Ontogenetic trajectories of septal spacing in Early Jurassic belemnites from Germany and France, and their palaeobiological implications

Wani, Ryoji; Tajika, Amane; Ikuno, Kenji; Iwasaki, Tetsuro

doi:10.1111/pala.12327

Cited by 11 publications

(16 citation statements)

References 57 publications

(75 reference statements)

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“…Belemnites are extinct coleoid cephalopods, i.e., relatives of modern squids, cuttlefishes and octopuses (Fuchs 2006;Kröger et al 2011;Iba et al 2012Iba et al , 2014Klug et al 2016;Hoffmann et al 2016. With the ten-armed coleoids, the decabrachians, they share an internal skeleton largely surrounded by a muscular mantle, a large brain compared to other invertebrates, ten arms, chitinous jaws, large lateral eyes, and a predatory mode of life (e.g., Naef 1922;Reitner and Urlichs 1983;Doguzhaeva et al 2002Doguzhaeva et al , 2003Weis and Delsate 2006;Klug and Fuchs 2010;Klug et al 2010aKlug et al , b, 2016Keupp and Mitta 2015;Clements et al 2016;Donovan & Fuchs 2016; Klug and Tajika 2018;Wani et al 2018;Jenny et al 2019;. In contrast to other hard parts, the low magnesium calcite rostra of belemnites represent abundant fossils in the Jurassic and Cretaceous, sometimes occurring in rock-forming numbers (Doyle and Macdonald 1993;Rita et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Jaws of a large belemnite and an ammonite from the Aalenian (Middle Jurassic) of Switzerland

et al. 2020

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Although belemnite rostra can be quite abundant in Jurassic and Cretaceous strata, the record of belemnite jaws was limited to a few specimens from Germany and Russia. Here, we describe and figure three cephalopod jaws from the Middle Jurassic Opalinus Clay of northern Switzerland. Although flattened, the carbonaceous fossils display enough morphological information to rule out an ammonoid, nautiloid or octobrachian origin of the two larger jaws. Their similarities to belemnite jaws from Germany and Russia conforms with our interpretation of these specimens as belemnite jaws. Based on their rather large size, we tentatively assign these two jaws to the megateuthidid Acrocoelites conoideus. The third jaw is a rather small upper jaw of an ammonoid. Since Leioceras opalinum is by far the most common ammonite in this unit in northern Switzerland, we tentatively suggest that the upper jaw belongs to this species.

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Section: Introductionmentioning

confidence: 99%

Jaws of a large belemnite and an ammonite from the Aalenian (Middle Jurassic) of Switzerland

et al. 2020

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“…Similar relationships between hatching and decreased septal spacing followed by increased septal spacing during the earliest ontogenetic stage have been recognized in other cephalopods (modern spirula and modern and fossil nautiloids (the order Nautilida); Landman et al 1983; Tanabe & Tsukahara 1987; Arnold et al 1987; Chirat & Rioult 1998; Wani & Ayyasami 2009; Wani & Mapes 2010; Yamaguchi et al 2015). These facts suggest that such a relationship is one common characteristic among cephalopods, except for ammonoids and belemnites (both are assumed to hatch with a protoconch and no chamber; Landman et al 1996; Arai & Wani 2012; De Baets et al 2015; Wani et al 2018).…”

Section: Discussionmentioning

confidence: 99%

Ontogenetic trajectories of septal spacing in modern cuttlefishes are phylogenetically dependent

Noba

Yasumuro

Ikeda

et al. 2020

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In this study, the ontogenetic trajectories of septal spacing between succeeding chambers of five modern cuttlefishes, Sepia esculenta, S. lycidas, S. latimanus, S. pharaonic and Sepiella japonica, which were all wild‐caught around Japan, were analysed. The ontogenetic trajectories of septal spacing of all examined cuttlefishes demonstrate a decrease in septal spacing followed by an increase during the earliest ontogenetic stage. This trend is assumed to be related to hatching. After the rapid decrease and increase in septal spacing, species‐dependent trends occur irrespective of sex and locality. Based on cluster analyses of general trends recognized in each species, the five examined species can be categorized into two groups: (1) a group by S. pharaonis, S. esculenta and Sepiella japonica; and (2) S. latimanus and S. lycidas as more distant branching groups within the five examined species. This classification is concordant with some phylogenetic clades determined from DNA analyses. Therefore, we hypothesized that the ontogenetic trajectories of septal spacing among modern cuttlefishes are phylogenetically dependent. If this hypothesis holds in fossil cuttlefishes, the examination of ontogenetic trajectories of septal spacing would give new insight into the recognition not only of the life history but also of the phylogeny of fossil cuttlefishes.

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“…; Landman ; Wani & Ayyasami ; Wani & Mapes ; belemnites: Wani et al . ; modern Spirula : Neige & Warnke ; Hoffmann et al . ; Yamaguchi et al .…”

Section: Discussionunclassified

Polymorphism in Late Cretaceous phylloceratid ammonoids: evidence from ontogenetic trajectories of septal spacing

Iwasaki

Wani

2019

Papers in Palaeontology

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The ontogenetic trajectories of septal spacing between succeeding chambers of two phylloceratid ammonoids, Hypophylloceras subramosum and Phyllopachyceras ezoense, from the Haboro and Kotanbetsu areas, north‐western Hokkaido, Japan, were analysed. The ontogenetic trajectories of septal spacing of H. subramosum demonstrate a general trend with large intraspecific variation: two cycles of increasing to decreasing spacing followed by almost constant spacing. The large intraspecific variation can be subdivided into three types, making this species polymorphic. The ontogenetic trajectories of septal spacing of P. ezoense also show intraspecific variation, but with a different trend: one cycle of increasing to decreasing spacing and an increasing trend after that. The intraspecific variation can be subdivided into two types, which suggests that this species is dimorphic, possibly sexually dimorphic. Dimorphism is supported by two observations: (1) the difference in the ontogenetic trajectories of septal spacing is only seen in the later ontogenetic stages; and (2) the two types co‐occur with comparable abundance throughout all stratigraphic horizons. Detailed analyses of ontogenetic trajectories of septal spacing may reveal polymorphism in other ammonoid clades.

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Ontogenetic trajectories of septal spacing in Early Jurassic belemnites from Germany and France, and their palaeobiological implications

Cited by 11 publications

References 57 publications

Jaws of a large belemnite and an ammonite from the Aalenian (Middle Jurassic) of Switzerland

Jaws of a large belemnite and an ammonite from the Aalenian (Middle Jurassic) of Switzerland

Ontogenetic trajectories of septal spacing in modern cuttlefishes are phylogenetically dependent

Polymorphism in Late Cretaceous phylloceratid ammonoids: evidence from ontogenetic trajectories of septal spacing

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