DOCSLIB.ORG

ECTOTHERMY and the SUCCESS of DINOSAURS Dinosaurs Were

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

Evolution, 33(3), 1979, pp. 983-997 ECTOTHERMY AND THE SUCCESS OF DINOSAURS MICHAEL J. BENTON Department of Geology, The University, Newcastle-upon-Tyne, NE1 7RU, England, U.K. Received February 28, 1978. Revised October 9, 1978 Dinosaurs were the dominant terrestrial AAAS symposium published as Olson and tetrapods of the Mesozoic and their eco- Thomas (1979) and references to papers logical roles and biological impact are gen- from this volume are, as a result, brief. erally compared with those of mammals in the Cenozoic. This has led to the as- DISCUSSION OF EVIDENCE FOR sumption that dinosaurs were endotherm- DINOSAUR ENDOTHERMY ic also (Bakker, 1971, 1979) and there Interest in the thermoregulatory physi- seems to be some evidence in support of ology of dinosaurs has revived recently this hypothesis. However, this evidence is (Bakker, 1975a; Desmond, 1975; Gould, not conclusive. Could it be that dinosaurs 1977; May, 1977; Marx, 1978; Olson and were in fact ectothermic and could their Thomas, 1979), although speculations success be explained most simply in terms have been made on this topic for at least of a normal reptilian physiology? 100 years. Audowa (1929) and Nopcsa In this paper I review the published evi- (1934) suggested that dinosaur extinction dence for and against dinosaur endother- might have been related to their ectother- my and attempt an assessment in terms of my, but other later authors have suggested the thermoregulatroy physiology of living that it was connected with their endother- animals, and I discuss the success and the my (Wieland, 1942; Russell, 1965; Cloud- extinction of dinosaurs in connection with sley-Thompson, 1971; Bakker, 1972, published data on Mesozoic paleoclima- 1973). tology. It is argued that endothermy in Broili (1941) and Schuh (1951), extrap- dinosaurs would have been energetically olating from finds in pterosaurs and syn- costly and yet there appears to have been apsids, predicted that dinosaurs would be no need for it. Ostrom (1979) complains found with "hair," necessary insulation in that critics of dinosaur endothermy merely an endotherm. However, others have re- offer alternatives and do not disprove the lated the large size and naked skin of di- arguments of their opponents. This paper nosaurs to endothermy, arguing that the attempts to show why dinosaurs (with the absence of small dinosaurs is connected possible exception of some theropods) had with the problems of excessive heat loss to be ectothermic. by small uninsulated endotherms with a Before proceeding, the four basic de- high surface/volume ratio (Bakker, 1971, scriptive terms used in thermoregulatory 1972, 1973; Ricqles, 1974). These latter physiology should be defined accurately interpretations were criticized by Thul- (Cowles, 1940, 1962; McNab, 1978). A born (1973) and Feduccia (1973) who poikilothermic animal has no control over pointed out that young dinosaurs were body temperature, which follows external small and naked and could only have conditions, while a homeothermic animal avoided cooling stress problems if they has a constant body temperature. An ec- were ectothermic. totherm derives heat from external sources The evidence most recently presented (generally solar radiation directly or indi- for dinosaur endothermy includes erect rectly) and an endotherm from internal gait, paleoclimates and distribution, small sources (generally metabolic or muscular agile dinosaurs, brain size, predator-prey heat). ratios, bone histology, and the parietal- This paper was written before the pineal complex. 983 This content downloaded from 137.222.249.97 on Fri, 29 Jan 2016 22:22:16 UTC All use subject to JSTOR Terms and Conditions 984 MICHAEL J. BENTON Erect gait. -Dinosaurs had erect stance saurs. However, this may be connected and advanced gait. Among living animals, with gait rather than thermoregulation. only endotherms have erect gait; and it Most living reptiles have a sprawling was suggested that this and the supposed stance, whereas the agile theropods had ability of dinosaurs to achieve fast speeds an erect stance. The erect posture which indicated endothermy (Schuh, 1951; Os- supported the great weight of brontosaurs trom, 1970, 1974; Bakker, 1971, 1972, allowed agile motion in smaller dinosaurs. 1973, 1974, 1975a; Dodson, 1974). How- The generally warm Mesozoic climates ever, this view has been widely criticized (see below) may have maintained their as a logical non sequitur (Thulborn, 1973; body temperatures high enough during the Bennett and Dalzell, 1973; Feduccia, day for activity and their carnivorous diet 1973, 1974; Bennett, 1974; Halstead, provided readily assimilable energy. After 1976). The fact that the only living ani- a cool night, body temperatures may have mals with erect gait are endotherms does been increased by basking or uptake of not mean that every animal with erect gait heat from rocks in the early morning as in is an endotherm-it should also be noted living reptiles. Ostrom (1978, 1979) sug- that many mammals and other endo- gests that the only possibly endothermic thermic animals (see below) have a dinosaurs were these small theropods, sprawling gait (Jenkins, 1971). In addi- particularly in view of their possible re- tion, Alexander (1976) calculated speeds lationship to birds. of only 1-3.6 ms-t from trackways of di- Brain size. -Feduccia (1973) suggested nosaur footprints, although one hadrosaur that the small lizard-like brain size of di- trackway indicates a speed of 7.5 ms- nosaurs speaks for ectothermy, but finds (Russell and Beland, 1976). Thus large of "ostrich dinosaurs" with large brains dinosaurs, at least, may have moved rel- (Russell, 1972) were interpreted as evi- atively slowly and the erect stance may be dence for endothermy (Dodson, 1974; no more than the most efficient way of Ricqles, 1974; Bakker, 1974, 1975a). supporting a heavy body (Bennett and However, the large brains of these dino- Dalzell, 1973; Feduccia, 1973; Bennett, saurs are associated with good eyesight 1974; McNab, 1978). and balance (Halstead, 1975b) and do not Paleoclimatology and distribution.- necessarily imply advanced mammal-like Finds of dinosaurs within the Cretaceous intelligence. In any case, internal ther- Arctic Circle (Russell, 1973) have been moregulation requires a smaller mass of thought to indicate endothermy also (Bak- neural tissue than that required by ecto- ker, 1975a; Desmond, 1975), but precise therms for the behavioral control of inter- data on Mesozoic climates are not given nal temperature (Jerison, 1973) and thus (Halstead, 1975b, 1976). There is no evi- brain size may not be a reliable indicator dence of glaciation in the Mesozoic of endothermy (cf. Robinson, 1971). (Schwarzbach, 1963; Bakker, 1975b) and Predator-prey ratios. -Herbivores climates at these high latitudes need not (whether endothermic or ectothermic) can have been cold. In general, Mesozoic cli- support about 5% of their biomass of en- mates were warmer than today (Dorf, dothermic predators, and for ectothermic 1970; see below). (reptile) carnivores, this predator-prey ra- Small agile dinosaurs. -Many smaller tio is apparently nearer 30-50% (Bakker, dinosaurs (especially lightly built thero- 1972, 1975a, 1975b, 1979). Bakker pods like Compsognathus, Saurorni- (1972, 1973, 1974, 1975a, 1975b) calcu- thoides and Deinonychus) were presum- lated predator--prey ratios for certain fos- ably agile and must have been able to sil populations and used the values he move rapidly (Ostrom, 1978). At first obtained as indices of ectothermy or en- sight, this is very different from many liv- dothermy. He noted a drop from 50% in ing lizards and might be thought to be the Early Permian to 10% in the Late good evidence for endothermy in dino- Permian and concluded that this repre- This content downloaded from 137.222.249.97 on Fri, 29 Jan 2016 22:22:16 UTC All use subject to JSTOR Terms and Conditions ECTOTHERMY AND THE SUCCESS OF DINOSAURS 985 sented the changeover from ectothermy to phocalcic salts, and they develop espe- endothermy in populations of fossil rep- cially in rapid growth (Ricqles, 1974). The tiles. idea has arisen that these Haversian sys- Charig (1976) listed many possible tems indicate endothermy (Enlow and sources of error in applying predator-prey Brown, 1957; Currey, 1962; Ricqles, ratios to fossil communities, such as col- 1969, 1972a, 1972b, 1974, 1976; Bakker, lector bias, incompleteness of the fossil re- 1972, 1974, 1975a; Dodson, 1974). cord, relative life spans, and interactions Large mammals, most birds, advanced of other animals in food chains. I would synapsids and dinosaurs have extensive add that some "prey" species (e.g., Bron- Haversian systems, and tunas, turtles and tosaurus) might have been unavailable for crocodiles have them less developed. They predation owing to very large size, al- are not present in small mammals, pas- though they could have been scavenged serine birds, lizards, snakes or primitive after they died, but their inclusion would reptiles (Enlow, 1969; Ricqles, 1974, greatly lower the apparent predator-prey 1976). The first two in this list are the ratio. The present-day elephants effective- "most" endothermic vertebrates (i.e., they ly have no natural predators because of have the highest rates of mass-specific their large size. Of course, the ratios can metabolism), and they might be expected only indicate whether the predator is en- to have such structures most highly de- dothermic or ectothermic: the amount of veloped (McNab, 1978). Thus, Haversian prey required would be the same whatever systems are present in most living endo- its thermoregulatory state. If ectothermic therms and some living ectotherms and tyrannosaurs ate their young or other car- tend to be associated with large size (Hal- nivores, or if they were partly scavengers, stead, 1976). Bouvier (1977) lists animals the ratios could be explained readily (Tra- with secondary Haversian systems and cy, 1976). shows that their presence is not correlated In fact, it seems that ratios of large with endothermy. The correlation seems ectothermic predators to prey closely ap- instead to be with homeothermy (McNab, proach those for endothermic predators, 1978).
Recommended publications
  • 1. Adaptation and the Evolution of Physiological Characters

    1. Adaptation and the Evolution of Physiological Characters

    Bennett, A. F. 1997. Adaptation and the evolution of physiological characters, pp. 3-16. In: Handbook of Physiology, Sect. 13: Comparative Physiology. W. H. Dantzler, ed. Oxford Univ. Press, New York. 1. Adaptation and the evolution of physiological characters Department of Ecology and Evolutionary Biology, University of California, ALBERT F. BENNETT 1 Irvine, California among the biological sciences (for example, behavioral CHAPTER CONTENTS science [I241). The Many meanings of "Adaptationn In general, comparative physiologists have been Criticisms of Adaptive Interpretations much more successful in, and have devoted much more Alternatives to Adaptive Explanations energy to, pursuing the former rather than the latter Historical inheritance goal (37). Most of this Handbook is devoted to an Developmentai pattern and constraint Physical and biomechanical correlation examination of mechanism-how various physiologi- Phenotypic size correlation cal systems function in various animals. Such compara- Genetic correlations tive studies are usually interpreted within a specific Chance fixation evolutionary context, that of adaptation. That is, or- Studying the Evolution of Physiological Characters ganisms are asserted to be designed in the ways they Macroevolutionary studies Microevolutionary studies are and to function in the ways they do because of Incorporating an Evolutionary Perspective into Physiological Studies natural selection which results in evolutionary change. The principal textbooks in the field (for example, refs. 33, 52, 102, 115) make explicit reference in their titles to the importance of adaptation to comparative COMPARATIVE PHYSIOLOGISTS HAVE TWO GOALS. The physiology, as did the last comparative section of this first is to explain mechanism, the study of how organ- Handbook (32). Adaptive evolutionary explanations isms are built functionally, "how animals work" (113).
  • Grand Challenges in Comparative Physiology

    Grand Challenges in Comparative Physiology

    GrandChallengesinComparative Physiology: Integration Across Disciplines and Across Levels of Biological Organization Donald L. Mykles,1,* Cameron K. Ghalambor,* Jonathon H. Stillman†,‡ and Lars Tomanekx *Department of Biology, Colorado State University, Fort Collins, CO 80523, USA; †Romberg Tiburon Center and Department of Biology, San Francisco State University, Tiburon, CA 94920, USA; ‡Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94703, USA; xCenter for Coastal Marine Sciences and Environmental Proteomics Laboratory, Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA 93407, USA Introduction the sixth paper in the ‘‘Grand understanding of the molecular mech- Challenges’’ series, which offers the anisms of cellular processes. The induc- Schwenk et al. (2009) provided an over­ view from comparative physiology. tive approach depends on observation view of five major challenges in organ- In this article, we expand upon three to develop universal principles. Charles ismal biology: (1) understanding the major challenges facing comparative Darwin, after all, used this approach to organism’s role in organism–environ­ physiology in the 21st century: vertical develop the theory of natural selection. ment linkages; (2) utilizing the func­ integration of physiological processes All too often these approaches are tional diversity of organisms; (3) across organizational levels within or- integrating living and physical systems viewed as mutually exclusive, when, in ganisms, horizontal integration of analysis; (4) understanding how fact, they are complementary and are genomes produce organisms; and (5) physiological processes across organ- used, to varying extents, by most biol­ understanding how organisms walk isms within ecosystems, and temporal ogists working today. Yet, we have the tightrope between stability and integration of physiological pro- fallen short of full integration across change.
  • Effect of Ethanol on Thermoregulation in the Goldfish, Carassius Auratus

    Effect of Ethanol on Thermoregulation in the Goldfish, Carassius Auratus

    Portland State University PDXScholar Dissertations and Theses Dissertations and Theses 1986 Effect of ethanol on thermoregulation in the goldfish, Carassius auratus Candace Sharon O'Connor Portland State University Follow this and additional works at: https://pdxscholar.library.pdx.edu/open_access_etds Part of the Biology Commons, and the Physiology Commons Let us know how access to this document benefits ou.y Recommended Citation O'Connor, Candace Sharon, "Effect of ethanol on thermoregulation in the goldfish, Carassius auratus" (1986). Dissertations and Theses. Paper 3703. https://doi.org/10.15760/etd.5587 This Thesis is brought to you for free and open access. It has been accepted for inclusion in Dissertations and Theses by an authorized administrator of PDXScholar. Please contact us if we can make this document more accessible: [email protected]. AN ABSTRACT OF THE THESIS of Candace Sharon O'Connor for the Master of Science in Biology presented May 16, 1986. Title: Effect of Ethanol on Thermoregulation in the Goldfish, Carassius auratus. APPROVED BY MEMBERS OF THE TIIBSIS COMMITTEE: Leonard Simpson In an attempt to elucidate the mechanism by which ethanol affects vertebrate thermoregulation, the effect of ethanol on temperature selection was studied in the goldfish, Carassius auratus. Ethanol was administered to 10 to 15 g fish by mixing it in the water of a temperature gradient. The dose response curve was very steep between 0.5% (v/v) ethanol (no response) and 0.7% (significant lowering of selected temperature in treated fish). Fish were exposed to concentrations of ethanol as high as 1.7%, at which concentration most experimental fish lost their ability to swim upright in the water.
  • Was Dinosaurian Physiology Inherited by Birds? Reconciling Slow Growth in Archaeopteryx

    Was Dinosaurian Physiology Inherited by Birds? Reconciling Slow Growth in Archaeopteryx

    Was Dinosaurian Physiology Inherited by Birds? Reconciling Slow Growth in Archaeopteryx Gregory M. Erickson1,6*, Oliver W. M. Rauhut2, Zhonghe Zhou3, Alan H. Turner4,6, Brian D. Inouye1, Dongyu Hu5, Mark A. Norell6 1 Department of Biological Science, Florida State University, Tallahassee, Florida, United States of America, 2 Bayerische Staatssammlung fu¨r Pala¨ontologie und Geologie and Department of Earth and Environmental Sciences, LMU Munich, Mu¨nchen, Germany, 3 Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology & Paleoanthropology, Chinese Academy of Science, Beijing, China, 4 Department of Anatomical Sciences, Stony Brook University, Stony Brook, New York, United States of America, 5 Paleontological Institute, Shenyang Normal University, Shenyang, China, 6 Division of Paleontology, American Museum of Natural History, New York, New York, United States of America Abstract Background: Archaeopteryx is the oldest and most primitive known bird (Avialae). It is believed that the growth and energetic physiology of basalmost birds such as Archaeopteryx were inherited in their entirety from non-avialan dinosaurs. This hypothesis predicts that the long bones in these birds formed using rapidly growing, well-vascularized woven tissue typical of non-avialan dinosaurs. Methodology/Principal Findings: We report that Archaeopteryx long bones are composed of nearly avascular parallel- fibered bone. This is among the slowest growing osseous tissues and is common in ectothermic reptiles. These findings dispute the hypothesis that non-avialan dinosaur growth and physiology were inherited in totality by the first birds. Examining these findings in a phylogenetic context required intensive sampling of outgroup dinosaurs and basalmost birds. Our results demonstrate the presence of a scale-dependent maniraptoran histological continuum that Archaeopteryx and other basalmost birds follow.
  • R~;: PHYSIOLOGICAL, MIGRATORIAL

    R~;: PHYSIOLOGICAL, MIGRATORIAL

    ....----------- 'r~;: i ! 'r; Pa/eont .. 62(4), 1988, pp. 64~52 Copyright © 1988, The Paleontological Society 0022-3360/88/0062-0640$03.00 PHYSIOLOGICAL, MIGRATORIAL, CLIMATOLOGICAL, GEOPHYSICAL, SURVIVAL, AND EVOLUTIONARY IMPLICATIONS OF CRETACEOUS POLAR DINOSAURS GREGORY S. PAUL 3109 North Calvert Street, Baltimore, Maryland 21218 ABSTRACTT- he presence of Late Cretaceous social dinosaurs in polar regions confronted them with winter conditions of extended dark, coolness, breezes, and precipitation that could best be coped with via an endothermic homeothermic physiology of at least the tenrec level. This is true whether the dinosaurs stayed year round in the polar regime-which in North America extended from Alaska south to Montana-or if they migrated away from polar winters. More reptilian physiologies fail to meet the demands of such winters -in certain key ways, a· point tentatively confirmed by the apparent failure of giant Late Cretaceous phobosuchid crocodilians to dwell north of Montana. Low metabolisms were also insufficient for extended annual migrations away from and towards the poles. It is shown that even high metabolic rate dinosaurs probably remained in their polar habitats year-round. The possibility that dinosaurs had avian-mammalian metabolic systems, and may have borne insulation at least seasonally, severely limits their use as polar paleoclimatic and Earth axial tilt indicators. Polar dinosaurs may have been a center of dinosaur evolution. The possible ability of polar dinosaurs to cope with conditions of cool and dark challenges theories that a gradual temperature decline, or a sudden, meteoritic or volcanic induced collapse in temperature and sunlight, destroyed the dinosaurs. INTRODUCTION America suggests that dinosaurs were regularly crossing, and NCREASINGNUMBERSof remains show that dinosaurs lived living upon, the Bering Land Bridge within a few degrees of the I near the North and South Poles during the Cretaceous.
  • State of the Palaeoart

    State of the Palaeoart

    Palaeontologia Electronica http://palaeo-electronica.org State of the Palaeoart Mark P. Witton, Darren Naish, and John Conway The discipline of palaeoart, a branch of natural history art dedicated to the recon- struction of extinct life, is an established and important component of palaeontological science and outreach. For more than 200 years, palaeoartistry has worked closely with palaeontological science and has always been integral to the enduring popularity of prehistoric animals with the public. Indeed, the perceived value or success of such products as popular books, movies, documentaries, and museum installations can often be linked to the quality and panache of its palaeoart more than anything else. For all its significance, the palaeoart industry ment part of this dialogue in the published is often poorly treated by the academic, media and literature, in turn bringing the issues concerned to educational industries associated with it. Many wider attention. We argue that palaeoartistry is standard practises associated with palaeoart pro- both scientifically and culturally significant, and that duction are ethically and legally problematic, stifle improved working practises are required by those its scientific and cultural growth, and have a nega- involved in its production. We hope that our views tive impact on the financial viability of its creators. inspire discussion and changes sorely needed to These issues create a climate that obscures the improve the economy, quality and reputation of the many positive contributions made by palaeoartists palaeoart industry and its contributors. to science and education, while promoting and The historic, scientific and economic funding derivative, inaccurate, and sometimes exe- significance of palaeoart crable artwork.
  • Impacts of Extreme Climatic Events on the Energetics of Long-Lived

    Impacts of Extreme Climatic Events on the Energetics of Long-Lived

    © 2014. Published by The Company of Biologists Ltd | The Journal of Experimental Biology (2014) 217, 3700-3707 doi:10.1242/jeb.106344 RESEARCH ARTICLE Impacts of extreme climatic events on the energetics of long-lived vertebrates: the case of the greater flamingo facing cold spells in the Camargue Anne-Sophie Deville1,2,*, Sophie Labaude1,*, Jean-Patrice Robin3, Arnaud Béchet1, Michel Gauthier-Clerc1,4, Warren Porter5, Megan Fitzpatrick5, Paul Mathewson5 and David Grémillet2,6,‡ ABSTRACT in geographic range (McCarty, 2001), changes in food web structure Most studies analyzing the effects of global warming on wild (Petchey et al., 1999), changes in population life-history features populations focus on gradual temperature changes, yet it is also (Forchhammer et al., 2001) and fluctuations in population patterns important to understand the impact of extreme climatic events. Here (Birkhofer et al., 2012; Duriez et al., 2012). Studies on the effects we studied the effect of two cold spells (January 1985 and February of climate change on species dynamics primarily focus on 2012) on the energetics of greater flamingos (Phoenicopterus roseus) consequences of gradual increase in temperature (Britton et al., in the Camargue (southern France). To understand the cause of 2010; Moses et al., 2012). However, climatologists also predict an observed flamingo mass mortalities, we first assessed the energy increase in the frequency, intensity and duration of extreme climatic stores of flamingos found dead in February 2012, and compared events (IPCC, 2011; Rahmstorf and Coumou, 2011). Extreme them with those found in other bird species exposed to cold spells climatic events are often ignored as potential drivers of population and/or fasting.
  • 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.
  • Visions of the Prehistoric Past Reviewed by Mark P. Witton

    Visions of the Prehistoric Past Reviewed by Mark P. Witton

    Palaeontologia Electronica http://palaeo-electronica.org Paleoart: Visions of the Prehistoric Past Reviewed by Mark P. Witton Paleoart: Visions of the Prehistoric Past. 2017. Written by Zoë Lescaze and Walton Ford. Taschen. 292 pages, ISBN 978-3-8365-5511-1 (English edition). € 75, £75, $100 (hardcover) Paleoart: Visions of the Prehistoric Past is a collection of palaeoartworks spanning 150 years of palaeoart history, from 1830 to the second half of the 20th century. This huge, supremely well-pre- sented book was primarily written by journalist, archaeological illustrator and art scholar Zoë Les- caze, with an introduction by artist Walton Ford (both are American, and use ‘paleoart’ over the European spelling ‘palaeoart’). Ford states that the genesis of the book reflects “the need for a paleo- art book that was more about the art and less about the paleo” (p. 12), and thus Paleoart skews towards artistic aspects of palaeoartistry rather than palaeontological theory or technical aspects of reconstructing extinct animal appearance. Ford and Lescaze are correct that this angle of palaeo- artistry remains neglected, and this puts Paleoart in prime position to make a big impact on this pop- ular, though undeniably niche subject. Paleoart is extremely well-produced and stun- ning to look at, a visual feast for anyone with an interest in classic palaeoart. 292 pages of thick, sturdy paper (9 chapters, hundreds of images, and four fold outs) and almost impractical dimensions (28 x 37.4 cm) make it a physically imposing, stately tome that reminds us why books belong on shelves and not digital devices. Focusing exclu- sively on 2D art, the layout is minimalist and clean, detail, unobscured by text and labelling.
  • Absorption of Radiant Energy in Redwinged Blackbirds ( Agelazus Zhoenzceus)’

    Absorption of Radiant Energy in Redwinged Blackbirds ( Agelazus Zhoenzceus)’

    SHORT COMMUNICATIONS ABSORPTION OF RADIANT ENERGY IN REDWINGED BLACKBIRDS ( AGELAZUS ZHOENZCEUS)’ SHELDON LUSTICK, SHARON TALBOT, AND EDWARD L. FOX Academic Faculty of Zoology Ohio State University Columbus, Ohio 43210 Previously (Lustick 1969) it was shown that black- Electric infrared lamp (R-40, 250 w clear end), was birds could use insolation to thermoregulate, and that centered over the window 40 cm above the floor of the thermal neutral zone was decreased at least 10” C the chamber. The bird in the chamber received light in those birds receiving artificial insolation. It was of wavelengths 400-1400 nm, the upper limit of hypothesized (confirmed by Heppner 1969, 1970) infrared passing through one cm of water (Ruttner that the downward shift in thermal neutrality was 1963:13). due to an effective increase in insulation; that is, The per cent transmittance of the glass window a decrease in the thermal gradient from the surface was measured with a Beckman spectrophotometer and of the skin to the surface of the feathers, thus de- found to range from 80 to 90 per cent over the creasing conductive heat loss. This suggests that the spectrum of 400-1400 nm, with the highest trans- bird is an endotherm (alI heat being produced by mittance at 500 nm. With the radiation source on, metabolism) and, under these conditions, loses heat the birds received approximately 0.9 cal cm-* mine1 more slowly. Cowles et al. (1967) has stated that at 7 cm above the floor of the submerged radiation “under the usual conditions prevailing in and around chamber. No air was passed through the chamber endotherms, and particularly in birds, the thermal (thus reducing convective heat loss) but the vents gradient usually slopes steeply from the body toward were open to the outside.
  • Wildlife Ecology Provincial Resources

    Wildlife Ecology Provincial Resources

    MANITOBA ENVIROTHON WILDLIFE ECOLOGY PROVINCIAL RESOURCES !1 ACKNOWLEDGEMENTS We would like to thank: Olwyn Friesen (PhD Ecology) for compiling, writing, and editing this document. Subject Experts and Editors: Barbara Fuller (Project Editor, Chair of Test Writing and Education Committee) Lindsey Andronak (Soils, Research Technician, Agriculture and Agri-Food Canada) Jennifer Corvino (Wildlife Ecology, Senior Park Interpreter, Spruce Woods Provincial Park) Cary Hamel (Plant Ecology, Director of Conservation, Nature Conservancy Canada) Lee Hrenchuk (Aquatic Ecology, Biologist, IISD Experimental Lakes Area) Justin Reid (Integrated Watershed Management, Manager, La Salle Redboine Conservation District) Jacqueline Monteith (Climate Change in the North, Science Consultant, Frontier School Division) SPONSORS !2 Introduction to wildlife ...................................................................................7 Ecology ....................................................................................................................7 Habitat ...................................................................................................................................8 Carrying capacity.................................................................................................................... 9 Population dynamics ..............................................................................................................10 Basic groups of wildlife ................................................................................11
  • Screaming Biplane Dromaeosaurs of the Air. June/July

    Screaming Biplane Dromaeosaurs of the Air. June/July

    5c.r~i~ ~l'tp.,ne pr~tl\USp.,urs 1tke.A-ir Written & illustrated by Gregory s. Paul It is questionable whether anyone even speculated that some dinosaurs were feathered until Ostrom detailed the evidence that birds descended from predatory avepod theropods a third of a century ago. The first illustration of a feathered dinosaur was a nice little study of a well ensconced Syntarsus dashing down a dune slope in pursuit of a gliding lizard in Robert Bakker's classic "Dinosaur Renaissance" article in the April 1975 Scientific American by Sarah Landry (can also be seen in the Scientific American Book of the Dinosaur I edited). My first feathered dinosaur was executed shortly after, an inappropriately shaggy Allosaurus attacking a herd of Diplodocus. I was soon doing a host of small theropods in feathers. Despite the logic of feath- / er insulation on the group ancestral birds and showing evidence of a high level energetics, images of feathered avepods were often harshly and unsci- Above: Proposed relationships based on flight adaptations of entifically criticized as unscientific in view of the lack of evidence for their preserved skeletons and feathers of Archaeopteryx, a generalized presence, ignoring the equal fact that no one had found scales on the little Sinornithosaurus, and Confuciusornis, with arrows indicating dinosaurs either. derived adaptations not present in Archaeopteryx as described in In the 1980s I further proposed that the most bird-like, avepectoran text. Not to scale. dinosaurs - dromaeosaurs, troodonts, oviraptorosaurs, and later ther- izinosaurs _were not just close to birds and the origin of flight, but were see- appear to represent the remnants of wings converted to display devices.