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Wyoteuthis linsterorum
Ippolitov, Lippincott, Wahl & Lomax, 2026
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Abstract
We describe and discuss two finds of large and untypical belemnite rostra originating from the upper part of the Sundance Formation (Oxfordian) of Wyoming, USA. With a diameter reaching c. 60 mm at the anterior end, these rostra are the thickest known for belemnites so far. Herein they are ascribed to a new genus Wyoteuthis, comprising a single new species, W. linsterorum. Both primary and secondary morphological features (rostrum shape, alveolus position, alveolar angle, details of apical grooves and striation) allow us to justify the placement of our new taxon in the family Megateuthididae, which flourished in Toarcian to middle Jurassic time but mostly disappeared during the Bathonian, and is represented by few extremely rare and stratigraphically isolated records from younger strata. In turn, externally similar rostra previously reported in the literature from the same basin belong to Cylindroteuthididae, a common and previously only known family-level group for the Oxfordian of northwestern USA. The new genus represents a relict offshoot of the family Megateuthididae, most likely deriving from the Bajocian members of the genus Brevibelus, formerly described from North America. It demonstrates the presence of a previously unrecognized megateuthidid refugium in the north-eastern Pacific. We also discuss evolutionary macro-trends in belemnites and the possible correlations between rostrum size and soft-body size.
SYSTEMATIC PALAEONTOLOGY
Subclass COLEOIDEA Bather 1888
Order BELEMNITIDA Zittel 1895
Family MEGATEUTHIDIDAE Sachs & Nalnjaeva 1967
‘BREVIBELUS-GROUP’ sensu Ippolitov & Desai 2019
Genus Wyoteuthis nov.
Type species: Wyoteuthis linsterorum sp. nov.
Derivation of name: A combination of ‘WYO’ (the abbreviation of the State name) and Greek τευθίς (‘squid’); together meaning ‘a squid from Wyoming’.
Differential diagnosis: It differs from Lotharingibelus Weis et al. 2025 by the much larger and more shortened rostrum, and absence of epirostrum; from Brevibelus Doyle 1992 by the same features and clear ventral displacement of the apex; from Arcobelus Sachs in Sachs & Nalnjaeva (1967) by the pronounced ventral, not dorsal displacement of the apex and less compressed cross-section, and smaller alveolar angle (29° in Wyoteuthis vs >35° in Arcobelus); from Pseudosimobelus Dzyuba & C.D. Schraer in Dzyuba et al. (2018) and from Dactyloteuthis Bayle 1878, by the absence of a single ventral groove and extremely short postalveolar part of the rostrum; from the latter additionally with a markedly less compressed rostrum. Other known members of the family Megateuthididae do not have blunt posterior ends comparable with Wyoteuthis.
Occurrence: Upper part of the Sundance Formation (Redwater Shale Member) of Wyoming, USA; late early to early middle Oxfordian (Late Jurassic).
Remarks
Systematic position: Wyoteuthis is a rare taxon with only two specimens known to date. It is stratigraphically isolated from other Megateuthididae, which are mainly restricted to the Toarcian–Bathonian interval. Explanation of its placement in that family and affinity with the genus Brevibelus is provided...
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Wyoteuthis linsterorum gen. et sp. nov., holotype, WYDICE INV-001;
upper lower to lower middle Oxfordian; upper part of Redwater Shale Member, Sundance Formation; 6 km south of Hyattville, Wyoming, USA. Collected by C. Linster.
A, dorsal view. B, right side view. C, alveolar view. D, cross-section 45 mm anterior to the presumed protoconch position. E, apical view. F, frontal CT section, view from ventral side. G, sagittal CT section, right side view. Scale bar represents: 10 mm (A–E; natural size); 30 mm (F, G). |
Wyoteuthis linsterorum sp. nov.
Derivation of name: After the Linster Family, who discovered the holotype and donated it to the WDC, making it available for science and for the present study.
Diagnosis: Rostrum of large diameter (up to 30–32 mm at protoconch and 65–70 mm anteriorly), conical to subconical with a very short postalveolar part (Pa/DV = 0.37–0.43), posteriorly blunt with ventrally displaced mucronate apex bearing striae, grouped in unclear bunches modified as pit-like depressions. Alveolus extends into most of the length of the rostrum.
Alexey P. Ippolitov, Jessica L. Lippincott, William R. Wahl, Dean R. Lomax. 2026. ‘The big chunky belemnite’: A New relict megateuthidid from the Oxfordian (Late Jurassic) of Wyoming, USA, and its place in the evolutionary history of the group.
Papers in Palaeontology. 12(5); e70123. DOI:
doi.org/10.1002/spp2.70123 [09 September 2026]
