Duvalia dilatata (de Blainville, 1827 )

Barroso-Barcenilla, Fernando, Antunes, Miguel Telles, Brandão, José Manuel, Callapez, Pedro Miguel, Santos, Vanda Faria dos & Segura, Manuel, 2018, The d’Orbigny Palaeontological Collection of the National Museum of Natural History and Science, Lisbon, Portugal: Historical perspective and revision of Cretaceous Cephalopoda, Geodiversitas 40 (20), pp. 505-519 : 514

Duvalia dilatata (de Blainville, 1827)

( Fig. 4 G-I)

MATERIAL. —Five internal moulds (one of them fragmentary) without written or glued indications. Original label: Nº 351/ Belemnites dilatatus (Blainville), Andar 17º Neocomiense, Terreno Cretaceo, Localidade Cheiron perto de [near of] Castellanne (Basses Alpes).See Figs 1D; 4J.

DESCRIPTION

Elongated and compressed guards with rounded apex orientated towards the dorsal side. Dorsal and ventral sides bended, nearly parallel flanks and subelliptical cross-section. Apical region usually showing a row bulge at the dorsal side. Nor grooves or alveoli can be observed.

DISCUSSION

According to d’Orbigny (1840: 42), this species characterizes the Neocomian of the surroundings of Castellane, specially the locality of Cheiron ( France), where it was already reported in 1825 by Émeric. Its wide morphological variability has allowed the individualization of three subspecies in literature, D. dilatata dilatata , D. dilatata majoriana Stoyanova-Vergilova, 1970 , with a deeper alveolus, and D. dilatata binervioides Stoyanova-Vergilova, 1965 , with a more compressed and a smaller adult size. Despite this, as detailed by Combémorel (1973), Janssen (1997) and Fischer & Gauthier (2006), some of the specimens assigned by d’Orbigny (1840) to D. dilatata have been subsequently remitted to other forms, such as Pseudoduvalia polygonalis (de Blainville, 1827) , Pseudoduvalia trabiformis (Duval-Jouve, 1841) , Duvalia binervia ( Raspail, 1829) and Duvalia emericii ( Raspail, 1829) . In detail, as already noted by d’Orbigny (1847), P. polygonalis and P. trabiformis show slenderer shapes with the lower parts of the flanks sharper, giving subquadrate dorso-ventral cross-sections. D. binervia reaches a lower compression and a more angular morphology, and D. emericii exhibits a wide and deep lateral depression over each side. In the last years, the Hauterivianlower Barremian species D. dilatata , type of the genus, has been studied by Avram & Grädinaru (1993), Janssen (1997, 2009), Janssen & Fözy (2004), Fischer & Gauthier (2006) and Janssen et al. (2012), among others.

Family MESOHIBOLITIDAE Nerodenko, 1983

Figures

FIG. 4. — Cretaceous ammonites and belemnites of the d’Orbigny Collection of the National Museum of Natural History and Science (Museu Nacional de História Natural e da Ciência):A-C, Coilopoceras requienianus (d’Orbigny,1840) in lateral (A) and ventral (B) views,and original label (C): Nº 518/Ammonites Requienianus (d’Orb),Andar 21º [corrected] Turoniense,Terreno Cretaceo,Localidade Uchaux (Vanduse);D-F, Turrilites (Turrilites) costatus Lamarck,1801 in lateral (D) and basal (E) views,and original label (F):Nº 466/Turrilites costatus (Lamarck),Andar 20º Cenomaniense,Terreno Cretaceo,Localidade Rouen (Seine inf.re);G-J, Duvalia dilatata (de Blainville,1827) in dorsal view (G),section (H), lateral view (I),and original label (J):Nº 351/Belemnites dilatatus (Blainville),Andar 17º Neocomiense,Terreno Cretaceo,Localidade Cheiron perto de [near of] Castellanne (Basses Alpes);K-N,Hibolithes subfusiformis(Raspail,1829) in dorsal view (K),section (L),ventral view (M),and original label (N):Nº 352/Belemnitessubfusiformis (Raspail),Andar 17º Neocomiense, Terreno Cretaceo,Localidade Cheiron (Basses Alpes); O-R, Belemnitella mucronata (von Schlotheim, 1813) in dorsal view (O), section (P), ventral view (Q), and original label (R): Nº 556/Belemnitella mucronata (d’Orb),Andar 22º Senoniense,Terreno Cretaceo,Localidade Epernay (Marne).Scale bar:2 cm.