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Gyrodes mahalanobisi

Gastropoda - Naticidae

Discussion

Popenoe et al. (1987) reported Gyrodes (Sohlella) quercus from the Late Cretaceous Chico Formation of California (p. 81, fig. 5.3, 5.4, 5.7, 5.125.14, 5.17, 5.18, 5.22, etc.). The present species is closely comparable with the American species in having a small-sized shell, obscurely biangulate umbilical margin, and convex whorl profile. Gyrodes (S.) quercus, however, has more whorls. Popenoe et al. (1987) also mentioned that G. (S.) quercus has tabulate and angulate shoulder and prosocline growth lines, whereas the shoulder is broadly rounded and growth lines are not discernible in G. mahalanobisi n. sp. The spire in G. (S.) quercus occupies 0.25 of the total height and the aperture is obliquely teardrop shaped, whereas G. mahalanobisi n. sp. has a characteristically semi-circular aperture and the spire occupies ~0.16 of the total height. Gyrodes mahalanobisi n. sp. may be compared with Gyrodes (Gyrodes) robustus Waring (1917, p. 84, p1. 13, figs. 11, 12; also see Popenoe et al., 1987, p. 77, fig. 4.2, 4.8) from the Paleocene of Lower Santa Susana Formation of Simi Hills, California, in having similar whorl profile, aperture, and spire height. However, the Paleocene species attains a large size compared to the present species. In G. mahalanobisi n. sp., the shoulder is broadly rounded with suture impressed and open umbilicus, whereas in G. (G.) robustus the shoulder is tabulate, angulate with adpressed suture. In addition, G. (G.) robustus growth lines are slightly prosocline, whereas growth lines are unknown in the Kutch species. The present species is comparable with the Cretaceous species, Gyrodes (Gyrodes) garudamangalami from southern India described by Bandel (2000b, p. 87, pl. 3, figs. 8, 9) in their overall shell shape, but the Kutch species is smaller (maximum observed height is 12 mm and diameter is 10 mm) than the Cretaceous species (having more or less similar height and diameter, i.e., 25 mm). Besides, the umbilical inner wall of the Cretaceous species, G. (G.) garudamangalami, has distinct growth lines that cannot be studied in the present species because of preservational state. Also, the present species has a rounded shoulder, whereas the Cretaceous species has a concave flattened shoulder.

Taxonomy
Gyrodes mahalanobisi was named by Das et al. (2019) [Etymology.—The species name is after Prasanta Chandra Mahalanobis, a noted statistician and the founder of the Indian Statistical Institute, Kolkata, India.]. Its type specimen is ISI/g/Jur/N 1, ISI/g/Jur/N 2-76, a shell, and it is a 3D body fossil.

Synonymy list
YearName and author
2019Gyrodes mahalanobisi Das et al. figs. 1-3

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RankNameAuthor
kingdomAnimalia()
Bilateria
EubilateriaAx 1987
Protostomia
Spiralia
superphylumLophotrochozoa
phylumMollusca
classGastropoda
RankNameAuthor
subclassCaenogastropoda(Cox 1959)
Sorbeoconcha(Ponder and Lindberg 1997)
Hypsogastropoda(Ponder and Lindberg 1997)
superfamilyNaticoidea(Forbes 1838)
familyNaticidaeGuilding 1834
subfamilyAmpullospirinaeCox 1930
genusGyrodesConrad 1860
speciesmahalanobisi

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

Gyrodes mahalanobisi Das et al. 2019
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Diagnosis
No diagnoses are available
Measurements
No measurements are available
Composition: aragonitef
Locomotion: actively mobileg
Life habit: infaunalg
Diet: carnivoreg
Vision: limitedc
Created: 2004-10-20 01:54:26
Modified: 2004-10-20 03:54:26
Source: g = genus, f = family, c = class
References: Kiessling 2004, Aberhan et al. 2004
Collections
No collection or age range data are available