Function and shape in late Paleozoic (mid-Carboniferous) ammonoids

Swan, Andrew; Saunders, W. Bruce

doi:10.1017/s0094837300008885

Cited by 60 publications

(77 citation statements)

References 12 publications

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“…One peculiar case of such covariation is often coined as Buckman's rules of covariation (Westermann 1966; for further details, see Monnet et al 2015a). Such covariations have also been reported above the species level between different taxa, both in the Paleozoic (Swan and Saunders 1987;Kaplan 1999) and Mesozoic (e.g., Yacobucci 2004a;Brayard and Escarguel 2013). It is, however, not obvious that this rule can be extended beyond intraspecific variation.…”

Section: Continuous Variationmentioning

confidence: 99%

Ammonoid Intraspecific Variability

Baets

Bert

Hoffmann

et al. 2015

Topics in Geobiology

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Because ammonoids have never been observed swimming, there is no alternative to seeking indirect indications of the locomotory abilities of ammonoids. This approach is based on actualistic comparisons with the closest relatives of ammonoids, the Coleoidea and the Nautilida, and on the geometrical and physical properties of the shell. Anatomical comparison yields information on the locomotor muscular systems and organs as well as possible modes of propulsion while the shape and physics of ammonoid shells provide information on buoyancy, shell orientation, drag, added mass, cost of transportation and thus on limits of acceleration and swimming speed. On these grounds, we conclude that ammonoid swimming is comparable to that of Recent nautilids and sepiids in terms of speed and energy consumption, although some ammonoids might have been slower swimmers than nautilids.

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Section: Continuous Variationmentioning

confidence: 99%

Ammonoid Intraspecific Variability

Baets

Bert

Hoffmann

et al. 2015

Topics in Geobiology

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“…The morphotype distribution in the Namurian of the Urals was heavily slanted toward evolute ammonoids, i.e., morphotypes II, VII, and VIII of Saunders and Swan (1984;Saunders and Shapiro, 1986;Swan and Saunders, 1987;Figs. 4, 10).…”

Section: Reefslopesmentioning

confidence: 99%

“…Morphotypes VII and VIII were cosmopolitan but less abundant than morphotype II in all facies (at least juveniles). They were unstable longidomes, including the serpenticonic gastrioceratids Cancelloceras and Phillipsoceras that were probably planktic (although Swan and Saunders, 1987, attributed a "benthic" habitat to morphotype VIII). The ancillary morphotypes V and VI ofthe Ural platform were longidomic discocones.…”

Section: Reefslopesmentioning

confidence: 99%

Ammonoid Life and Habitat

Westermann

1996

Topics in Geobiology

225

361

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“…Similarly, using a variety of methods can help to identify biases inherent in any individual approach (Macleod 1999). Such studies have been highly successful in analyzing molluscan shell architecture (Williamson 1981;Saunders and Swan 1984;Swan and Saunders 1987;Saunders and Work 1996).…”

mentioning

confidence: 99%

Morphological Disparity as a Biodiversity Metric in Lower Bathyaland Abyssal Gastropod Assemblages

2004

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Abstract. Studies of deep-sea biodiversity focus almost exclusively on geographic patterns of ␣-diversity. Few include the morphological or ecological properties of species that indicate their actual roles in community assembly. Here, we explore morphological disparity of shell architecture in gastropods from lower bathyal and abyssal environments of the western North Atlantic as a new dimension of deep-sea biodiversity. The lower bathyal-abyssal transition parallels a gradient of decreasing species diversity with depth and distance from land. Morphological disparity measures how the variety of body plans in a taxon fills a morphospace. We examine disparity in shell form by constructing both empirical (eigenshape analysis) and theoretical (Schindel's modification of Raup's model) morphospaces. The two approaches provide very consistent results. The centroids of lower bathyal and abyssal morphospaces are statistically indistinguishable. The absolute volumes of lower bathyal morphospaces exceed those of the abyss; however, when the volumes are standardized to a common number of species they are not significantly different. The abyssal morphospaces are simply more sparsely occupied. In terms of the variety of basic shell types, abyssal species show the same disparity values as random subsets of the lower bathyal fauna. Abyssal species possess no evident evolutionary innovation. There are, however, conspicuous changes in the relative abundance of shell forms between the two assemblages. The lower bathyal fauna contains a fairly equable mix of species abundances, trophic modes, and shell types. The abyssal group is numerically dominated by species that are deposit feeders with compact unsculptured shells.

show abstract

Function and shape in late Paleozoic (mid-Carboniferous) ammonoids

Cited by 60 publications

References 12 publications

Ammonoid Intraspecific Variability

Ammonoid Intraspecific Variability

Ammonoid Life and Habitat

Morphological Disparity as a Biodiversity Metric in Lower Bathyaland Abyssal Gastropod Assemblages

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