orphan genes play a central role in limb regeneration and may also be involved in the preaxial patterning during limb development. Here we show that preaxial polarity in limb development was present in various groups of temnospondyl amphibians of the Carboniferous and Permian periods, including the dissorophoids Apateon and Micromelerpeton, as well as the stereospondylomorph Sclerocephalus. Limb regeneration has also been reported in Micromelerpeton, demonstrating that both features were already present together in antecedents of modern salamanders 290 million years ago. Furthermore, data from lepospondyl 'microsaurs' on the amniote stem indicate that these taxa may have shown some capacity for limb regeneration and were capable of tail regeneration, including re-patterning of the caudal vertebral column that is otherwise only seen in salamander tail regeneration. The data from fossils suggest that salamander-like regeneration is an ancient feature of tetrapods that was subsequently lost at least once in the lineage leading to amniotes. Salamanders are the only modern tetrapods that retained regenerative capacities as well as preaxial polarity in limb development. ©2015 Macmillan Publishers Limited. All rights reserved.

Nurnberg S.,Leibniz Institute for Evolution and Biodiversity Science | Aberhan M.,Leibniz Institute for Evolution and Biodiversity Science
Nature Communications | Year: 2015

Studies of the dynamics of biodiversity often suggest that diversity has upper limits, but the complex interplay between ecological and evolutionary processes and the relative role of biotic and abiotic factors that set upper limits to diversity are poorly understood. Here we statistically assess the relationship between global biodiversity and the degree of habitat specialization of benthic marine invertebrates over the Phanerozoic eon. We show that variation in habitat specialization correlates positively with changes in global diversity, that is, times of high diversity coincide with more specialized faunas. We identify the diversity dynamics of specialists but not generalists, and origination rates but not extinction rates, as the main drivers of this ecological interdependence. Abiotic factors fail to show any significant relationship with specialization. Our findings suggest that the overall level of specialization and its fluctuations over evolutionary timescales are controlled by diversity-dependent processes - driven by interactions between organisms competing for finite resources. © 2015 Macmillan Publishers Limited. All rights reserved.

News Article | February 9, 2017
Site: www.sciencenews.org

A cautionary tale in evolutionary theory is coming straight from the horse’s mouth. When ancient horses diversified into new species, those bursts of evolution weren’t accompanied by drastic changes to horse teeth, as scientists have long thought. A new evolutionary tree of horses reveals three periods when several new species emerged, scientists report in the Feb. 10 Science. The researchers found that changes in teeth morphology and body size didn’t change very much during these periods of rapid speciation. “This knocks traditional notions that rapid diversification of new species comes with morphological diversification as well,” says paleontologist Bruce MacFadden of the University of Florida in Gainesville. “This is a very sophisticated and important paper.” The emergence of several new species in a relatively short time is often accompanied by the evolution of special new traits. Classic notions of evolution say that these traits — such as longer teeth with extensive enamel — are adaptive, enabling an animal to succeed in a particular environment. In horses, the evolution of such teeth might permit a shift from browsing on leafy, shrubby trees to grazing on grasses in open spaces with windblown dust and grit. “You can’t live on a grassland as a grazer and have short teeth,” says MacFadden, an expert in horse evolution. “You’ll wear your teeth down and that’s not a recipe for success as a species.” Similarly, a big change in body size can indicate a move to a new environment. Animals that live in forests tend to be smaller and more solitary than the larger herd animals that live in open grasslands. Paleontologist Juan Cantalapiedra and colleagues compiled decades of previous work to create an evolutionary tree of 138 horse species (seven of which exist today), spanning roughly 18 million years. The tree reveals three major branchings of new species: a North American burst between 15 million and 18 million years ago, and two bursts coinciding with dispersals into Eurasia about 11 million and 4.5 million years ago. The researchers expected to see evidence of an “adaptive radiation,” major changes in teeth and body size that allowed the new horse species to succeed. But rates of body size evolution didn’t differ much in sections of the family tree with low and high speciation rates. And rates of change in tooth characteristics were actually lower in sections of the tree with fast speciation rates, the team reports. “It’s very tempting to see some change in body size, for example, and say, ‘Oh, that’s adaptive radiation,’” says Cantalapiedra, of the Leibniz Institute for Evolution and Biodiversity Science at the Museum für Naturkunde in Berlin. “But that’s not what we see.” Cantalapiedra and his collaborators speculate that during the periods of rapid speciation, the environment was so expansive and productive that there just wasn’t a lot of competition to drive the evolution of adaptive traits. Perhaps, for example, North American grasslands were so rich and dense that there was enough energy for various species to evolve without having to develop traits that gave them an edge. That scenario might be special to horses, says MacFadden, but it might not. Similarly, classic adaptive radiation scenarios might be true in many cases, but as this work shows, not always.

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