Les Oppeliidae (Ammonitina) de l'horizon à Collotiformis (Callovien supérieur, zone à Athleta) de la région dijonnaise (Côte-d'Or, France)

Bonnot, Alain; Marchand, Didier; Neige, Pascal

doi:10.1016/s0753-3969(00)87931-8

Cited by 5 publications

(6 citation statements)

References 2 publications

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“…Earlier investigations (Birkelund and Hansen 1968; Druschits and Khiami 1970;Kulicki 1974Kulicki , 1979 Druschits et al 1977;Bandel and Boletzky 1979;Tanabe et al 1980;Druschits and Doguzhaeva 1981;Bandel et al 1982;Landman 1982;Tanabe 1989) and analogy with recent cephalopods (Boletzky 1974) support the hypothesis that ammonoids developed directly without a larval stage. Most workers divide ammonite development into embryonic (secretion of the ammonitella) and post-embryonic (secretion of the remaining shell) stages.…”

mentioning

confidence: 76%

“…Burgundy (Athleta Zone, Collotiformis Subzone; see Bonnot et al 1999)]. The specimens were all collected from a 10-cm-thick limestone bed.…”

Section: P a L A E O N T O L O G Y V O L U M E 4mentioning

confidence: 99%

“…Secondary and intercalated ribs arise near the middle of the¯ank. The occurrence of two different adult morphologies (presence of lappet on small specimens), exhibiting similar juvenile stages suggests sexual dimorphism (Bonnot et al 1999).…”

Section: P a L A E O N T O L O G Y V O L U M E 4mentioning

confidence: 99%

“…At approximately one whorl, a characteristic constriction of the tube (primary constriction) and associated thickening of the shell outer wall (primary varix) mark the end of the ammonitella phase. The siphuncle originates as a bulbous cñcum attached to the inner wall of the protoconch by prosiphonal sheets (prosiphon).Earlier investigations (Birkelund and Hansen 1968; Druschits and Khiami 1970;Kulicki 1974Kulicki , 1979 Druschits et al 1977;Bandel and Boletzky 1979;Tanabe et al 1980;Druschits and Doguzhaeva 1981;Bandel et al 1982;Landman 1982;Tanabe 1989) and analogy with recent cephalopods (Boletzky 1974) support the hypothesis that ammonoids developed directly without a larval stage. Most workers divide ammonite development into embryonic (secretion of the ammonitella) and post-embryonic (secretion of the remaining shell) stages.…”

mentioning

confidence: 99%

“…Druschits and Khiami 1970;Kulicki 1974;Dauphin 1978; Tanabe et al 1979; Landman 1987). The embryonic shell (or ammonitella) consists of a spheroidal or ellipsoidal initial chamber (or protoconch), followed by a planispiral whorl (Text-®g.…”

mentioning

confidence: 99%

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Embryonic Ammonoid Shell Features: Intraspecific Variation Revisited

Rouget

Neige

2001

Palaeontology

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ABSTRACT. Two samples of ammonoids belonging to the Oppeliidae, Sublunuloceras virguloides and Hecticoceras (Brightii) canaliculatum, are analyzed to estimate the intraspeci®c variability of embryonic shell features. The study of embryonic shell characters reveals two main shapes of protoconch,¯attened and round. Prosiphons may be straight or slightly curved. New parameters for area are added to the linear parameters commonly found in the literature. Prosiphon length and caecum area vary greatly whereas protoconch and ammonitella diameter vary only slightly, and the ammonitella angle is almost constant. The protoconch-to-ammonitella size ratio behaves differently in each species, suggesting different patterns of embryonic growth. We compare our results with published data and discuss their signi®cance for species determination and ontogenetic interpretation. The main ®nding is that intraspeci®c embryonic variation is greater than was previously believed.KEY WORDS: ammonoid, embryonic shell, intraspeci®c variation, Callovian, Hecticoceratinae.M A N Y palaeontologists have investigated the ontogenetic development of ammonites through the microstructure of the shell and the morphology of the early whorls (e.g. Druschits and Khiami 1970;Kulicki 1974;Dauphin 1978; Tanabe et al. 1979; Landman 1987). The embryonic shell (or ammonitella) consists of a spheroidal or ellipsoidal initial chamber (or protoconch), followed by a planispiral whorl (Text-®g. 1). At approximately one whorl, a characteristic constriction of the tube (primary constriction) and associated thickening of the shell outer wall (primary varix) mark the end of the ammonitella phase. The siphuncle originates as a bulbous cñcum attached to the inner wall of the protoconch by prosiphonal sheets (prosiphon).Earlier investigations (Birkelund and Hansen 1968; Druschits and Khiami 1970;Kulicki 1974Kulicki , 1979 Druschits et al. 1977;Bandel and Boletzky 1979;Tanabe et al. 1980;Druschits and Doguzhaeva 1981;Bandel et al. 1982;Landman 1982;Tanabe 1989) and analogy with recent cephalopods (Boletzky 1974) support the hypothesis that ammonoids developed directly without a larval stage. Most workers divide ammonite development into embryonic (secretion of the ammonitella) and post-embryonic (secretion of the remaining shell) stages. The transition point between the two stages is marked by sudden changes in surface ornament, the appearance of a nacreous layer, and acceleration of growth (e.g. Erben et al.

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mentioning

confidence: 76%

“…Burgundy (Athleta Zone, Collotiformis Subzone; see Bonnot et al 1999)]. The specimens were all collected from a 10-cm-thick limestone bed.…”

Section: P a L A E O N T O L O G Y V O L U M E 4mentioning

confidence: 99%

Section: P a L A E O N T O L O G Y V O L U M E 4mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Embryonic Ammonoid Shell Features: Intraspecific Variation Revisited

Rouget

Neige

2001

Palaeontology

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Cosmopolitan Status for Taramelliceras kachhense (Waagen) (Ammonoidea) from Kutch, Western India

Roy

Mandal

Sur

et al. 2021

Mesozoic Stratigraphy of India

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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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Les Oppeliidae (Ammonitina) de l'horizon à Collotiformis (Callovien supérieur, zone à Athleta) de la région dijonnaise (Côte-d'Or, France)

Cited by 5 publications

References 2 publications

Embryonic Ammonoid Shell Features: Intraspecific Variation Revisited

Embryonic Ammonoid Shell Features: Intraspecific Variation Revisited

Cosmopolitan Status for Taramelliceras kachhense (Waagen) (Ammonoidea) from Kutch, Western India

Ammonoid Intraspecific Variability

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