Coleoidea Bather, 1888
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publication ID |
https://doi.org/10.1186/s13358-024-00319-4 |
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persistent identifier |
https://treatment.plazi.org/id/EB37F410-504D-D42C-D944-A662B1BA1578 |
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treatment provided by |
Felipe |
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scientific name |
Coleoidea Bather, 1888 |
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Subclass Coleoidea Bather, 1888 View in CoL
Stem Neocoleoidea Haas, 1997
Order UNCERTAIN
“ MOJSISOVICSTEUTHIS Group”
Family UNCERTAIN
Genus MOJSISOVICSTEUTHIS sp.
( Figs. 2a, b View Fig , 3d View Fig , 4 View Fig ).
Remarks: Te genus Mojsisovicsteuthis is here regarded as a waste-basket taxon for endocochleate cephalopods that exhibit a long and tubular body chamber, a phragmocone opening angle of 15° to 20°, and that lack a massive rostrum covering the apex of the phragmocone.
It appears to be transitional between rostrum-bearing Aulacoceratida typified by a comparatively wide septal spacing, and proostracum-bearing Phragmoteuthida with a comparatively dense septal spacing (compare Fuchs & Donovan, 2018; Mariotti et al., 2021).
Material: Overall 54 specimens were assigned to Mojsisovicsteuthis sp. Tese specimens encompass three that are of uncertain affinity and hence cf. Mojsisovicsteuthis sp. , 28 from historical collections at the NHMW, and 26 from recent excavations, inventoried at the NHMW. Exceptional specimens are NHMW 2005z0005/0027 ( Fig. 4g View Fig ), NHMW 2005z0005/0028
( Fig. 4a View Fig ), NHMW 2005z0005/0039, NHMW 2005z0005/0010 ( Fig. 4d View Fig ), NHMW 2006z0235/0001, NHMW 2012/0228/0515 ( Fig. 4c View Fig ), NHMW 2012/0228/0561 ( Fig. 4e View Fig ), NHMW 2021/0124/0057
( Fig. 4f View Fig ) and NHMW 2021/0124/0092, as they preserved their long and tubular body chamber including its dorsal crest. Specimen NHMW 2005z0005/0028ab exhibits a nearly complete shell allowing to reliably reconstruct its relative length.
Description: Te orthoconic phragmocone opens with angles ranging from 10° to 20° (mean: 15.25°). Te almost fully preserved specimen (apex poorly visible) NHMW 2012/0228/0515 ( Fig. 4c View Fig ) is 143.37 mm long, and 35.62 mm wide (at its widest; corresponding to its maximum diameter). Statements about the phragmocones cross sections are impossible owing to the flattened state of preservation. Sutures are poorly visible, but NHMW 2006z0235/0004 suggests a ratio chamber length to chamber diameter of approximately 0.2. Phragmocones with preserved apex lack a rostrum proper. Te body chamber is nearly tubular (opening angle<5°) without evidence of a ventral opening. It is almost as long as the phragmocone (ratio body chamber length to total shell length c. 1) and furnished with a short dorsal projection. Tis projection (dorsal crest after Jeletzky, 1966) is evenly rounded and takes c. 15% of the body chamber length (or 8% of the total shell length).
A specimen with in situ arm crown and hooks was not available for examination, but scattered type 4 hooks are preserved next to specimen NHMW 2005 View Materials z0005/0002 (= NHMW 2006 View Materials z0235/0001) ( Fig. 3d View Fig ). Tese hooks are curved with a bimodal base and prominent knobbed inner process. Cephalic cartilages associated with shell remains belonging to Mojsisovicsteuthis sp. are still unknown .
Comparisons: Apart from the opening angle, which is larger in P. bisinuata than in Mojsisovicsteuthis sp. , the long tubular body chamber is strikingly different from the three-lobed proostracum of P. bisinuata . Te dorsal crest is similar to that described for aulacoceratids ( Jeletzky & Zapfe, 1967) and cannot be confused with the anteriorly rounded median field of P. bisinuata . Moreover, the specimens appear larger and more massive than those of Phragmoteuthis from Polzberg.
Te strongly curved hooks of morphotype 4 associated with NHMW 2006z0235/0001 are not observed in the arm crowns attributed to P. bisinuata .
Tree specimens described and figured as P. bisinuata in Doguzhaeva et al. (2007b: NHMW 2006z0235/0001, 0003, 0004) are here reinterpreted as Mojsisovicsteuthis sp. Comparisons of the specimens indicate that the presence of a three lobed proostracum is questionable, while a tubular body chamber is likely. Te apical angle of the phragmocone ranges between 18.4° and 19.9°. Te total lengths of these specimens are extrapolated as 135.00 mm (NHMW 2006z0235/0001), 150.00 (NHMW 2006z0235/0003) and 150.00 mm (NHMW 2006z0235/0004).
Te here described specimens and the previously described materials of Mojsisovicsteuthis (e.g., Pohle & Klug, 2024) share a comparatively short septal spacing, and the lack a massive rostrum. Tese characters exclude a systematic affinity with the order Aulacoceratida . More specifically, the Polzberg specimens resemble forms with a longiconic phragmocone such as Mojsisovicsteuthis boekhi ( Košťák et al., 2023) , M. convergens , the type species of the genus ( Jeletzky, 1966) and the recently described Ticinoteuthis chuchichaeschtli Pohle & Klug, 2024. In the latter taxa, the phragmocone cross section is elliptical (laterally compressed in M. boekhi and M. convergens ; dorsoventrally depressed in T. chuchichaeschtli). Unfortunately, this character is difficult to determine in our flattened specimens. Similarly, we are currently unable to determine the suture line course, which usually exhibits lateral lobes in at least some species of Mojsisovicsteuthis ( Košťák et al., 2023) .
Until now, our knowledge of the genus Mojsisovicsteuthis was solely based on phragmocones and internal moulds of partially preserved body chambers ( Rieber, 1973); complete body chambers were unknown until now.
Te genus Mojsisovicsteuthis is known to be morphologically intermediate between Aulacoceratida and Phragmoteuthida ( Jeletzky, 1966; Košťák et al., 2023; Pohle & Klug, 2024; Rieber, 1974). Its identification is supported by smaller phragmocone angles, presence of a tubular body chamber (rather than a tripartite proostracum) and various hook types, which apparently do not belong to phragmoteuthid belemnoids. Hence, there is strong evidence that the genus Mojsisovicsteuthis contemporaneously lived in the same area as Phragmoteuthis . Both taxa were believed to share their stratigraphic ranges but they have not been found in the same localities yet.
We reject systematic affinities with the Aulacoceratida for the following reasons. Unambiguous aulacoceratids (as well as orthoceratoids; see Pohle & Klug, 2024) are known from different regions of the Alps ( Bülow, 1916; Hauer, 1847; Mojsisovics von Mojsvar, 1871; Wöhrmann, 1893), but not from Polzberg. As aragonitic shell elements are preserved in Polzberg, it is unlikely that the aragonitic rostra of Mojsisovicsteuthis are diagenetically lost. Instead, it indicates that aulacoceratids were absent in this locality. Westermann (1973) states for aulacoceratids meso- to epipelagic habitats, while Mojsisovicsteuthis had implosion depths of around 250 m.
At least four taxa were described from the lower Carnian of Austria and neighbouring countries (“ Aulacoceras ” convergens Hauer, 1847 , “ Aulacoceras ” ellipticum Mojsisovics, 1871 , “ Aulacoceras ” obeliscus Mojsisovics, 1871 , “ Orthoceras ” boeckhi Stürzenbaum, 1876 ). “O rthoceras ” styriacum Mojsisovics von Mojsvar, 1873 (pl. 1, Figs. 6 View Fig , 7 View Fig ) is potentially another member of this group, and seems to have a similar dorsal crest (see also Pohle & Klug, 2024). Further species, tentatively assigned to Mojsisovicsteuthis are “ Atractites ” meneghini and “ Atractites ” subrotundus Rieber (1973) .
It is likely that their arms were equipped with hooks. Our results support the presence of primitive hook types such as type 1 and 4 ( Fig. 3 View Fig ) and the probable megaonychites (type 2) within this belemnoid group.
Crown group node Neocoleoidea Haas, 1997
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
Coleoidea Bather, 1888
| Lukeneder, Petra, Fuchs, Dirk & Lukeneder, Alexander 2024 |
PHRAGMOTEUTHIDA
| Mojsisovics von Mojsvar 1882 |