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Family Naticidae (Gastropoda) from the Upper Jurassic of Kutch, India and a critical reappraisal of taxonomy and time of origination of the family

Published online by Cambridge University Press:  14 March 2019

Shiladri S. Das
Affiliation:
Geological Studies Unit, Indian Statistical Institute, 203, B.T. Road, Kolkata -700108, India
Subhronil Mondal
Affiliation:
Department of Geology, University of Calcutta, 35, Ballygunge Circular Road, Kolkata -700019, India
Sandip Saha
Affiliation:
Geological Studies Unit, Indian Statistical Institute, 203, B.T. Road, Kolkata -700108, India
Subhendu Bardhan
Affiliation:
Geological Studies Unit, Indian Statistical Institute, 203, B.T. Road, Kolkata -700108, India
Ranita Saha
Affiliation:
Department of Applied Geology, IIT(ISM) Dhanbad, Jharkhand 826004, India

Abstract

Naticid taxonomy is in a state of flux owing to non-descript shell morphology and frequent convergence. Inadequate preservation of naticid body fossils has further complicated the matter in determining the true affinity and the exact time of origin of the clade. As a result, a plethora of classificatory schemes of naticid phylogeny and times of origin has been proposed. In many previous studies, true naticid affinities of fossils have been sought based on single or a few morphological characters, which are susceptible to poor preservation. In the present paper, we have attempted a holistic reappraisal of naticid taxonomy based on an extensive database of shell morphological characters and identified many distinct family- and subfamily-specific characters that survived fossilization. This approach has enabled us to identify three new naticid species from the Late Jurassic horizons of Kutch, India, thus extending back the time of origin of the family Naticidae by 30 Ma.

Analysis of character matrix data reveals that the present species—Gyrodes mahalanobisi new species, Euspira jhuraensis new species, and Euspira lakhaparensis new species—belong to two subfamilies, Gyrodinae and Polinicinae. The occurrence of typical naticid drill holes on various coeval gastropod and bivalve taxa along with these body fossils provides strong supporting evidence for the naticid affinity of these forms.

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Copyright © 2019, The Paleontological Society 
Figure 0

Figure 1.(1–12) Gyrodes mahalanabisi n. sp. (1–4) Apertural, abapertural, apical, and basal views (holotype no. ISI/g/Jur/N 1); note Turritella jhuraensis Mitra and Ghosh, 1979, is attached at the base (1, 4) and the presence of subsutural wrinkle (3, indicated by arrow); (5–8) apertural, abapertural, apical, and basal views (paratype no. ISI/g/Jur/N 8); note (7) showing subsutural wrinkle (arrow); (9) apertural view (paratype no. ISI/g/Jur/N 21); (10–12) apertural, abapertural, and apical views (paratype no. ISI/g/Jur/N 13). Scale bars = 1 cm.

Figure 1

Table 1.List of characters and character states used for the identification of the usable and excellent characters of the four subfamilies of the family Naticidae, and to distinguish them from the outgroup Ampullospirinae.

Figure 2

Figure 2.(1–4) Scanning electron micrographs of the apical part of different specimens of Gyrodes mahalanabisi n. sp. (1) Depressed and smooth protoconch (paratype no. ISI/g/Jur/N 5); (2) depressed protoconch (paratype no. ISI/g/Jur/N 7); (3) depressed and smooth protoconch (paratype no. ISI/g/Jur/N 8); (4) smooth and globular protoconch comprising about two whorls (paratype no. ISI/g/Jur/N 26). Scale bars are (1) 200 μm; (2–4) 300 μm.

Figure 3

Figure 3.(1, 2) Scanning electron micrographs of the apical part of two specimens of Gyrodes mahalanabisi n. sp. (1) Apical view showing presence of subsutural wrinkles at shoulder, indicated by arrow (paratype no. ISI/g/Jur/N 42); (2) apical view showing presence of subsutural wrinkles at shoulder, indicated by arrows (paratype no. ISI/g/Jur/N 46). Scale bar = 300 μm.

Figure 4

Figure 4.(1–14) Euspira jhuraensis n. sp. (1–3) Apertural, abapertural, and apical views (paratype no. ISI/g/Jur/N 80); (4–7) apertural, abapertural, apical, and basal views (holotype no. ISI/g/Jur/N 77); note moderately open umbilicus, distinct semicircular callus with low funicles (see arrows in 1, 4); (8–11) apertural, abapertural, apical, and basal views (paratype no. ISI/g/Jur/N 82); note large, ear-shaped aperture (8); (12) apertural view (paratype no. ISI/g/Jur/N 83); note semicircular callus with low funicles (arrow); (13) apical view (paratype no. ISI/g/Jur/N 92); (14) apical view (paratype no. ISI/g/Jur/N 89); note an oyster bivalve is attached at the base. Scale bars = 1 cm.

Figure 5

Figure 5.(1, 2) Scanning electron micrographs of the apical part of Euspira jhuraensis n. sp. (1) Smooth and depressed protoconch (paratype no. ISI/g/Jur/ N 84); (2) smooth, globular, and depressed protoconch comprising about two whorls (paratype no. ISI/g/Jur/ N 88). Scale bars are (1) 100 μm; (2) 300 μm.

Figure 6

Figure 6.(1–5) Euspira lakhaparaensis n. sp. (holotype no. ISI/g/Jur/N 99). (1–4) Apertural, abapertural, apical, and basal views; (2, 5) abapertural and slightly tilted abapertural views showing closely spaced slightly prosocline to straight growth lines. Scale bars = 1 cm.

Figure 7

Table 2.Several excellent characters for the four naticid subfamilies, as identified from the character matrix in Supplementary Table 1.

Figure 8

Figure 7.Complete naticid drill holes (see arrows) on various gastropod and bivalve prey from the Upper Jurassic Dhosa Oolite Member at Jhura pond section. (1) Turritella jadavpurensis Mitra and Ghosh, 1979, abapertural view; (2) Turritella jhuraensis Mitra and Ghosh, 1979, abapertural view; (3) confamilial naticid drill hole on Gyrodes mahalanobisi n. sp., abapertural view; (4) Lenticorbula sp., dorsal view; (5) Corbula sp., lateral external view. Scale bars = 1 cm.