Continental-drift opus turns 100

One hundred years ago this year, the legendary German explorer, geophysicist and meteorologist Alfred Wegener published his milestone book The Origin of Continents and Oceans. His theory of continental drift was initially viewed as heresy by the scientific community, yet his book was later translated into many languages and updated regularly until 1929. For his opus, Wegener assembled an array of geological, palaeontological and geophysical data. They are best explained, he argued, by hypothesizing that major landmasses eventually broke apart and went their separate ways. After his death, his ideas were largely forgotten until the 1960s, when geophysicists demonstrated the phenomenon of sea-floor spreading. Plate tectonics has since gained acceptance as a synthetic theory with huge explanatory power. Wegener died in 1930 while exploring in Greenland. Buried in the ice, his body has sailed westwards at a rate of about 2 centimetres per year on the back of the North American plate. He would have been glad to know that it will have travelled some 20 kilometres in a million years' time — in accordance with his visionary theory

A Ceratopsian Dinosaur from the Lower Cretaceous of Western North America, and the Biogeography of Neoceratopsia

Competing interests: Andrew A. Farke has read the journal's policy and the authors of this manuscript have the following competing interests: Andrew A. Farke is a volunteer section editor and academic editor for PLOS ONE. This does not alter the authors' adherence to PLOS ONE policies on sharing data and materials.Acknowledgments It is a pleasure to offer our most heartfelt thanks to Scott K. Madsen, who found OMNH 34557 and prepared it with consummate skill. We are grateful to James Taylor, Jack Owen, the Keebler family, and the Montana Bureau of Land Management for access to outcrops of the Cloverly Formation. We thank Xu Xing (IVPP) and Hai-Lu You (formerly CAGS-IG) for facilitating access to specimens, Mark Loewen, Joseph Frederickson, Darren Naish, and Leonardo Maiorino for productive discussion and comments, and Roger Burkhalter for assistance in photography. Gary Wisser, from the scientific visualization center at Western University of Health Sciences, is gratefully acknowledged for the high resolution scan of the cranium. Reviews by Peter Makovicky, Hai-Lu You, and editor Peter Wilf improved the manuscript.Author Contributions Conceived and designed the experiments: AAF WDM RLC. Performed the experiments: AAF WDM RLC. Analyzed the data: AAF WDM RLC MJW. Contributed reagents/materials/analysis tools: AAF WDM RLC MJW. Wrote the paper: AAF WDM RLC MJW.The fossil record for neoceratopsian (horned) dinosaurs in the Lower Cretaceous of North America primarily comprises isolated teeth and postcrania of limited taxonomic resolution, hampering previous efforts to reconstruct the early evolution of this group in North America. An associated cranium and lower jaw from the Cloverly Formation (?middle–late Albian, between 104 and 109 million years old) of southern Montana is designated as the holotype for Aquilops americanus gen. et sp. nov. Aquilops americanus is distinguished by several autapomorphies, including a strongly hooked rostral bone with a midline boss and an elongate and sharply pointed antorbital fossa. The skull in the only known specimen is comparatively small, measuring 84 mm between the tips of the rostral and jugal. The taxon is interpreted as a basal neoceratopsian closely related to Early Cretaceous Asian taxa, such as Liaoceratops and Auroraceratops. Biogeographically, A. americanus probably originated via a dispersal from Asia into North America; the exact route of this dispersal is ambiguous, although a Beringian rather than European route seems more likely in light of the absence of ceratopsians in the Early Cretaceous of Europe. Other amniote clades show similar biogeographic patterns, supporting an intercontinental migratory event between Asia and North America during the late Early Cretaceous. The temporal and geographic distribution of Upper Cretaceous neoceratopsians (leptoceratopsids and ceratopsoids) suggests at least intermittent connections between North America and Asia through the early Late Cretaceous, likely followed by an interval of isolation and finally reconnection during the latest Cretaceous.Funding was received from the National Science Foundation (DEB 9401094, 9870173, http://www.nsf.gov); National Geographic Society (5918-97, http://www.nationalgeographic.com/); and American Chemical Society (PRF #38572-AC8, http://www.acs.org). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Yeshttp://www.plosone.org/static/editorial#pee

Les "condylarthres" (ongulés archaïques, Mammalia) du Paléocène inférieur de Tiupampa (Bolivie) : implications sur l'origine des ongulés sud-américains.

La plus ancienne faune de "condylarthres" du Tertiaire sud-américain provient du Paléocène basal de la Formation Santa Lucía à Tiupampa (Bolivie). Elle comprend cinq genres et sept espèces : Molinodus suarezi, Tiuclaenus (T. minutus, T. cotasi n.sp., T. robustus n.sp.), Pucanodus gagnieri, Andinodus boliviensis et Simoclaenus sylvaticus, n.gen., n.sp. Ce travail présente une revue de tous les fossiles précédemment décrits, lesquels sont interprétés à la lumière de nombreux spécimens récemment découverts, incluant trois nouveaux taxons. L \u27échantillon contient 33 mâchoires et 43 dents isolées. Les "condylarthres" de Tiupampa sont inclus dans les Kollpaniinae Marshall Case &amp;Woodburne, 1990 (=Molinodinae Bonaparte, Van Valen &amp; Kramartz, 1993), une sous-famille des Mioclaenidae (Kollpania tiupampina Marshall &amp; Muizon, 1988, l\u27espèce-type de la famille des Kollpaniidae Marshall, Case &amp; Woodburne, 1990, est considérée comme un synonyme plus récent de Tiuclaenus minutus Muizon &amp; Marshall, 1987). Certain des taxons (Molinodus suarezi, Tiuclaenus cotasi)sont bien représentés et les dents jugales de ces derniers sont presque toutes connues. Cependant, certains genres comme Andinodus et Simoclaenus, sont encore mal connus (par quelques dents inférieures seulement pour Andinodus) et, en raison de la pauvreté de cet échantillon, leur position au sein des Kollpaniinae devra être confirmée par la découverte de nouveaux spécimens, en particulier de dents supérieures d\u27Andinodus. Les "condylarthres" de Tiupampa sont, de toute évidence, apparentés aux Mioclaenidae nord-américains, bien qu\u27il ne soit pas possible de les relier avec certitude à un genre précis. Ils partagent avec les formes nord-américaines les caractères dérivés suivants, par comparaison avec Protungulatum: cuspides bulbeuses dont les apex sont rapprochés en vue occlusale ; grand protocone ; plate-forme stylaire très réduite ou perdue ; styles réduits et tendant à s\u27aligner avec les para-et metacristas ; paraconide plaqué contre le métaconide ; entoconide et hypoconulide accolés, voire fusionnés, et formant une crête postéro-linguale oblique. Les principales caractéristiques des Kollpaniinae sont : très gros métaconide renflé, très postérieur au protoconide et envahissant partiellement le bassin du talonide postérieurement ; perte de l\u27entocristide ; hypoconide extrêmement gonflé occupant au moins la moitié labiale du bassin du talonide ; bassin du talonide réduit à un sillon oblique largement ouvert lingualement ; flanc postérieur de l\u27hypoconulide de m3 moins gonflé et moins convexe que chez les autre Mioclaenidae. Les Kollpaniinae ("condylarthres" de Tiupampa et Escribania)sont également considérés comme ayant des relations étroites avec les Didolodontidae et les Litopterna (particulièrement les Protolipternidae). La synapomorphie majeure qui réunit les trois groupes réside dans la morphologie et le développement de la paracristide. Celle-ci est plus étroite que la moitié de la largeur du trigonide, profondément arquée postérieurement, fortement saillante antérieurement et prend attache sur les bords antérieurs à antéro-internes des para-et protoconides. L\u27étude des "condylarthres" de Tiupampa confirme donc l \u27origine septentrionale, au sein des Mioclaenidae, des Didolodontidae et des Litopterna d\u27Amérique du Sud. Une analyse de parcimonie conduit à la monophylie probable du clade incluant les Mioclaenidae d\u27Amérique du Nord, les Kollpaniinae (Mioclaenidae d\u27Amérique du Sud), les Didolodontidae et les Litopterna. Le clade est formellement désigné comme un nouvel ordre de mammifères, les Panameriungulata. Étant donné qu\u27aucune relation étroite fondée sur des caractères dentaires n\u27a pu être mise en évidence avec les autres groupes d\u27ongulés (ou considérés comme tels) sud-américains,-Astrapotheria, Pyrotheria, Xenungulata, Notoungulata-, cette étude donne du poids à l\u27invraisemblance d\u27une origine unique des ongulés sud-américains et met en question la monophylie des Meridiungulata.The oldest known "condylarth "fauna of the Tertiary of South America comes from basal Palaeocene strata of the Santa Lucía Formation at Tiupampa (Bolivia). It includes five genera and seven species: Molinodus suarezi, Tiuclaenus minutus, T. cotasi n.sp., T.robustus n.sp., Pucanodus gagnieri, Andinodus boliviensis, and Simoclaenus sylvaticus, n.gen., n.sp. Thiswork presents a thorough revision of all the fossils previously described, which are interpreted in the light of recently discovered specimens including materials belonging to three new taxa. The sample contains 33 jaws and 43 isolated teeth. The Tiupampa "condylarths" are included in the Kollpaniinae Marshall, Case &amp; Woodburne, 1990 (=Molinodinae Bonaparte, Van Valen &amp; Kramartz, 1993), a subfamily of the Mioclaenidae (Kollpania tiupampina Marshall &amp; Muizon,1988, the type species of the type genus of the Kollpaniidae Marshall, Case &amp; Woodburne, 1990 is regarded as a junior synonym of Tiuclaenus minutus Muizon &amp; Marshall, 1987). Some of the taxa (e.g., Molinodus suarezi, Tiuclaenus cotasi)are well represented and the cheek dentition of the former is almost completely known. However, other genera such as Andinodus and Simoclaenus are still poorly known (a few lower teeth only in the case of Andinodus). Because of their scant representation, their position within the Kollpaniinae still has to be confirmed by the discovery of new specimens,especially upper molars of Andinodus. The Tiupampa "condylarths" are clearly related to the North American Mioclaenidae, although it is not possible to securely relate them to a specific genus. They share with the North American taxa the following derived characters when compared to Protungulatum: bulbous cusps, the apices of which are approximated in occlusal view; protocone enlarged;stylar shelf greatly reduced or lost; styles reduced and tending to be aligned with para-and metacristae; paraconid appressed against metaconid;entoconid and hypoconulid connate to fused, and forming an obliquely oriented posterolingual crest. The major characteristics of the Kollpaniinae are: metaconid well posterior to protoconid, strongly inflated, and invading the talonid basin posteriorly; loss of the entocristid; hypoconid extremely inflated, occupying at least the medial half of the talonid (generally more); talonid basin reduced to an obliquely oriented groove that is widely opened lingually; posterior slope of the hypoconulid of m3 less convex than in the other mioclaenids. The Kollpaniinae (Tiupampa "condylarths" and Escribania)are also regarded as closely related to the Didolodontidae and Litopterna (especially the Protolipternidae). The key synapomorphy of the three groups is the morphology and development of the paracristid, which is narrower than half the width of the trigonid, deeply arched posteriorly, projected anteriorly, and attaching on the anterior to anterolingual side of the proto-and paraconids. Study of the Tiupampa "condylarths" confirms that the South American Didolodontidae and Litopterna have their origins in North American Mioclaenidae. A parsimony analysis establishes the monophyly of the clade including the North American Mioclaenidae, the Kollpaniinae (South American Mioclaenidae), the Didolodontidae, and the Litopterna. This clade is formally designated as a new order of mammals, the Panameriungulata. Because no close relationships based on dental characters were found with the other groups of South American ungulates (or so-called ungulates)-Astrapotheria, Pyrotheria, Xenungulata, Notoungulata-, it reinforces the unlikelihood of a single origin of the South American ungulates and therefore brings into question the monophyly of the Meridiungulata.</p