# The first gladius-bearing coleoid cephalopods from the lower Toarcian “Schistes Cartons” Formation of the Causses Basin (southeastern France)

Romain Jattiot, Nathalie Coquel-Poussy, Isabelle Kruta, Isabelle Rouget, Alison J Rowe, Jean-David Moreau

► To cite this version:

Romain Jattiot, Nathalie Coquel-Poussy, Isabelle Kruta, Isabelle Rouget, Alison J Rowe, et al.. The first gladius-bearing coleoid cephalopods from the lower Toarcian “Schistes Cartons” Formation of the Causses Basin (southeastern France). PeerJ, 2024, 12, pp.e16894. 10.7717/peerj.16894. hal-04490124

HAL Id: hal-04490124

https://hal.sorbonne-universite.fr/hal-04490124

Submitted on 5 Mar 2024

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
# The first gladius-bearing coleoid cephalopods from the lower Toarcian “Schistes Cartons” Formation of the Causses Basin (southeastern France)

Romain Jattiot, Nathalie Coquel-Poussy, Isabelle Kruta, Isabelle Rouget, Alison Rowe, Jean-David Moreau

<figure><img src="image_1.png" /></figure>

## To cite this version:

Romain Jattiot, Nathalie Coquel-Poussy, Isabelle Kruta, Isabelle Rouget, Alison Rowe, et al.. The first gladius-bearing coleoid cephalopods from the lower Toarcian “Schistes Cartons” Formation of the Causses Basin (southeastern France). PeerJ, 2024, 12, pp.e16894. 10.7717/peerj.16894. hal-04490124

HAL Id: hal-04490124

https://hal.sorbonne-universite.fr/hal-04490124v1

Submitted on 5 Mar 2024

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

<figure><img src="image_2.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
# The first gladius-bearing coleoid cephalopods from the lower Toarcian “Schistes Cartons” Formation of the Causses Basin (southeastern France)

Romain Jattiot<fnref n="1" />,<fnref n="2" />, Nathalie Coquel-Poussy<fnref n="3" />, Isabelle Kruta<fnref n="1" />, Isabelle Rouget<fnref n="1" />, Alison J. Rowe<fnref n="1" /> and Jean-David Moreau<fnref n="2" />

## ABSTRACT

The fossil record of gladius-bearing coleoids is scarce and based only on a few localities with geological horizons particularly favourable to their preservation (the so-called Konservat-Lagerstätten), which naturally leads to strongly limited data on geographical distributions. This emphasizes the importance of every new locality providing gladius-bearing coleoids. Here, we assess for the first time the gladius-bearing coleoid taxonomic diversity within the lower Toarcian “Schistes Cartons” of the Causses Basin (southeastern France). The material includes two fragmentary gladii, identified as *Paraplesioteuthis sagittata* and ?Loligosepia sp. indet. Just with these two specimens, two (Prototeuthina and Loligosepiina) of the three (Prototeuthina, Loligosepiina and Teudopseina) suborders of Mesozoic gladius-bearing coleoids are represented. Thus, our results hint at a rich early Toarcian gladius-bearing coleoid diversity in the Causses Basin and point out the need for further field investigations in the lower Toarcian “Schistes Cartons” in this area. This new record of *Paraplesioteuthis sagittata* is only the second one in Europe and the third in the world (western Canada, Germany and now France). Based on these occurrences, we tentatively suggest that *P. sagittata* originated in the Mediterranean domain and moved to the Arctic realm through the Viking Corridor to eventually move even farther to North America.

**Subjects** Paleontology, Taxonomy

**Keywords** Coleoids, Lower Toarcian, Causses Basin, Paleobiogeography, Schistes Cartons

## INTRODUCTION

Within the cephalopod subclass Coleoidea *Bather, 1888*, the cohort Neocoleoidea *Haas, 1997* includes present-day organisms (e.g., vampire squid, octopods, squids, cuttlefishes and their relatives) that are mainly characterized by their internal shell. The latter is called gladius and consists of a sturdy but flexible chitinous structure within the dorsal mantle. The evolutionary history, anatomy and paleobiology of Mesozoic gladius-bearing coleoids has been extensively studied in the last two decades (*Fischer & Riou, 2002*; *Haas, 2002*; *Košák, 2002*; *Fuchs, Keupp & Engeser, 2003*; *Fuchs, Engeser & Keupp, 2007a*; *Fuchs, Klinghammer & Keupp, 2007b*; *Fuchs et al., 2007c*; *Fuchs, 2009*; *Fuchs & Iba, 2015*; *Fuchs*

<footnote n="1">¹Centre de Recherche en Paléontologie -Paris (CR2P), MNHN, CNRS, Sorbonne Université, Paris, France</footnote>

<footnote n="2">²Biogéosciences, CNRS, Université Bourgogne, Dijon, France</footnote>

<footnote n="3">³Saint Bauzile, France</footnote>
# The first gladius-bearing coleoid cephalopods from the lower Toarcian “Schistes Cartons” Formation of the Causses Basin (southeastern France)

Romain Jattiot<fnref n="1" />,<fnref n="2" />, Nathalie Coquel-Poussy<fnref n="3" />, Isabelle Kruta<fnref n="1" />, Isabelle Rouget<fnref n="1" />, Alison J. Rowe<fnref n="1" /> and Jean-David Moreau<fnref n="2" />

## ABSTRACT

The fossil record of gladius-bearing coleoids is scarce and based only on a few localities with geological horizons particularly favourable to their preservation (the so-called Konservat-Lagerstätten), which naturally leads to strongly limited data on geographical distributions. This emphasizes the importance of every new locality providing gladius-bearing coleoids. Here, we assess for the first time the gladius-bearing coleoid taxonomic diversity within the lower Toarcian “Schistes Cartons” of the Causses Basin (southeastern France). The material includes two fragmentary gladii, identified as *Paraplesioteuthis sagittata* and ?Loligosepia sp. indet. Just with these two specimens, two (Prototeuthina and Loligosepiina) of the three (Prototeuthina, Loligosepiina and Teudopseina) suborders of Mesozoic gladius-bearing coleoids are represented. Thus, our results hint at a rich early Toarcian gladius-bearing coleoid diversity in the Causses Basin and point out the need for further field investigations in the lower Toarcian “Schistes Cartons” in this area. This new record of *Paraplesioteuthis sagittata* is only the second one in Europe and the third in the world (western Canada, Germany and now France). Based on these occurrences, we tentatively suggest that *P. sagittata* originated in the Mediterranean domain and moved to the Arctic realm through the Viking Corridor to eventually move even farther to North America.

**Subjects** Paleontology, Taxonomy

**Keywords** Coleoids, Lower Toarcian, Causses Basin, Paleobiogeography, Schistes Cartons

## INTRODUCTION

Within the cephalopod subclass Coleoidea *Bather, 1888*, the cohort Neocoleoidea *Haas, 1997* includes present-day organisms (e.g., vampire squid, octopods, squids, cuttlefishes and their relatives) that are mainly characterized by their internal shell. The latter is called gladius and consists of a sturdy but flexible chitinous structure within the dorsal mantle. The evolutionary history, anatomy and paleobiology of Mesozoic gladius-bearing coleoids has been extensively studied in the last two decades (*Fischer & Riou, 2002*; *Haas, 2002*; *Košák, 2002*; *Fuchs, Keupp & Engeser, 2003*; *Fuchs, Engeser & Keupp, 2007a*; *Fuchs, Klinghammer & Keupp, 2007b*; *Fuchs et al., 2007c*; *Fuchs, 2009*; *Fuchs & Iba, 2015*; *Fuchs*

<footnote n="1">¹Centre de Recherche en Paléontologie –Paris (CR2P), MNHN, CNRS, Sorbonne Université, Paris, France</footnote>

<footnote n="2">²Biogéosciences, CNRS, Université Bourgogne, Dijon, France</footnote>

<footnote n="3">³Saint Bauzile, France</footnote>
et al., 2016; Bizikov, 2004; Bizikov, 2008; Fuchs & Weis, 2004; Fuchs & Weis, 2008; Fuchs & Weis, 2009; Fuchs & Weis, 2010; Wilby et al., 2004; Riccardi, 2005; Fuchs, 2006a; Fuchs, 2006b; Fuchs, 2006c; Fuchs, 2007; Fuchs, 2009; Fuchs, 2015; Fuchs, 2016; Fuchs, 2019; Fuchs, 2020; Fuchs & Schultze, 2008; Larson, 2010; Donovan & Strugnell, 2010; Keupp et al., 2010; Klug, Schweigert & Dietl, 2010; Klug et al., 2015; Klug et al., 2021a; Klug et al., 2021b; Fuchs & Larson, 2011a; Fuchs & Larson, 2011b; Schlögl, Košák & Hyžny, 2012; Breton, Strugnell & Donovan, 2013; Donovan & Boletzky, 2014; Fuchs & Iba, 2015; Jattiot et al., 2015a; Donovan & Fuchs, 2016; Kruta et al., 2016; Marroquín, Martindale & Fuchs, 2018; Košák et al., 2021; Moreau et al., 2022; Rowe et al., 2022; Rowe et al., 2023) thanks to a few localities with geological horizons particularly favourable to their preservation, the so-called Konservat-Lagerstätten. Thus, studies on exceptionally preserved Mesozoic gladius-bearing coleoids are based on Konservat-Lagerstätten such as the Lower Jurassic Posidonia Shales of Holzmaden, Germany (e.g., Hauff & Hauff, 1981; Riegraf, Werner & Lörcher, 1984; Klug et al., 2021a), the Middle Jurassic of Christian Malford and Rixon Gate, England (e.g., Wilby et al., 2004), the Middle Jurassic of La Voulte-sur-Rhône, France (e.g., Fischer & Riou, 1982; Fischer & Riou, 2002; Charbonnier, 2009; Kruta et al., 2016; Rowe et al., 2022; Rowe et al., 2023), the Upper Jurassic of Eichstätt, Solnhofen, Painten and Nusplingen Plattenkalks, Germany (e.g., Fuchs, 2006b; Fuchs, 2015; Klug, Schweigert & Dietl, 2010; Klug et al., 2015; Keupp et al., 2010), the Upper Jurassic of the Causse Méjean, France (Moreau et al., 2022) and the Upper Cretaceous of Hâkel, Hâdjoula and Sâhel Aalma, Lebanon (e.g., Fuchs, 2006c; Fuchs, Bracchi & Weis, 2009; Fuchs & Larson, 2011a; Fuchs & Larson, 2011b; Jattiot et al., 2015a; Klug et al., 2021b).

However, as these Lagerstätten are not continuous in time and space, the record of Mesozoic gladius-bearing coleoids is intermittent. As noted by Fuchs et al. (2016), our knowledge on geographical distributions of species still needs to be greatly improved, which confers great importance upon every new locality yielding gladius-bearing coleoids.

Here, we describe fossils of gladius-bearing coleoids from the lower Toarcian “Schistes Cartons” Formation (contemporaneous with the famous Posidonia Shales of Holzmaden; see references above) of the Causses Basin in southeastern France. The material described here represents the first gladius-bearing coleoid remains documented from this area. Thus, this work is the first attempt to assess the taxonomic diversity of gladius-bearing coleoids from the lower Toarcian “Schistes Cartons” of the Causses Basin. These findings also allow to provide new insights on the paleobiogeography of Toarcian gladius-bearing coleoids and are a first step towards discussions on hypothetical migration corridors.

## MATERIALS & METHODS

The material studied herein was collected by one of us (N.C.P.) in the northern part of the Causses Basin, Lozère, France (more precisely in the vicinity of Saint Bauzile village in the Valdonnez valley, at the base of the Balduc plateau, 5 km southern of Mende; Fig. 1). It consists of two gladius-bearing coleoid specimens (M486_2024.1.1 and M486_2024.1.2) preserved as compressions on slabs, which are housed in the paleontological collections of the Musée du Gévaudan (Mende, Lozère). We used UV-light to highlight soft tissues,
et al., 2016; Bizikov, 2004; Bizikov, 2008; Fuchs & Weis, 2004; Fuchs & Weis, 2008; Fuchs & Weis, 2009; Fuchs & Weis, 2010; Wilby et al., 2004; Riccardi, 2005; Fuchs, 2006a; Fuchs, 2006b; Fuchs, 2006c; Fuchs, 2007; Fuchs, 2009; Fuchs, 2015; Fuchs, 2016; Fuchs, 2019; Fuchs, 2020; Fuchs & Schultze, 2008; Larson, 2010; Donovan & Strugnell, 2010; Keupp et al., 2010; Klug, Schweigert & Dietl, 2010; Klug et al., 2015; Klug et al., 2021a; Klug et al., 2021b; Fuchs & Larson, 2011a; Fuchs & Larson, 2011b; Schlögl, Košák & Hyžny, 2012; Breton, Strugnell & Donovan, 2013; Donovan & Boletzky, 2014; Fuchs & Iba, 2015; Jattiot et al., 2015a; Donovan & Fuchs, 2016; Kruta et al., 2016; Marroquín, Martindale & Fuchs, 2018; Košák et al., 2021; Moreau et al., 2022; Rowe et al., 2022; Rowe et al., 2023) thanks to a few localities with geological horizons particularly favourable to their preservation, the so-called Konservat-Lagerstätten. Thus, studies on exceptionally preserved Mesozoic gladius-bearing coleoids are based on Konservat-Lagerstätten such as the Lower Jurassic Posidonia Shales of Holzmaden, Germany (e.g., Hauff & Hauff, 1981; Riegraf, Werner & Lörcher, 1984; Klug et al., 2021a), the Middle Jurassic of Christian Malford and Rixon Gate, England (e.g., Wilby et al., 2004), the Middle Jurassic of La Voulte-sur-Rhône, France (e.g., Fischer & Riou, 1982; Fischer & Riou, 2002; Charbonnier, 2009; Kruta et al., 2016; Rowe et al., 2022; Rowe et al., 2023), the Upper Jurassic of Eichstätt, Solnhofen, Painten and Nusplingen Plattenkalks, Germany (e.g., Fuchs, 2006b; Fuchs, 2015; Klug, Schweigert & Dietl, 2010; Klug et al., 2015; Keupp et al., 2010), the Upper Jurassic of the Causse Méjean, France (Moreau et al., 2022) and the Upper Cretaceous of Hâkel, Hâdjoula and Sâhel Aalma, Lebanon (e.g., Fuchs, 2006c; Fuchs, Bracchi & Weis, 2009; Fuchs & Larson, 2011a; Fuchs & Larson, 2011b; Jattiot et al., 2015a; Klug et al., 2021b).

However, as these Lagerstätten are not continuous in time and space, the record of Mesozoic gladius-bearing coleoids is intermittent. As noted by Fuchs et al. (2016), our knowledge on geographical distributions of species still needs to be greatly improved, which confers great importance upon every new locality yielding gladius-bearing coleoids.

Here, we describe fossils of gladius-bearing coleoids from the lower Toarcian “Schistes Cartons” Formation (contemporaneous with the famous Posidonia Shales of Holzmaden; see references above) of the Causses Basin in southeastern France. The material described here represents the first gladius-bearing coleoid remains documented from this area. Thus, this work is the first attempt to assess the taxonomic diversity of gladius-bearing coleoids from the lower Toarcian “Schistes Cartons” of the Causses Basin. These findings also allow to provide new insights on the paleobiogeography of Toarcian gladius-bearing coleoids and are a first step towards discussions on hypothetical migration corridors.

## MATERIALS & METHODS

The material studied herein was collected by one of us (N.C.P.) in the northern part of the Causses Basin, Lozère, France (more precisely in the vicinity of Saint Bauzile village in the Valdonnez valley, at the base of the Balduc plateau, 5 km southern of Mende; Fig. 1). It consists of two gladius-bearing coleoid specimens (M486_2024.1.1 and M486_2024.1.2) preserved as compressions on slabs, which are housed in the paleontological collections of the Musée du Gévaudan (Mende, Lozère). We used UV-light to highlight soft tissues,
<figure><img src="image_2.png" /><figcaption>**Figure 1** Geographical location of the Causses Basin. The black star indicates the Saint Bauzile site, where the studied material was retrieved. Image source credit: Moreau et al. (2021) ©Cambridge University Press, reproduced with permission.</figcaption></figure>

Full-size DOI: 10.7717/peerj.16894/fig-1

<figure><img src="image_3.png" /></figure>

using a UV wavelength of 360 nm. The anatomical terminology of the gladius and systematic paleontology follows *Fuchs & Weis (2010)*, *Fuchs & Larson (2011a)*, *Fuchs & Larson (2011b)*, *Fuchs (2016)* and *Fuchs (2020)*. Measured characters (see Appendix S1A) are: preserved gladius length, maximum gladius width, median field width$_{hypz}$, hyperbolar zone length, maximum lateral fields width. These measurements are standard in most published studies on gladius-bearing coleoids (e.g., *Fuchs & Larson, 2011a*; *Fuchs & Larson, 2011b*; *Fuchs, 2016*; *Fuchs, 2020*).

**Geological settings and stratigraphy**

The Causses Basin area is constituted by Jurassic limestone plateaus that are located south of the Massif Central (southeastern France). The studied material was collected *in situ* near Saint Bauzile (Fig. 1) from a ravine exhibiting a 27 m thick stratigraphic section showing upper Pliensbachian to middle Toarcian deposits (Lower Jurassic, Fig. 2). The upper Pliensbachian corresponds with the Villeneuve Formation and consists of grey
<figure><img src="image_3.png" /><figcaption>**Figure 1** Geographical location of the Causses Basin. The black star indicates the Saint Bauzile site, where the studied material was retrieved. Image source credit: Moreau et al. (2021) ©Cambridge University Press, reproduced with permission.</figcaption></figure>

Full-size DOI: 10.7717/peerj.16894/fig-1

<figure><img src="image_4.png" /></figure>

using a UV wavelength of 360 nm. The anatomical terminology of the gladius and systematic paleontology follows *Fuchs & Weis (2010)*, *Fuchs & Larson (2011a)*, *Fuchs & Larson (2011b)*, *Fuchs (2016)* and *Fuchs (2020)*. Measured characters (see Appendix S1A) are: preserved gladius length, maximum gladius width, median field width*hypz*, hyperbolar zone length, maximum lateral fields width. These measurements are standard in most published studies on gladius-bearing coleoids (e.g., *Fuchs & Larson, 2011a*; *Fuchs & Larson, 2011b*; *Fuchs, 2016*; *Fuchs, 2020*).

**Geological settings and stratigraphy**

The Causses Basin area is constituted by Jurassic limestone plateaus that are located south of the Massif Central (southeastern France). The studied material was collected *in situ* near Saint Bauzile (Fig. 1) from a ravine exhibiting a 27 m thick stratigraphic section showing upper Pliensbachian to middle Toarcian deposits (Lower Jurassic, Fig. 2). The upper Pliensbachian corresponds with the Villeneuve Formation and consists of grey
marls alternating with nodular and lenticular limestone beds (Fig. 2). At Saint Bauzile, this formation mainly yields large belemnite rostra, bivalves (Plicatula (Harpax) spinosa (Sowerby, 1812–1822)), brachiopods (e.g., Cirpa boscensis (Reynès, 1868)) as well as some ammonites (e.g., Juraphyllites, Pleuroceras) and invertebrate burrows (Tisoa siphonalis de Serres, 1840). The Toarcian is divided into two formations, the “Schistes Cartons” Formation (lower Toarcian) and the Marnes de Fontaneilles Formation (lower to upper Toarcian). The “Schistes Cartons” Formation is about 7.5 m thick and consists of dark grey, thinly laminated, organic-rich “shales” (Fig. 2). This formation is characterized by the abundance of ammonite compressions (e.g., Harpoceras falciferum (Sowerby, 1820), Dactylioceras spp.), aptychii, belemnite rostra and large wood trunks. In other sites from the Causses Basin, the “Schistes Cartons” also yielded rare vertebrate remains (e.g., crocodiles, ichthyosaurs; Bomou et al., 2021). At Saint Bauzile, the first meter of the formation displays an alternation of centimetric, orange and oxidized shale beds with centimetric black shale beds. The lower part of the formation shows two hard and thinly laminated limestone beds. The first one, regionally called the “Leptolepis bed” by several authors (e.g., Mattei, 1969; Trümpy, 1983), is very fossiliferous, displays a characteristic bituminous smell and constitutes a benchmark bed observed all over the Causses Basin. The two gladius-bearing coleoid specimens were retrieved from this bed. At Saint Bauzile, the “Leptolepis bed” is quite isopach and 20 cm thick. It shows a strong concentration of fish such as Leptolepis cf. coryphaenoides (Bronn, 1830; see Coquel-Poussy, 2013). Near the Saint Bauzile locality, this bed also yields rare crustaceans (Gabalerion; Audo et al., 2017). In the Causses Basin, the biozone associated with the “Leptolepis bed” is variable depending on the localities and the authors. Based on ammonites, most authors stratigraphically locate these beds in the Serpentinum Zone (e.g., Harazim et al., 2013; Pinard et al., 2014; Gatto et al., 2015), others in the Tenuicostatum Zone (e.g., Fonseca et al., 2018). In the Balduc area, the detailed biostratigraphic analysis conducted by Harazim et al. (2013) demonstrated that the “Leptolepis bed” corresponds to the Serpentinum Zone. Regionally, the Marnes de Fontaneilles Formation consists of grey to blue marls yielding a diversified, pyritized, marine, middle to upper Toarcian fauna mainly including ammonites (e.g., Mattei, 1969; Mattei, Combémorel & Enay, 1987; Jattiot et al., 2015b), belemnites (e.g., Pinard et al., 2014), bivalves (Fürsich et al., 2001), gastropods (e.g., Gatto et al., 2015) and rare vertebrates remains (e.g., Sciau, Crochet & Mattei, 1990; Bomou et al., 2021).

The Toarcian sediments of the Causses Basin were deposited in a shallow epicontinental sea located at a paleolatitude of 25 to 30°N. At the base of the “Schistes Cartons” Formation, Bomou et al. (2021) documented a negative carbon isotope excursion and higher mercury fluxes that were linked with the Toarcian Oceanic Anoxic Event (T-OAE). This event, originating from the intense volcanic activity of the Karoo Ferrar igneous province, is characterized by a widespread deposition of organic-rich shales concomitant with the onset to an episode of global warming. Bomou et al. (2021) showed that the deposition of the “Schistes Cartons” Formation took place during a prolongated period of widespread oxygen-deficiency and elevated carbon burial.
marls alternating with nodular and lenticular limestone beds (Fig. 2). At Saint Bauzile, this formation mainly yields large belemnite rostra, bivalves (Plicatula (Harpax) spinosa (Sowerby, 1812–1822)), brachiopods (e.g., Cirpa boscensis (Reynès, 1868)) as well as some ammonites (e.g., Juraphyllites, Pleuroceras) and invertebrate burrows (Tisoa siphonalis de Serres, 1840). The Toarcian is divided into two formations, the “Schistes Cartons” Formation (lower Toarcian) and the Marnes de Fontaneilles Formation (lower to upper Toarcian). The “Schistes Cartons” Formation is about 7.5 m thick and consists of dark grey, thinly laminated, organic-rich “shales” (Fig. 2). This formation is characterized by the abundance of ammonite compressions (e.g., Harpoceras falciferum (Sowerby, 1820), Dactylioceras spp.), aptychii, belemnite rostra and large wood trunks. In other sites from the Causses Basin, the “Schistes Cartons” also yielded rare vertebrate remains (e.g., crocodiles, ichthyosaurs; Bomou et al., 2021). At Saint Bauzile, the first meter of the formation displays an alternation of centimetric, orange and oxidized shale beds with centimetric black shale beds. The lower part of the formation shows two hard and thinly laminated limestone beds. The first one, regionally called the “Leptolepis bed” by several authors (e.g., Mattei, 1969; Trümpy, 1983), is very fossiliferous, displays a characteristic bituminous smell and constitutes a benchmark bed observed all over the Causses Basin. The two gladius-bearing coleoid specimens were retrieved from this bed. At Saint Bauzile, the “Leptolepis bed” is quite isopach and 20 cm thick. It shows a strong concentration of fish such as Leptolepis cf. coryphaenoides (Brolln, 1830; see Coquel-Poussy, 2013). Near the Saint Bauzile locality, this bed also yields rare crustaceans (Gabalerion; Audo et al., 2017). In the Causses Basin, the biozone associated with the “Leptolepis bed” is variable depending on the localities and the authors. Based on ammonites, most authors stratigraphically locate these beds in the Serpentinum Zone (e.g., Harazim et al., 2013; Pinard et al., 2014; Gatto et al., 2015), others in the Tenuicostatum Zone (e.g., Fonseca et al., 2018). In the Balduc area, the detailed biostratigraphic analysis conducted by Harazim et al. (2013) demonstrated that the “Leptolepis bed” corresponds to the Serpentinum Zone. Regionally, the Marnes de Fontaneilles Formation consists of grey to blue marls yielding a diversified, pyritized, marine, middle to upper Toarcian fauna mainly including ammonites (e.g., Mattei, 1969; Mattei, Combémorel & Enay, 1987; Jattiot et al., 2015b), belemnites (e.g., Pinard et al., 2014), bivalves (Fürsich et al., 2001), gastropods (e.g., Gatto et al., 2015) and rare vertebrates remains (e.g., Sciau, Crochet & Mattei, 1990; Bomou et al., 2021).

The Toarcian sediments of the Causses Basin were deposited in a shallow epicontinental sea located at a paleolatitude of 25 to 30°N. At the base of the “Schistes Cartons” Formation, Bomou et al. (2021) documented a negative carbon isotope excursion and higher mercury fluxes that were linked with the Toarcian Oceanic Anoxic Event (T-OAE). This event, originating from the intense volcanic activity of the Karoo Ferrar igneous province, is characterized by a widespread deposition of organic-rich shales concomitant with the onset to an episode of global warming. Bomou et al. (2021) showed that the deposition of the “Schistes Cartons” Formation took place during a prolongated period of widespread oxygen-deficiency and elevated carbon burial.
<figure><img src="image_4.png" /><figcaption>**Figure 2** Stratigraphic section of the Saint Bauzile site showing the location of the coleoid-bearing bed (black star = "*Leptolepis* bed"). Thi., thickness (m); Form., formations; Lith., lithology.</figcaption></figure>

Full-size

<figure><img src="image_5.png" /></figure>

DOI: 10.7717/peerj.16894/fig-2

RESULTS

Among Mesozoic gladius-bearing coleoids, three different morphotypes of gladii can be
recognized: prototeuthid, loligosepid and teudopseid (Fuchs, 2009). Each is associated
with the corresponding suborders Prototeuthina *Naef, 1921*, Loligosepiina (*Jeletzky, 1965*)
and Teudopseina *Starobogatov, 1983* (Fig. 3), respectively. The two individuals described
<figure><img src="image_5.png" /><figcaption>**Figure 2** Stratigraphic section of the Saint Bauzile site showing the location of the coleoid-bearing bed (black star = "*Leptolepis* bed"). Thi., thickness (m); Form., formations; Lith., lithology.</figcaption></figure>

Full-size

<figure><img src="image_6.png" /></figure>

DOI: 10.7717/peerj.16894/fig-2

RESULTS

Among Mesozoic gladius-bearing coleoids, three different morphotypes of gladii can be
recognized: prototeuthid, loligosepid and teudopseid (Fuchs, 2009). Each is associated
with the corresponding suborders Prototeuthina *Naef, 1921*, Loligosepiina (*Jeletzky, 1965*)
and Teudopseina *Starobogatov, 1983* (Fig. 3), respectively. The two individuals described
<figure><img src="image_6.png" /><figcaption>**Figure 3** Morphology, terminology and measurements of the three different gladius morphotypes among Mesozoic gladius-bearing coleoids. Data source credit: *Marroquín, Martindale & Fuchs (2018)*.
Full-size DOI: 10.7717/peerj.16894/fig-3</figcaption></figure>

in this study belong to the Prototeuthina and Loligosepina, indicating that at least two of
the three Mesozoic gladius-bearing suborders were present in this locality.

Subclass Coleoidea Bather, 1888

Superorder Octobrachia Haeckel, 1866

Suborder Prototeuthina Naef, 1921

*Diagnosis* (after Fuchs, 2020). Octobrachiates with torpedo-shaped body; gladius length (= median field length) equals mantle length; gladius with triangular median field and ventrally closed (funnel-like) conus; gladius very slender to moderately wide, maximum gladius width usually coincides with maximum median field width (by contrast to Loligosepina and Teudopseina); median field slender (compared to most loligosepoids and teudopseids), with median and lateral reinforcements; lateral reinforcements and central median field may be projected; median field area large to very large compared to lateral fields (gladius is median field dominated); hyperbolar zone indistinct or absent, hyperbolar zone length to median field length <0.6; lateral fields very slender to moderately wide.
<figure><img src="image_7.png" /><figcaption>**Figure 3** Morphology, terminology and measurements of the three different gladius morphotypes among Mesozoic gladius-bearing coleoids. Data source credit: *Marroquín, Martindale & Fuchs (2018).*
Full-size DOI: 10.7717/peerj.16894/fig-3</figcaption></figure>

in this study belong to the Prototeuthina and Loligosepina, indicating that at least two of
the three Mesozoic gladius-bearing suborders were present in this locality.

Subclass Coleoidea Bather, 1888

Superorder Octobrachia Haeckel, 1866

Suborder Prototeuthina Naef, 1921

*Diagnosis* (after Fuchs, 2020). Octobrachiates with torpedo-shaped body; gladius length (= median field length) equals mantle length; gladius with triangular median field and ventrally closed (funnel-like) conus; gladius very slender to moderately wide, maximum gladius width usually coincides with maximum median field width (by contrast to Loligosepina and Teudopseina); median field slender (compared to most loligosepoids and teudopseids), with median and lateral reinforcements; lateral reinforcements and central median field may be projected; median field area large to very large compared to lateral fields (gladius is median field dominated); hyperbolar zone indistinct or absent, hyperbolar zone length to median field length <0.6; lateral fields very slender to moderately wide.
Family Plesioteuthidae Naef, 1921

Type genus. Plesioteuthis Wagner, 1859

*Diagnosis* (after Fuchs, 2020). Medium-sized prototeuthids; gladius very slender to moderately wide (gladius width$_{max}$ to gladius length 0.05–0.25), with triangular median field and ventrally closed (funnel-like) conus; median field very slender to slender (median field width$_{hypz}$ to hyperbolar zone length <0.35 = opening angle <20°); median field area large to very large (median field area to gladius area 0.70–1.0); lateral fields very slender to moderately wide; hyperbolar zone very short to long (hyperbolar zone length to median field length <0.6); median and lateral reinforcements present on the median field; vestiges of septa and guard unknown, eight arms equipped with uniserial circular suckers, sucker-rings absent; arm length variable; funnel-and nuchal-locking cartilages absent; fins terminal; fin shape variable.

*Included genera* (after Fuchs, 2020). Plesioteuthis Wagner, 1859; Boreopeltis Engeser & Reitner, 1985; Dorateuthis Woodward, 1883; Eromangateuthis Fuchs, 2019; Nesisoteuthis Doguzhaeva, 2005; Normanoteuthis Breton, Strugnell & Donovan, 2013; Paraplesioteuthis Naef, 1921; Romaniteuthis Fischer & Riou, 1982; Rhomboteuthis Fischer & Riou, 1982; Senefelderiteuthis Engeser & Keupp, 1999.

*Stratigraphical and geographical range* (after Fuchs & Larson, 2011a). (?)Late Triassic (Rhaetian), Early Jurassic (Toarcian)–Late Cretaceous (Maastrichtian); Europe, Central Russia, Lebanon, North America and Australia.

Genus *Paraplesioteuthis* Naef, 1921

*Type species.* *Geoteuthis sagittata* Münster 1843 by the subsequent designation of Naef (1922, p. 111).

*Diagnosis* (after Fuchs, 2020). Gladius medium-sized, slender to moderately wide (gladius width$_{max}$ to gladius length 0.15–0.25) with a bipartite median ridge. Median field slender to moderately wide (median field width$_{hypz}$ to hyperbolar zone length 0.25–0.35 = opening angle 14°–20°), triangular and with lateral platelike reinforcements. Lateral reinforcements and central median field anteriorly projected. Median field area large to very large (median field area to gladius area 0.75–0.85). Lateral fields slender (lateral fields width$_{max}$ to median field width$_{max}$ 0.85–0.95). Hyperbolar zone moderately long to long (hyperbolar zone length to median field length 0.45–0.55). Soft parts poorly known.

*Included species.* *Paraplesioteuthis sagittata* (Münster 1843) only.

*Stratigraphical and geographical range.* Upper Pliensbachian–lower Toarcian; southern Germany (Holzmaden region; Fuchs, 2006b), western Canada (Fernie Formation; Hall, 1985, Marroquín, Martindale & Fuchs, 2018), southeastern France (Causse Basin; this study).
Family Plesioteuthidae Naef, 1921

Type genus. Plesioteuthis Wagner, 1859

*Diagnosis* (after Fuchs, 2020). Medium-sized prototeuthids; gladius very slender to moderately wide (gladius width$_{max}$ to gladius length 0.05–0.25), with triangular median field and ventrally closed (funnel-like) conus; median field very slender to slender (median field width$_{hypz}$ to hyperbolar zone length <0.35 = opening angle <20°); median field area large to very large (median field area to gladius area 0.70–1.0); lateral fields very slender to moderately wide; hyperbolar zone very short to long (hyperbolar zone length to median field length <0.6); median and lateral reinforcements present on the median field; vestiges of septa and guard unknown, eight arms equipped with uniserial circular suckers, sucker-rings absent; arm length variable; funnel-and nuchal-locking cartilages absent; fins terminal; fin shape variable.

*Included genera* (after Fuchs, 2020). Plesioteuthis Wagner, 1859; Boreopeltis Engeser & Reitner, 1985; Dorateuthis Woodward, 1883; Eromangateuthis Fuchs, 2019; Nesisoteuthis Doguzhaeva, 2005; Normanoteuthis Breton, Strugnell & Donovan, 2013; Paraplesioteuthis Naef, 1921; Romaniteuthis Fischer & Riou, 1982; Rhomboteuthis Fischer & Riou, 1982; Senefelderiteuthis Engeser & Keupp, 1999.

*Stratigraphical and geographical range* (after Fuchs & Larson, 2011a). (?)Late Triassic (Rhaetian), Early Jurassic (Toarcian)–Late Cretaceous (Maastrichtian); Europe, Central Russia, Lebanon, North America and Australia.

Genus *Paraplesioteuthis* Naef, 1921

*Type species.* *Geoteuthis sagittata* Münster 1843 by the subsequent designation of Naef (1922, p. 111).

*Diagnosis* (after Fuchs, 2020). Gladius medium-sized, slender to moderately wide (gladius width$_{max}$ to gladius length 0.15–0.25) with a bipartite median ridge. Median field slender to moderately wide (median field width$_{hypz}$ to hyperbolar zone length 0.25–0.35 = opening angle 14°–20°), triangular and with lateral platelike reinforcements. Lateral reinforcements and central median field anteriorly projected. Median field area large to very large (median field area to gladius area 0.75–0.85). Lateral fields slender (lateral fields width$_{max}$ to median field width$_{max}$ 0.85–0.95). Hyperbolar zone moderately long to long (hyperbolar zone length to median field length 0.45–0.55). Soft parts poorly known.

*Included species.* *Paraplesioteuthis sagittata* (Münster 1843) only.

*Stratigraphical and geographical range.* Upper Pliensbachian–lower Toarcian; southern Germany (Holzmaden region; Fuchs, 2006b), western Canada (Fernie Formation; Hall, 1985, Marroquín, Martindale & Fuchs, 2018), southeastern France (Causse Basin; this study).
*Paraplesioteuthis sagittata* (Münster 1843)

figs. 4 and 5

1843. *Geoteuthis sagittata* Münster, pp. 672–673, pl. 7, fig. 3, pl. 8, fig. 4.

p 1843. *Geoteuthis hastata* Münster, p. 73, pl. 14, fig. 4.

non 1843. *Geoteuthis hastata* Münster, p. 73, pl. 8, fig. 3.

1860. *Geoteuthis sagittata* Münster; *Wagner, 1860*, p. 807.

1922. *Paraplesioteuthis hastata* (Münster); Naef, p. 114, fig. 41a-c.

1978. *Paraplesioteuthis sagittata* (Münster); Reitner, p. 210, fig. 6.

1984*Paraplesioteuthis sagittata* (Münster); Riegraf et al. p. 36.

1984. *Paraplesioteuthis hastata* (Münster); Riegraf et al. p. 36.

1985. *Paraplesioteuthis hastata* (Münster); Hall, p. 871, fig. 1.

1990. *Paraplesioteuthis sagittata* (Münster); Doyle, p. 205.

2006b. *Paraplesioteuthis hastata* (Münster); Fuchs, pl. 16a-c.

2009. *Paraplesioteuthis hastata* (Münster); Fuchs, fig 1. a-b.

2011a. *Paraplesioteuthis sagittata* (Münster); Fuchs & Larson, fig 7.1.

? 2018. *Paraplesioteuthis cf. sagittata* (Münster); Marroquín et al., figs. 6–10.

2020. *Paraplesioteuthis sagittata* (Münster); Fuchs, p. 10, fig. 4,1a-b

*Holotype*. The original specimen of Münster (1843, pl. 7, fig. 3) was lost during World War II.

*Lectotype* (designated by Marroquín, Martindale & Fuchs, 2018). Original of Münster (1843, pl. 8, fig. 4), Geologisch-Paläontologisches Museum Tübingen, GPIT 1529-2 (original of Reitner, 1978, fig. 6).

*Type locality*. Holzmaden region, southern Germany.

*Type horizon*. Posidonia Shales Formation, lower Toarcian (Lower Jurassic).

*Stratigraphical and geographical range*. As for genus.

*Material*. One incomplete specimen (M486_2024.1.1) from the lower Toarcian “Schistes Cartons” Formation of the Causses Basin, in the vicinity of Saint Bauzile village (Lozère, France).

*Description*. Although the single specimen (M486_2024.1.1) is only partially preserved, morphological description and taxonomic identification at the species level remain possible. The specimen consists of a long and slender gladius (interpreted here as in dorsal view) with a triangular, anteriorly diverging median field (Figs. 4A-4C). The preserved gladius length (= median field length) is 203 mm. Although the anterior end of the gladius is not preserved, we hypothesize that the original gladius length did not exceed 220 mm (according to Klug et al., 2021a, gladii of *Paraplesioteuthis sagittata* rarely reach 200 mm). Of note, we suspect that the anterior part of the gladius, which is poorly preserved, was affected by slight disruptions and distortions (Figs. 4A, Fig. 4B). In our opinion, this impedes providing a reliable measurement of the anteriormost gladius width. Partially preserved lateral reinforcements (most conspicuous in the posterior part of the gladius, Figs. 4A-4C, 5) diverge from posterior to anterior extremities. Based on the estimated median field width hypz to hyperbolar zone length (see Fig. 3 and Appendix S1A), we
*Paraplesioteuthis sagittata* (Münster 1843)

figs. 4 and 5

1843. *Geoteuthis sagittata* Münster, pp. 672–673, pl. 7, fig. 3, pl. 8, fig. 4.

p 1843. *Geoteuthis hastata* Münster, p. 73, pl. 14, fig. 4.

non 1843. *Geoteuthis hastata* Münster, p. 73, pl. 8, fig. 3.

1860. *Geoteuthis sagittata* Münster; *Wagner, 1860*, p. 807.

1922. *Paraplesioteuthis hastata* (Münster); Naef, p. 114, fig. 41a-c.

1978. *Paraplesioteuthis sagittata* (Münster); Reitner, p. 210, fig. 6.

1984*Paraplesioteuthis sagittata* (Münster); Riegraf et al. p. 36.

1984. *Paraplesioteuthis hastata* (Münster); Riegraf et al. p. 36.

1985. *Paraplesioteuthis hastata* (Münster); Hall, p. 871, fig. 1.

1990. *Paraplesioteuthis sagittata* (Münster); Doyle, p. 205.

2006b. *Paraplesioteuthis hastata* (Münster); Fuchs, pl. 16a-c.

2009. *Paraplesioteuthis hastata* (Münster); Fuchs, fig 1. a-b.

2011a. *Paraplesioteuthis sagittata* (Münster); Fuchs & Larson, fig 7.1.

? 2018. *Paraplesioteuthis cf. sagittata* (Münster); Marroquín et al., figs. 6–10.

2020. *Paraplesioteuthis sagittata* (Münster); Fuchs, p. 10, fig. 4,1a-b

*Holotype*. The original specimen of Münster (1843, pl. 7, fig. 3) was lost during World War II.

*Lectotype* (designated by Marroquín, Martindale & Fuchs, 2018). Original of Münster (1843, pl. 8, fig. 4), Geologisch-Paläontologisches Museum Tübingen, GPIT 1529-2 (original of Reitner, 1978, fig. 6).

*Type locality*. Holzmaden region, southern Germany.

*Type horizon*. Posidonia Shales Formation, lower Toarcian (Lower Jurassic).

*Stratigraphical and geographical range*. As for genus.

*Material*. One incomplete specimen (M486_2024.1.1) from the lower Toarcian “Schistes Cartons” Formation of the Causses Basin, in the vicinity of Saint Bauzile village (Lozère, France).

*Description*. Although the single specimen (M486_2024.1.1) is only partially preserved, morphological description and taxonomic identification at the species level remain possible. The specimen consists of a long and slender gladius (interpreted here as in dorsal view) with a triangular, anteriorly diverging median field (Figs. 4A-4C). The preserved gladius length (= median field length) is 203 mm. Although the anterior end of the gladius is not preserved, we hypothesize that the original gladius length did not exceed 220 mm (according to Klug et al., 2021a, gladii of *Paraplesioteuthis sagittata* rarely reach 200 mm). Of note, we suspect that the anterior part of the gladius, which is poorly preserved, was affected by slight disruptions and distortions (Figs. 4A, Fig. 4B). In our opinion, this impedes providing a reliable measurement of the anteriormost gladius width. Partially preserved lateral reinforcements (most conspicuous in the posterior part of the gladius, Figs. 4A-4C, 5) diverge from posterior to anterior extremities. Based on the estimated median field width hypz to hyperbolar zone length (see Fig. 3 and Appendix S1A), we
estimate that the lateral reinforcements form an opening angle of ~11° (see Appendix S1A). The lateral fields are relatively slender. Although the outline of the hyperbolar zone is hardly discernible, it appears relatively long (estimated hyperbolar zone length to median field length ratio is 0.44). Finally, it cannot be determined whether the median ridge is bipartite as commonly described for *Paraplesioteuthis* representatives.

*Remarks.* In our opinion, the gladius is too poorly preserved to provide an accurate measurement of the original gladius width$_{max}$. Nevertheless, based on the general shape of the gladius, we consider that the original gladius width$_{max}$ to gladius length ratio likely fell within the range of values mentioned by Fuchs (2020, p. 10) for *Paraplesioteuthis* (i.e., 0.15–0.25). Of note, the opening angle of ~11° framed by the lateral reinforcements in the present specimen is lower than the range of values given by Fuchs (2020, p. 10) for *Paraplesioteuthis* (i.e., 14°–20°). On the other hand, it is comparable to the opening angle of 10° mentioned by Hall (1985) for the *P. hastata* (Münster 1843) specimen from western Canada (*P. hastata* is regarded as conspecific with *P. sagittata* by Fuchs & Larson, 2011a). Thus, we suggest that values of opening angle for *Paraplesioteuthis* should be redefined as ranging from about 10° to 20°.

According to *Fuchs & Larson* (2011b), the Middle Jurassic genus *Romaniteuthis* differs from *Paraplesioteuthis* by having a reduced median field width (i.e., gladius width$_{max}$ to gladius length ratio 0.05–0.15; *Fuchs, 2020*) and lateral reinforcements as keels. Although the specimen described herein is too poorly preserved to provide a reliable measurement of the preserved gladius width$_{max}$, its original gladius width$_{max}$ to gladius length ratio was probably not less than 0.15. Furthermore, it does not exhibit prominent lateral keels.

*Paraplesioteuthis* lateral fields are relatively short (*Fuchs & Larson, 2011a*; see Fig. 4D, Fig. 4E). In this regard, the lateral fields of the present specimen seem more similar to that of *Romaniteuthis*, since they appear slightly elongated, in oval shape (compare Figs. 4A–4C, 5 with fig 7.2 in *Fuchs & Larson, 2011a*). This may however be due to slight intraspecific variability. Finally, the estimated hyperbolar zone length to median field length ratio for the present specimen is 0.44, which nearly falls within the range of values given by *Fuchs* (2020) for *Paraplesioteuthis* (i.e., 0.45–0.55).

In sum, despite a possible slight difference in shape of lateral fields, we consider that other features of the present gladius support its attribution to the species *Paraplesioteuthis sagittata*.

Order Vampyromorpha Robson, 1929

Suborder Loligosepiina Jeletzky, 1965

*Diagnosis* (after *Fuchs, 2020*). Small- to large-sized octobrachiates with bullet-shaped body; gladius length (= median field length) equals mantle length; gladius with triangular median field and cup-shaped conus; gladius slender to wide, maximum gladius width always exceeds maximum median field width; median field width very slender to moderately wide without pronounced median reinforcements, anterior median field margin concave, straight or
estimate that the lateral reinforcements form an opening angle of ~11° (see Appendix S1A). The lateral fields are relatively slender. Although the outline of the hyperbolar zone is hardly discernible, it appears relatively long (estimated hyperbolar zone length to median field length ratio is 0.44). Finally, it cannot be determined whether the median ridge is bipartite as commonly described for *Paraplesioteuthis* representatives.

*Remarks.* In our opinion, the gladius is too poorly preserved to provide an accurate measurement of the original gladius width$_{max}$. Nevertheless, based on the general shape of the gladius, we consider that the original gladius width$_{max}$ to gladius length ratio likely fell within the range of values mentioned by *Fuchs* (2020, p. 10) for *Paraplesioteuthis* (i.e., 0.15–0.25). Of note, the opening angle of ~11° framed by the lateral reinforcements in the present specimen is lower than the range of values given by *Fuchs* (2020, p. 10) for *Paraplesioteuthis* (i.e., 14°–20°). On the other hand, it is comparable to the opening angle of 10° mentioned by *Hall* (1985) for the *P. hastata* (*Münster 1843*) specimen from western Canada (*P. hastata* is regarded as conspecific with *P. sagittata* by *Fuchs & Larson, 2011a*). Thus, we suggest that values of opening angle for *Paraplesioteuthis* should be redefined as ranging from about 10° to 20°.

According to *Fuchs & Larson* (2011b), the Middle Jurassic genus *Romaniteuthis* differs from *Paraplesioteuthis* by having a reduced median field width (i.e., gladius width$_{max}$ to gladius length ratio 0.05–0.15; *Fuchs, 2020*) and lateral reinforcements as keels. Although the specimen described herein is too poorly preserved to provide a reliable measurement of the preserved gladius width$_{max}$, its original gladius width$_{max}$ to gladius length ratio was probably not less than 0.15. Furthermore, it does not exhibit prominent lateral keels.

*Paraplesioteuthis* lateral fields are relatively short (*Fuchs & Larson, 2011a*; see Fig. 4D, Fig. 4E). In this regard, the lateral fields of the present specimen seem more similar to that of *Romaniteuthis*, since they appear slightly elongated, in oval shape (compare Figs. 4A–4C, 5 with fig 7.2 in *Fuchs & Larson, 2011a*). This may however be due to slight intraspecific variability. Finally, the estimated hyperbolar zone length to median field length ratio for the present specimen is 0.44, which nearly falls within the range of values given by *Fuchs* (2020) for *Paraplesioteuthis* (i.e., 0.45–0.55).

In sum, despite a possible slight difference in shape of lateral fields, we consider that other features of the present gladius support its attribution to the species *Paraplesioteuthis sagittata*.

Order Vampyromorpha Robson, 1929

Suborder Loligosepiina Jeletzky, 1965

*Diagnosis* (after *Fuchs, 2020*). Small- to large-sized octobrachiates with bullet-shaped body; gladius length (= median field length) equals mantle length; gladius with triangular median field and cup-shaped conus; gladius slender to wide, maximum gladius width always exceeds maximum median field width; median field width very slender to moderately wide without pronounced median reinforcements, anterior median field margin concave, straight or
convex; median field area small to large; hyperbolar zone mostly well-arcuated, rarely
indistinct, long to very long; lateral fields usually moderately wide.

Family Loligosepiidae *Regteren Altena, 1949*

*Type genus. Loligosepia Quenstedt, 1839.*

*Diagnosis (after Fuchs, 2020).* Medium-sized loligosepiids; gladius slender to wide (gladius width$_{max}$ to gladius length 0.10–0.60), with deeply concave (V-shaped) hyperbolar zone; median field very slender to moderately wide (median field width$_{hypz}$ to hyperbolar zone length 0.10–0.40 = opening angle 7°–23°), anterior median field margin slightly convex; median field area small to moderate (median field area to gladius area 0.35–0.45); hyperbolar zone very long (hyperbolar zone length to median field length 0.85–0.95); lateral fields moderately wide (lateral fields width$_{max}$ to median field width$_{max}$ 1.30–1.85), anterior limit of lateral fields clearly pointed (spine-like); inner and outer asymptotes ridge-like.

*Included genera. Loligosepia Quenstedt, 1839 and Jeletzkyteuthis Doyle, 1990.*

*Stratigraphical and geographical range.* Lower Sinemurian–lower Toarcian; Germany, Luxembourg, France, Switzerland, UK, Canada (Alberta).

Genus *Loligosepia* Quenstedt, 1839

*Type species. Loligo aalensis Schübler in Zieten, 1832* (by subsequent designation of *Regteren Altena, 1949*, p. 57) from the lower Toarcian Posidonia Shales of Holzmaden (Germany).

*Diagnosis (after Fuchs, 2020).* Medium-sized loligosepiids, gladius moderately wide to wide (gladius width$_{max}$ to median field length 0.30–0.60); median field slender to moderately wide (median field width$_{hypz}$ to hyperbolar zone length 0.20–0.40 = opening angle 12°–23°); anterior median field margin convex; median field area small to moderate (median field area to gladius area 0.35–0.45); hyperbolar zone very long (hyperbolar zone length to median field length 0.85–0.95); lateral fields moderately wide (lateral fields width$_{max}$ to median field width$_{max}$ 1.35–1.80; arms short to moderate (arm length to mantle length ~0.45).

*Included species. Loligosepia bucklandi (Voltz, 1840)* from the lower Sinemurian of Dorset (UK) and *L. aalensis* (Schübler in *Zieten, 1832*) from the lower Toarcian of Holzmaden.

*Stratigraphical and geographical range.* Lower Sinemurian–lower Toarcian of Germany,
Luxembourg, France, UK and Canada (Alberta).

?*Loligosepia* sp. indet.

Figures 6 and 7

*Material.* One incomplete specimen (M486_2024.1.2) from the lower Toarcian “Schistes Cartons” Formation of the Causses Basin, in the vicinity of Saint Bauzile village (Lozère, France).

*Description.* The preserved gladius length (= median field length) of this specimen (M486_2024.1.2) is 76 mm and the maximum preserved gladius width is approximatively 33 mm. Although a significant part of the original gladius is most certainly missing, we
convex; median field area small to large; hyperbolar zone mostly well-arcuated, rarely
indistinct, long to very long; lateral fields usually moderately wide.

Family Loligosepiidae *Regteren Altena, 1949*

*Type genus. Loligosepia Quenstedt, 1839.*

*Diagnosis (after Fuchs, 2020).* Medium-sized loligosepiids; gladius slender to wide (gladius width$_{max}$ to gladius length 0.10–0.60), with deeply concave (V-shaped) hyperbolar zone; median field very slender to moderately wide (median field width$_{hypz}$ to hyperbolar zone length 0.10–0.40 = opening angle 7°–23°), anterior median field margin slightly convex; median field area small to moderate (median field area to gladius area 0.35–0.45); hyperbolar zone very long (hyperbolar zone length to median field length 0.85–0.95); lateral fields moderately wide (lateral fields width$_{max}$ to median field width$_{max}$ 1.30–1.85), anterior limit of lateral fields clearly pointed (spine-like); inner and outer asymptotes ridge-like.

*Included genera. Loligosepia Quenstedt, 1839 and Jeletzkyteuthis Doyle, 1990.*

*Stratigraphical and geographical range.* Lower Sinemurian–lower Toarcian; Germany,
Luxembourg, France, Switzerland, UK, Canada (Alberta).

Genus *Loligosepia* Quenstedt, 1839

*Type species. Loligo aalensis Schübler in Zieten, 1832* (by subsequent designation of *Regteren Altena, 1949*, p. 57) from the lower Toarcian Posidonia Shales of Holzmaden (Germany).

*Diagnosis (after Fuchs, 2020).* Medium-sized loligosepiids, gladius moderately wide to wide (gladius width$_{max}$ to median field length 0.30–0.60); median field slender to moderately wide (median field width$_{hypz}$ to hyperbolar zone length 0.20–0.40 = opening angle 12°–23°); anterior median field margin convex; median field area small to moderate (median field area to gladius area 0.35–0.45); hyperbolar zone very long (hyperbolar zone length to median field length 0.85–0.95); lateral fields moderately wide (lateral fields width$_{max}$ to median field width$_{max}$ 1.35–1.80; arms short to moderate (arm length to mantle length ~0.45).

*Included species. Loligosepia bucklandi (Voltz, 1840)* from the lower Sinemurian of Dorset
(UK) and *L. aalensis* (Schübler in *Zieten, 1832*) from the lower Toarcian of Holzmaden.

*Stratigraphical and geographical range.* Lower Sinemurian–lower Toarcian of Germany,
Luxembourg, France, UK and Canada (Alberta).

?*Loligosepia* sp. indet.

Figures 6 and 7

*Material.* One incomplete specimen (M486_2024.1.2) from the lower Toarcian “Schistes Cartons” Formation of the Causses Basin, in the vicinity of Saint Bauzile village (Lozère, France).

*Description.* The preserved gladius length (= median field length) of this specimen (M486_2024.1.2) is 76 mm and the maximum preserved gladius width is approximatively 33 mm. Although a significant part of the original gladius is most certainly missing, we
<figure><img src="image_7.png" /><figcaption>**Figure 4** *Paraplesioteuthis sagittata* (Münster, 1843), specimen M486_2024.1.1 (lower Toarcian, Saint Bauzile, Causses Basin) in dorsal view, under natural (A) and UV (B) light. (C) Interpretative drawing of specimen M486_2024.1.1. (D) *Paraplesioteuthis sagittata* specimen from the lower Toarcian Posidonia Shale Formation, Germany (UMH collection, *Fuchs, 2020*), Fig. 4-1a Dirk Fuchs. 2020. Part M, Chapter 23G: Systematic Descriptions: Octobrachia. Treatise Online 138: p. 12). (E) Gladius reconstruction of *Paraplesioteuthis sagittata* (*Fuchs, 2020*, Fig. 4-1b). Scale bars: 10 mm.</figcaption></figure>

Full-size

<figure><img src="image_8.png" /></figure>

DOI: 10.7717/peerj.16894/fig-4

tentatively hypothesize that the original gladius did not exceed 150 mm. Unfortunately, few features can be described on this specimen. On the posterior part of the specimen, inconspicuous lines are interpreted as a disrupted median line and inner asymptotes (Figs. 6A–6C, 7). The black structure preserved anteriorly is interpreted as the ink sac (Figs. 6A–6C). The specimen outline appears weakly constricted posteriorly, although it cannot be determined whether it is a genuine feature, or if it is due to slight taphonomic disruptions. The median field width*max* of the original gladius cannot be assessed.

*Remarks.* The overall shape of the gladius combined with the presence of lines interpreted as a median line and inner asymptotes hint at the possibility that this specimen belongs to the suborder Loligosepiina. Mesozoic gladius-bearing coleoids belonging to the suborder Teudopseina exhibit a characteristically constricted median field anteriorly, which does not seem to be the case in specimen M486_2024.1.2. Within the suborder Loligosepiina, the assignment of this specimen to the genus *Loligosepia* is unsettled. It is only based on a conjectural original size of the specimen (estimated around 150 mm) that is comparable with that of representatives of the *Loligosepia* species *L. bucklandi* (Voltz, 1840) and *L. aaalensis* (Schübler in Zieten, 1832). In our opinion, *Jeletzkyteuthis* species differ mostly by their larger gladius size. For example, *J. coriaceus* (Quenstedt, 1849) gladiuses regularly exceed 200 mm in length, according to Klug et al. (2021a). Besides, the poor preservation of both specimens prevents a robust comparison between the present specimen and the *J. coriaceus* specimen from the coeval locality of Langres (*Guérin-Franiatte & Gouspy*,
<figure><img src="image_8.png" /><figcaption>**Figure 4** *Paraplesioteuthis sagittata* (Münster, 1843), specimen M486_2024.1.1 (lower Toarcian, Saint Bauzile, Causses Basin) in dorsal view, under natural (A) and UV (B) light. (C) Interpretative drawing of specimen M486_2024.1.1. (D) *Paraplesioteuthis sagittata* specimen from the lower Toarcian Posidonia Shale Formation, Germany (UMH collection, *Fuchs, 2020*), Fig. 4-1a Dirk Fuchs. 2020. Part M, Chapter 23G: Systematic Descriptions: Octobrachia. Treatise Online 138: p. 12). (E) Gladius reconstruction of *Paraplesioteuthis sagittata* (*Fuchs, 2020*, Fig. 4-1b). Scale bars: 10 mm.</figcaption></figure>

Full-size

<figure><img src="image_9.png" /></figure>

DOI: 10.7717/peerj.16894/fig-4

tentatively hypothesize that the original gladius did not exceed 150 mm. Unfortunately, few features can be described on this specimen. On the posterior part of the specimen, inconspicuous lines are interpreted as a disrupted median line and inner asymptotes (Figs. 6A–6C, 7). The black structure preserved anteriorly is interpreted as the ink sac (Figs. 6A–6C). The specimen outline appears weakly constricted posteriorly, although it cannot be determined whether it is a genuine feature, or if it is due to slight taphonomic disruptions. The median field widthmax of the original gladius cannot be assessed.

*Remarks*. The overall shape of the gladius combined with the presence of lines interpreted as a median line and inner asymptotes hint at the possibility that this specimen belongs to the suborder Loligosepiina. Mesozoic gladius-bearing coleoids belonging to the suborder Teudopseina exhibit a characteristically constricted median field anteriorly, which does not seem to be the case in specimen M486_2024.1.2. Within the suborder Loligosepiina, the assignment of this specimen to the genus *Loligosepia* is unsettled. It is only based on a conjectural original size of the specimen (estimated around 150 mm) that is comparable with that of representatives of the *Loligosepia* species *L. bucklandi* (Voltz, 1840) and *L. aaalensis* (Schübler in Zieten, 1832). In our opinion, *Jeletzkyteuthis* species differ mostly by their larger gladius size. For example, *J. coriaceus* (Quenstedt, 1849) gladiuses regularly exceed 200 mm in length, according to Klug et al. (2021a). Besides, the poor preservation of both specimens prevents a robust comparison between the present specimen and the *J. coriaceus* specimen from the coeval locality of Langres (*Guérin-Franiatte & Gouspy*,
<figure><img src="image_9.png" /><figcaption>**Figure 5** *Paraplesioteuthis sagittata* (Münster, 1843), close-up of the posterior part of specimen M486_2024.1.1 (lower Toarcian, Saint Bauzile, Causses Basin) under natural light. Scale bar: 10 mm.
Full-size DOI: 10.7717/peerj.16894/fig-5</figcaption></figure>

1993). Ultimately, the hypothesis that the present specimen would represent a juvenile of *a Jeletzkyteuthis* cannot be discarded.
<figure><img src="image_10.png" /><figcaption>**Figure 5** *Paraplesioteuthis sagittata* (Münster, 1843), close-up of the posterior part of specimen M486_2024.1.1 (lower Toarcian, Saint Bauzile, Causses Basin) under natural light. Scale bar: 10 mm.
Full-size DOI: 10.7717/peerj.16894/fig-5</figcaption></figure>

1993). Ultimately, the hypothesis that the present specimen would represent a juvenile of *a Jeletzkyteuthis* cannot be discarded.
<figure><img src="image_10.png" /><figcaption>**Figure 6** ?Loligosepia sp. indet., specimen M486_2024.1.2 (lower Toarcian, Saint Bauzile, Causses Basin) in dorsal view, under natural (A) and UV (B) light. (C) Interpretative drawing of specimen M486_2024.1.2. Scale bar: 10 mm.</figcaption></figure>

Full-size

<figure><img src="image_11.png" /></figure>

DOI: 10.7717/peerj.16894/fig-6

DISCUSSION: PALEOBIOGEOGRAPHY OF PARAPLESIO-
TEUTHIS SAGITTATA

The present record of *Paraplesioteuthis sagittata* is only the second one in Europe and the third in the world (western Canada, Germany and now France; Fig. 8). During the Early Jurassic, the NW Tethyan and Artic realms (which consisted of two epicontinental seas) were linked by a narrow seaway named the Viking Corridor (Ziegler, 1988; Fig. 8). In this time interval, the Serpentinum Zone (from where the gladius-bearing coleoids described herein come) marks the onset of the disruption of a previous ammonite provincialism, with a strong homogenization of all Tethyan and Arctic ammonite species (Dera et al., 2011). This event is linked with the origination of numerous cosmopolitan ammonite taxa in the Mediterranean domain (Macchioni & Cecca, 2002). In this context, the Viking Corridor probably regulated the mixing between Artic and Euro-Boreal ammonites (Smith, Tipper & Ham, 2001; Dera et al., 2011).

Based on this, it can be hypothesized that some Early Jurassic gladius-bearing coleoids (such as *P. sagittata*), similarly to ammonites, broadly originated in the NW Tethyan realm and moved to the Arctic realm through the Viking Corridor, to eventually move even farther to North America (in the context of the Early Toarcian global warming event; see, e.g., *Dera & Donnadieu, 2012*). Other routes cannot be excluded, such as the Hispanic Corridor (Fig. 8), a narrow epicontinental seaway that was sporadically active since the Late Sinemurian –Early Pliensbachian time interval (Aberhan, 2001; Aberhan, 2002; Venturi, Bilotta & Ricci, 2006; Dera et al., 2009). However, according to Dera et al. (2011, p. 100), the Hispanic Corridor “…was certainly too shallow for allowing massive movements of hemipelagic organisms such as ammonites”. Since gladius-bearing coleoids are also hemipelagic organisms, we presume that gladius-bearing coleoids, similarly to ammonites, were not able to go through the Hispanic corridor.
A

<figure><img src="image_11.png" /></figure>

B

<figure><img src="image_12.png" /></figure>

C

<figure><img src="image_13.png" /><figcaption>**Figure 6** ?Loligosepia sp. indet., specimen M486_2024.1.2 (lower Toarcian, Saint Bauzile, Causses Basin) in dorsal view, under natural (A) and UV (B) light. (C) Interpretative drawing of specimen M486_2024.1.2. Scale bar: 10 mm.</figcaption></figure>

Full-size

<figure><img src="image_14.png" /></figure>

DOI: 10.7717/peerj.16894/fig-6

DISCUSSION: PALEOBIOGEOGRAPHY OF PARAPLESIO-
TEUTHIS SAGITTATA

The present record of *Paraplesioteuthis sagittata* is only the second one in Europe and the third in the world (western Canada, Germany and now France; Fig. 8). During the Early Jurassic, the NW Tethyan and Artic realms (which consisted of two epicontinental seas) were linked by a narrow seaway named the Viking Corridor (Ziegler, 1988; Fig. 8). In this time interval, the Serpentinum Zone (from where the gladius-bearing coleoids described herein come) marks the onset of the disruption of a previous ammonite provincialism, with a strong homogenization of all Tethyan and Arctic ammonite species (Dera et al., 2011). This event is linked with the origination of numerous cosmopolitan ammonite taxa in the Mediterranean domain (Macchioni & Cecca, 2002). In this context, the Viking Corridor probably regulated the mixing between Artic and Euro-Boreal ammonites (Smith, Tipper & Ham, 2001; Dera et al., 2011).

Based on this, it can be hypothesized that some Early Jurassic gladius-bearing coleoids (such as *P. sagittata*), similarly to ammonites, broadly originated in the NW Tethyan realm and moved to the Arctic realm through the Viking Corridor, to eventually move even farther to North America (in the context of the Early Toarcian global warming event; see, e.g., *Dera & Donnadieu, 2012*). Other routes cannot be excluded, such as the Hispanic Corridor (Fig. 8), a narrow epicontinental seaway that was sporadically active since the Late Sinemurian –Early Pliensbachian time interval (Aberhan, 2001; Aberhan, 2002; Venturi, Bilotta & Ricci, 2006; Dera *et al.*, 2009). However, according to Dera *et al.* (2011, p. 100), the Hispanic Corridor “…was certainly too shallow for allowing massive movements of hemipelagic organisms such as ammonites”. Since gladius-bearing coleoids are also hemipelagic organisms, we presume that gladius-bearing coleoids, similarly to ammonites, were not able to go through the Hispanic corridor.
<figure><img src="image_12.png" /><figcaption>**Figure 7** ?Loligosepia sp. indet., close-up of the posterior part of specimen M486_2024.1.2 (lower Toarcian, Saint Bauzile, Causses Basin) under natural light. Scale bar: 10 mm.</figcaption></figure>

Full-size

<figure><img src="image_13.png" /></figure>

DOI: 10.7717/peerj.16894/fig-7

In the hypothesis that gladius-bearing coleoids moved from the Mediterranean domain to North America through the Viking Corridor, we would expect to find *P. sagittata* specimens in localities from the Artic Realm, provided that the geological time interval is represented and that there are geological horizons peculiarly favourable to the preservation of gladius-bearing coleoids.
<figure><img src="image_15.png" /><figcaption>**Figure 7** ?Loligosepia sp. indet., close-up of the posterior part of specimen M486_2024.1.2 (lower Toarcian, Saint Bauzile, Causses Basin) under natural light. Scale bar: 10 mm.</figcaption></figure>

Full-size

<figure><img src="image_16.png" /></figure>

DOI: 10.7717/peerj.16894/fig-7

In the hypothesis that gladius-bearing coleoids moved from the Mediterranean domain to North America through the Viking Corridor, we would expect to find *P. sagittata* specimens in localities from the Artic Realm, provided that the geological time interval is represented and that there are geological horizons peculiarly favourable to the preservation of gladius-bearing coleoids.
<figure><img src="image_14.png" /></figure>

**Figure 8** Worldwide occurrences of *Paraplesioteuthis sagittata*. Worldwide occurrences of *Paraplesioteuthis sagittata* (black stars, 1 = western Canada, 2 = southern Germany and 3 = southeastern France) in the paleogeographical context of the Pliensbachian–Toarcian interval. (A) Global paleogeography. (B) Paleogeographical details of the NW Tethyan realm (scale bar = 250 km). Maps are modified after *Dera et al. (2010)*.

Full-size

<figure><img src="image_15.png" /></figure>

DOI: 10.7717/peerj.16894/fig-8

## CONCLUSIONS

Two of the three suborders of Mesozoic gladius-bearing coleoids are present in the studied material, which comprises so far only two specimens. This implies a previously unrecognized early Toarcian gladius-bearing coleoid diversity in the Causses Basin and points out the need for further field investigations in the lower Toarcian black shales in this area. Finally, based on the known worldwide occurrences of *P. sagittata*, we tentatively suggest that this species originated in the Mediterranean domain and moved to the Arctic realm through the Viking Corridor to eventually move even farther to North America.

## ACKNOWLEDGEMENTS

The authors are indebted to Christian Klug, Dirk Fuchs and an anonymous reviewer whose suggestions greatly improved the manuscript. We also thank P. Loubry and L. Cazes for photographing the specimens, as well as A. Lethiers for his work on the figures.

## ADDITIONAL INFORMATION AND DECLARATIONS

### Funding

The authors received no funding for this work.

### Competing Interests

The authors declare there are no competing interests.
<figure><img src="image_17.png" /></figure>

**Figure 8** Worldwide occurrences of *Paraplesioteuthis sagittata*. Worldwide occurrences of *Paraplesioteuthis sagittata* (black stars, 1 = western Canada, 2 = southern Germany and 3 = southeastern France) in the paleogeographical context of the Pliensbachian–Toarcian interval. (A) Global paleogeography. (B) Paleogeographical details of the NW Tethyan realm (scale bar = 250 km). Maps are modified after *Dera et al. (2010)*.

Full-size

<figure><img src="image_18.png" /></figure>

DOI: 10.7717/peerj.16894/fig-8

## CONCLUSIONS

Two of the three suborders of Mesozoic gladius-bearing coleoids are present in the studied material, which comprises so far only two specimens. This implies a previously unrecognized early Toarcian gladius-bearing coleoid diversity in the Causses Basin and points out the need for further field investigations in the lower Toarcian black shales in this area. Finally, based on the known worldwide occurrences of *P. sagittata*, we tentatively suggest that this species originated in the Mediterranean domain and moved to the Arctic realm through the Viking Corridor to eventually move even farther to North America.

## ACKNOWLEDGEMENTS

The authors are indebted to Christian Klug, Dirk Fuchs and an anonymous reviewer whose suggestions greatly improved the manuscript. We also thank P. Loubry and L. Cazes for photographing the specimens, as well as A. Lethiers for his work on the figures.

## ADDITIONAL INFORMATION AND DECLARATIONS

### Funding

The authors received no funding for this work.

### Competing Interests

The authors declare there are no competing interests.
## Author Contributions

* Romain Jattiot conceived and designed the experiments, performed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the article, and approved the final draft.

* Nathalie Coquel-Poussy conceived and designed the experiments, analyzed the data, authored or reviewed drafts of the article, and approved the final draft.

* Isabelle Kruta conceived and designed the experiments, performed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the article, and approved the final draft.

* Isabelle Rouget conceived and designed the experiments, performed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the article, and approved the final draft.

* Alison J. Rowe conceived and designed the experiments, performed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the article, and approved the final draft.

* Jean-David Moreau conceived and designed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the article, and approved the final draft.

## Data Availability

The following information was supplied regarding data availability:
The specimen measurements are available in the Supplemental File.

## Supplemental Information

Supplemental information for this article can be found online at http://dx.doi.org/10.7717/peerj.16894#supplemental-information.

## REFERENCES

* Aberhan M. 2001. Bivalve paleobiogeography and the Hispanic Corridor: time of opening and effectiveness of a proto-Atlantic seaway. *Palaeogeography, Palaeoclimatology, Palaeoecology* **165**(3–4):375–394 DOI 10.1016/S0031-0182(00)00172-3.

* Aberhan M. 2002. Opening of the Hispanic Corridor and the Early Jurassic bivalve biodiversity. *Geological Society of London, Special Publications* **194**:127–139 DOI 10.1144/GSL.SP.2002.194.01.10.

* Audo D, Williams M, Charbonnier S, Schweigert G. 2017. Gabaleryon, a new genus of widespread early Toarcian polychelidan lobsters. *Journal of Systematic Palaeontology* **15**(3):205–222 DOI 10.1080/14772019.2016.1167786.

* Bather FA. 1888. Shell-growth in Cephalopoda (Siphonopoda). *Annals and Magazine of Natural History* **6**:421–427.

* Bizikov VA. 2004. The shell in Vampyropoda (Cephalopoda): morphology, functional role and evolution. *Ruthenica Supplement* **3**:1–88.

* Bizikov VA. 2008. *Evolution of the shell in Cephalopoda*. Moscow: VNIRO Publishing, 445 p.
## Author Contributions

* Romain Jattiot conceived and designed the experiments, performed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the article, and approved the final draft.

* Nathalie Coquel-Poussy conceived and designed the experiments, analyzed the data, authored or reviewed drafts of the article, and approved the final draft.

* Isabelle Kruta conceived and designed the experiments, performed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the article, and approved the final draft.

* Isabelle Rouget conceived and designed the experiments, performed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the article, and approved the final draft.

* Alison J. Rowe conceived and designed the experiments, performed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the article, and approved the final draft.

* Jean-David Moreau conceived and designed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the article, and approved the final draft.

## Data Availability

The following information was supplied regarding data availability:
The specimen measurements are available in the Supplemental File.

## Supplemental Information

Supplemental information for this article can be found online at http://dx.doi.org/10.7717/peerj.16894#supplemental-information.

## REFERENCES

* Aberhan M. 2001. Bivalve paleobiogeography and the Hispanic Corridor: time of opening and effectiveness of a proto-Atlantic seaway. *Palaeogeography, Palaeoclimatology, Palaeoecology* **165**(3–4):375–394 DOI 10.1016/S0031-0182(00)00172-3.

* Aberhan M. 2002. Opening of the Hispanic Corridor and the Early Jurassic bivalve biodiversity. *Geological Society of London, Special Publications* **194**:127–139 DOI 10.1144/GSL.SP.2002.194.01.10.

* Audo D, Williams M, Charbonnier S, Schweigert G. 2017. Gabaleryon, a new genus of widespread early Toarcian polychelidan lobsters. *Journal of Systematic Palaeontology* **15**(3):205–222 DOI 10.1080/14772019.2016.1167786.

* Bather FA. 1888. Shell-growth in Cephalopoda (Siphonopoda). *Annals and Magazine of Natural History* **6**:421–427.

* Bizikov VA. 2004. The shell in Vampyropoda (Cephalopoda): morphology, functional role and evolution. *Ruthenica Supplement* **3**:1–88.

* Bizikov VA. 2008. *Evolution of the shell in Cephalopoda*. Moscow: VNIRO Publishing, 445 p.
Bomou B, Suan G, Schlögl J, Grosjean AS, Suchéras-Marx B, Adatte T, Spangenberg JE, Fouché S, Zacaï A, Gibert C, Brazier JM, Perrier V, Vincent P, Janneau K, Martin JE. 2021. The paleoenvironmental context of Toarcian vertebrate-yielding shales of southern France (Hérault). *Geological Society, London, Special Publications* 514(1):121–152.

Breton G, Strugnell JM, Donovan DT. 2013. A coleoid gladius (Mollusca, Cephalopoda) from the Albian of Normandy (France): a new squid genus and species. *Annales de Paléontologie* 99(3):275–283 DOI 10.1016/j.annpal.2013.07.004.

Bronn HG. 1830. Ueber zwei fossile Fischarten: *Cyprinus coryphaenoides* und *Tetragonolepis semicinctus* aus dem Gryphitenkalke bei Donau-Eschingen. *Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefaktenkunde* 1(1):14–30.

Charbonnier S. 2009. Le Lagerstätte de La Voulte: un environnement bathyal au Jurassique. *Mémoires du Muséum national d'Histoire naturelle* 199:1–272.

Coquel-Poussy N. 2013. Recherches paléontologiques dans le Toarcien basal de la Lozère. *Fossiles* 15:5–15.

de Serres M. 1840. Description de quelques mollusques fossiles nouveaux des terrains infraliassiques et de la craie compacte inferieure du Midi de la France. *Annales des Sciences Naturelles (Zoologie)* 14:5–25.

Dera G, Donnadieu Y. 2012. Modeling evidences for global warming, Arctic seawater freshening, and sluggish oceanic circulation during the Early Toarcian anoxic event. *Paleoceanography* 27(PA2211):1–15.

Dera G, Neige P, Dommergues J-L, Brayard A. 2011. Ammonite paleobiogeography during the Pliensbachian–Toarcian crisis (Early Jurassic) reflecting paleoclimate, eustasy, and extinctions. *Global and Planetary Change* 78:92–105 DOI 10.1016/j.gloplacha.2011.05.009.

Dera G, Neige P, Dommergues J-L, Fara E, Laffont R, Pellenard P. 2010. High-resolution dynamics of Early Jurassic marine extinctions: the case of Pliensbachian–“Toarcian ammonites (Cephalopoda). *Journal of the Geological Society, London* 167:21–33 DOI 10.1144/0016-76492009-068.

Dera G, Pucéat E, Pellenard P, Neige P, Delsate D, Joachimski MM, Reisberg L, Martinez M. 2009. Water mass exchange and variations in seawater temperature in the NW Tethys during the Early Jurassic: evidence from neodymium and oxygen isotopes of fish teeth and belemnites. *Earth and Planetary Science Letters* 286(1–2):198–207 DOI 10.1016/j.epsl.2009.06.027.

Doguzhaeva LA. 2005. A gladius-bearing coleoid cephalopod from the Aptian of Central Russia. *Mitteilungen des Geologisch-Paläontologischen Instituts, Universität Hamburg* 89:41–48.

Donovan DT, Boletzky SV. 2014. Loligosepia (Cephalopoda: Coleoidea) from the Lower Jurassic of the Dorset coast, England. *Neues Jahrbuch für Geologie und Paläontologie Abhandlungen* 273:45–63 DOI 10.1127/0077-7749/2014/0415.

Donovan DT, Fuchs D. 2016. Part M, Chapter 13: Fossilized soft tissues in Coleoidea. *Treatise Online* 73:1–30.
Bomou B, Suan G, Schlögl J, Grosjean AS, Suchéras-Marx B, Adatte T, Spangenberg JE, Fouché S, Zacaï A, Gibert C, Brazier JM, Perrier V, Vincent P, Janneau K, Martin JE. 2021. The paleoenvironmental context of Toarcian vertebrate-yielding shales of southern France (Hérault). *Geological Society, London, Special Publications* 514(1):121–152.

Breton G, Strugnell JM, Donovan DT. 2013. A coleoid gladius (Mollusca, Cephalopoda) from the Albian of Normandy (France): a new squid genus and species. *Annales de Paléontologie* 99(3):275–283 DOI 10.1016/j.annpal.2013.07.004.

Bronn HG. 1830. Ueber zwei fossile Fischarten: *Cyprinus coryphaenoides* und *Tetragonolepis semicinctus* aus dem Gryphitenkalke bei Donau-Eschingen. *Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefaktenkunde* 1(1):14–30.

Charbonnier S. 2009. Le Lagerstätte de La Voulte: un environnement bathyal au Jurassique. *Mémoires du Muséum national d'Histoire naturelle* 199:1–272.

Coquel-Poussy N. 2013. Recherches paléontologiques dans le Toarcien basal de la Lozère. *Fossiles* 15:5–15.

de Serres M. 1840. Description de quelques mollusques fossiles nouveaux des terrains infraliassiques et de la craie compacte inferieure du Midi de la France. *Annales des Sciences Naturelles (Zoologie)* 14:5–25.

Dera G, Donnadieu Y. 2012. Modeling evidences for global warming, Arctic seawater freshening, and sluggish oceanic circulation during the Early Toarcian anoxic event. *Paleoceanography* 27(PA2211):1–15.

Dera G, Neige P, Dommergues J-L, Brayard A. 2011. Ammonite paleobiogeography during the Pliensbachian–Toarcian crisis (Early Jurassic) reflecting paleoclimate, eustasy, and extinctions. *Global and Planetary Change* 78:92–105 DOI 10.1016/j.gloplacha.2011.05.009.

Dera G, Neige P, Dommergues J-L, Fara E, Laffont R, Pellenard P. 2010. High-resolution dynamics of Early Jurassic marine extinctions: the case of Pliensbachian–“Toarcian ammonites (Cephalopoda). *Journal of the Geological Society, London* 167:21–33 DOI 10.1144/0016-76492009-068.

Dera G, Pucéat E, Pellenard P, Neige P, Delsate D, Joachimski MM, Reisberg L, Martinez M. 2009. Water mass exchange and variations in seawater temperature in the NW Tethys during the Early Jurassic: evidence from neodymium and oxygen isotopes of fish teeth and belemnites. *Earth and Planetary Science Letters* 286(1–2):198–207 DOI 10.1016/j.epsl.2009.06.027.

Doguzhaeva LA. 2005. A gladius-bearing coleoid cephalopod from the Aptian of Central Russia. *Mitteilungen des Geologisch-Paläontologischen Instituts, Universität Hamburg* 89:41–48.

Donovan DT, Boletzky SV. 2014. Loligosepia (Cephalopoda: Coleoidea) from the Lower Jurassic of the Dorset coast, England. *Neues Jahrbuch für Geologie und Paläontologie Abhandlungen* 273:45–63 DOI 10.1127/0077-7749/2014/0415.

Donovan DT, Fuchs D. 2016. Part M, Chapter 13: Fossilized soft tissues in Coleoidea. *Treatise Online* 73:1–30.
**Donovan DT, Strugnell J. 2010.** A redescription of the fossil coleoid cephalopod genus *Palaeololigo* Naef. *Journal of Natural History* **44**:1475–1492 DOI 10.1080/00222931003624838.

**Doyle P. 1990.** Teuthid cephalopods from the Lower Jurassic of Yorkshire. *Palaeontology* **33**(1):193–207.

**Engeser T, Keupp H. 1999.** Zwei neue vampyromorphe Tintenfische (Coleoidea, Cephalopoda) aus dem oberjurassischen Solnhofener Plattenkalk von Eichstätt. *Archaeopteryx* **17**:21–32.

**Engeser T, Reitner J. 1985.** Teuthiden aus dem Unterapt (Töck) von Helgoland (Schleswig-Holstein, Norddeutschland). *Paläontologische Zeitschrift* **59**:245–260 DOI 10.1007/BF02988811.

**Fischer J-C, Riou B. 1982.** Les Teuthoïdes (Cephalopoda, Dibranchiata) du Callovien inférieur de La Voulte-sur-Rhône (Ardèche, France). *Annales de Paléontologie* **68**:295–325.

**Fischer J-C, Riou B. 2002.** Vampyronassa rhodanica nov, gen. nov sp. vampyromorphe (Cephalopoda, Coleoidea) du Callovien inférieur de La Voulte-sur-Rhône (Ardèche, France). *Annales de Paléontologie* **88**:1–17 DOI 10.1016/S0753-3969(02)01037-6.

**Fonseca C, MendonçaFilho JG, Lézin C, Duarte LV, Fauré P. 2018.** Organic facies variability during the Toarcian Oceanic anoxic event record of the Grands causses and Quercy Basins (southern France). *International Journal of Coal Geology* **190**:218–235 DOI 10.1016/j.coal.2017.10.006.

**Fuchs D. 2006a.** Re-description of *Doryanthes munsterii* (D'ORBIGNY, 1845), a poorly known vampyropod coleoid (Cephalopoda) from the Late Jurassic Solnhofen Plattenkalks. *Archaeopteryx* **24**:79–88.

**Fuchs D. 2006b.** Fossil erhaltungsfähige Merkmalskomplexe der Coleoidea (Cephalopoda) und ihre phylogenetische Bedeutung. *Berliner Paläobiologische Abhandlungen* **8**:1–122.

**Fuchs D. 2006c.** Diversity, taxonomy and morphology of vampyropod coleoids (Cephalopoda) from the Upper Cretaceous of Lebanon. *Memorie della Società Italiana di Scienze Naturali et del Museo Civico di Storia Naturale di Milano* **34**:1–28.

**Fuchs D. 2007.** Coleoid cephalopods from the Plattenkalks of the Late Jurassic of Southern Germany and the Late Cretaceous of Lebanon–a faunal comparison. *Neues Jahrbuch für Geologie und Paläontologie Abhandlungen* **245**:59–69 DOI 10.1127/0077-7749/2007/0245-0059.

**Fuchs D. 2009.** Octobrachia –a diphyletic taxon? *Berliner Paläobiologische Abhandlungen* **10**:181–192.

**Fuchs D. 2015.** Tintenfische (Coleoidea, Endocochleata, Dibranchiata). In: Arratia G. Schultze, H.-P. Tischlinger H, Viohl G, eds. *Solnhofen –Ein Fenster in die Jurazeit*. Munich: Pfeil, 229–2381+2 (in German).

**Fuchs D. 2016.** Part M. Chapter 9B: The gladius and gladius vestige in fossil Coleoidea. *Treatise Online* **83**:1–23.

**Fuchs D. 2019.** *Eromangateuthis* n. gen. a new genus for a late Albian gladius-bearing giant octobrachian (cephalopoda: coleoidea). *Paleontological Contributions* **21**:1–3.
**Donovan DT, Strugnell J. 2010.** A redescription of the fossil coleoid cephalopod genus *Palaeololigo* Naef. *Journal of Natural History* **44**:1475–1492 DOI 10.1080/00222931003624838.

**Doyle P. 1990.** Teuthid cephalopods from the Lower Jurassic of Yorkshire. *Palaeontology* **33**(1):193–207.

**Engeser T, Keupp H. 1999.** Zwei neue vampyromorphe Tintenfische (Coleoidea, Cephalopoda) aus dem oberjurassischen Solnhofener Plattenkalk von Eichstätt. *Archaeopteryx* **17**:21–32.

**Engeser T, Reitner J. 1985.** Teuthiden aus dem Unterapt (Töck) von Helgoland (Schleswig-Holstein, Norddeutschland). *Paläontologische Zeitschrift* **59**:245–260 DOI 10.1007/BF02988811.

**Fischer J-C, Riou B. 1982.** Les Teuthoïdes (Cephalopoda, Dibranchiata) du Callovien inférieur de La Voulte-sur-Rhône (Ardèche, France). *Annales de Paléontologie* **68**:295–325.

**Fischer J-C, Riou B. 2002.** Vampyronassa rhodanica nov, gen. nov sp. vampyromorphe (Cephalopoda, Coleoidea) du Callovien inférieur de La Voulte-sur-Rhône (Ardèche, France). *Annales de Paléontologie* **88**:1–17 DOI 10.1016/S0753-3969(02)01037-6.

**Fonseca C, MendonçaFilho JG, Lézin C, Duarte LV, Fauré P. 2018.** Organic facies variability during the Toarcian Oceanic anoxic event record of the Grands causses and Quercy Basins (southern France). *International Journal of Coal Geology* **190**:218–235 DOI 10.1016/j.coal.2017.10.006.

**Fuchs D. 2006a.** Re-description of *Doryanthes munsterii* (D'ORBIGNY, 1845), a poorly known vampyropod coleoid (Cephalopoda) from the Late Jurassic Solnhofen Plattenkalks. *Archaeopteryx* **24**:79–88.

**Fuchs D. 2006b.** Fossil erhaltungsfähige Merkmalskomplexe der Coleoidea (Cephalopoda) und ihre phylogenetische Bedeutung. *Berliner Paläobiologische Abhandlungen* **8**:1–122.

**Fuchs D. 2006c.** Diversity, taxonomy and morphology of vampyropod coleoids (Cephalopoda) from the Upper Cretaceous of Lebanon. *Memorie della Società Italiana di Scienze Naturali et del Museo Civico di Storia Naturale di Milano* **34**:1–28.

**Fuchs D. 2007.** Coleoid cephalopods from the Plattenkalks of the Late Jurassic of Southern Germany and the Late Cretaceous of Lebanon–a faunal comparison. *Neues Jahrbuch für Geologie und Paläontologie Abhandlungen* **245**:59–69 DOI 10.1127/0077-7749/2007/0245-0059.

**Fuchs D. 2009.** Octobrachia –a diphyletic taxon? *Berliner Paläobiologische Abhandlungen* **10**:181–192.

**Fuchs D. 2015.** Tintenfische (Coleoidea, Endocochleata, Dibranchiata). In: Arratia G. Schultze, H.-P. Tischlinger H, Viohl G, eds. *Solnhofen –Ein Fenster in die Jurazeit*. Munich: Pfeil, 229–2381+2 (in German).

**Fuchs D. 2016.** Part M. Chapter 9B: The gladius and gladius vestige in fossil Coleoidea. *Treatise Online* **83**:1–23.

**Fuchs D. 2019.** *Eromangateuthis* n. gen. a new genus for a late Albian gladius-bearing giant octobrachian (cephalopoda: coleoidea). *Paleontological Contributions* **21**:1–3.
**Fuchs D. 2020.** Part M. Chapter 23G: systematic descriptions: Octobrachia. *Treatise Online* **138**:1–52.

**Fuchs D, Beard G, Tanabe K, Ross R. 2007c.** Coleoid cephalopods from the Late Cretaceous North eastern Pacific. In: *Abstracts volume of the 7th international symposium international symposium Cephalopods –present and past, 2007, Sapporo*.

**Fuchs D, Bracchi G, Weis R. 2009.** New records of octopods (Cephalopoda: Coleoidea) from the Late Cretaceous (Upper Cenomanian) of Hakel and Hadjoula (Lebanon). *Palaeontology* **52**:65–81 DOI 10.1111/j.1475-4983.2008.00828.x.

**Fuchs D, Engeser T, Keupp H. 2007a.** Gladius shape variation in coleoid cephalopod *Trachyteuthis* from the Upper Jurassic Nusplingen and Solnhofen Plattenkalks. *Acta Palaeontologica Polonica* **52**:575–589.

**Fuchs D, Iba Y. 2015.** The gladiuses in coleoid cephalopods homology, parallelism, or convergence? *Swiss Journal of Palaeontology* **134**:187–197 DOI 10.1007/s13358-015-0100-3.

**Fuchs D, Keupp H, Engeser T. 2003.** New records of soft parts of *Muensterella scutellaris* Muenster, 1842 (Coleoidea) from the Late Jurassic Plattenkalks of Eichstätt and their significance for octobrachian relationships. *Berliner Paläobiologische Abhandlungen* **3**:101–111.

**Fuchs D, Klinghammer A, Keupp H. 2007b.** Taxonomy, morphology and phylogeny of plesioteuthid coleoids from the Upper Jurassic (Tithonian) Plattenkalks of Solnhofen. *Neues Jahrbuch für Geologie und Paläontologie Abhandlungen* **245**:239–252 DOI 10.1127/0077-7749/2007/0245-0239.

**Fuchs D, Larson N. 2011a.** Diversity, morphology and phylogeny of coleoid cephalopods from the Upper Cretaceous Plattenkalks of Lebanon–Part I: Prototeuthidina. *Journal of Paleontology* **85**:234–249 DOI 10.1666/10-089.1.

**Fuchs D, Larson N. 2011b.** Diversity, morphology and phylogeny of coleoid cephalopods from the Upper Cretaceous Plattenkalks of Lebanon–Part II: Teudopseina. *Journal of Paleontology* **85**:815–834 DOI 10.1666/10-159.1.

**Fuchs D, Reitano A, Insacco G, Iba Y. 2016.** The first coleoid cephalopods from the Upper Cenomanian of Sicily (Italy) and their implications for the systematic-phylogenetic position of the Palaeololiginidae (Teudopseina). *Journal of Systematic Palaeontology* **15**(6):499–512.

**Fuchs D, Schultze H-P. 2008.** Trachyteuthis covacevichi n. sp. a Late Jurassic coleoid cephalopod from the Paleopacific. *Fossil Record* **11**:39–49 DOI 10.1002/mmng.200700012.

**Fuchs D, Weis R. 2004.** The Schistes Cartons (Lower Toarcian) of Luxembourg and its unnoticed coleoid diversity. In: Mapes RH, Landman NH, eds. *Abstract volume of the 6th international symposium Cephalopods –present and past, 2004, Fayette-ville*. 43–44.

**Fuchs D, Weis R. 2008.** Taxonomy, morphology and phylogeny of Lower Jurassic loligosepid coleoids (Cephalopoda). *Neues Jahrbuch für Geologie und Paläontologie Abhandlungen* **249**:93–112 DOI 10.1127/0077-7749/2008/0249-0093.
**Fuchs D. 2020.** Part M. Chapter 23G: systematic descriptions: Octobrachia. *Treatise Online* **138**:1–52.

**Fuchs D, Beard G, Tanabe K, Ross R. 2007c.** Coleoid cephalopods from the Late Cretaceous North eastern Pacific. In: *Abstracts volume of the 7th international symposium international symposium Cephalopods –present and past, 2007, Sapporo*.

**Fuchs D, Bracchi G, Weis R. 2009.** New records of octopods (Cephalopoda: Coleoidea) from the Late Cretaceous (Upper Cenomanian) of Hakel and Hadjoula (Lebanon). *Palaeontology* **52**:65–81 DOI 10.1111/j.1475-4983.2008.00828.x.

**Fuchs D, Engeser T, Keupp H. 2007a.** Gladius shape variation in coleoid cephalopod *Trachyteuthis* from the Upper Jurassic Nusplingen and Solnhofen Plattenkalks. *Acta Palaeontologica Polonica* **52**:575–589.

**Fuchs D, Iba Y. 2015.** The gladiuses in coleoid cephalopods homology, parallelism, or convergence? *Swiss Journal of Palaeontology* **134**:187–197 DOI 10.1007/s13358-015-0100-3.

**Fuchs D, Keupp H, Engeser T. 2003.** New records of soft parts of *Muensterella scutellaris* Muenster, 1842 (Coleoidea) from the Late Jurassic Plattenkalks of Eichstätt and their significance for octobrachian relationships. *Berliner Paläobiologische Abhandlungen* **3**:101–111.

**Fuchs D, Klinghammer A, Keupp H. 2007b.** Taxonomy, morphology and phylogeny of plesioteuthid coleoids from the Upper Jurassic (Tithonian) Plattenkalks of Solnhofen. *Neues Jahrbuch für Geologie und Paläontologie Abhandlungen* **245**:239–252 DOI 10.1127/0077-7749/2007/0245-0239.

**Fuchs D, Larson N. 2011a.** Diversity, morphology and phylogeny of coleoid cephalopods from the Upper Cretaceous Plattenkalks of Lebanon–Part I: Prototeuthidina. *Journal of Paleontology* **85**:234–249 DOI 10.1666/10-089.1.

**Fuchs D, Larson N. 2011b.** Diversity, morphology and phylogeny of coleoid cephalopods from the Upper Cretaceous Plattenkalks of Lebanon–Part II: Teudopseina. *Journal of Paleontology* **85**:815–834 DOI 10.1666/10-159.1.

**Fuchs D, Reitano A, Insacco G, Iba Y. 2016.** The first coleoid cephalopods from the Upper Cenomanian of Sicily (Italy) and their implications for the systematic-phylogenetic position of the Palaeololiginidae (Teudopseina). *Journal of Systematic Palaeontology* **15**(6):499–512.

**Fuchs D, Schultze H-P. 2008.** Trachyteuthis covacevichi n. sp. a Late Jurassic coleoid cephalopod from the Paleopacific. *Fossil Record* **11**:39–49 DOI 10.1002/mmng.200700012.

**Fuchs D, Weis R. 2004.** The Schistes Cartons (Lower Toarcian) of Luxembourg and its unnoticed coleoid diversity. In: Mapes RH, Landman NH, eds. *Abstract volume of the 6th international symposium Cephalopods –present and past, 2004, Fayette-ville*. 43–44.

**Fuchs D, Weis R. 2008.** Taxonomy, morphology and phylogeny of Lower Jurassic loligosepid coleoids (Cephalopoda). *Neues Jahrbuch für Geologie und Paläontologie Abhandlungen* **249**:93–112 DOI 10.1127/0077-7749/2008/0249-0093.
**Fuchs D, Weis R. 2009.** A new Cenomanian (Late Cretaceous) coleoid (Cephalopoda) from Hâdjoula, Lebanon. *Fossil Record* **12**:175–181 DOI 10.1002/mmng.200900005.

**Fuchs D, Weis R. 2010.** Taxonomy, morphology and phylogeny of Lower Jurassic teudopseid coleoids (Cephalopoda). *Neues Jahrbuch für Geologie und Paläontologie Abhandlungen* **257**:351–366 DOI 10.1127/0077-7749/2010/0083.

**Fürsich FT, Berndt R, Scheuer T, Gahr M. 2001.** Comparative ecological analysis of Toarcian (Lower Jurassic) benthic faunas from southern France and east-central Spain. *Lethaia* **34**(3):169–199.

**Gatto R, Monari S, Neige P, JD Pinard, Weis R. 2015.** Gastropods from upper Pliensbachian–Toarcian (Lower Jurassic) sediments of Causses Basin, southern France and their recovery after the early Toarcian anoxic event. *Geological Magazine* **152**(5):871–901 DOI 10.1017/S0016756814000788.

**Guérin-Franiatte S, Gouspy C. 1993.** Découverte de Céphalopodes Teuthides (Coleoidea) dans le Lias supérieur de Haute-Marne, France. *Geobios*, M.S. **15**:181–189.

**Haas W. 1997.** Der ablauf der entwicklungsgeschichte der Decabrachia (Cephalopoda, Coleoidea). *Palaeontographica*, Abteilung A **254**:63–81.

**Haas W. 2002.** The evolutionary history of the eight-armed Coleoidea. In: Summesberger H, Histon K, Daurer A, eds. *Cephalopods—present & past*. Wien: Abhandlungen der Geologischen Bundesanstalt, 57, 341–351.

**Haeckel E. 1866.** *Generelle morphologie der organismen*. Berlin: Georg Reiner, 462 p.

**Hall RL. 1985.** Paraplesioteuthis hastata (Münster), the first teuthid squid recorded from the Jurassic of North America. *Journal of Paleontology* **59**(4):870–874.

**Harazim D, Van De Schootbrugge BAS, Sorichter K, Fiebig J, Weug A, Suan G, Oschmann W. 2013.** Spatial variability of watermass conditions within the European Epicontinental Seaway during the Early Jurassic (Pliensbachian–Toarcian). *Sedimentology* **60**(2):359–390 DOI 10.1111/j.1365-3091.2012.01344.x.

**Hauff B, Hauff RB. 1981.** *Das Holzmadenbuch*. 3rd edn. 136 pHolzmaden.

**Jattiot R, Brayard A, Fara E, Charbonnier S. 2015a.** Gladius-bearing coleoids from the Upper Cretaceous Lebanese Lagerstätten: diversity, morphology, and phylogenetic implications. *Journal of Paleontology* **89**:148–167 DOI 10.1017/jpa.2014.13.

**Jattiot R, Trincal V, Moreau JD, Brocard A. 2015b.** Guide des ammonites pyriteuses, Toarcien moyen et supérieur des Causses (Lozère-France). In: *Les Editions du Piat*. 144 p.

**Jeletzky JA. 1965.** Taxonomy and phylogeny of fossil Coleoidea (=Dibranchiata). *Geological Survey of Canada, Papers* **65**(2):76–78.

**Keupp H, Engeser T, Fuchs D, Haechel W. 2010.** Ein *Trachyteuthis hastiformis* (Cephalopoda, Coleoidea) mit Spermatophoren aus dem Ober-Kimmeridgium von Painten (Ostbayern). *Archaeopteryx* **28**:23–30.

**Klug C, Di Silvestro G, Hoffmann R, Schweigert G, Fuchs D, Clements T, Guériau P. 2021b.** Diagenetic phosphatic Liesegang rings deceptively resemble chromatophores in Mesozoic coleoids. *PeerJ* **9**:e10703 DOI 10.7717/peerj.10703.
**Fuchs D, Weis R. 2009.** A new Cenomanian (Late Cretaceous) coleoid (Cephalopoda) from Hâdjoula, Lebanon. *Fossil Record* **12**:175–181 DOI 10.1002/mmng.200900005.

**Fuchs D, Weis R. 2010.** Taxonomy, morphology and phylogeny of Lower Jurassic teudopseid coleoids (Cephalopoda). *Neues Jahrbuch für Geologie und Paläontologie Abhandlungen* **257**:351–366 DOI 10.1127/0077-7749/2010/0083.

**Fürsich FT, Berndt R, Scheuer T, Gahr M. 2001.** Comparative ecological analysis of Toarcian (Lower Jurassic) benthic faunas from southern France and east-central Spain. *Lethaia* **34**(3):169–199.

**Gatto R, Monari S, Neige P, JD Pinard, Weis R. 2015.** Gastropods from upper Pliensbachian–Toarcian (Lower Jurassic) sediments of Causses Basin, southern France and their recovery after the early Toarcian anoxic event. *Geological Magazine* **152**(5):871–901 DOI 10.1017/S0016756814000788.

**Guérin-Franiatte S, Gouspy C. 1993.** Découverte de Céphalopodes Teuthides (Coleoidea) dans le Lias supérieur de Haute-Marne, France. *Geobios*, M.S. **15**:181–189.

**Haas W. 1997.** Der ablauf der entwicklungsgeschichte der Decabrachia (Cephalopoda, Coleoidea). *Palaeontographica*, Abteilung A **254**:63–81.

**Haas W. 2002.** The evolutionary history of the eight-armed Coleoidea. In: Summesberger H, Histon K, Daurer A, eds. *Cephalopods—present & past*. Wien: Abhandlungen der Geologischen Bundesanstalt, 57, 341–351.

**Haeckel E. 1866.** *Generelle morphologie der organismen*. Berlin: Georg Reiner, 462 p.

**Hall RL. 1985.** Paraplesioteuthis hastata (Münster), the first teuthid squid recorded from the Jurassic of North America. *Journal of Paleontology* **59**(4):870–874.

**Harazim D, Van De Schootbrugge BAS, Sorichter K, Fiebig J, Weug A, Suan G, Oschmann W. 2013.** Spatial variability of watermass conditions within the European Epicontinental Seaway during the Early Jurassic (Pliensbachian–Toarcian). *Sedimentology* **60**(2):359–390 DOI 10.1111/j.1365-3091.2012.01344.x.

**Hauff B, Hauff RB. 1981.** *Das Holzmadenbuch*. 3rd edn. 136 pHolzmaden.

**Jattiot R, Brayard A, Fara E, Charbonnier S. 2015a.** Gladius-bearing coleoids from the Upper Cretaceous Lebanese Lagerstätten: diversity, morphology, and phylogenetic implications. *Journal of Paleontology* **89**:148–167 DOI 10.1017/jpa.2014.13.

**Jattiot R, Trincal V, Moreau JD, Brocard A. 2015b.** Guide des ammonites pyriteuses, Toarcien moyen et supérieur des Causses (Lozère-France). In: *Les Editions du Piat*. 144 p.

**Jeletzky JA. 1965.** Taxonomy and phylogeny of fossil Coleoidea (=Dibranchiata). *Geological Survey of Canada, Papers* **65**(2):76–78.

**Keupp H, Engeser T, Fuchs D, Haechel W. 2010.** Ein *Trachyteuthis hastiformis* (Cephalopoda, Coleoidea) mit Spermatophoren aus dem Ober-Kimmeridgium von Painten (Ostbayern). *Archaeopteryx* **28**:23–30.

**Klug C, Di Silvestro G, Hoffmann R, Schweigert G, Fuchs D, Clements T, Guériau P. 2021b.** Diagenetic phosphatic Liesegang rings deceptively resemble chromatophores in Mesozoic coleoids. *PeerJ* **9**:e10703 DOI 10.7717/peerj.10703.
**Klug C, Fuchs D, Schweigert G, Röper M, Tischlinger H. 2015.** *New anatomical information on arms and fins from exceptionally preserved *Plesioteuthis* (Coleoidea) from the Late Jurassic of Germany.* *Swiss Journal of Palaeontology* **134**:245–255 DOI 10.1007/s13358-015-0093-y.

**Klug C, Schweigert G, Dietl G. 2010.** A new *Plesioteuthis* with beak from the Kimmeridgian of Nusplingen (Germany). In: Fuchs D, ed. *Proceedings of the third international Coleoid symposium. Ferrantia*. 73–77.

**Klug C, Schweigert G, Fuchs D, De Baets K. 2021a.** Distraction sinking and fossilized coleoid predatory behaviour from the German Early Jurassic. *Swiss Journal of Palaeontology* **140**(1):1–12 DOI 10.1186/s13358-020-00214-8.

**Košák M. 2002.** Teuthoidea from the Bohemian Cretaceous Basin (Czech Republik) –a critical review. *Abhandlungen der geologischen Bundesanstalt* **57**:359–369.

**Košák M, Schlögl J, Fuchs D, Holcová K, Hudáčková N, Culka A, Fözy I, Tomašových A, Milovský R, Šurka J, Mazuch M. 2021.** Fossil evidence for vampire squid inhabiting oxygen-depleted ocean zones since at least the Oligocene. *Communications Biology* **4**:216 DOI 10.1038/s42003-021-01714-0.

**Krutá I, Rouget I, Charbonnier S, Bardin J, Fernandez V, Germain D, Brayard A, Landman N. 2016.** *Proteroctopus ribeti* in coleoid evolution. *Palaeontology* **59**(6):767–773 DOI 10.1111/pala.12265.

**Larson NL. 2010.** Fossil coleoids from the Late Cretaceous (Campanian & Maastrichtian) of the Western Interior. *Ferrantia* **59**:78–113.

**Macchioni F, Cecca F. 2002.** Biodiversity and biogeography of middle-late liassic ammonoids: implications for the early Toarcian mass extinction. *Geobios* **35**(Supplement 1):165–175.

**Marroquín SM, Martindale RC, Fuchs D. 2018.** New records of the late Pliensbachian to early Toarcian (Early Jurassic) gladius-bearing coleoid cephalopods from the Ya Ha Tinda Lagerstätte, Canada. *Papers in Palaeontology* **4**(2):245–276 DOI 10.1002/spp2.1104.

**Mattei J. 1969.** Définition et interprétation de *Pseudopolyplectus*, nov. gen. (Harpoceratinae, Ammonoidea) du Toarcien d'après un matériel des Causses et du Bas-Languedoc. *Geobios* **2**:7–79 DOI 10.1016/S0016-6995(69)80001-X.

**Mattei J, Combémorel R, Enay R. 1987.** Sur la présence du genre *Atractites* (Aulacoceratida) dans le Lias moyen des Causses du Sud du Massif central Français. *Geobios* **20**(1):133–139 DOI 10.1016/S0016-6995(87)80063-3.

**Moreau J-D, Trincal V, Deconinck J-F, Philippe M, Bourel B. 2021.** Lowermost Jurassic dinosaur ecosystem from the Bleymard Strait (southern France): sedimentology, mineralogy, palaeobotany and palaeoichnology of the Dolomitic Formation. *Geological Magazine* **158**:1830–1846 DOI 10.1017/S001675682100039X.

**Moreau J-D, Vullo R, Charbonnier S, Jattiot R, Trincal V, Néraudeau D, Fara E, Baret L, Garassino A, Gand G, Lafaurie G. 2022.** Konservat- Lagerstätten from the Upper Jurassic lithographic limestone of the Causse Méjean (Lozère, southern France): palaeontological and palaeoenvironmental synthesis. *Geological Magazine* DOI 10.1017/S0016756821001382.
**Klug C, Fuchs D, Schweigert G, Röper M, Tischlinger H. 2015.** *New anatomical information on arms and fins from exceptionally preserved *Plesioteuthis* (Coleoidea) from the Late Jurassic of Germany.* *Swiss Journal of Palaeontology* **134**:245–255 DOI 10.1007/s13358-015-0093-y.

**Klug C, Schweigert G, Dietl G. 2010.** A new *Plesioteuthis* with beak from the Kimmeridgian of Nusplingen (Germany). In: Fuchs D, ed. *Proceedings of the third international Coleoid symposium. Ferrantia*. 73–77.

**Klug C, Schweigert G, Fuchs D, De Baets K. 2021a.** Distraction sinking and fossilized coleoid predatory behaviour from the German Early Jurassic. *Swiss Journal of Palaeontology* **140**(1):1–12 DOI 10.1186/s13358-020-00214-8.

**Košák M. 2002.** Teuthoidea from the Bohemian Cretaceous Basin (Czech Republik) –a critical review. *Abhandlungen der geologischen Bundesanstalt* **57**:359–369.

**Košák M, Schlögl J, Fuchs D, Holcová K, Hudáčková N, Culka A, Fözy I, Tomašových A, Milovský R, Šurka J, Mazuch M. 2021.** Fossil evidence for vampire squid inhabiting oxygen-depleted ocean zones since at least the Oligocene. *Communications Biology* **4**:216 DOI 10.1038/s42003-021-01714-0.

**Krutá I, Rouget I, Charbonnier S, Bardin J, Fernandez V, Germain D, Brayard A, Landman N. 2016.** *Proteroctopus ribeti* in coleoid evolution. *Palaeontology* **59**(6):767–773 DOI 10.1111/pala.12265.

**Larson NL. 2010.** Fossil coleoids from the Late Cretaceous (Campanian & Maastrichtian) of the Western Interior. *Ferrantia* **59**:78–113.

**Macchioni F, Cecca F. 2002.** Biodiversity and biogeography of middle-late liassic ammonoids: implications for the early Toarcian mass extinction. *Geobios* **35**(Supplement 1):165–175.

**Marroquín SM, Martindale RC, Fuchs D. 2018.** New records of the late Pliensbachian to early Toarcian (Early Jurassic) gladius-bearing coleoid cephalopods from the Ya Ha Tinda Lagerstätte, Canada. *Papers in Palaeontology* **4**(2):245–276 DOI 10.1002/spp2.1104.

**Mattei J. 1969.** Définition et interprétation de *Pseudopolyplectus*, nov. gen. (Harpoceratinae, Ammonoidea) du Toarcien d'après un matériel des Causses et du Bas-Languedoc. *Geobios* **2**:7–79 DOI 10.1016/S0016-6995(69)80001-X.

**Mattei J, Combémorel R, Enay R. 1987.** Sur la présence du genre *Atractites* (Aulacoceratida) dans le Lias moyen des Causses du Sud du Massif central Français. *Geobios* **20**(1):133–139 DOI 10.1016/S0016-6995(87)80063-3.

**Moreau J-D, Trincal V, Deconinck J-F, Philippe M, Bourel B. 2021.** Lowermost Jurassic dinosaur ecosystem from the Bleymard Strait (southern France): sedimentology, mineralogy, palaeobotany and palaeoichnology of the Dolomitic Formation. *Geological Magazine* **158**:1830–1846 DOI 10.1017/S001675682100039X.

**Moreau J-D, Vullo R, Charbonnier S, Jattiot R, Trincal V, Néraudeau D, Fara E, Baret L, Garassino A, Gand G, Lafaurie G. 2022.** Konservat- Lagerstätten from the Upper Jurassic lithographic limestone of the Causse Méjean (Lozère, southern France): palaeontological and palaeoenvironmental synthesis. *Geological Magazine* DOI 10.1017/S0016756821001382.
**Münster G, zu Graf. 1843.** Die schalenlosen Cephalopoden im unteren Jura, den Lias-Schiefern von Franken und Schwaben. *Beiträge zur Petrefaktenkunde* **6**:57–77.

**Naef A. 1921.** Die Cephalopoden: Fauna und Flora des Golfes von Neapel, Monografia 35. In: *R. Friedländer und Sohn, Berlin*. 863 p.

**Naef A. 1922.** Die fossilen Tintenfische: eine paläozoologische Monographie. In: *Fischerverlag, G. Fischer, Jena*. 322 p.

**Pinard JD, Weis R, Neige P, Mariotti N, Di Cencio A. 2014.** Belemnites from the Upper Pliensbachian and the Toarcian (Lower Jurassic) of Tournadous (Causses, France). *Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen* **273**(2):155–177 DOI 10.1127/0077-7749/2014/0421.

**Quenstedt FA. 1839.** Loligo bollensis ist kein Belemnitenorgan. *Neues Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefaktenkunde* 156–167.

**Quenstedt FA. 1849.** Petrefactenkunde Deutschlands, 1. Abteilung, 1. Band, Cephalopoden. In: *Verlag Fues, Tübingen*. 581 p.

**Regteren Altena CO v. 1949.** Teyler’s Museum systematic catalogue of the palaeontological collection–sixth supplement (Teuthoidea). *Archives du Musée Teyler* **3**:53–62.

**Reitner J. 1978.** Ein Teuthiden-Rest aus dem Obernor (Kössener-Schichten) der Lahnewies-Neidernachmulde bei Garmisch-Partenkirchen (Bayern). *Paläontologische Zeitschrift* **52**(3/4):205–212 DOI 10.1007/BF02987702.

**Reynès P. 1868.** *Essai de Géologie et de Paléontologie aveyronnaises*. Paris: Baillière édit, 109 p.

**Riccardi AC. 2005.** First teuthid cephalopod from the Lower Jurassic of South America (Neuquén Basin, Argentina). *Geologica Acta* **3**:179–184.

**Riegraf W, Werner G, Lörcher F. 1984.** *Der Posidonienschiefer–Biostratigraphie, Fauna und Fazies des südwestdeutschen Untertoarciums (Lias e).* Stuttgart: Ferdinan Enke, 195.

**Robson GC. 1929.** On the rare abyssal octopod *Melanoteuthis beebei* (sp. n.): a contribution to the phylogeny of the Octopoda. *Proceedings of the Zoological Society of London* **99**(3):469–486 DOI 10.1111/j.1469-7998.1929.tb07702.x.

**Rowe AJ, Kruta I, Landman NH, Villier L, Fernandez V, Rouget I. 2022.** Exceptional soft-tissue preservation of Jurassic *Vampyronassa rhodanica* provides new insights on the evolution and palaeoecology of vampyroteuthids. *Scientific Reports* **12**(1):8292 DOI 10.1038/s41598-022-12269-3.

**Rowe AJ, Kruta I, Villier L, Rouget I. 2023.** A new vampyromorph species from the Middle Jurassic La Voulte-sur-Rhône Lagerstätte. *Papers in Palaeontology* **9**(3):e1511 DOI 10.1002/spp2.1511.

**Schlögl J, Košák M, Hyžny M. 2012.** First record of a gladius-bearing coleoid *Teudopsis bollensis* Voltz (Cephalopoda, Coleoidea) in the Toarcian of the Western Carpathians (Slovakia).

**Sciau J, Crochet JY, Mattei J. 1990.** Le premier squelette dePlesiosaure de France sur le Causse du Larzac (Toarcien, Jurassique inférieur). *Geobios* **23**(1):111–116 DOI 10.1016/0016-6995(90)80021-7.
**Münster G, zu Graf. 1843.** Die schalenlosen Cephalopoden im unteren Jura, den Lias-Schiefern von Franken und Schwaben. *Beiträge zur Petrefaktenkunde* **6**:57–77.

**Naef A. 1921.** Die Cephalopoden: Fauna und Flora des Golfes von Neapel, Monografia 35. In: *R. Friedländer und Sohn, Berlin*. 863 p.

**Naef A. 1922.** Die fossilen Tintenfische: eine paläozoologische Monographie. In: *Fischerverlag, G. Fischer, Jena*. 322 p.

**Pinard JD, Weis R, Neige P, Mariotti N, Di Cencio A. 2014.** Belemnites from the Upper Pliensbachian and the Toarcian (Lower Jurassic) of Tournadous (Causses, France). *Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen* **273**(2):155–177 DOI 10.1127/0077-7749/2014/0421.

**Quenstedt FA. 1839.** Loligo bollensis ist kein Belemnitenorgan. *Neues Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefaktenkunde* 156–167.

**Quenstedt FA. 1849.** Petrefactenkunde Deutschlands, 1. Abteilung, 1. Band, Cephalopoden. In: *Verlag Fues, Tübingen*. 581 p.

**Regteren Altena CO v. 1949.** Teyler’s Museum systematic catalogue of the palaeontological collection–sixth supplement (Teuthoidea). *Archives du Musée Teyler* **3**:53–62.

**Reitner J. 1978.** Ein Teuthiden-Rest aus dem Obernor (Kössener-Schichten) der Lahnewies-Neidernachmulde bei Garmisch-Partenkirchen (Bayern). *Paläontologische Zeitschrift* **52**(3/4):205–212 DOI 10.1007/BF02987702.

**Reynès P. 1868.** *Essai de Géologie et de Paléontologie aveyronnaises*. Paris: Baillière édit, 109 p.

**Riccardi AC. 2005.** First teuthid cephalopod from the Lower Jurassic of South America (Neuquén Basin, Argentina). *Geologica Acta* **3**:179–184.

**Riegraf W, Werner G, Lörcher F. 1984.** *Der Posidonienschiefer–Biostratigraphie, Fauna und Fazies des südwestdeutschen Untertoarciums (Lias e).* Stuttgart: Ferdinan Enke, 195.

**Robson GC. 1929.** On the rare abyssal octopod *Melanoteuthis beebei* (sp. n.): a contribution to the phylogeny of the Octopoda. *Proceedings of the Zoological Society of London* **99**(3):469–486 DOI 10.1111/j.1469-7998.1929.tb07702.x.

**Rowe AJ, Kruta I, Landman NH, Villier L, Fernandez V, Rouget I. 2022.** Exceptional soft-tissue preservation of Jurassic *Vampyronassa rhodanica* provides new insights on the evolution and palaeoecology of vampyroteuthids. *Scientific Reports* **12**(1):8292 DOI 10.1038/s41598-022-12269-3.

**Rowe AJ, Kruta I, Villier L, Rouget I. 2023.** A new vampyromorph species from the Middle Jurassic La Voulte-sur-Rhône Lagerstätte. *Papers in Palaeontology* **9**(3):e1511 DOI 10.1002/spp2.1511.

**Schlögl J, Košák M, Hyžny M. 2012.** First record of a gladius-bearing coleoid *Teudopsis bollensis* Voltz (Cephalopoda, Coleoidea) in the Toarcian of the Western Carpathians (Slovakia).

**Sciau J, Crochet JY, Mattei J. 1990.** Le premier squelette dePlesiosaure de France sur le Causse du Larzac (Toarcien, Jurassique inférieur). *Geobios* **23**(1):111–116 DOI 10.1016/0016-6995(90)80021-7.
**Smith PL, Tipper HW, Ham DM. 2001.** Lower Jurassic Amaltheidae (Ammonitina) in North America: paleobiogeography and tectonic implications. *Canadian Journal of Earth Sciences* **38**:1439–1449 DOI 10.1139/e01-034.

**Sowerby J. 1812–1822.** The Mineral Conchology of Great Britain, 1, pls 1–9 (1812), pls 10–44 (1813), pls 45–78 (1814), pls 79–102 (1815); 2, pls 103–114 (1815), pls 115–150 (1816), pls 151–186 (1817), pls 187–203 (1818); 3, pls 204–221 (1818), pls 222–253 (1819), pls 254–271 (1820), pls 272–306 (1821); 4, pls 307–318 (1821), pls 319–383 (1822). The Author; London.

**Starobogatov YI. 1983.** The System of the Cephalopoda, p. 4–7. In: *Taxonomy and ecology of Cephalopoda*. Leningrad: Zoological Institute, USSR Academy of Sciences.

**Trümpy DM. 1983.** Le Lias Moyen et Supérieur des Grands Causses et de la région de Rodez : contributions stratigraphiques, sédimentologiques et géochimiques à la connaissance d'un bassin à sédimentation marneuse. *Cahiers de l'Université, Université de Pau et des Pays de l'Adour* **19**:1–363.

**Venturi F, Bilotta M, Ricci C. 2006.** Comparison between western Tethys and eastern Pacific ammonites: further evidence for a possible late Sinemurian–early Pliensbachian trans-Pangaean marine connection. *Geological Magazine* **143**:699–711 DOI 10.1017/S0016756806002068.

**Voltz PL. 1840.** Observations sur les Belopeltis ou lames dorsales de Bélemnites. *Mémoires de la Société d'Histoire Naturelle de Strasbourg* **1**:1–38.

**Wagner A. 1859.** Revision der bisherigen systematischen Bestimmungen der Überreste von nackten Dintenfischen aus dem Süddeutschen Juragebirge. *Gelehrte Anzeigen der königlich bayerische Akademie der Wissenschaften, München* **34**:273–278.

**Wagner A. 1860.** Die fossilen Überreste von nackten Dintenfischen aus dem lithographischen Schiefer und dem Lias des süddeutschen Juragebirges. *Abhandlungen der königlich bayerische Akademie der Wissenschaften, München* **8**:700–821.

**Wilby PR, Clements RG, Hudson JD, Hollingworth NTJ. 2004.** Taphonomy and origin of an accumulate of soft-bodied cephalopods in the Oxford Clay Formation (Jurassic, England). *Palaeontology* **45**:1159–1180.

**Woodward H. 1883.** On a new genus of fossil calamary from the Cretaceous formation of Sahel Alma, near Beirût, Lebanon, Syria. *Geological Magazine, new series* **10**:1–5 DOI 10.1017/S0016756800159667.

**Ziegler PA. 1988.** Evolution of the Arctic –North Atlantic and the Western Tethys. *AAPG Memoir* **43**:1–198.

**Zieten C. H. von. 1830–1833.** *Die Versteinerungen Württembergs*. Stuttgart: Verlag & Lithographie der Expedition des Werkes unserer Zeit, 102 p.
**Smith PL, Tipper HW, Ham DM. 2001.** Lower Jurassic Amaltheidae (Ammonitina) in North America: paleobiogeography and tectonic implications. *Canadian Journal of Earth Sciences* **38**:1439–1449 DOI 10.1139/e01-034.

**Sowerby J. 1812–1822.** The Mineral Conchology of Great Britain, 1, pls 1–9 (1812), pls 10–44 (1813), pls 45–78 (1814), pls 79–102 (1815); 2, pls 103–114 (1815), pls 115–150 (1816), pls 151–186 (1817), pls 187–203 (1818); 3, pls 204–221 (1818), pls 222–253 (1819), pls 254–271 (1820), pls 272–306 (1821); 4, pls 307–318 (1821), pls 319–383 (1822). The Author; London.

**Starobogatov YI. 1983.** The System of the Cephalopoda, p. 4–7. In: *Taxonomy and ecology of Cephalopoda*. Leningrad: Zoological Institute, USSR Academy of Sciences.

**Trümpy DM. 1983.** Le Lias Moyen et Supérieur des Grands Causses et de la région de Rodez : contributions stratigraphiques, sédimentologiques et géochimiques à la connaissance d'un bassin à sédimentation marneuse. *Cahiers de l'Université, Université de Pau et des Pays de l'Adour* **19**:1–363.

**Venturi F, Bilotta M, Ricci C. 2006.** Comparison between western Tethys and eastern Pacific ammonites: further evidence for a possible late Sinemurian–early Pliensbachian trans-Pangaean marine connection. *Geological Magazine* **143**:699–711 DOI 10.1017/S0016756806002068.

**Voltz PL. 1840.** Observations sur les Belopeltis ou lames dorsales de Bélemnites. *Mémoires de la Société d'Histoire Naturelle de Strasbourg* **1**:1–38.

**Wagner A. 1859.** Revision der bisherigen systematischen Bestimmungen der Überreste von nackten Dintenfischen aus dem Süddeutschen Juragebirge. *Gelehrte Anzeigen der königlich bayerische Akademie der Wissenschaften, München* **34**:273–278.

**Wagner A. 1860.** Die fossilen Überreste von nackten Dintenfischen aus dem lithographischen Schiefer und dem Lias des süddeutschen Juragebirges. *Abhandlungen der königlich bayerische Akademie der Wissenschaften, München* **8**:700–821.

**Wilby PR, Clements RG, Hudson JD, Hollingworth NTJ. 2004.** Taphonomy and origin of an accumulate of soft-bodied cephalopods in the Oxford Clay Formation (Jurassic, England). *Palaeontology* **45**:1159–1180.

**Woodward H. 1883.** On a new genus of fossil calamary from the Cretaceous formation of Sahel Alma, near Beirût, Lebanon, Syria. *Geological Magazine, new series* **10**:1–5 DOI 10.1017/S0016756800159667.

**Ziegler PA. 1988.** Evolution of the Arctic –North Atlantic and the Western Tethys. *AAPG Memoir* **43**:1–198.

**Zieten C. H. von. 1830–1833.** *Die Versteinerungen Württembergs*. Stuttgart: Verlag & Lithographie der Expedition des Werkes unserer Zeit, 102 p.