Les genres Subgrossouvria Spath et Orionoides Spath (Ammonitina, Perisphinctidae) de l'Horizon à Leckenbyi (Callovien supérieur, Zone à Athleta) de Montreuil-Bellay (Maine-et-Loire, France)

Bonnot, Alain; Boursicot, Pierre-Yves; Ferchaud, Patrice

doi:10.4267/2042/54363

Cited by 3 publications

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“…aberrans Waagen, 1875. For example, Gerard and Contaut (1936), Callomon (1963), and Bonnot et al (2014) treated Subgrossouvria as a distinct genus. Elmi (1962) considered Subgrossouvria as a macroconch subgenus within Choffatia (Siemiradzki, 1898).…”

Section: Introductionmentioning

confidence: 99%

A taxonomic correction after 140 years

Dutta

Bardhan

2016

J. Paleontol.

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Abstract.-Waagen (1875) was the first who dealt with the Jurassic ammonites of Kutch based on detailed taxonomic work. In his monograph, he described among many species Perisphinctes spirorbis Neumayr, 1870 and P. aberrans Waagen, 1875 from the Callovian of Kutch, but the figures mentioned in the description did not correspond to the actual species. For P. spirorbis, the plate illustrated the holotype of an entirely different species (P. aberrans). On the other hand, P. spirorbis was illustrated as the lectotype of P. aberrans. Later, Spath (1924) introduced a new genus, Subgrossouvria, based on Waagen's P. aberrans as type species. He also erected another genus, Indosphinctes, and included P. spirorbis Waagen, 1875 within the synonymy of I. indicus (Siemiradzki, 1899). Spath (1931) was aware of wrong numbering of plates of Waagen's two species. But subsequent workers were ignorant of these taxonomic errors and continued to refer Waagen's wrong plate numbers. We have here described both the type specimens and provided diagnoses for Spath's two genera. We plead for this taxonomic correction in the incoming revised Treatise on Jurassic ammonites.

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Section: Introductionmentioning

confidence: 99%

A taxonomic correction after 140 years

Dutta

Bardhan

2016

J. Paleontol.

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A new sedimentary and biostratigraphic framework for the Callovian-Oxfordian transition on the Atlantic margin of Morocco

Duval-Arnould,

Bulot,

Masrour

et al. 2024

Journal of African Earth Sciences

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Another lesson from beautiful monsters: the case of 'sex reversals' in the Ammonoidea and their significance

Frau

Boursicot²

2021

BMC Ecol Evo

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Background Expression of sexual dimorphism is recognised in various fossil groups of molluscs such as the Ammonoidea, an extinct group of shelled cephalopods. During the Mesozoic, the best-documented sexual dimorphic examples are seen in the Jurassic superfamily Perisphinctoidea. It is usually expressed by distinct adult size and apertural modifications between the antidimorphs. Putative males (otherwise referred to as microconch) are small in size and develop lappets at the end of the shell while the females (macroconch) are larger and bear a simple peristome. Dubious cases are, however, known in that superfamily, which often relate to taxonomic biases or lack of diagnostic characters, and some others expose ontogenetic anomalies illustrated by ‘sex reversals’ in the shell morphology and ornamentation. Results The discovery of two specimens of the Callovian Aspidoceratidae Peltoceras athleta (Phillips), having both female and male features, questions the significance and causes of ‘sex reversals’ in the Ammonoidea. The two specimens have started with the macroconch ontogeny of Peltoceras athleta and show an apparent change toward maleness in the adult, as illustrated by their rounded whorl section, ribs retroversion, fading of the tubercles and lappets typical of the microconchs. Few other cases of female-to-male, as well as male-to-female ‘sex reversal’, are known in the fossil record, all belonging to the Jurassic Perisphinctoidea (families Perisphinctidae or Aspidoceratidae). Since all Jurassic Perisphinctoidea are strictly gonochoristic, these ‘sex reversals’ are pathological in nature and are herein referred to as a new forma-type pathology: namely “forma hermaphrodita”. Conclusions In the absence of any clear evidence of injury or parasitism, we hypothesize that such “forma hermaphrodita” individuals illustrate pathologic cases of intersexuality. Little is known about the ammonoid soft parts, and it is not possible to determine which internal sexual organs occur in specimens having both male and female external shell features. Abnormal feminisation and/or masculinisation also occur in modern cephalopods, the latter also grouping only gonochoric species. This phenomenon is similarly illustrated by a change in the adult body size and a mixing of both female and male structures. In that case, intersexuality is either advantageous in the population or caused sterility. The causes of intersexuality are not clearly established but environmental pollutants are evoked in modern cephalopods because they act as endocrine disrupters. ‘Sex reversals’ and/or non-functional reproductive abnormalities have also been caused by endocrine disrupters in various gonochoric gastropods species, but infestation, genetic abnormalities, temperature fluctuations or viruses are multiple causes, which can stimulate or inhibit neural-endocrinal activity by direct gonadal influence, and ultimately lead to feminisation or masculinisation in fishes, isopods, crustaceans, and gastropods as well. Regardless of whether “forma hermaphrodita” is due to an exogenic or endogenic cause, the record of intersex Perisphinctoidea in the Jurassic can be explained by the ready recognition of dimorphic pairs, and the easy collection of large and sufficiently preserved fossil palaeopopulations in which intersex specimens have statistically more chance to be found.

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Les genres Subgrossouvria Spath et Orionoides Spath (Ammonitina, Perisphinctidae) de l'Horizon à Leckenbyi (Callovien supérieur, Zone à Athleta) de Montreuil-Bellay (Maine-et-Loire, France)

Cited by 3 publications

References 0 publications

A taxonomic correction after 140 years

A taxonomic correction after 140 years

A new sedimentary and biostratigraphic framework for the Callovian-Oxfordian transition on the Atlantic margin of Morocco

Another lesson from beautiful monsters: the case of 'sex reversals' in the Ammonoidea and their significance

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