7331 Chapters
Medium 9780253355089

8. How to Get Big in the Mesozoic: The Evolution of the Sauropodomorph Body Plan

Nicole Klein Indiana University Press ePub


Sauropod (or, more correctly, eusauropod) dinosaurs are highly distinctive, not only in their overall body form, but also in respect to many details of their anatomy. In comparison with basal dinosaurs, typical sauropods are characterized by small skulls, elongate necks, massive bodies, and an obligatory quadrupedal stance with elongate forelimbs and straight limbs in general. Tracing the anatomical changes that led to this distinctive body plan through sauropodomorph evolution is problematic as a result of the incompleteness of many basal taxa and phylogenetic uncertainty at the base of the clade. The decrease in skull size in sauropodomorphs seems to be abrupt at the base of the clade, but it is even more pronounced toward sauropods. Major changes in the sauropod skull are a relative shortening and broadening of the snout and an enlargement and retraction of the nares. Although the ultimate causes for these evolutionary changes are certainly manifold, most if not all of them seem to be related to the ecological and biomechanical requirements of the transition from a carnivorous to an herbivorous lifestyle, in which the skull is mainly used as a cropping device. A relatively elongate neck seems to be ancestral for sauropodomorphs, but the neck is further elongated on the lineage toward sauropods, especially by incorporation of two additional vertebrae at the base of Sauropoda. The relatively simple structure of the cervical vertebrae in basal sauropodomorphs might be a secondary reduction relative to basal saurischians as a result of changes in neck biomechanics in connection with the reduction of the size of the skull. Thus, the more complicated structure of sauropod cervicals probably reflects changing biomechanical requirements in connection with an elongation of the neck and an increase in body size, as does the opisthocoelous structure of the cervical vertebral centra. Limb evolution in sauropodomorphs is dominated by adaptations toward increasing body size and thus graviportality, with the limbs getting straighter and the distal limb segments relatively shorter. Body size increase in sauropodomorphs seems to have been rapid but even-paced, with the ancestral body size of the clade being in the 0–10 kg category, and the ancestral body size for sauropods probably being in the 1,000–10,000 kg category.

See All Chapters
Medium 9780253009920

6 - “Intelligent Leadership in the Cause of Racial Brotherhood”: Quakers, Social Science, and the American Friends Service Committee's Interwar Racial Activism

NoContributor Indiana University Press ePub

Quakers, Social Science, and the American Friends Service Committee's Interwar Racial Activism

Allan W. Austin

RECALLING THE EARLY years of the American Friends Service Committee (AFSC), Rufus Jones wrote that he and the organization's first members, “conscious of a divine leading,” had gone to work “aware, even if only dimly, that we were ‘fellow-laborers with God’ in the rugged furrows of the somewhat brambly fields of the world.”1 Jones's remark reveals a fundamental characteristic of Quaker religious identity: a belief in “the duty of Friends to live their faith and in so doing make the world a better place.”2 The many Quaker books of discipline today with “faith and practice” in their titles bear clear witness to this enduring foundational tenet of Quaker identity. The 1997 edition of Philadelphia Yearly Meeting's Faith and Practice, for example, connects belief and activism in Friends’ testimonies, which it describes as “expressions of lives turned toward the Light, outward expressions reflective of the inward experience of divine leading.”3

See All Chapters
Medium 9780253006455

19 The History of Behavioral Gender Assignment

Elof Axel Carlson Indiana University Press ePub

Identifying genes for homosexuality is difficult, but it is even more difficult to assign a genetic or innate basis for gender roles. Why should this be so difficult? Because gender roles are notoriously variable. At the time of this writing, I am 79 years old. Almost three generations ago, when I was a child, my father was known as a breadwinner and my mother was known as a housewife. Most males were expected to earn a living for the family. If you mentioned the word “doctor,” I thought of a male. If you mentioned the word “nurse,” I thought of a female. In those days the police were policemen. Firefighters were firemen. Job assignments were sometimes genderized with suffixes—an actor was a male and an actress was a female. It was also widely believed that women were nurturing, emotional, and not as cerebral as men. Men were the thinkers, deciders, and protectors. Women cried, and men were supposed to tough it out. I remember my surprise when in June of 1940 I came home and saw my father crying. He told us Paris had fallen to the Nazis. It was so unusual I have never forgotten it.

See All Chapters
Medium 9780253010452

Part 4. Toward the Postcolony

NoContributor Indiana University Press ePub



Moussa the African’s Blues

Abdourahman A. Waberi

Gustave Flaubert once wrote: “Those who read a book in order to know if the baroness marries the count are fools.” I would add: those who read this text in order to find out how France is doing will have the right to feel cheated, for if you want a prognosis, or if you want to develop some kind of perspective on the situation, you’ll have to hurry over to Marcel Pagnol’s beloved Bar de la Marine. Onward.1

Vacation is a time of idleness, of flânerie and light reading (even mindless newspapers are an ordeal), of collective and simple expression: here, I’m speaking of the emotion felt all the way into the depths of the Ardennes by the story of a bear that had escaped from its Pyrenean zoo, or the compassion for a cycling team suspected of doping. In such moments, I feel a bit ashamed of my receding concern for undocumented subjects and other asylum-seeking misfits, those worn down by uncertainty and worry. I think of them at the detention center for foreigners in Vincennes, me with not exactly pale skin, who chose to move to this country where I always have to spell out my first and last names.

See All Chapters
Medium 9780253356758

4 Setting the Scene: The Devonian World

Jennifer A. Clack Indiana University Press ePub

4.1. Graph of (A) and (B) levels through time from Graham et al. (1997). C = Carboniferous; ε = Cambrian; D = Devonian; J = Jurassic; K = Cretaceous; T = Tertiary; Tr = Triassic; O = Ordovician; P = Permian; PAL = present atmospheric levels; S = Silurian.

Devonian Biogeography and Climate

The Devonian period opened onto a world far different from the present day. In the earliest stages, over 400 million years ago, even the oxygen content of the air was different from today. According to some models, at the beginning of the Devonian, the air contained about half the present levels of oxygen (O2) but about 10 times the present amount of carbon dioxide (CO2) (Fig. 4.1). Estimates of O2 and CO2 levels were produced by Berner and colleagues (Berner 1993, 1999) based on factors including increasing radiation from the sun over the last 570 million years and how that has affected weathering rates of carbonates and silicates, and how the increase in plant cover changed the rate of weathering as well as the uptake of CO2 from the air. The models were backed up by evidence from carbon isotope studies of fossil soils. The effects mean that because CO2 is less dense than O2, the total air density was less than it is now. Generally speaking, the levels of CO2 are estimated to have been higher than present levels throughout the Devonian, dropping from about 0.35% in the Early and Mid Devonian to about 0.3% by the end of the Famennian. Causes for this drop are suggested to be the increased rates of burial of organic carbon and enhanced weathering of silicates. These processes also had an effect on climate cooling (Algeo et al. 2001). Present atmospheric levels of 0.03% were reached by the mid-Carboniferous (late Mississippian) (Fig. 4.1). It is an example of the influence of the increase in land plants covering the Earth, using CO2 and giving out O2.

See All Chapters

See All Chapters