university of chicago press fins into limbs evolution development and transformation feb 2007

[...]...Part I Evolution Chapter 1 Fins and Limbs and Fins into Limbs: The Historical Context, 1840–1940 Peter J Bowler T HE HISTORY OF how biologists in the 100 years between 1840 and 1940 tackled the question of how the vertebrates emerged onto land provides insights into the ways in which evolutionary thinking itself has evolved Whereas in the mid-19th century this and other major transformations... one of the earliest suggestions of such a scenario, and it was not proposed until the 1930s (Romer 1933; see also Bowler 1996) Fins and Limbs and Fins into Limbs 9 The Fin Problem One of the most controversial issues that emerged from the study of fish evolution was the origin of the paired fins It was natural to turn to those living vertebrates deemed to be the most primitive Most turned to jawless and. .. relations of the parts of animal bodies understood by the German word ‘Bedeutung’” (Owen 1849, 2) Indeed, Owen provided as a title for his lecture—in what he termed “the technical language of anatomical sciences”—“On the General and Serial Homologies of the Locomotory Extremities” (2) Limbs for Owen meant the arms and legs in man, fore- and hindlegs of beasts, wings and legs of bats and birds, and the... that the question of how fins were transformed into limbs could only be asked after the theory of evolution had been accepted In 1849, the doyen of British morphology, Richard Owen, published On the Nature of Limbs, an influential summary of a lecture delivered before the Royal Institution of Great Britain Owen evaluated and discussed the Bedeutung—the signification or essential essence of limbs as archetypes,... understand the pattern of stresses and strains that would have shaped the transformation as the ancestral fish began to move out of the water How had transitional forms coped with a way of life that was partly aquatic and partly terrestrial (see Coates and Ruta, chap 2, and Akimenko and Smith, chap 11 in this volume), and perhaps more important—why would a fish have taken the risk of first venturing out into. .. how biologists tackled the question of how the vertebrates emerged onto land illustrates the depth of the questions, and, despite over 150 years of concentrated effort, the comparative shallowness of our understanding of the causes of this remarkable transition Chapter 2 Skeletal Changes in the Transition from Fins to Limbs Michael I Coates and Marcello Ruta F of this chapter, tetrapods are considered... would a fish have taken the risk of first venturing out into a new and hostile environment? (Also, why did terrestrial tetrapods make the secondary transition back to the water? See Thewissen Fins and Limbs and Fins into Limbs 13 and Taylor, chap 18 in this volume.) Evolutionists of this school were no longer satisfied with the construction of phylogenetic trees based on morphological relationships They... relative, the ropefish, Calamoichthys calabaricus The presumed existence of living representatives of the crossopterygians became particularly significant later in the century when earlier members of the suborder were postulated as ancestors of the amphibians; morphologists expended a great deal of effort Fins and Limbs and Fins into Limbs 11 on Polypterus in the hope that it would throw light on this crucial... imprecise, and the entire issue can be muddied with debates about the presence or absence of key characteristics and the minutiae thereof For alternative and more elaborate hierarchies of names, see Ahlberg (1991), Ahlberg and Johanson (1998), and Johanson et al (2003) Irrespective of whichever Tetrapoda definition is used (cf Gaffney 1979; Lebedev and Coates 1995; Coates 1996; Ahlberg and Clack 1998; Anderson... Rackoff 1980, fig 9) (F) Pectoral girdle of Eusthenopteron in ventral view (after Andrews and Westoll 1970, fig 2e) (G) Left pelvic girdle, fin, and lepidotrichia in extensor view (reversed from Andrews and Westoll 1970, fig 17) Arrows indicate leading edge of fins thrum, anocleithrum, and supracleithrum (fig 2.7A, F) The latter contacts the posttemporal and thus articulates with the rear of the skull roof . alt="" Fins into Limbs