DOCSLIB.ORG

Ichthyornis.Pdf

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

THE TEXAS JOURNAL OF SCIENCE GENERAL INFORMATION MEMBERSHIP.—Any person or members of any group engaged in scientific work or interested in the promotion of science are eligible for membership in The Texas Academy of Science. Dues for members are $30.00 annually; associate (student) members, $15.00; family members, $35.00; affiliate members, $5.00; emeritus members, $10.00; life members, 20 times annual dues; patrons, $750.00 or more in one payment; corporate members, $250.00 annually; corporate life members, $2000.00 in one payment. Library subscription rate is $45.00 annually. Payments should be sent to Dr. Michael J. Carlo, P.O. Box 10986, Angelo State University, San Angelo, Texas 76909. The Texas Journal of Science is a quarterly publication of The Texas Academy of Science and is sent to most members and all subscribers. Changes of address and inquiries regarding missing or back issues should be sent to Dr. Robert D. Owen, Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409-3131, (806) 742-3232. AFFILIATED ORGANIZATIONS Texas Section, American Association of Physics Teachers Texas Section, Mathematical Association of America Texas Section, National Association of Geology Teachers American Association for the Advancement of Science Texas Society of Mammalogists The Texas Journal of Science (ISSN 0040-4403) is published quarterly at Lubbock, Texas U.S.A. Second class postage paid at Post Office, Lubbock, Texas 79402. Postmaster: Send address changes, and returned copies to The Texas Journal of Science, Box 43151, Texas Tech University, Lubbock, Texas 79409-3151, U.S.A. THE FOSSIL BIRD ICHTHYORNIS IN THE CRETACEOUS OF TEXAS DAVID C. PARRIS AND JOAN ECHOLS Bureau of Natural History, New Jersey State Museum, CN-530, Trenton, New Jersey 08625-0530, and Department oj Earth Sciences, East Texas State University, Commerce, Texas 75428 ABSTRACT.—Four avian fossils from the Cretaceous of Texas are referred to Ichthyornis. Two specimens identified as /. dispar (Marsh, 1872) are from the Ector Chalk (Coniacian) of Fannin County. One specimen referred to /. antecessor (Wetmore, 1962) is from the Pflugerville Formation of Travis County, and another is from the Roxton Member of the Gober Chalk of Fannin County, both Campanian. The Texas specimens can be correlated with greater precision than most material of Ichthyornis and span a period essentially equal to that during which the Niobrara Formation, source of the classic specimens, was deposited. Key words: Ichthyornis; Cretaceous; paleontology; geology; bird. Since it was first described, the avian genus Ichthyornis has been among the taxa most associated with the classic chalk strata of North America. The six species described by Marsh (summarized in Marsh, 1880) from the Niobrara Formation (Coniacian-Campanian) established Ichthyornis as one of the notable toothed birds of the Cretaceous of Kansas, a genus familiar to anyone with a basic knowledge of vertebrate paleontology. Interest in Ichthyornis has increased in the last few decades (Walker, 1967; Stewart, 1990; Stewart et al., 1990). Descriptions of better specimens than those available to Marsh have reinforced knowledge of the anatomy of the genus (Gingerich, 1972; Martin and Stewart, 1977). The geologic and geographic ranges have been greatly expanded in other published reports (Olson, 1975; Lucas and Sullivan, 1982; Martin and Stewart, 1982; Fox, 1984; Zinsmeister, 1985; Nesov, 1986). As yet, however, no comprehensive taxonomic review of the genus has been published, although such a study is much to be desired. Ichthyornis was reported from the Cretaceous of Texas by Marsh (1877). The Yale University specimen (YPM 1796), the only published report of an alleged Cretaceous bird from Texas, was designated the type of a distinct species, Ichthyornis lentus (originally referred to the genus Graculavus). The specimen was attributed to the Austin Chalk near Fort McKinney (now McKinney), Collin County (misprinted as Colling County in Brodkorb, 1967). The taxonomic identity and geologic age of that specimen have been questioned, however (Shufeldt, 1915; Martin and Stewart, 1982). Despite skepticism about /. lentus, the genus Ichthyornis would be expected to occur in the chalk horizons of Texas. In fact, two well-documented Texas specimens of Ichthyornis have been known since 1940, although they apparently have not been described. Their existence presumably was noted in organizational reports 202 THE TEXAS JOURNAL OF SCIENCE—VOL. 44, NO. 2, 1992 and they were studied by leading authorities on the genus. Unfortunately, reviewers of Cretaceous faunas (Russell, 1988) generally were unaware of these specimens. We describe here four Texas specimens of Ichthyornis, the two noted above and two that have been collected more recently. All are from the Austin Division of Young (1986), a single transgression-inundation event (Fig. 1). Texas specimens of Ichthyornis are of particular importance because of their intermediate geographic position between records from Kansas and Alabama, and because the well-studied biostratigraphy of Texas (especially ammonite zonation) enables a high degree of age resolution for them. Institutional collection prefixes used here are: ET, East Texas State University; TMM, Texas Memorial Museum; USNM, National Museum of Natural History (Smithsonian Institution); YPM, Yale University (Peabody Museum of Natural History). SYSTEMATIC PALEONTOLOGY Order Ichthyornithiformes Marsh, 1873 Family Ichthyornithidae Marsh, 1873 Genus Ichthyornis Marsh, 1872 Ichthyornis dispar (Marsh, 1872) Holotype.—YPM 1450, an incomplete postcranial skeleton from the Smoky Hill Chalk Member of the Niobrara Formation in Section 1, Township 6 S, Range 19 W, Rooks Co., Kansas. Referred specimens.—TMM 31051-24, a complete right humerus (Fig. 2), and TMM 31051-25, a right wing with complete humerus, partial ulna, partial radius, and portion of carpometacarpus (Fig. 3), both specimens from the Ector Chalk Formation of the Austin Group at the Savoy Pit, Fannin Co., Texas (Ector 7.5' Quadrangle). For descriptions of the locality and Bureau of Economic Geology collecting projects, refer to Springer (1957) and Bardack (1968). Collected by Bureau of Economic Geology field party (Gregory) in 1940. Description.—The specimens are well preserved except for minor breakage and crushing, and include the conspicuous pectoral crests of the humerus that are diagnostic of the genus. Pending a generic revision, the best means of species determination remains comparison of measure­ ments to specimens described by Marsh himself. As shown in Table 1, the TMM humeri are similar to the Marsh specimens of Ichthyornis dispar, including the type. Other species of the genus for which the humerus is known differ significantly in dimensions. Both of the referred specimens from Texas are prepared in relief on blocks of matrix, somewhat limiting the views available for detailed description. However, the shaft is ICHTHYORNIS FROM THE CRETACEOUS OF TEXAS 203 FIGURE 1. Part of northeastern Texas with primary outcrop area of Austin Group (after Oetking, 1959). Localities of specimens are Gober (G) and Savoy (S) in Fannin County, and Austin (A) in Travis County. Inset shows relationships of Austin Division rocks (after Young, 1986). relatively robust in both of the distal ends of the humeri, a characteristic of /. dispar noted by Olson (1975). Length of the ulna as preserved is 63.5 mm. Discussion.—Although a revision of the genus probably will result in a reduction in the number of species of Ichthyornis, the validity of the 204 THE TEXAS JOURNAL OF SCIENCE—VOL. 44, NO. 2, 1992 FIGURE 2 (upper). TMM 31051-24, Ichthyornis dispar, right humerus, oblique view of anconal side. FIGURE 3. TMM 31051-25, Ichthyornis dispar, semiarticulated partial right wing, oblique view of distorted humerus. species /. dispar likely will be sustained. Although it was the second species of Ichthyornis to be described, it was the first to be directly attributed to the genus, and is, therefore, considered the type species (Brodkorb, 1967). It is certainly the most appropriate name in this case, because the type specimen is adequate for diagnosis and includes skeletal elements that are directly comparable. The type of /. anceps (the only species of Ichthyornis described prior to /. dispar) is too fragmentary to be useful for most specific diagnoses, being merely the distal end of a ICHTHYORNIS FROM THE CRETACEOUS OF TEXAS 205 TABLE 1. Measurements of Ichthyornis humeri (mm). /. dispar /. dispar YPM 1450 YPM 1730 TMM 31051-24 TMM 31051-25 Length 58.0 62.5 63.8 62.5 Greatest proximal diameter 13.0 15. - - Distal width 9.6 9. 9.6 8.2 Humerus distal depth 5.0 - - - Ulnar condyle diameter - 5. 4.6 5.2 Measurements of YPM specimens published by Marsh (1880). carpometarcarpus. However, it seems distinct from /. dispar based on size, as noted by Marsh (1880), who published dimensions of the types. Stratigraphy.—The Ector Chalk is the basal formation of the Austin Group and is the lowest unit of the Austin Division in the lithogenetic classification of Young (1986). It is within the Peroniceras haasi Zone of Young (1963) and correlates with the lower Coniacian Stage. The type specimen of Ichthyornis dispar is from Rooks County, Kansas, from a locality mapped in the combined zones of Cladoceramus undulatoplicatus and Platyceramus platinus by Stewart (1988),—his Protosphyraena Zone D. Thus it probably correlates with the Santonian Stage. Ichthyornis antecessor (Wetmore, 1962) Holotype.—USNM 22820, the distal end of left humerus from the Mooreville Formation (Selma Group) at Hewletts Farm, Greene Co., Alabama. Referred specimens.—TMM 42522-1 (Figs. 4 and 5), distal end of left humerus from the Pflugerville Formation at the Little Walnut Creek-Old Sprinkle Bridge Locality in Austin, Travis Co., Texas (Austin East 7.5' Quadrangle). For description of the locality, see Young (1977). Obtained by A. Busbey in 1985. ET 4396 (L85-6), the proximal end of a left carpometacarpus (Figs. 6- 8), from the Roxton Limestone Member of the Gober Formation at East Texas State Locality 36, "Dig 2," obtained by D. Galbraith, J. Echols, G.
Recommended publications
  • Flying Dromaeosaurs

    Flying Dromaeosaurs

    A winged, but flightless, Deinonychus by Stephen A. Czerkas FLYING DROMAEOSAURS Stephen A. Czerkas, Dianshuang Zhang, Jinglu Li and Yinxian Li The Dinosaur Museum, 754 South 200 West, Blanding, Utah 84511, USA; Liaoning Provincial Bureau of Land Resources Management, Liaoning Fossil Administration Office, and Liaoning Museum of Paleontology, Left of Nanshan Park, Beipiao, Liaoning Province 122100, People’s Republic of China. The Dinosaur Museum © 2002 Abstract Dromaeosaurs have been regarded as theropod dinosaurs that were among the closest avian ancestors which were strictly terrestrial having not yet evolved the ability to fly. Consequently, phylogenetic analyses have resulted in the claims of birds having evolved from “the ground up” within a dinosaurian ancestry. Though widely accepted, the relationship between birds and dinosaurs has remained highly controversial and disputed by advocates of birds as having been derived from an arboreal, non-dinosaurian type of archosaur. The cladistical interpretation of the dinosaur/bird relationship hinges upon the presumption of the dromaeosaurs inability to fly. Recent discoveries of dromaeosaurs have revealed impressions of feathers and avian characters in the skeleton that nearly equal and even surpass that of Archaeopteryx. Yet despite this, the ability to fly has been discounted due to the shorter length of the forelimbs. Described below are two such dromaeosaurs, but preserved with impressions of primary flight feathers extending from the manus which demonstrate an undeniable correlation towards the ability to fly. This compelling evidence refutes the popular interpretation of birds evolving from dinosaurs by revealing that dromaeosaurs were already birds and not the non-avian theropod dinosaurs as previously believed.
  • The Petroleum Potential of H Serpentine Plugs" and Associated Rocks, Central and South Texas

    The Petroleum Potential of H Serpentine Plugs" and Associated Rocks, Central and South Texas

    BAYLOR FALL 1986 ulletin No. 44 The Petroleum Potential of H Serpentine Plugs" and Associated Rocks, Central and South Texas TRUITT F. MATTHEWS Baylor Geological Studies EDITORIAL STAFF Jean M. Spencer Jenness, M.S., Ed.ttpr environmental and medical geology CONTENTS Page O. T. Hayward, Ph.D., Advisor. Cartographic Editor Abstract .............................................................. 5 general and urban geology and what have you Introduction. .. 5 Peter M. Allen, Ph.D. Purpose ........................................................... 5 urban and environmental geology, hydrology Location .......................................................... 6 Methods .......................................................... 6 Harold H. Beaver, Ph.D. Previous works. .. 7 stratigraphy, petroleum geology Acknowledgments .................................................. 11 Regional setting of "serpentine plugs" ..................................... 11 Rena Bonem, Ph.D. Descriptive geology of "serpentine plugs" .................................. 12 paleontology, paleoecology Northern subprovince ............................................... 13 Middle subprovince ................................................. 15 William Brown, M.S. Southern subprovince ............................................... 18 structural tectonics Origin and history of "serpentine plugs" ................................... 26 Robert C. Grayson, Ph.D. Production histories of "serpentine plugs" ................................. 30 stratigraphy, conodont biostratigraphy
  • Evaluation of the Depositional Environment of the Eagle Ford

    Evaluation of the Depositional Environment of the Eagle Ford

    Louisiana State University LSU Digital Commons LSU Master's Theses Graduate School 2012 Evaluation of the depositional environment of the Eagle Ford Formation using well log, seismic, and core data in the Hawkville Trough, LaSalle and McMullen counties, south Texas Zachary Paul Hendershott Louisiana State University and Agricultural and Mechanical College, [email protected] Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_theses Part of the Earth Sciences Commons Recommended Citation Hendershott, Zachary Paul, "Evaluation of the depositional environment of the Eagle Ford Formation using well log, seismic, and core data in the Hawkville Trough, LaSalle and McMullen counties, south Texas" (2012). LSU Master's Theses. 863. https://digitalcommons.lsu.edu/gradschool_theses/863 This Thesis is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Master's Theses by an authorized graduate school editor of LSU Digital Commons. For more information, please contact [email protected]. EVALUATION OF THE DEPOSITIONAL ENVIRONMENT OF THE EAGLE FORD FORMATION USING WELL LOG, SEISMIC, AND CORE DATA IN THE HAWKVILLE TROUGH, LASALLE AND MCMULLEN COUNTIES, SOUTH TEXAS A Thesis Submitted to the Graduate Faculty of the Louisiana State University Agricultural and Mechanical College in partial fulfillment of the requirements for degree of Master of Science in The Department of Geology and Geophysics by Zachary Paul Hendershott B.S., University of the South – Sewanee, 2009 December 2012 ACKNOWLEDGEMENTS I would like to thank my committee chair and advisor, Dr. Jeffrey Nunn, for his constant guidance and support during my academic career at LSU.
  • The Cretaceous Birds of New Jersey

    The Cretaceous Birds of New Jersey

    The Cretaceous Birds of New Jersey <^' STORRS L. OLSON and DAVID C. PARRIS SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY • NUMBER 63 SERIES PUBLICATIONS OF THE SMITHSONIAN INSTITUTION Emphasis upon publication as a means of "diffusing knowledge' was expressed by the first Secretary of the Smithsonian. In his formal plan for the Institution, Joseph Henry outlined a program that included the following statement: "It is proposed to publish a series of reports, giving an account of the new discovenes In science, and of the changes made from year to year in all branches of knowledge." This theme of basic research has been adhered to through the years by thousands of titles issued in series publications under the Smithsonian imprint, commencing with Smithsonian Contributions to Knowledge in 1848 and continuing with the following active series; Smithsonian Contributions to Anthropology Smithsonian Contributions to Astrophysics Smithsonian Contributions to Botany Smithsonian Contributions to the Earth Sciences Smithsonian Contributions to the f^arine Sciences Smithsonian Contributions to Paleobiology Smithsonian Contributions to Zoology Smithsonian Folklife Studies Smithsonian Studies in Air and Space Smithsonian Studies in History and Technology In these series, the Institution publishes small papers and full-scale monographs that report the research and collections of its various museums and bureaux or of professional colleagues in the world of science and scholarship. The publications are distributed by mailing lists to libraries, universities, and similar institutions throughout the world. Papers or monographs submitted for senes publication are received by the Smithsonian Institution Press, subject to its own review for format and style, only through departments of the various Smithsonian museums or bureaux, where the manuscnpts are given substantive review.
  • Mapping Lower Austin Chalk Secondary Porosity Using Modern

    Mapping Lower Austin Chalk Secondary Porosity Using Modern

    University of Arkansas, Fayetteville ScholarWorks@UARK Theses and Dissertations 8-2018 Mapping Lower Austin Chalk Secondary Porosity Using Modern 3-D Seismic and Well Log Methods in Zavala County, Texas David Kilcoyne University of Arkansas, Fayetteville Follow this and additional works at: http://scholarworks.uark.edu/etd Part of the Geology Commons, and the Geophysics and Seismology Commons Recommended Citation Kilcoyne, David, "Mapping Lower Austin Chalk Secondary Porosity Using Modern 3-D Seismic and Well Log Methods in Zavala County, Texas" (2018). Theses and Dissertations. 2835. http://scholarworks.uark.edu/etd/2835 This Thesis is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of ScholarWorks@UARK. For more information, please contact [email protected], [email protected]. Mapping Lower Austin Chalk Secondary Porosity Using Modern 3-D Seismic and Well Log Methods in Zavala County, Texas A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Geology by David Joseph Kilcoyne University College Cork Bachelor of Science in Geoscience, 2016 August 2018 University of Arkansas This thesis is approved for recommendation to the Graduate Council. ____________________________________ Christopher L. Liner, PhD Thesis Director ____________________________________ ___________________________________ Thomas A. McGilvery, PhD Robert Liner, M.S. Committee Member Committee Member Abstract Establishing fracture distribution and porosity trends is key to successful well design in a majority of unconventional plays. The Austin Chalk has historically been referred to as an unpredictable producer due to high fracture concentration and lateral variation in stratigraphy, however recent drilling activity targeting the lower Austin Chalk has been very successful.
  • Winter Bird Feeding

    Winter Bird Feeding

    BirdNotes 1 Winter Bird Feeding birds at feeders in winter If you feed birds, you’re in good company. Birding is one of North America’s favorite pastimes. A 2006 report from the U.S. Fish and Wildlife Service estimates that about 55.5 mil- lion Americans provide food for wild birds. Chickadees Titmice Cardinals Sparrows Wood- Orioles Pigeons Nuthatches Finches Grosbeaks Blackbirds Jays peckers Tanagers Doves Sunflower ◆ ◆ ◆ ◆ ◆ ◆ ◆ Safflower ◆ ◆ ◆ Corn ◆ ◆ ◆ Millet ◆ ◆ ◆ Milo ◆ ◆ Nyjer ◆ Suet ◆ ◆ ◆ ◆ ◆ Preferred ◆ Readily Eaten Wintertime—and the Living’s counting birds at their feeders during selecting the best foods daunting. To Not Easy this winterlong survey. Great Back- attract a diversity of birds, provide a yard Bird Count participants provide variety of food types. But that doesn’t n much of North America, winter valuable data with a much shorter mean you need to purchase one of ev- Iis a difficult time for birds. Days time commitment—as little as fifteen erything on the shelf. are often windy and cold; nights are minutes in mid-February! long and even colder. Lush vegeta- Which Seed Types tion has withered or been consumed, Types of Bird Food Should I Provide? and most insects have died or become uring spring and summer, most dormant. Finding food can be espe- lack-oil sunflower seeds attract songbirds eat insects and spi- cially challenging for birds after a D Bthe greatest number of species. ders, which are highly nutritious, heavy snowfall. These seeds have a high meat-to- abundant, and for the most part, eas- shell ratio, they are nutritious and Setting up a backyard feeder makes ily captured.
  • Late Cretaceous and Tertiary Burial History, Central Texas 143

    Late Cretaceous and Tertiary Burial History, Central Texas 143

    A Publication of the Gulf Coast Association of Geological Societies www.gcags.org L C T B H, C T Peter R. Rose 718 Yaupon Valley Rd., Austin, Texas 78746, U.S.A. ABSTRACT In Central Texas, the Balcones Fault Zone separates the Gulf Coastal Plain from the elevated Central Texas Platform, comprising the Hill Country, Llano Uplift, and Edwards Plateau provinces to the west and north. The youngest geologic for- mations common to both regions are of Albian and Cenomanian age, the thick, widespread Edwards Limestone, and the thin overlying Georgetown, Del Rio, Buda, and Eagle Ford–Boquillas formations. Younger Cretaceous and Tertiary formations that overlie the Edwards and associated formations on and beneath the Gulf Coastal Plain have no known counterparts to the west and north of the Balcones Fault Zone, owing mostly to subaerial erosion following Oligocene and Miocene uplift during Balcones faulting, and secondarily to updip stratigraphic thinning and pinchouts during the Late Cretaceous and Tertiary. This study attempts to reconstruct the burial history of the Central Texas Platform (once entirely covered by carbonates of the thick Edwards Group and thin Buda Limestone), based mostly on indirect geological evidence: (1) Regional geologic maps showing structure, isopachs and lithofacies; (2) Regional stratigraphic analysis of the Edwards Limestone and associated formations demonstrating that the Central Texas Platform was a topographic high surrounded by gentle clinoform slopes into peripheral depositional areas; (3) Analysis and projection
  • Onetouch 4.0 Scanned Documents

    Onetouch 4.0 Scanned Documents

    / Chapter 2 THE FOSSIL RECORD OF BIRDS Storrs L. Olson Department of Vertebrate Zoology National Museum of Natural History Smithsonian Institution Washington, DC. I. Introduction 80 II. Archaeopteryx 85 III. Early Cretaceous Birds 87 IV. Hesperornithiformes 89 V. Ichthyornithiformes 91 VI. Other Mesozojc Birds 92 VII. Paleognathous Birds 96 A. The Problem of the Origins of Paleognathous Birds 96 B. The Fossil Record of Paleognathous Birds 104 VIII. The "Basal" Land Bird Assemblage 107 A. Opisthocomidae 109 B. Musophagidae 109 C. Cuculidae HO D. Falconidae HI E. Sagittariidae 112 F. Accipitridae 112 G. Pandionidae 114 H. Galliformes 114 1. Family Incertae Sedis Turnicidae 119 J. Columbiformes 119 K. Psittaciforines 120 L. Family Incertae Sedis Zygodactylidae 121 IX. The "Higher" Land Bird Assemblage 122 A. Coliiformes 124 B. Coraciiformes (Including Trogonidae and Galbulae) 124 C. Strigiformes 129 D. Caprimulgiformes 132 E. Apodiformes 134 F. Family Incertae Sedis Trochilidae 135 G. Order Incertae Sedis Bucerotiformes (Including Upupae) 136 H. Piciformes 138 I. Passeriformes 139 X. The Water Bird Assemblage 141 A. Gruiformes 142 B. Family Incertae Sedis Ardeidae 165 79 Avian Biology, Vol. Vlll ISBN 0-12-249408-3 80 STORES L. OLSON C. Family Incertae Sedis Podicipedidae 168 D. Charadriiformes 169 E. Anseriformes 186 F. Ciconiiformes 188 G. Pelecaniformes 192 H. Procellariiformes 208 I. Gaviiformes 212 J. Sphenisciformes 217 XI. Conclusion 217 References 218 I. Introduction Avian paleontology has long been a poor stepsister to its mammalian counterpart, a fact that may be attributed in some measure to an insufRcien- cy of qualified workers and to the absence in birds of heterodont teeth, on which the greater proportion of the fossil record of mammals is founded.
  • Mass Extinction of Birds at the Cretaceous–Paleogene (K–Pg) Boundary

    Mass Extinction of Birds at the Cretaceous–Paleogene (K–Pg) Boundary

    Mass extinction of birds at the Cretaceous–Paleogene (K–Pg) boundary Nicholas R. Longricha,1, Tim Tokarykb, and Daniel J. Fielda aDepartment of Geology and Geophysics, Yale University, New Haven, CT 06520-8109; and bRoyal Saskatchewan Museum Fossil Research Station, Eastend, SK, Canada S0N 0T0 Edited by David Jablonski, University of Chicago, Chicago, IL, and approved August 10, 2011 (received for review June 30, 2011) The effect of the Cretaceous-Paleogene (K-Pg) (formerly Creta- conflicting signals. Many studies imply “mass survival” among ceous–Tertiary, K–T) mass extinction on avian evolution is de- birds, with numerous Neornithine lineages crossing the K–Pg bated, primarily because of the poor fossil record of Late boundary (18, 19), although one study found evidence for limited Cretaceous birds. In particular, it remains unclear whether archaic Cretaceous diversification followed by explosive diversification in birds became extinct gradually over the course of the Cretaceous the Paleogene (20). Regardless, molecular studies cannot de- or whether they remained diverse up to the end of the Cretaceous termine whether archaic lineages persisted until the end of the and perished in the K–Pg mass extinction. Here, we describe a di- Cretaceous; only the fossil record can provide data on the timing verse avifauna from the latest Maastrichtian of western North of their extinction. America, which provides definitive evidence for the persistence of The only diverse avian assemblage that can be confidently a range of archaic birds to within 300,000 y of the K–Pg boundary. dated to the end of the Maastrichtian, and which can therefore A total of 17 species are identified, including 7 species of archaic be brought to bear on this question (SI Appendix), is from the bird, representing Enantiornithes, Ichthyornithes, Hesperornithes, late Maastrichtian (Lancian land vertebrate age) beds of the and an Apsaravis-like bird.
  • Geologic Models and Evaluation of Undiscovered Conventional and Continuous Oil and Gas Resources— Upper Cretaceous Austin Chalk, U.S

    Geologic Models and Evaluation of Undiscovered Conventional and Continuous Oil and Gas Resources— Upper Cretaceous Austin Chalk, U.S

    Geologic Models and Evaluation of Undiscovered Conventional and Continuous Oil and Gas Resources— Upper Cretaceous Austin Chalk, U.S. Gulf Coast Scientific Investigations Report 2012–5159 U.S. Department of the Interior U.S. Geological Survey Front Cover. Photos taken by Krystal Pearson, U.S. Geological Survey, near the old Sprinkle Road bridge on Little Walnut Creek, Travis County, Texas. Geologic Models and Evaluation of Undiscovered Conventional and Continuous Oil and Gas Resources—Upper Cretaceous Austin Chalk, U.S. Gulf Coast By Krystal Pearson Scientific Investigations Report 2012–5159 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director U.S. Geological Survey, Reston, Virginia: 2012 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod To order this and other USGS information products, visit http://store.usgs.gov Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report. Suggested citation: Pearson, Krystal, 2012, Geologic models and evaluation of undiscovered conventional and continuous oil and gas resources—Upper Cretaceous Austin Chalk, U.S.
  • A Bird's Eye View of the Evolution of Avialan Flight

    A Bird's Eye View of the Evolution of Avialan Flight

    Chapter 12 Navigating Functional Landscapes: A Bird’s Eye View of the Evolution of Avialan Flight HANS C.E. LARSSON,1 T. ALEXANDER DECECCHI,2 MICHAEL B. HABIB3 ABSTRACT One of the major challenges in attempting to parse the ecological setting for the origin of flight in Pennaraptora is determining the minimal fluid and solid biomechanical limits of gliding and powered flight present in extant forms and how these minima can be inferred from the fossil record. This is most evident when we consider the fact that the flight apparatus in extant birds is a highly integrated system with redundancies and safety factors to permit robust performance even if one or more components of their flight system are outside their optimal range. These subsystem outliers may be due to other adaptive roles, ontogenetic trajectories, or injuries that are accommodated by a robust flight system. This means that many metrics commonly used to evaluate flight ability in extant birds are likely not going to be precise in delineating flight style, ability, and usage when applied to transitional taxa. Here we build upon existing work to create a functional landscape for flight behavior based on extant observations. The functional landscape is like an evolutionary adap- tive landscape in predicting where estimated biomechanically relevant values produce functional repertoires on the landscape. The landscape provides a quantitative evaluation of biomechanical optima, thus facilitating the testing of hypotheses for the origins of complex biomechanical func- tions. Here we develop this model to explore the functional capabilities of the earliest known avialans and their sister taxa.
  • Norntates PUBLISHED by the AMERICAN MUSEUM of NATURAL HISTORY CENTRAL PARK WEST at 79TH STREET, NEW YORK, NY 10024 Number 3265, 36 Pp., 15 Figures May 4, 1999

    Norntates PUBLISHED by the AMERICAN MUSEUM of NATURAL HISTORY CENTRAL PARK WEST at 79TH STREET, NEW YORK, NY 10024 Number 3265, 36 Pp., 15 Figures May 4, 1999

    AMERICANt MUSEUM Norntates PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024 Number 3265, 36 pp., 15 figures May 4, 1999 An Oviraptorid Skeleton from the Late Cretaceous of Ukhaa Tolgod, Mongolia, Preserved in an Avianlike Brooding Position Over an Oviraptorid Nest JAMES M. CLARK,I MARK A. NORELL,2 AND LUIS M. CHIAPPE3 ABSTRACT The articulated postcranial skeleton of an ovi- presence of a single, ossified ventral segment in raptorid dinosaur (Theropoda, Coelurosauria) each rib as well as ossified uncinate processes from the Late Cretaceous Djadokhta Formation associated with the thoracic ribs. Remnants of of Ukhaa Tolgod, Mongolia, is preserved over- keratinous sheaths are preserved with four of the lying a nest. The eggs are similar in size, shape, manal claws, and the bony and keratinous claws and ornamentation to another egg from this lo- were as strongly curved as the manal claws of cality in which an oviraptorid embryo is pre- Archaeopteryx and the pedal claws of modern served, suggesting that the nest is of the same climbing birds. The skeleton is positioned over species as the adult skeleton overlying it and was the center of the nest, with its limbs arranged parented by the adult. The lack of a skull pre- symmetrically on either side and its arms spread cludes specific identification, but in several fea- out around the nest perimeter. This is one of four tures the specimen is more similar to Oviraptor known oviraptorid skeletons preserved on nests than to other oviraptorids. The ventral part of the of this type of egg, comprising 23.5% of the 17 thorax is exceptionally well preserved and pro- oviraptorid skeletons collected from the Dja- vides evidence for other avian features that were dokhta Formation before 1996.