Archaeotolithus trigonalis Stolley, 1912

Schwarzhans, Werner & Keupp, Helmut, 2022, Early teleost otolith morphogenesis observed in the Jurassic of Franconia, Bavaria, southern Germany, Zitteliana 96, pp. 51-67 : 51

Animalia

Taxon classification Archaeotolithus trigonalis Stolley, 1912

Plate 4, figs 5-7

Archaeotolithus trigonalis 1912 Archaeotolithus trigonalis - Stolley: pl. 7, figs 1-3.

Archaeotolithus 2014 archaeotoliths group 2 - Hesse: fig. 29A-E.

Archaeotolithus trigonalis 2018 Archaeotolithus trigonalis Stolley, 1912 - Schwarzhans: fig. 8K.

Material.

25 specimens from the late Pliensbachian of Buttenheim : 2 specimens Apyrenum subzone (SNSB-BSPG 2022 IV 10), 1 specimen “Quellhorizon” (SNSB-BSPG 2022 IV 11), 22 specimens Hawkerense subzone (figured specimens SNSB-BSPG 2022 IV 12, Plate 4 , figs 5-7) .

Differential diagnosis.

Otoliths with nearly equilateral triangular shape similar to A. bornholmiensis but distinctly less high-bodied than A. doppelsteini . Archaeotolithus trigonalis differs from A. bornholmiensis in being thinner, having a smooth outer face with exposed growth rings (vs with fine radial furrows starting from the middorsal angle), and showing a clear sulcus. It differs from A. doppelsteini not only in the otolith proportions and shape but also in the very short and strongly ventrally extended ostium and the rather straight, inclined cauda.

Discussion.

Archaeotolithus trigonalis is the most common species of the genus in Buttenheim. It almost always shows some kind of incrustation on the inner face, which often obliterates the sulcus morphology. However, in some instances, such as the figured specimens, it can still be reliably identified. A similar incrustation is also seen on the large paratype of A. doppelsteini , which could have been caused by organic material that was attached to it during the early process of fossilization and mineralization.

Figures

Plate 4. Otoliths of Archaeotolithus. fig. 1: Achaeotolithus bornholmiensis (Malling & Gronwall, 1909), from the late Pliensbachian of Buttenheim, holotype SNSB-BSPG 2022 IV 7, EPH horizon. figs 2 - 4: Archaeotolithus doppelsteini sp. nov., from the late Pliensbachian of Buttenheim, EPH horizon; 2: holotype SNSB-BSPG 2022 IV 8; 3 - 4: paratypes SNSB-BSPG 2022 IV 9. figs 5 - 7: Archaeotolithus trigonalis Stolley, 1912, from the late Pliensbachian of Buttenheim, EPH horizon, figured specimens SNSB-BSPG 2022 IV 12.