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Berlin Brandenburg

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  • 1
    Language: English
    In: Science (New York, N.Y.), 23 December 2011, Vol.334(6063), pp.1699-703
    Description: Several groups of tetrapods have expanded sesamoid (small, tendon-anchoring) bones into digit-like structures ("predigits"), such as pandas' "thumbs." Elephants similarly have expanded structures in the fat pads of their fore- and hindfeet, but for three centuries these have been overlooked as mere cartilaginous curiosities. We show that these are indeed massive sesamoids that employ a patchy mode of ossification of a massive cartilaginous precursor and that the predigits act functionally like digits. Further, we reveal clear osteological correlates of predigit joint articulation with the carpals/tarsals that are visible in fossils. Our survey shows that basal proboscideans were relatively "flat-footed" (plantigrade), whereas early elephantiforms evolved the more derived "tip-toed" (subunguligrade) morphology, including the predigits and fat pad, of extant elephants. Thus, elephants co-opted sesamoid bones into a role as false digits and used them for support as they changed their foot posture.
    Keywords: Biological Evolution ; Elephants -- Anatomy & Histology ; Foot -- Anatomy & Histology ; Sesamoid Bones -- Anatomy & Histology ; Toes -- Anatomy & Histology
    ISSN: 00368075
    E-ISSN: 1095-9203
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  • 2
    In: PLoS ONE, 2015, Vol.10(10)
    Description: While supertrees have been built for many vertebrate groups (notably birds, mammals and dinosaurs), invertebrates have attracted relatively little attention. The paucity of supertrees of arthropods is particularly surprising given their economic and ecological importance, as well as their overwhelming contribution to biodiversity. The absence of comprehensive archives of machine-readable source trees, coupled with the need for software implementing repeatable protocols for managing them, has undoubtedly impeded progress. Here we present a supertree of Achelata (spiny, slipper and coral lobsters) as a proof of concept, constructed using new supertree specific software (the Supertree Toolkit; STK) and following a published protocol. We also introduce a new resource for archiving and managing published source trees. Our supertree of Achelata is synthesised from morphological and molecular source trees, and represents the most complete species-level tree of the group to date. Our findings are consistent with recent taxonomic treatments, confirming the validity of just two families: Palinuridae and Scyllaridae; Synaxidae were resolved within Palinuridae. Monophyletic Silentes and Stridentes lineages are recovered within Palinuridae, and all sub-families within Scyllaridae are found to be monophyletic with the exception of Ibacinae. We demonstrate the feasibility of building larger supertrees of arthropods, with the ultimate objective of building a complete species-level phylogeny for the entire phylum using a divide and conquer strategy.
    Keywords: Research Article
    E-ISSN: 1932-6203
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  • 3
    In: Acta Palaeontologica Polonica, 2009, Vol.54(4), p.561-580
    Description: Near the end of the twentieth century, a medium-sized early proboscidean found in Dor El Talha (late Eocene to early Oligocene), Libya, originally identified as a small species of Barytherium, was described as a new species of Numidotherium and designated Numidotherium savagei. Poorly known, this taxon has been excluded from most of the recent debate about the origin and diversification of the order Proboscidea. New specimens described herein show strong structural similarities of the upper teeth with those of bunolophodont early proboscideans (e.g., Moeritherium and Phiomia) and document the shared presence of derived traits in the postcranial skeleton. The newly referred material also demonstrates some unique characteristics of this taxon, notably in its mandibular morphology and the microstructure of its dental enamel. Included for the first time in a cladistic analysis (207 anatomical characters applied to all early tethytheres), N. savagei is distinct from both Numidotherium and Barytherium, and lies in an “intermediate” position between the strictly lophodont Eocene proboscideans and the bunolophodont moeritheres and elephantiforms. Accordingly, the species is herein referred to a new genus, Arcanotherium. New data on its mandibular symphysis and, especially, on its lower incisors loci and morphology, bring new support to a hypothesis of homology between the lower incisors of early proboscideans and the ever-growing lower tusks of the elephantiforms, which are identified here as di1 and i1.
    Keywords: Proboscidea ; 〈kwd〉numidotherium ; 〈kwd〉barytherium ; Elephantiformes ; Phylogeny ; Palaeogene ; Libya
    ISSN: 0567-7920
    E-ISSN: 17322421
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  • 4
    Language: English
    In: Communications Biology, 01 February 2018, Vol.1(1), pp.1-7
    Description: Katie Davis et al. test the hypothesis that ecological traits are linked to diversification in caridean shrimps. They find that transitions from marine to freshwater habitats contributed to higher diversification rates, whereas symbiosis is associated with a slight decrease in diversification rates.
    Keywords: Article;
    E-ISSN: 2399-3642
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  • 5
    Language: English
    In: Communications Biology, 01 November 2018, Vol.1(1), pp.1-8
    Description: Chufei Tang and Katie E. Davis et al. show that an elevated atmospheric CO2 promotes the speciation rates of mosquitoes. They demonstrate that climate change can expedite the evolution of mammalian disease vectors, potentially increasing vector−pathogen...
    Keywords: Article;
    ISSN: Communications Biology
    E-ISSN: 2399-3642
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  • 6
    In: Palaeontology, March 2006, Vol.49(2), pp.421-434
    Description: A new species of (Proboscidea, Mammalia), sp. nov., is described from remains discovered in the early late Eocene locality of Bir El Ater, Algeria. Although mainly represented by isolated teeth, it shows distinct synapomorphies which justify its attribution to the genus , together with exclusive features that led to the creation of the new species. The main characteristic of this new taxon is the almost complete lophodonty shown by its molars, while is commonly regarded as a bunolophodont to bunodont taxon. In addition to this lophodonty, this new taxon shows anatomical features as yet unknown for the genus, but often met within lophodont early proboscidean taxa such as and . Although a revision of the whole genus is outside the scope of this paper, the main controversies and discussion about the definition of species within the genus are discussed. The surprising lophodonty of , together with its small size, its early late Eocene age and the weak molarization of its P support the hypothesis of a lophodont hypothetical ancestor for moeritheres, and therefore strengthen the growing hypothesis of a lophodont dental ancestral morphotype for proboscideans.
    Keywords: Proboscidea ; Moeritherium ; Eocene ; Algeria ; Lophodonty
    ISSN: 0031-0239
    E-ISSN: 1475-4983
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  • 7
    Language: English
    In: Comptes rendus - Palevol, 2010, Vol.9(6), pp.455-461
    Description: Finite element analysis (FEA) is a powerful tool to characterize the functional behaviour of bone. Here we use this technique to study the metacarpal arrangement of the Asian elephant. The objective of this work is to search for valid criteria that distinguish the known natural arrangement among a variety of configurations, including some fictitious ones. FEA yields significant statistical differences within the three arrangements tested. Our calculations suggest that the median value of stress (von Mises) could be a discriminant criterion, at least in graviportal taxa. Such a method could thus be applied to other graviportal organisms such as sauropod dinosaurs. L’analyse par éléments finis (FEA) est un outil puissant permettant de caractériser le comportement fonctionnel de l’os. Nous proposons ici d’utiliser cette technique pour étudier l’arrangement métacarpien de l’éléphant d’Asie, dans le but de mettre en évidence un critère valide permettant de caractériser l’arrangement naturel connu parmi plusieurs possibilités, dont certaines fictives. L’analyse en éléments finis réalisée ici révèle des différences statistiques significatives entre trois arrangements testés, et suggère que la valeur médiane de stress (von Mises) pourrait être un critère discriminant, au moins chez les taxons graviporteurs. Une telle méthode pourrait donc être appliquée à d’autres organismes graviporteurs tels que les dinosaures sauropodes.
    Keywords: Biomechanics ; Functional Morphology ; Metacarpal Arrangement ; Finite Element Analysis ; Stress Distribution ; Biomécanique ; Morphologie Fonctionnelle ; Arrangement Métacarpien ; Analyse En Éléments Finis ; Distribution Du Stress ; Geology
    ISSN: 1631-0683
    E-ISSN: 1777571X
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  • 8
    In: Davis, K. E., Hesketh, T. W., Delmer, C. and Wills, M. A., 2015. Towards a supertree of Arthropoda:a species-level supertree of the spiny, slipper and coral lobsters (Decapoda: Achelata). PLoS ONE, 10 (10), e0140110.
    Description: While supertrees have been built for many vertebrate groups (notably birds, mammals and dinosaurs), invertebrates have attracted relatively little attention. The paucity of supertrees of arthropods is particularly surprising given their economic and ecological importance, as well as their overwhelming contribution to biodiversity. The absence of comprehensive archives of machine-readable source trees, coupled with the need for software implementing repeatable protocols for managing them, has undoubtedly impeded progress. Here we present a supertree of Achelata (spiny, slipper and coral lobsters) as a proof of concept, constructed using new supertree specific software (the Supertree Toolkit; STK) and following a published protocol. We also introduce a new resource for archiving and managing published source trees. Our supertree of Achelata is synthesised from morphological and molecular source trees, and represents the most complete species-level tree of the group to date. Our findings are consistent with recent taxonomic treatments, confirming the validity of just two families: Palinuridae and Scyllaridae; Synaxidae were resolved within Palinuridae. Monophyletic Silentes and Stridentes lineages are recovered within Palinuridae, and all sub-families within Scyllaridae are found to be monophyletic with the exception of Ibacinae. We demonstrate the feasibility of building larger supertrees of arthropods, with the ultimate objective of building a complete species-level phylogeny for the entire phylum using a divide and conquer strategy.
    Source: University of Bath
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  • 9
    Language: English
    In: Journal of Vertebrate Paleontology, 29 January 2010, Vol.30(1), pp.293-299
    Keywords: Geology
    ISSN: 0272-4634
    E-ISSN: 1937-2809
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  • 10
    Language: English
    In: Journal of African Earth Sciences, November 2014, Vol.99, pp.463-489
    Description: The extensive outpouring of the Oligocene Trap basalts over eastern Africa and western Arabia was interrupted by a period of quiescence marked by the deposition of terrestrial sediments. These so-called intertrappean beds are often lignitiferous and yield recurrent floras and faunas, sometimes represented by endemic mammals. We intended to highlight the peculiar features of these sedimentary intercalations using a large-scale approach including eastern Africa and the western Arabian peninsula. Starting from a new mapping in the Eritrean highland, the intertrappean beds resulted a continuous level that was a few tens of meters thick and traceable for some tens of kilometers. They consist of fluvial red, green and gray mudstones and siltstones with subordinate channelized pebbly sandstones, and lignite seams. Two new Ar– Ar datings constraint the age of the intertrappean beds between 29.0 Ma and 23.6 Ma. The outcrops near Mendefera have yielded the remains of two proboscidean families, the Deinotheriidae and the Gomphoteriidae. The morphological grade of the two Mendefera proboscideans would suggest a more derived stage than that of representatives of the same families from other Oligocene African sites (e.g., Chilga, Ethiopia). An Oligocene age could be inferred for them. The occurrence of the genus at Mai Gobro possibly represents the first occurrence of this taxon, while the sp. might represent the oldest occurrence of this taxon in Africa before its dispersal towards Asia and Europe. Proboscideans have also been found in the lowland intertrappean beds of Dogali near Massawa. These sediments were contiguous with the Eritrean highland intertrappean beds during the Oligocene, but are now tectonically displaced from them by two thousand meters of vertical topographical distance. Dogali is also known for the occurrence of possible Deinotheriidae remains and the primitive elephantoid . Entering the Ethiopian highland, an inspection of the Agere Selam (Mekele) intertrappean beds revealed the occurrence of lacustrine limestones and diatomites, which were contrastingly quite subordinate with respect to the fine clastic sediments found in the nearby Amba Alaji area. Further south, the intertrappean section in the Jema valley (100 km north of Addis Ababa and close to the Blue Nile gorge) is 120 m thick with predominant clastic sediments and a few diatomites at the top. Literature information from 35 additional sites, including northern Kenya, Yemen, Sudan and Saudi Arabia sections, confirms the fluvial and lacustrine depositional environment of the intertrappean beds, underlines the interest in their mammal fauna (Chilga, Losodok), and reports exploitable coal seams for some of them. As for the vegetal landscape in which the intertrappean beds were deposited, pollen and plant analysis results indicative of a tropical wet forest, similar to that of present-day western Africa. Another common feature of the intertrappean beds is their relatively limited thickness, averaging a few tens of meters, but reaching a few hundred meters in graben-related basins, such as Delbi Moye in southern Ethiopia. In most cases only thin, lens-shaped successions were deposited above the hummocky topography of their volcanic substratum, commonly unaffected by significant faulting. An average duration of the intertrappean beds is from one to three million years. This time interval is commonly matched by a few tens (or more rarely, hundreds) of meters of sediments left over after erosive episodes or depositional starvation. As to the lateral continuity of the intertrappean beds, the present-day outcrops show large differences: from some tens of kilometers in the Mendefera area, to a few tens of kilometres in the Jema valley, and to a few hundreds meters in the Agere Selam (Mekele) area. Even if it is difficult to quantify the original size of the sedimentation areas, it nevertheless proves that the intertrappean basins exceed thousands of square kilometers in only a single case (Mendefera), but were quite restricted in most cases. Their most likely endorheic and local character, together with a regional ill-defined fluvial network, was the effect of a water-course rerouting caused by the progressive rising of the eastern African and Arabian plateaux. Chronological constraints for the intertrappean beds can be inferred from the age of the hosting Trap succession and by the stratigraphical position that they occupy. Intervolcanic sedimentary episodes are typically found in the basaltic and subordinately rhyolitic successions that followed the 31–29 Ma old basaltic widespread paroxysm. With due caveats deriving from the discontinuous availability of datings specifically dedicated to this issue, we regard the age of the intertrappean beds as mostly encompassed in the interval from 29 to 27 Ma at the transition between the Early and Late Oligocene in the Ethiopia/Yemen Trap core. In marginal areas, such as SW Arabia, Eritrea and Kenya, the volcanic activity above the intertrappean beds resumed later, and its quiescence allowed a more prolonged period of sedimentation. The intertrappean beds fall in the second cooling event of the Oligocene climatic deterioration. During the contemporaneous apparent drop in the global sea-level and closure of the Tethyan Ocean between Arabia and southwestern Asia, connections were established between the African and the Eurasian continents. At that time, southwestern Asia was experiencing severe aridity with faunal exchanges toward the luxuriously vegetated eastern Africa.
    Keywords: Intertrappean Beds ; Volcanic Quiescence ; Oligocene Mammal Radiation ; Deinotheriidae ; Gomphotheriidae ; Proboscidean Datum Event ; Geology
    ISSN: 1464-343X
    E-ISSN: 1879-1956
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