ALBERT

Description: Understanding how ecological communities are organized and how they change through time is critical to predicting the effects of climate change. Recent work documenting the co-occurrence structure of modern communities found that most significant species pairs co-occur less frequently than would be expected by chance. However, little is known about how co-occurrence structure changes through time. Here we evaluate changes in plant and animal community organization over geological time by quantifying the co-occurrence structure of 359,896 unique taxon pairs in 80 assemblages spanning the past 300 million years. Co-occurrences of most taxon pairs were statistically random, but a significant fraction were spatially aggregated or segregated. Aggregated pairs dominated from the Carboniferous period (307 million years ago) to the early Holocene epoch (11,700 years before present), when there was a pronounced shift to more segregated pairs, a trend that continues in modern assemblages. The shift began during the Holocene and coincided with increasing human population size and the spread of agriculture in North America. Before the shift, an average of 64% of significant pairs were aggregated; after the shift, the average dropped to 37%. The organization of modern and late Holocene plant and animal assemblages differs fundamentally from that of assemblages over the past 300 million years that predate the large-scale impacts of humans. Our results suggest that the rules governing the assembly of communities have recently been changed by human activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lyons, S Kathleen -- Amatangelo, Kathryn L -- Behrensmeyer, Anna K -- Bercovici, Antoine -- Blois, Jessica L -- Davis, Matt -- DiMichele, William A -- Du, Andrew -- Eronen, Jussi T -- Faith, J Tyler -- Graves, Gary R -- Jud, Nathan -- Labandeira, Conrad -- Looy, Cindy V -- McGill, Brian -- Miller, Joshua H -- Patterson, David -- Pineda-Munoz, Silvia -- Potts, Richard -- Riddle, Brett -- Terry, Rebecca -- Toth, Aniko -- Ulrich, Werner -- Villasenor, Amelia -- Wing, Scott -- Anderson, Heidi -- Anderson, John -- Waller, Donald -- Gotelli, Nicholas J -- England -- Nature. 2016 Jan 7;529(7584):80-3. doi: 10.1038/nature16447. Epub 2015 Dec 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington DC 20013, USA. ; Department of Environmental Science and Biology, The College at Brockport - SUNY, Brockport, New York 14420, USA. ; School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California 95343, USA. ; Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06520, USA. ; Hominid Paleobiology Doctoral Program, Center for the Advanced Study of Hominid Paleobiology, Department of Anthropology, George Washington University, Washington DC 20052, USA. ; Department of Geosciences and Geography, University of Helsinki, PO Box 64, 00014 University of Helsinki, Finland. ; School of Social Science, The University of Queensland, Brisbane, Queensland 4072, Australia. ; Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington DC 20013, USA. ; Center for Macroecology, Evolution and Climate, University of Copenhagen, Copenhagen 2100, Denmark. ; Biological Sciences Graduate Program, University of Maryland, College Park, Maryland 20742, USA. ; Florida Museum of Natural History, University of Florida, Gainsville, Florida 32611, USA. ; Department of Entomology, University of Maryland College Park, College Park, Maryland 20742, USA. ; Key Lab of Insect Evolution and Environmental Changes, Capital Normal University, Beijing 100048, China. ; Department of Integrative Biology and Museum of Paleontology, University of California Berkeley, Berkeley, California 94720, USA. ; School Biology and Ecology &Sustainability Solutions Initiative, University of Maine, Orono, Maine 04469, USA. ; Department of Geology, University of Cincinnati, Cincinnati, Ohio 45221, USA. ; Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia. ; Department of Anthropology, Human Origins Program, National Museum of Natural History, Smithsonian Institution, Washington DC 20013, USA. ; School of Life Sciences, University of Nevada-Las Vegas, Las Vegas, Nevada 89154, USA. ; Department of Integrative Biology, Oregon State University, Corvallis, Oregon 97331, USA. ; Chair of Ecology and Biogeography, Nicolaus Copernicus University, Lwowska 1, 87-100 Torun, Poland. ; Evolutionary Studies Institute, University of the Witwatersrand, Jorissen Street, Braamfontein, Johannesburg 2001, South Africa. ; Department of Botany, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA. ; Department of Biology, University of Vermont, Burlington, Vermont 05405, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26675730" target="_blank"〉PubMed〈/a〉

Description: Sauropod dinosaurs are rare in the Cretaceous North American fossil record in general and are absent from that record for most of the Late Cretaceous. Sonorasaurus thompsoni from the Turney Ranch Formation of the Bisbee Group of Arizona, USA, potentially represents one of the youngest sauropods before their ca. 30-million-year-long hiatus from the record. The anatomy of Sonorasaurus has only been briefly described, its taxonomic validity has been questioned, several hypotheses have been proposed regarding its phylogenetic relationships, and its life history, geologic age, and reported paleoenvironment are ambiguous. Herein we assess the systematics, paleoenvironment, life history, and geologic age of Sonorasaurus based on firsthand observation, bone histology, and fieldwork in the holotypic quarry and environs. The validity of S . thompsoni is substantiated by autapomorphies. Cladistic analysis firmly places it within the Brachiosauridae, in contrast to results of some recent analyses. Bone histology suggests that the only known exemplar of Sonorasaurus grew slowly and sporadically compared to other sauropods and was approaching its adult size. In contrast with previous assessments of a coastal/estuarine paleoenvironment for the Turney Ranch Formation, our sedimentological and plant macrofossil data indicate that Sonorasaurus lived in a semiarid, low relief evergreen woodland that received highly variable (perhaps seasonal) precipitation. We obtained detrital zircons from the holotypic quarry for U-Pb dating, which only yielded Barremian-aged and older grains, whereas other radiometric and biostratigraphic data suggest that the sediments at the quarry were deposited near the Albian-Cenomanian boundary. Sonorasaurus is taxonomically valid, represents one of the geologically youngest brachiosaurid sauropods, and inhabited a harsh inland evergreen-dominated woodland environment that limited its growth. A review of other Bisbee Group dinosaurs suggests that its fauna, although poorly sampled, exhibits broad similarity to those from coeval North American horizons, reinforcing the apparent faunal homogeneity at the time.

Description: The diversification of flowering plants and marked turnover in vertebrate faunas during the mid-Cretaceous transformed terrestrial communities, but the transition is obscured by reduced terrestrial deposition attributable to high sea levels. We report a new fossil assemblage from multiple localities in the Upper Cretaceous Ferron Sandstone Member of the Mancos Shale Formation in Utah. The fossils date to the Turonian, a severely underrepresented interval in the terrestrial fossil record of North America. A large silicified log (maximum preserved diameter, 1.8 m; estimated height, ca. 50 m) is assigned to the genus Paraphyllanthoxylon ; it is the largest known pre-Campanian angiosperm and the earliest documented occurrence of an angiosperm tree more than 1.0 m in diameter. Foliage and palynomorphs of ferns, conifers, and angiosperms confirm the presence of mixed forest or woodland vegetation. Previously known terrestrial vertebrate remains from the Ferron Sandstone Member include fish teeth, two short dinosaur trackways, and a pterosaur; we report the first turtle and crocodilian remains and an ornithopod sacrum. Previous studies indicate that angiosperm trees were present by the Cenomanian, but this discovery demonstrates that angiosperm trees approaching 2 m in diameter were part of the forest canopies across southern North America by the Turonian (~92 million years ago), nearly 15 million years earlier than previously thought.