Mode and Rate of Growth in Ammonoids

Bucher, Hugo; Landman, Neil H.; Klofak, Susan M.; Guex, Jean

doi:10.1007/978-1-4757-9153-2_12

Cited by 111 publications

(184 citation statements)

References 81 publications

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“…The small size of micromorph ammonites is usually explained by adaptative response to a less than optimal environment (Bucher et al 1996). This phenomenon has occasionally been reported in the literature on Cretaceous ammonites and led to several taxonomic problems at the genus and supra-generic levels (see for example Kennedy and Cooper 1977;Wright and Kennedy 1979;Kennedy and Cobban 1990).…”

Section: Significance Of the New Faunamentioning

confidence: 98%

New Heteroceratidae (Ammonoidea) from the late Barremian deepening succession of Marseille (Bouches-du-Rhône, France)

Frau¹,

Delanoy²,

Massé³

et al. 2016

Acta Geologica Polonica

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Investigation of the late Barremian deepening succession of the Provence platform, cropping out south of Marseille (Bouches-du-Rhône, France), has yielded a new ammonite fauna belonging to the Martelites sarasini Subzone (Martelites sarasini Zone). The fauna is dominated by representatives of the Heteroceratidae Spath, characterized by different patterns of coiling, high intraspecific variabilities and dwarfism. These heteroceratids are distinctive and utterly different from all previously known taxa, and this justifies the introduction of the new taxa Heteroceras denizoti sp. nov., Heteroceras veratiae sp. nov., Calanquites gen. nov., based on Imerites katsharavai Rouchadzé; Giovaraites gen. nov., based on Giovaraites massiliae gen. et sp. nov., Barguesiella gen. nov., based on Barguesiella goudesense gen. et sp. nov. and the closely allied Barguesiella mantei gen. et sp. nov. The occurrence of the latter species at the top of the Maiolica Formation in Italy questions its early Aptian age assumed in the literature. The newly described fauna could be considered as the first case of micromorphy in the Heteroceratidae. Its biostratigraphy, palaeoenvironmental and palaeobiogeographical significance are discussed.

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Section: Significance Of the New Faunamentioning

confidence: 98%

New Heteroceratidae (Ammonoidea) from the late Barremian deepening succession of Marseille (Bouches-du-Rhône, France)

Frau¹,

Delanoy²,

Massé³

et al. 2016

Acta Geologica Polonica

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“…Shell thickenings are also found as internal ridges or pseudo-constrictions, without external structures (Westermann, 1990;Bucher et al, 1996). These periodic shell thickenings are thought to indicate episodic growth and have occasionally been called varices, but are generally called constrictions (Seeley, 1865;Moore, Lalicker & Fischer, 1952;Bucher et al, 1996).…”

Section: Ammonoideamentioning

confidence: 99%

“…This is almost certainly due to the septa and sutures present in ammonoids, but not in gastropods. Another major form of ammonoid shell sculpture similar to varices is megastriae, distinct radial elements that include a discontinuity in shell secretion (Bucher & Guex, 1990;Bucher et al, 1996). The most intriguing type of megastriae are the parabolae of Phylloceratoidea, Lytoceratoidea, Perisphinctoidea, and the simpler flares of some Lytoceratoidea (Radtke, Hoffmann & Keupp, 2016).…”

Section: Ammonoideamentioning

confidence: 99%

The varix: evolution, distribution, and phylogenetic clumping of a repeated gastropod innovation

Webster

Vermeij

2017

Zoological Journal of the Linnean Society

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A recurrent theme in evolution is the repeated, independent origin of broadly adaptive, architecturally and functionally similar traits and structures. One such is the varix, a shell-sculpture innovation in gastropods. This periodic shell thickening functions mainly to defend the animal against shell crushing and peeling predators. Varices can be highly elaborate, forming broad wings or spines, and are often aligned in synchronous patterns. Here we define the different types of varices, explore their function and morphological variation, document the recent and fossil distribution of varicate taxa, and discuss emergent patterns of evolution. We conservatively found 41 separate origins of varices, which were concentrated in the more derived gastropod clades and generally arose since the mid-Mesozoic. Varices are more prevalent among marine, warm, and shallow waters, where predation is intense, on high-spired shells and in clades with collabral ribs. Diversification rates were correlated in a few cases with the presence of varices, especially in the Muricidae and Tonnoidea, but more than half of the origins are represented by three or fewer genera. Varices arose many times in many forms, but generally in a phylogenetically clumped manner (more frequently in particular higher taxa), a pattern common to many adaptations.ADDITIONAL KEYWORDS: evolutionary trends -fossil record -Gastropoda -shell sculpture -snails.

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“…First, we applied a 3D GIS-based methodology to 4 the flank surface of each ammonoid to globally quantify and visualize morphological variance, focusing on the surface roughness or "topography" of the shell. Second, we synthesized these data and compared the exposed phragmocone, formed during the juvenile stages (Bucher et al, 1996), to the final body chamber, formed during the morphogenetic countdown to full sexual maturity, between both dimorphs of the ammonoid species. From these comparisons, we determined the target of evolutionary change, that is, the ontogenetic stage exhibiting the broadest spectrum of variation that may provide the most "raw material" for natural selection.…”

Section: Geographic Information Systems (Gis) As a Morphometric Toolmentioning

confidence: 99%

Geographic Information Systems technology as a morphometric tool for quantifying morphological variation in an ammonoid clade

Knauss

Yacobucci

2014

Palaeontologia Electronica

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Ammonoids are known for their intraspecific and interspecific morphological variation through ontogeny, particularly in shell shape and ornamentation. Many features covary and individual elements are difficult to homologize, which make qualitative descriptions and widely-used morphometric tools inappropriate for quantifying these complex morphologies. However, spatial analyses conducted in a geographic information systems (GIS) environment allow for quantification and visualization of global shell form. Here, we present a GIS-based methodology in which the variation of shell features is assessed to evaluate evolutionary patterns in an ammonoid clade from the Late Cretaceous Western Interior Seaway of North America. We investigate the ancestral and more variable scaphitid heteromorph ammonoid Hoploscaphites spedeni and its less variable descendant H. nebrascensis. We created three-dimensional (3D) digital models of the fossil shells' lateral surfaces using photogrammetric software and imported the reconstructions into a GIS environment. We used the number of discrete aspect patches and the surface-to-planimetric (3D to 2D) area ratios of the lateral surface as terrain roughness indices. These 3D spatial analyses demonstrate the overlapping morphological ranges of H. spedeni and H. nebrascensis in ornamentation despite differences in shell compression. Additionally, the target for evolutionary change in this clade resides in the macroconch body chamber, which becomes less variable through development from H. spedeni to subsequent H. nebrascensis in macroconchs; however, microconchs retain the ancestral variation through ontogeny. These geospatial analyses not only successfully quantified variation in complex morphologies, but also demonstrated the versatility of this method to address questions related to ontogeny and phylogeny.

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Mode and Rate of Growth in Ammonoids

Cited by 111 publications

References 81 publications

New Heteroceratidae (Ammonoidea) from the late Barremian deepening succession of Marseille (Bouches-du-Rhône, France)

New Heteroceratidae (Ammonoidea) from the late Barremian deepening succession of Marseille (Bouches-du-Rhône, France)

The varix: evolution, distribution, and phylogenetic clumping of a repeated gastropod innovation

Geographic Information Systems technology as a morphometric tool for quantifying morphological variation in an ammonoid clade

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