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

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.UUID http://zoobank.org/94188d64-075b-4bd0-8303-1ce9a0d86eb0

Predatory drill holes in the oldest thyasirid bivalve, from the Lower Jurassic of South Germany

“…Recently, Das et al . (2019) reported naticids from the Oxfordian of Kachchh, India, which would be the earliest occurrence of naticids although the preservation of the specimens seems insufficient for a safe attribution to Naticidae. The identity of the drilling predator(s) before the Late Jurassic is still unknown (Harper et al .…”

“…Recently, Das et al . (2019) documented the occurrence of naticid gastropods together with naticid‐type drill holes from the Oxfordian of Kachchh and suggested naticids as the culprit for the drill holes in gastropod and bivalve shells found there. This would extend the record of naticids back to the Upper Jurassic.…”

Morphological conservatism of the family Naticidae (Gastropoda) through time: potential causes and consequences

“…Morphologically, naticids have a very simple shell, and as discussed by previous authors, external shell characters may not be sufficient to segregate the members of this family (Bandel 1999;Das et al 2019). Perhaps for this reason, several workers in the past related naticids with other diverse gastropod families such as the Ampullinidae, Calyptridae, Cypridae, Littorinidae, Neritidae, and Xenophoridae (Bandel 1999;Kase and Ishikawa 2003;Strong 2003;Colgan et al 2007; for reviews, see Aronowsky 2003;Hülsken 2008).…”

“…To counteract problems related to convergent shell characteristics, some authors have suggested the use of soft part anatomy (Aronowsky 2003) and molecular coding (Hülsken et al 2006(Hülsken et al , 2008(Hülsken et al , 2012. However, soft parts are not preserved in the fossil record, and thus their use is limited to extant taxa only (for a similar argument, see Das et al 2019). Das et al (2019) suggested a few subfamilybased hard part characters that can be used to distinguish among the four subfamilies-Naticinae, Polinicinae, Sininae, and Gyrodinaealthough clear distinctions could not be made.…”

“…However, soft parts are not preserved in the fossil record, and thus their use is limited to extant taxa only (for a similar argument, see Das et al 2019). Das et al (2019) suggested a few subfamilybased hard part characters that can be used to distinguish among the four subfamilies-Naticinae, Polinicinae, Sininae, and Gyrodinaealthough clear distinctions could not be made. Similar uncertainty in the grouping of subtaxa was evident even when both hard and soft morphological characters were combined with the genetic characters of extant species (Aronowsky 2003).…”