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| Simoniteuthis michaelyi Fuchs, Weis & Thuy, 2024 |
Abstract
The evolutionary history of the cephalopod order Vampyromorpha with its only recent representative, Vampyroteuthis infernalis, the deep-sea vampire squid, is still obscure and a new specimen from the Early Jurassic of Luxembourg, provides new information on the vampyromorph morphology at this period. The new taxon Simoniteuthis michaelyi n. gen. n. sp., which is based on a nearly complete gladius with associated head–arm complex, is morphologically intermediate between the families Loligosepiidae and Geopeltidae. Interestingly, the arm crown displays only four arm pairs, although an arm configuration consisting of five arm pairs should be expected in vampyromorph stem lineage representatives. This observation encouraged us to critically review the presumed homology of the filaments of Vampyroteuthis and the lost arm pair in cirrate and incirrate octopods. Moreover, two bony fishes in the mouth region implicated that Simoniteuthis michaelyi n. gen. n. sp. preyed upon them in hostile water depths, a taphonomic phenomenon called distraction sinking. By contrast to modern Vampyroteuthis infernalis, Simoniteuthis michaelyi n. gen. n. sp. roamed and hunted in shallower waters as typical for Mesozoic stem lineage vampyromorphs. According to the current fossil record, a vertical migration into deeper waters (probably associated with a shift in feeding behaviour) occurred at least since the Oligocene.
Keywords: Octobrachia, Vampyromorpha, Leptolepis, Toarcian, Bascharage, Evolution, Predation
Systematic palaeontology
Class Coleoidea Bather, 1888
Subclass Octobrachia Haeckel, 1866
Order Vampyromorpha Robson, 1929
Suborder Loligosepiina Jeletzky, 1965
Family undetermined (?Loligosepiidae Regteren Altena, 1949 Or Geopeltidae Regteren Altena, 1949)
Remarks: The main difference between the Loligosepiidae and the Geopeltidae concerns the length of the hyperbolar zone, which is shorter in Geopeltidae than in Loligosepiidae. An additional character that delimits these two closely related families represents the shape of the hyperbolar zone (V-shaped in Loligosepiidae and arcuated in Geopeltidae).
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| Simoniteuthis michaelyi n. gen. n. sp., holotype (MNHNL TI024), Lower Toarcian, Serpentinum Chronozone, Exaratum Subchronozone, Bascharage. A–D slab; E–G counter-slab. A overview; B camera lucida drawing of A; C close-up of the head–arm complex; D same under UV-light showing the weakly illuminating arm musculature; E overview; F close-up of the preyed fishes, red colour Specimen 1 (op = opercle; sop = subopercle), blue colour Specimen 2 (caud = caudal fin; sop = subopercle; centra = central vertebra); G same under UV-light. Scale bars = 10 mm |
Genus Simoniteuthis n. gen.
Derivation of name: Dedicated to Jo Simon, scientific volunteer collaborator of the National Museum of Natural History Luxembourg, who skilfully and patiently cleaned the fossil in the nodule and unveiled the soft part preservation.
Diagnosis: Medium-sized loligosepiids, gladius moderately wide (gladius widthmax-to-gladius length 0.30–0.40); median field very slender to slender (median field widthhypz-to-hyperbolar zone length 0.15–0.25; = opening angle 9–14°), laterally reinforced, anterior median field margin convex; hyperbolar zone very long (hyperbolar zone length-to-median field length 0.80–0.89), deeply V-shaped incised; anterior limit of lateral field thus distinctly projected, spine-like pointed, lateral fields moderately wide (lateral field widthmax-to-median field widthmax 1.85–1.95).
Simoniteuthis michaelyi n. sp.
Derivation of name: Dedicated to Patrick Michaely, Director of the Natural History Museum Luxembourg with a passion for palaeontological research.
Dirk Fuchs, Robert Weis and Ben Thuy. 2024. Simoniteuthis, A New vampyromorph coleoid with prey in its arms from the Early Jurassic of Luxembourg. Swiss Journal of Palaeontology. 143, 6. DOI: 10.1186/s13358-024-00303-y
