Idahoteuthis Doguzhaeva and Brayard, 2018
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publication ID |
https://doi.org/ 10.4202/app.00393.2017 |
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persistent identifier |
https://treatment.plazi.org/id/038587AD-FFE1-BE1F-FCCC-F981FF5A2BF3 |
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treatment provided by |
Felipe |
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scientific name |
Idahoteuthis Doguzhaeva and Brayard |
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Genus Idahoteuthis Doguzhaeva and Brayard nov.
Type species: Idahoteuthis parisiana Doguzhaeva and Brayard gen. et sp. nov., see below, monotypic.
Etymology: Named after the state of Idaho, USA where the specimen was found.
Diagnosis. —Slender gladius; maximum width/length ratio, ca. 0.2, in middle part; long, narrow, anteriorly angulated lateral fields; median and lateral keels; conus large, ca. 0.25 gladius length without rachis length.
Remarks. —At the juvenile stage, the gladius is narrow, with three narrow fields each of which shows a broadly rounded anterior outline (Fig. 2C). The median field is slightly longer that lateral fields. This morphology suggests that the rachis and anteriorly tapered median and angulated lateral fields appeared at later ontogenetic stage. The new family Idahoteuthidae assumedly falls in the order Myopsida . Extant myopsids are neritic, often dwelling in very shallow waters, or are upper slope demersal species; many species are also efficient swimmers ( Vecchione and Young 2008). Combined observed features in Idahoteuhis gen. nov. and comparisons with present-day coleoids therefore suggest that members of Idahoteuthidae had a streamlined body, a micro-laminated ultrastructure and a non-biomineralized, supposedly chitinous composition of gladius providing a light and flexible skeleton, as well as well-developed fin cartilages favoring effective maneuvering in swimming.
Idahoteuthis parisiana Doguzhaeva and Brayard
sp. nov.
Figs. 2–9.
Etymology: Named after the city of Paris, Idaho ( USA), where the specimen was found.
Holotype: UBGD 30545 . The specimen is exposed on two split surfaces of the broken concretion. It is compressed because of compaction and strongly deformed according to original differences in morphology and composition observed between its anterior, middle and posterior parts. It reveals a multi-way fossilization resulted in different preservation of chitin gladius, and arm hooks and soft tissue remains..
Type horizon: Early Triassic, middle Olenekian (early Spathian).
Type locality: West of the city of Paris, southeastern Idaho, western USA.
Diagnosis. —Tapered, slender, ca. 40–50 mm long, gladius with maximum width/length ratio, ca. 0.2, in its middle part; narrow median field with rachis; narrow, anteriorly angulated long lateral fields; median and lateral keels; conus large, ca. 0.25 gladius length without rachis length.
Description. —The holotype is a 48.7 mm long specimen showing non-biomineralized structures. Its anterior, central and posterior parts are differently deformed. The middle part of the gladius is embedded in soft body that retains its cylindrical shape in the middle part of the specimen; the cephalic area is not preserved (Fig. 2A). The gladius is thin-walled, micro-laminated, flexible, diagenetically phosphatized and apparently originally chitinous ( SOM: table 1; Fig. 9C View Fig ). It is ca. 42.2 mm long, anteriorly tapered and exhibits a large conus at its posterior end (Figs. 2, 3). The median field is narrow and anteriorly ended by a free rachis (Figs. 2A, 3). The extremity of the rachis is broken and its actual length is unknown; the measured length is about 4 mm. The lateral fields are narrow, long, and acute anteriorly (Fig. 2A 1). The conus is ca. 8.3 mm long, that is ca. 0.25 of the gladius length (Fig. 2A, C 1). The posterior extremity of the conus approximately corresponds to the top of the V-shape “sinus” between fins (Fig. 2C). The conus shows a small lateral tooth-like structure (Fig. 2A 2, B, C 1). The smooth outer surface of the gladius is exposed in its most anterior tapered part (Fig. 2A), in the conus (Fig. 2A 1, C 1) and in a tiny ~ 3 mm apical part of the gladius that is displaced from its original position and seen in the marginal part of the conus (Fig. 2C). The apical gladius has slowly expanded narrow median and two lateral fields with broadly rounded anterior outline; the central field being slightly longer and broader that lateral ones. This highlights the presumed ontogenetic transformation of the rounded frontal outline of the juvenile gladius into the tapered frontal outline in later ontogenetic stages. It is worth noting that the ontogenetic stage that would be characterized by a Loligosepia -type gladius showing a broad triangular median field, is missing in the ontogeny of Idahoteuthis parisiana Doguzhaeva and Brayard gen. et sp. nov. In the middle part, the gladius is deformed in a way that its sides are brought together and overlap one another. Because the left half of the gladius is broken and removed, soft tissue remains are exposed there
Fig. 2A, B). This part of the specimen is occupied by a large, oval, phosphatized stomach (Fig. 2A 1). Due to compaction, the latter likely looks larger, than it was originally. The stomach exhibits a lighter color than other structures in this area. It has a gently folded periphery along the ventral side but it is less deformed along the dorsal side (Fig. 2A). The stomach contains irregularly dispersed deformed arm hooks, ten of which have been found on a fracture plan ( Fig. 4 View Fig ). It is worth to note that the stomach of the Late Cretaceous fossil squid” Dorateuthis contained the undigested fish remains ( Lukeneder and Harzhauzer 2004). In addition to the arm hooks, the exposed surface of the stomach displays scattered tiny, black sheet fragments of potential flooded ink. Like the arm hooks, ink exhibits a micro-globular ultrastructure and a carbon composition ( Fig. 9A View Fig ; SOM: table 1). Posteriorly, a pair of pear-like, fin-supported cartilages and fins complete the specimen (Figs. 2A, C 1, 5, 6, 8A). They adjoin the conus; both being approximately equally long. The mantle is exposed like a ventral band-shape structure extending from the conus along the ventral margin of the soft body (Fig. 2A 2, B). It might provide postmortem fixation of the cylindrical shape of the body on the ventral side where other supporting structures were missing. The ventral mantle is also represented by a patch preserved in front of the conus; it has thin, wavy longitudinal ridges (Fig. 2B). On the dorsal side, the gladius is coated by a band-shape structure of thin cartilaginous mantle (Figs. 2A 2, C 1, 7, 8). This cartilage tissue is canalicular ( Figs. 7B View Fig , 8 View Fig ), like in fin cartilages ( Figs. 5C View Fig , 6 View Fig , 8A View Fig ). Additionally, sporadically-dispersed mantle debris are identified by their plastic micro-deformation and micro-granular ultrastructures typical for fossilized non-biomineralized materials ( Fig. 9A, E, F View Fig ; for comparison see Doguzhaeva et al. 2004 b: figs. 2A, B; Doguzhaeva et al. 2007a: figs. 6.7A–E; Doguzhaeva et al. 2007b: figs. 11.3–11.7; Doguzhaeva et al. 2010b: figs. 2–9).
Stratigraphic and geographic range.— Type locality and horizon only.
| SOM |
Bulgarian Academy of Sciences |
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.