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Education in Twins and Their Parents Across Birth Cohorts Over 100 years: An Individual-Level Pooled Analysis of 42-Twin Cohorts
- Karri Silventoinen, Aline Jelenkovic, Antti Latvala, Reijo Sund, Yoshie Yokoyama, Vilhelmina Ullemar, Catarina Almqvist, Catherine A. Derom, Robert F. Vlietinck, Ruth J. F. Loos, Christian Kandler, Chika Honda, Fujio Inui, Yoshinori Iwatani, Mikio Watanabe, Esther Rebato, Maria A. Stazi, Corrado Fagnani, Sonia Brescianini, Yoon-Mi Hur, Hoe-Uk Jeong, Tessa L. Cutler, John L. Hopper, Andreas Busjahn, Kimberly J. Saudino, Fuling Ji, Feng Ning, Zengchang Pang, Richard J. Rose, Markku Koskenvuo, Kauko Heikkilä, Wendy Cozen, Amie E. Hwang, Thomas M. Mack, Sisira H. Siribaddana, Matthew Hotopf, Athula Sumathipala, Fruhling Rijsdijk, Joohon Sung, Jina Kim, Jooyeon Lee, Sooji Lee, Tracy L. Nelson, Keith E. Whitfield, Qihua Tan, Dongfeng Zhang, Clare H. Llewellyn, Abigail Fisher, S. Alexandra Burt, Kelly L. Klump, Ariel Knafo-Noam, David Mankuta, Lior Abramson, Sarah E. Medland, Nicholas G. Martin, Grant W. Montgomery, Patrik K. E. Magnusson, Nancy L. Pedersen, Anna K. Dahl Aslan, Robin P. Corley, Brooke M. Huibregtse, Sevgi Y. Öncel, Fazil Aliev, Robert F. Krueger, Matt McGue, Shandell Pahlen, Gonneke Willemsen, Meike Bartels, Catharina E. M. van Beijsterveldt, Judy L. Silberg, Lindon J. Eaves, Hermine H. Maes, Jennifer R. Harris, Ingunn Brandt, Thomas S. Nilsen, Finn Rasmussen, Per Tynelius, Laura A. Baker, Catherine Tuvblad, Juan R. Ordoñana, Juan F. Sánchez-Romera, Lucia Colodro-Conde, Margaret Gatz, David A. Butler, Paul Lichtenstein, Jack H. Goldberg, K. Paige Harden, Elliot M. Tucker-Drob, Glen E. Duncan, Dedra Buchwald, Adam D. Tarnoki, David L. Tarnoki, Carol E. Franz, William S. Kremen, Michael J. Lyons, José A. Maia, Duarte L. Freitas, Eric Turkheimer, Thorkild I. A. Sørensen, Dorret I. Boomsma, Jaakko Kaprio
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- Journal:
- Twin Research and Human Genetics / Volume 20 / Issue 5 / October 2017
- Published online by Cambridge University Press:
- 04 October 2017, pp. 395-405
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Whether monozygotic (MZ) and dizygotic (DZ) twins differ from each other in a variety of phenotypes is important for genetic twin modeling and for inferences made from twin studies in general. We analyzed whether there were differences in individual, maternal and paternal education between MZ and DZ twins in a large pooled dataset. Information was gathered on individual education for 218,362 adult twins from 27 twin cohorts (53% females; 39% MZ twins), and on maternal and paternal education for 147,315 and 143,056 twins respectively, from 28 twin cohorts (52% females; 38% MZ twins). Together, we had information on individual or parental education from 42 twin cohorts representing 19 countries. The original education classifications were transformed to education years and analyzed using linear regression models. Overall, MZ males had 0.26 (95% CI [0.21, 0.31]) years and MZ females 0.17 (95% CI [0.12, 0.21]) years longer education than DZ twins. The zygosity difference became smaller in more recent birth cohorts for both males and females. Parental education was somewhat longer for fathers of DZ twins in cohorts born in 1990–1999 (0.16 years, 95% CI [0.08, 0.25]) and 2000 or later (0.11 years, 95% CI [0.00, 0.22]), compared with fathers of MZ twins. The results show that the years of both individual and parental education are largely similar in MZ and DZ twins. We suggest that the socio-economic differences between MZ and DZ twins are so small that inferences based upon genetic modeling of twin data are not affected.
Stratigraphy, mammalian paleontology, paleoecology, and age correlation of the Wasatch Formation, Fossil Butte National Monument, Wyoming
- Gregg F. Gunnell, John-Paul Zonneveld, William S. Bartels
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- Journal:
- Journal of Paleontology / Volume 90 / Issue 5 / September 2016
- Published online by Cambridge University Press:
- 14 September 2016, pp. 981-1011
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Fieldwork conducted in the Wasatch Formation in and around Fossil Butte has yielded a diverse assemblage of early Eocene vertebrates. Fossil vertebrates are distributed through three discrete stratigraphic intervals within the uppermost 180 m of the main body of the Wasatch Formation underlying the Green River Formation. These assemblages were derived primarily from fluvial overbank mudstone units overprinted with variably well-developed paleosols. The lowest (20 m) and highest (60 m) sections are characterized by less mature and more hydromorphic paleosols, whereas the middle section (100 m) is typified by more mature paleosols and more abundant channel sandstones.
The combined assemblages contain at least 46 species of mammals. Faunal characteristics include high abundances of equid perissodactyls and a relatively high abundance and diversity of notharctines primates, an apparent absence of omomyid primates, relatively high rodent diversity, and relatively diverse and abundant artiodactyls. One new genus (Eoictops new genus) and three new species (Eoictops novaceki new species, Palaeosinopa lacus new species, and ?Notoparamys blochi new species) are included in the Fossil Butte assemblage. Also recorded are late occurrences of two hyopsodontid condylarths and an early occurrence of a rare phenacodontid condylarth. The relatively high abundances of equids and notharctines suggest that vertebrate samples were derived from relatively open paleohabitats that included forested areas along water courses.
All three assemblages contain characteristic Lysitean (Wasatchian biochron Wa-6) elements, but the occurrence of the palaeotheriid perissodactyl Lambdotherium in the uppermost horizon indicates a Lostcabinian (Wa-7) age for at least the top of the Wasatch Formation. The overlying predominantly fish-bearing Fossil Butte Member of the Green River Formation also contains Lambdotherium and is therefore Wa-7 in age as well.
Borings in early Eocene turtle shell from the Wasatch Formation, South Pass, Wyoming
- John-Paul Zonneveld, William S. Bartels, Gregg F. Gunnell, Luke P. McHugh
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- Journal:
- Journal of Paleontology / Volume 89 / Issue 5 / September 2015
- Published online by Cambridge University Press:
- 29 March 2016, pp. 802-820
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Borings in fossil turtle shells collected from the lowermost beds of the early Eocene Cathedral Bluffs Tongue of the Wasatch Formation in the northwestern part of the Green River Basin near South Pass, Wyoming, are herein described. Individual turtle shells in the study area are characterized by as few as one or two and as many as >100 borings. The borings include both non-penetrative forms (those which do not pass fully though the shell) as well as penetrative forms (those which pass fully from the exterior to the interior surface of the shell). All non-penetrative forms occur on external surfaces of the carapace and plastron (i.e. those that would have been accessible while the host taxon was alive). Two new ichnogenera and four new ichnospecies are established to describe these borings. Karethraichnus (new ichnogenus) includes three ichnospecies: K. lakkos (new ichnospecies), K. kulindros (new ichnospecies), and K. fiale (new ichnospecies). Karethraichnus lakkos are shallow (non-penetrating), hemispherical pits with rounded, to flattened bases. Karethraichnus kulindros are deep, non-penetrative traces with a cylindrical profile, an axis approximately perpendicular to the substrate surface and with rounded to flattened, hemispherical termini. Karethraichnus fiale are penetrative traces with a cylindrical to bi-convex or flask-shaped profile, and an axis approximately perpendicular to the substrate surface. Thatchtelithichnus (new ichnogenus) Thatchtelithichnus holmani (new ichnospecies) consist of non-penetrative borings into a bone substrate. They consist of a ring-shaped trace, with a central pedestal or platform. The position of the borings on the shells, and evidence of syn-emplacement healing of the borings in several of the turtles, indicates that these borings were emplacement by ectoparasites/mesoparasites while the animals were living. Similar traces in modern emydid turtles are attributed to ticks, leeches, or spirorchid liver flukes.
Zygosity Differences in Height and Body Mass Index of Twins From Infancy to Old Age: A Study of the CODATwins Project
- Aline Jelenkovic, Yoshie Yokoyama, Reijo Sund, Chika Honda, Leonie H Bogl, Sari Aaltonen, Fuling Ji, Feng Ning, Zengchang Pang, Juan R. Ordoñana, Juan F. Sánchez-Romera, Lucia Colodro-Conde, S. Alexandra Burt, Kelly L. Klump, Sarah E. Medland, Grant W. Montgomery, Christian Kandler, Tom A. McAdams, Thalia C. Eley, Alice M. Gregory, Kimberly J. Saudino, Lise Dubois, Michel Boivin, Adam D. Tarnoki, David L. Tarnoki, Claire M. A. Haworth, Robert Plomin, Sevgi Y. Öncel, Fazil Aliev, Maria A. Stazi, Corrado Fagnani, Cristina D’Ippolito, Jeffrey M. Craig, Richard Saffery, Sisira H. Siribaddana, Matthew Hotopf, Athula Sumathipala, Fruhling Rijsdijk, Timothy Spector, Massimo Mangino, Genevieve Lachance, Margaret Gatz, David A. Butler, Gombojav Bayasgalan, Danshiitsoodol Narandalai, Duarte L Freitas, José Antonio Maia, K. Paige Harden, Elliot M. Tucker-Drob, Bia Kim, Youngsook Chong, Changhee Hong, Hyun Jung Shin, Kaare Christensen, Axel Skytthe, Kirsten O. Kyvik, Catherine A. Derom, Robert F. Vlietinck, Ruth J. F. Loos, Wendy Cozen, Amie E. Hwang, Thomas M. Mack, Mingguang He, Xiaohu Ding, Billy Chang, Judy L. Silberg, Lindon J. Eaves, Hermine H. Maes, Tessa L. Cutler, John L. Hopper, Kelly Aujard, Patrik K. E. Magnusson, Nancy L. Pedersen, Anna K. Dahl Aslan, Yun-Mi Song, Sarah Yang, Kayoung Lee, Laura A. Baker, Catherine Tuvblad, Morten Bjerregaard-Andersen, Henning Beck-Nielsen, Morten Sodemann, Kauko Heikkilä, Qihua Tan, Dongfeng Zhang, Gary E. Swan, Ruth Krasnow, Kerry L. Jang, Ariel Knafo-Noam, David Mankuta, Lior Abramson, Paul Lichtenstein, Robert F. Krueger, Matt McGue, Shandell Pahlen, Per Tynelius, Glen E. Duncan, Dedra Buchwald, Robin P. Corley, Brooke M. Huibregtse, Tracy L. Nelson, Keith E. Whitfield, Carol E. Franz, William S. Kremen, Michael J. Lyons, Syuichi Ooki, Ingunn Brandt, Thomas Sevenius Nilsen, Fujio Inui, Mikio Watanabe, Meike Bartels, Toos C. E. M. van Beijsterveldt, Jane Wardle, Clare H. Llewellyn, Abigail Fisher, Esther Rebato, Nicholas G. Martin, Yoshinori Iwatani, Kazuo Hayakawa, Joohon Sung, Jennifer R. Harris, Gonneke Willemsen, Andreas Busjahn, Jack H. Goldberg, Finn Rasmussen, Yoon-Mi Hur, Dorret I. Boomsma, Thorkild I. A. Sørensen, Jaakko Kaprio, Karri Silventoinen
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- Journal:
- Twin Research and Human Genetics / Volume 18 / Issue 5 / October 2015
- Published online by Cambridge University Press:
- 04 September 2015, pp. 557-570
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A trend toward greater body size in dizygotic (DZ) than in monozygotic (MZ) twins has been suggested by some but not all studies, and this difference may also vary by age. We analyzed zygosity differences in mean values and variances of height and body mass index (BMI) among male and female twins from infancy to old age. Data were derived from an international database of 54 twin cohorts participating in the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins), and included 842,951 height and BMI measurements from twins aged 1 to 102 years. The results showed that DZ twins were consistently taller than MZ twins, with differences of up to 2.0 cm in childhood and adolescence and up to 0.9 cm in adulthood. Similarly, a greater mean BMI of up to 0.3 kg/m2 in childhood and adolescence and up to 0.2 kg/m2 in adulthood was observed in DZ twins, although the pattern was less consistent. DZ twins presented up to 1.7% greater height and 1.9% greater BMI than MZ twins; these percentage differences were largest in middle and late childhood and decreased with age in both sexes. The variance of height was similar in MZ and DZ twins at most ages. In contrast, the variance of BMI was significantly higher in DZ than in MZ twins, particularly in childhood. In conclusion, DZ twins were generally taller and had greater BMI than MZ twins, but the differences decreased with age in both sexes.
Presentation of the 2008 Harrell L. Strimple Award of the Paleontological Society to Thomas C. Witherspoon
- William S. Bartels
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- Journal of Paleontology / Volume 85 / Issue 4 / July 2011
- Published online by Cambridge University Press:
- 14 July 2015, pp. 812-813
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The CODATwins Project: The Cohort Description of Collaborative Project of Development of Anthropometrical Measures in Twins to Study Macro-Environmental Variation in Genetic and Environmental Effects on Anthropometric Traits
- Karri Silventoinen, Aline Jelenkovic, Reijo Sund, Chika Honda, Sari Aaltonen, Yoshie Yokoyama, Adam D. Tarnoki, David L. Tarnoki, Feng Ning, Fuling Ji, Zengchang Pang, Juan R. Ordoñana, Juan F. Sánchez-Romera, Lucia Colodro-Conde, S. Alexandra Burt, Kelly L. Klump, Sarah E. Medland, Grant W. Montgomery, Christian Kandler, Tom A. McAdams, Thalia C. Eley, Alice M. Gregory, Kimberly J. Saudino, Lise Dubois, Michel Boivin, Claire M. A. Haworth, Robert Plomin, Sevgi Y. Öncel, Fazil Aliev, Maria A. Stazi, Corrado Fagnani, Cristina D’Ippolito, Jeffrey M. Craig, Richard Saffery, Sisira H. Siribaddana, Matthew Hotopf, Athula Sumathipala, Timothy Spector, Massimo Mangino, Genevieve Lachance, Margaret Gatz, David A. Butler, Gombojav Bayasgalan, Danshiitsoodol Narandalai, Duarte L. Freitas, José Antonio Maia, K. Paige Harden, Elliot M. Tucker-Drob, Kaare Christensen, Axel Skytthe, Kirsten O. Kyvik, Changhee Hong, Youngsook Chong, Catherine A. Derom, Robert F. Vlietinck, Ruth J. F. Loos, Wendy Cozen, Amie E. Hwang, Thomas M. Mack, Mingguang He, Xiaohu Ding, Billy Chang, Judy L. Silberg, Lindon J. Eaves, Hermine H. Maes, Tessa L. Cutler, John L. Hopper, Kelly Aujard, Patrik K. E. Magnusson, Nancy L. Pedersen, Anna K. Dahl Aslan, Yun-Mi Song, Sarah Yang, Kayoung Lee, Laura A. Baker, Catherine Tuvblad, Morten Bjerregaard-Andersen, Henning Beck-Nielsen, Morten Sodemann, Kauko Heikkilä, Qihua Tan, Dongfeng Zhang, Gary E. Swan, Ruth Krasnow, Kerry L. Jang, Ariel Knafo-Noam, David Mankuta, Lior Abramson, Paul Lichtenstein, Robert F. Krueger, Matt McGue, Shandell Pahlen, Per Tynelius, Glen E. Duncan, Dedra Buchwald, Robin P. Corley, Brooke M. Huibregtse, Tracy L. Nelson, Keith E. Whitfield, Carol E. Franz, William S. Kremen, Michael J. Lyons, Syuichi Ooki, Ingunn Brandt, Thomas Sevenius Nilsen, Fujio Inui, Mikio Watanabe, Meike Bartels, Toos C. E. M. van Beijsterveldt, Jane Wardle, Clare H. Llewellyn, Abigail Fisher, Esther Rebato, Nicholas G. Martin, Yoshinori Iwatani, Kazuo Hayakawa, Finn Rasmussen, Joohon Sung, Jennifer R. Harris, Gonneke Willemsen, Andreas Busjahn, Jack H. Goldberg, Dorret I. Boomsma, Yoon-Mi Hur, Thorkild I. A. Sørensen, Jaakko Kaprio
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- Twin Research and Human Genetics / Volume 18 / Issue 4 / August 2015
- Published online by Cambridge University Press:
- 27 May 2015, pp. 348-360
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For over 100 years, the genetics of human anthropometric traits has attracted scientific interest. In particular, height and body mass index (BMI, calculated as kg/m2) have been under intensive genetic research. However, it is still largely unknown whether and how heritability estimates vary between human populations. Opportunities to address this question have increased recently because of the establishment of many new twin cohorts and the increasing accumulation of data in established twin cohorts. We started a new research project to analyze systematically (1) the variation of heritability estimates of height, BMI and their trajectories over the life course between birth cohorts, ethnicities and countries, and (2) to study the effects of birth-related factors, education and smoking on these anthropometric traits and whether these effects vary between twin cohorts. We identified 67 twin projects, including both monozygotic (MZ) and dizygotic (DZ) twins, using various sources. We asked for individual level data on height and weight including repeated measurements, birth related traits, background variables, education and smoking. By the end of 2014, 48 projects participated. Together, we have 893,458 height and weight measures (52% females) from 434,723 twin individuals, including 201,192 complete twin pairs (40% monozygotic, 40% same-sex dizygotic and 20% opposite-sex dizygotic) representing 22 countries. This project demonstrates that large-scale international twin studies are feasible and can promote the use of existing data for novel research purposes.
Looking Backward, Looking Forward: MLA Members Speak
- April Alliston, Elizabeth Ammons, Jean Arnold, Nina Baym, Sandra L. Beckett, Peter G. Beidler, Roger A. Berger, Sandra Bermann, J.J. Wilson, Troy Boone, Alison Booth, Wayne C. Booth, James Phelan, Marie Borroff, Ihab Hassan, Ulrich Weisstein, Zack Bowen, Jill Campbell, Dan Campion, Jay Caplan, Maurice Charney, Beverly Lyon Clark, Robert A. Colby, Thomas C. Coleman III, Nicole Cooley, Richard Dellamora, Morris Dickstein, Terrell Dixon, Emory Elliott, Caryl Emerson, Ann W. Engar, Lars Engle, Kai Hammermeister, N. N. Feltes, Mary Anne Ferguson, Annie Finch, Shelley Fisher Fishkin, Jerry Aline Flieger, Norman Friedman, Rosemarie Garland-Thomson, Sandra M. Gilbert, Laurie Grobman, George Guida, Liselotte Gumpel, R. K. Gupta, Florence Howe, Cathy L. Jrade, Richard A. Kaye, Calhoun Winton, Murray Krieger, Robert Langbaum, Richard A. Lanham, Marilee Lindemann, Paul Michael Lützeler, Thomas J. Lynn, Juliet Flower MacCannell, Michelle A. Massé, Irving Massey, Georges May, Christian W. Hallstein, Gita May, Lucy McDiarmid, Ellen Messer-Davidow, Koritha Mitchell, Robin Smiles, Kenyatta Albeny, George Monteiro, Joel Myerson, Alan Nadel, Ashton Nichols, Jeffrey Nishimura, Neal Oxenhandler, David Palumbo-Liu, Vincent P. Pecora, David Porter, Nancy Potter, Ronald C. Rosbottom, Elias L. Rivers, Gerhard F. Strasser, J. L. Styan, Marianna De Marco Torgovnick, Gary Totten, David van Leer, Asha Varadharajan, Orrin N. C. Wang, Sharon Willis, Louise E. Wright, Donald A. Yates, Takayuki Yokota-Murakami, Richard E. Zeikowitz, Angelika Bammer, Dale Bauer, Karl Beckson, Betsy A. Bowen, Stacey Donohue, Sheila Emerson, Gwendolyn Audrey Foster, Jay L. Halio, Karl Kroeber, Terence Hawkes, William B. Hunter, Mary Jambus, Willard F. King, Nancy K. Miller, Jody Norton, Ann Pellegrini, S. P. Rosenbaum, Lorie Roth, Robert Scholes, Joanne Shattock, Rosemary T. VanArsdel, Alfred Bendixen, Alarma Kathleen Brown, Michael J. Kiskis, Debra A. Castillo, Rey Chow, John F. Crossen, Robert F. Fleissner, Regenia Gagnier, Nicholas Howe, M. Thomas Inge, Frank Mehring, Hyungji Park, Jahan Ramazani, Kenneth M. Roemer, Deborah D. Rogers, A. LaVonne Brown Ruoff, Regina M. Schwartz, John T. Shawcross, Brenda R. Silver, Andrew von Hendy, Virginia Wright Wexman, Britta Zangen, A. Owen Aldridge, Paula R. Backscheider, Roland Bartel, E. M. Forster, Milton Birnbaum, Jonathan Bishop, Crystal Downing, Frank H. Ellis, Roberto Forns-Broggi, James R. Giles, Mary E. Giles, Susan Blair Green, Madelyn Gutwirth, Constance B. Hieatt, Titi Adepitan, Edgar C. Knowlton, Jr., Emanuel Mussman, Sally Todd Nelson, Robert O. Preyer, David Diego Rodriguez, Guy Stern, James Thorpe, Robert J. Wilson, Rebecca S. Beal, Joyce Simutis, Betsy Bowden, Sara Cooper, Wheeler Winston Dixon, Tarek el Ariss, Richard Jewell, John W. Kronik, Wendy Martin, Stuart Y. McDougal, Hugo Méndez-Ramírez, Ivy Schweitzer, Armand E. Singer, G. Thomas Tanselle, Tom Bishop, Mary Ann Caws, Marcel Gutwirth, Christophe Ippolito, Lawrence D. Kritzman, James Longenbach, Tim McCracken, Wolfe S. Molitor, Diane Quantic, Gregory Rabassa, Ellen M. Tsagaris, Anthony C. Yu, Betty Jean Craige, Wendell V. Harris, J. Hillis Miller, Jesse G. Swan, Helene Zimmer-Loew, Peter Berek, James Chandler, Hanna K. Charney, Philip Cohen, Judith Fetterley, Herbert Lindenberger, Julia Reinhard Lupton, Maximillian E. Novak, Richard Ohmann, Marjorie Perloff, Mark Reynolds, James Sledd, Harriet Turner, Marie Umeh, Flavia Aloya, Regina Barreca, Konrad Bieber, Ellis Hanson, William J. Hyde, Holly A. Laird, David Leverenz, Allen Michie, J. Wesley Miller, Marvin Rosenberg, Daniel R. Schwarz, Elizabeth Welt Trahan, Jean Fagan Yellin
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- Journal:
- PMLA / Publications of the Modern Language Association of America / Volume 115 / Issue 7 / December 2000
- Published online by Cambridge University Press:
- 23 October 2020, pp. 1986-2078
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- December 2000
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Taphonomy of Paleogene and Neogene vertebrate assemblages
- William S. Bartels, Thomas M. Bown, Catherine Badgley, Anna Kay Behrensmeyer, Michele Morgan, S. Mahmood. Raza
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- Journal:
- The Paleontological Society Special Publications / Volume 6 / 1992
- Published online by Cambridge University Press:
- 26 July 2017, p. 19
- Print publication:
- 1992
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The Paleogene of Wyoming and Montana and the Neogene Siwaliks of Pakistan contain deposits representing a wide variety of terrestrial environments. Although fossils are preserved in all of these environments, fossil vertebrates are abundant in only certain facies. These principal preservational environments vary within and, particularly, between formations in each region.
The Bighorn and Crazy Mountain basins of Wyoming and Montana contain abundant remains of Paleocene and Eocene vertebrates. Over 1800 localities in this region have been established in the Paleocene Fort Union and Paleocene to Eocene Willwood formations. The distribution of vertebrate remains changes dramatically upsection in this sequence. The Fort Union consists of thick fluvial sandstones and minor swampy floodplain mudstones in the lower part, and more widely separated channel sandstones interbedded with better drained floodplain deposits that include paleosol horizons in the upper part. These changes reflect a local increase in aggradation rate. Vertebrates are preserved almost exclusively in channel mud-clast conglomerates in the lower part of the formation, but appear in a wider variety of environments (channels, splays, swamps, and paleosols) in the upper part. The Willwood Formation continues the changes evident in the upper Fort Union. With increased aggradation rates, floodplain deposits became thicker and more well drained. Except for rare occurrences in other environments (channels, a variety of calcareous environments, and oxbows), fossils are recovered primarily from paleosol horizons developed in fine grained floodplain deposits.
The Fort Union channel deposits contain assemblages that are often highly biased samples of faunal composition with large aquatic taxa well represented and small terrestrial forms unevenly represented. The upper Fort Union and Willwood floodplain paleosols contain more homogeneous (and therefore comparable) assemblages. These paleosols differ systematically, however, in terms of soil maturity and vertebrate composition, and they are commonly biased against large or aquatic taxa.
The distribution of Siwalik vertebrate localities among sedimentary environments is known for four formations spanning early middle to late Miocene: Kamlial, Chinji, Nagri, and Dhok Pathan. The principal deposits in which fossils occur are: major stream channel complexes, secondary (floodplain) channels, crevasse splays, and floodplains. The Kamlial and Nagri formations, dominated by coarse lithologies (>50% sandstone), are notably less productive of fossil localities than the Chinji and Dhok Pathan formations, dominated by fine grained lithologies (>50% mudstone). In the Kamlial and Nagri formations, major channel complexes form the most prevalent environment, and more localities are associated with these channels than with any other environment. In the Chinji and Dhok Pathan formations, the most prevalent environment is floodplain, but more localities are associated with the secondary channels on these floodplains than with any other environment. In the Chinji Formation, most localities developed in secondary channels occur in fining-upward fill sequences, whereas in the Dhok Pathan Formation, most sites in these channels occur in their lag deposits. In these more productive formations, the abundance of certain mammalian taxa is correlated with specific depositional environments. Change upsection in the abundance of these taxa could result largely from change in facies productivity.
The taphonomy of the two areas is similar in that channel lag deposits are an important source of fossil vertebrates. The major difference is that the Rocky Mountain Paleogene contains fewer, but highly productive, environments that changed significantly through time, including the Eocene emergence of floodplain paleosols as the primary environment of vertebrate preservation.
Preservational, paleoecological, and evolutionary patterns in the Wyoming-Montana Paleogene and Siwalik Neogene records
- Catherine Badgley, Anna Kay Behrensmeyer, William S. Bartels, Thomas M. Bown
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- Journal:
- The Paleontological Society Special Publications / Volume 6 / 1992
- Published online by Cambridge University Press:
- 26 July 2017, p. 13
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- 1992
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The Paleocene to early Eocene sequence of Wyoming-Montana and the Miocene to Pleistocene Siwalik record of Pakistan are exceptionally long, continental sequences, each containing a rich and well documented fossil record, especially of mammals. The two sequences are broadly similar in tectonic setting and sedimentary environment, in duration and facies changes, and in diversity of fossils. Each contains a paleoclimatic record in stable isotopes and, in the Paleogene, floras. Comparison of these two sequences has focused our attention on the interaction of tectonic, climatic, sedimentologic, and taphonomic factors that produce a particular fossil record and on the co-occurring ecological and evolutionary changes that result in a historical series of biotas, each the product of local and global events.
In the Paleogene record, the geographic scope of the record encompasses much of the floodbasin, and the spatial distribution of paleoenvironments formed fairly straightforward gradients from channel to distal floodplain. The Siwalik record has a smaller window onto a larger, heterogeneous fluvial system often with multiple, contemporaneous river systems that differ in magnitude. The spatial distribution of paleoenvironments was a mosaic without long proximal to distal gradients. In both records, major facies changes are correlated with striking changes in fossil productivity.
The overall pattern of fossil preservation by depositional environment differs substantially in the two areas. The Siwalik sequence has a greater variety of depositional environments that produce fossils throughout the section. The primary productive environment in the older part of the Paleocene record declined in productivity upsection, while a previously unproductive facies became the major source of fossils. Much of the record represents attritional accumulation in each area, but a significant portion is transported. The taphonomic processes that created fossil concentrations led to better taxonomic resolution for most Paleogene localities than in most Siwalik localities.
In each record, both aquatic and terrestrial components of the vertebrate faunas are correlated with facies. Since facies varied in productivity over time, some changes in faunal composition may have resulted from change in the prevalence or productivity of particular facies. At least one faunal turnover coincided with major facies changes in each sequence.
For mammals in each record, immigration rather than speciation in situ was the primary means of appearance of new species. Episodes of immigration were not closely followed by extinctions of resident species. Mean species longevity appears to have been more than twice as great in the Neogene than in the Paleogene record. Changes in faunal composition and species richness occurred during times of global climatic change; causal connections are still being explored. Changes in species richness did not track changes in relative abundance of taxa or changes in size within lineages or faunas. In terms of guild structure, the herbivore guild had high relative generic diversity through most of both sequences. The Paleogene record had a more even distribution of taxa in the five principal guilds, while the Siwalik record was heavily dominated by the herbivore guild. Size distributions differed substantially, reflecting the early and late windows into the mammalian radiation, rather than sampling bias.