Combined data analysis of fossil and living mammals: a Paleogene sister taxon of Placentalia and the antiquity of Marsupialia

The Cretaceous–Paleogene (KPg) boundary, one of Earth’s five major extinction events, occurred just before the appearance of Placentalia in the fossil record. The Gobi Desert, Mongolia and the Western Interior of North America have important fossil mammals occurring just before and after the KPg boundary (e.g. Prodiacodon, Deltatheridium) that have yet to be phylogenetically tested in a character-rich context with molecular data. We present here phylogenetic analyses of >6000 newly scored anatomical observations drawn from six untested fossils and added to the largest existing morphological matrix for mammals. These data are combined with sequence data from 27 nuclear genes. Results show the existence of a new eutherian sister clade to Placentalia, which we name and characterize. The extinct clade Leptictidae is part of this placental sister clade, indicating that the sister clade survived the KPg event to co-exist in ancient ecosystems during the Paleogene radiation of placentals. Analysing the Cretaceous metatherian Deltatheridium in this character-rich context reveals it is a member of Marsupialia, a finding that extends the minimum age of Marsupialia before the KPg boundary. Numerous shared-derived features from multiple anatomical systems support the assignment of Deltatheridium to Marsupialia. Computed tomography scans of exquisite new specimens better document the marsupial-like dental replacement pattern of Deltatheridium. The new placental sister clade has both Asian and North American species, and is ancestrally characterized by shared derived features such as a hind limb modified for saltatorial locomotion

RESEARCH Open Access

Involving consumers and the community in the development of a diagnostic instrument for fetal alcohol spectrum disorders in Australi

Gills and epipods in Penaeoidea.

<p>Among the shallow-water clades, Agripenaeina (and other members of Penaeini) have the highest number of gills and epipods. Deep-water clades have the highest numbers across all of Penaeoidea. Listed are the total numbers of gills and epipods per side, based on the ancestral states for each clade, using parsimony. App = associated appendix, Max = maxilliped, Per = pereiopod.</p

Members of Agripenaeina and Trachypenaeini from the Late Jurassic.

<p>^†<i>Antrimpos speciosus</i> (panels <b>a</b> and <b>b</b>, CM-33420) and ^<b>†</b><i>Drobna deformis</i> (panels <b>e</b> and <b>f</b>, CM-29467), fossils from the Solnhofen limestone, Germany (ca. 145 mya [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158840#pone.0158840.ref018" target="_blank">18</a>]) preserve key features that link them phylogenetically to shallow-water penaeoideans. ^†<i>Antrimpos speciosus</i> belongs to Agripenaeina, the clade accounting for 90% of shrimp farmed for human consumption, and is shown in comparison to <i>Penaeus monodon</i> (<b>c</b>, giant tiger shrimp), a living member of Agripenaeina. ^<b>†</b><i>Drobna deformis</i> is the sister taxon of <i>Sicyonia</i> (Trachypenaini), and is shown in comparison to the living <i>Sicyonia lancifer</i> (<b>g</b>, rock shrimp). <b>d</b> and <b>h</b> show derived features shared by fossil and living shrimp. Additional synapomorphies for all clades are listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158840#pone.0158840.s006" target="_blank">S2</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158840#pone.0158840.s007" target="_blank">S3</a> Tables. Scale bars = 3 cm.</p

Minimum age phylogenetic tree of Penaeoidea.

<p>Agripenaeina, the clade of farmed shrimp, acquired a large body size despite the physiological constraints of their warm and shallow-water habitats. This clade is at least 145 my old because it includes a Late Jurassic species (^<b>†</b><i>Antrimpos speciosus</i>) that inhabited the warm waters preserved in the Late Jurassic Solnhofen limestone [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158840#pone.0158840.ref014" target="_blank">14</a>,<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158840#pone.0158840.ref015" target="_blank">15</a>]. Ecological associations between shallow-water penaeoideans and mangrove forests occurred independently more than once, as clades of mangrove-associated shrimp (e.g., Agripenaeina and Trachypenaeini) predate the proposed Late Cretaceous origin of modern mangroves [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158840#pone.0158840.ref016" target="_blank">16</a>]. Shrimp silhouettes illustrate differences in maximum body size for each clade. Topology shown emerges from parsimony (strict consensus of 24 trees) and Bayesian analyses, with some Bayesian incongruences noted in the Extended Results. Topology mapped to stratigraphic record with range extensions (cones) dictated by fossil placements (black dots indicate first appearance datum in the stratigraphic record) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158840#pone.0158840.ref017" target="_blank">17</a>]. Bremer Support (blue) and jackknife values over 50% (green) are indicated. Values in parentheses were calculated without fossil taxa (fossil exclusion produces a congruent tree). Bayesian posterior probabilities in black, with values italicized for clades that are congruent except for the placement of ^†<i>Aeger tipularius</i>, which occupies a different position in the Bayesian tree (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158840#pone.0158840.s004" target="_blank">S4 Fig</a>). Tree icon and vertical shading indicate earliest evidence of modern mangroves [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158840#pone.0158840.ref016" target="_blank">16</a>].</p

Ice sheet collapse following a prolonged period of stable sea level during the last interglacial

During the last interglacial period, 127-116 kyr ago, global mean sea level reached a peak of 5-9m above present-day sea level. However, the exact timing and magnitude of ice sheet collapse that contributed to the sea-level highstand is unclear. Here we explore this timing using stratigraphic and geomorphic mapping and uranium-series geochronology of fossil coral reefs and geophysical modelling of sea-level records from Western Australia. We show that between 127 and 119 kyr ago, eustatic sea level remained relatively stable at about 3-4 m above present sea level. However, stratigraphically younger fossil corals with U-series ages of 118.1±1.4 kyr are observed at elevations of up to 9.5 m above present mean sea level. Accounting for glacial isostatic adjustment and localized tectonics, we conclude that eustatic sea level rose to about 9 m above present at the end of the last interglacial. We suggest that in the last few thousand years of the interglacial, a critical ice sheet stability threshold was crossed, resulting in the catastrophic collapse of polar ice sheets and substantial sea-level rise

Response to Comment on “The Placental Mammal Ancestor and the Post–K-Pg Radiation of Placentals”

Tree-building with diverse data maximizes explanatory power. Application of molecular clock models to ancient speciation events risks a bias against detection of fast radiations subsequent to the Cretaceous-Paleogene (K-Pg) event. Contrary to Springer et al., post–K-Pg placental diversification does not require “virus-like” substitution rates. Even constraining clade ages to their model, the explosive model best explains placental evolution.Fil: O’Leary, Maureen A.. Stony Brook University; Estados UnidosFil: Bloch, Jonathan I.. University of Florida; Estados UnidosFil: Flynn, John J.. American Museum Of Natural History; Estados UnidosFil: Gaudin, Timothy J.. University of Tennessee; Estados UnidosFil: Giallombardo, Andres. American Museum Of Natural History; Estados UnidosFil: Giannini, Norberto Pedro. American Museum Of Natural History; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Goldberg, Suzann L.. American Museum Of Natural History; Estados UnidosFil: Kraatz, Brian P.. American Museum Of Natural History; Estados UnidosFil: Luo, Zhe-Xi. University of Chicago; Estados UnidosFil: Meng, Jin. American Museum Of Natural History; Estados UnidosFil: Ni, Xijun. American Museum Of Natural History; Estados UnidosFil: Novacek, Michael J.. American Museum Of Natural History; Estados UnidosFil: Perini, Fernando A.. Universidade Federal do Minas Gerais; BrasilFil: Randall, Zachary. University of Florida; Estados UnidosFil: Rougier, Guillermo Walter. The University Of Louisville; Estados UnidosFil: Sargis, Eric J.. University of Yale; Estados UnidosFil: Silcox, Mary T.. University of Toronto; CanadáFil: Simmons, Nancy B.. American Museum Of Natural History; Estados UnidosFil: Spaulding, Michelle. Carnegie Museum of Natural Histor; Estados UnidosFil: Velazco, Paúl M.. American Museum Of Natural History; Estados UnidosFil: Weksler, Marcelo. Universidade Federal do Rio de Janeiro; BrasilFil: Wible, John R.. American Museum Of Natural History; Estados UnidosFil: Cirranello, Andrea L.. American Museum Of Natural History; Estados Unido