Miocene instead of Jurassic: the importance of sound fieldwork for paleontological data analysis

Abstract

A diverse molluscan assemblage dominated by turritellid gastropods found in Kachchh, western India, has been interpreted in the past as Late Jurassic (Oxfordian) in age, based on associated undoubtedly Oxfordian ammonites. Recently, several investigations focused on the assemblage dealing with taxonomic, paleoecological, and evolutionary aspects. An analysis of the associated bivalve fauna, foraminiferal assemblage, and the geological context strongly suggests a Miocene rather than a Jurassic age and invalidates several conclusions drawn from the alleged Jurassic age of the fossils.

Miocene instead of Jurassic: the importance of sound fieldwork for paleontological data analysis—a reply

“…In order to keep this reply short, we support our point by referring to just to two aspects: the position of the outcrop and the composition of the fauna. Rather than refuting each of the other arguments of Das et al (2023), we think that a joint visit to the locality would be more productive for arriving at a consensus on the origin and age of the fauna of the Jhura pond locality.…”

“…In their detailed comments, Das et al (2023) try to discount our arguments that the strata cropping out at the so-called Jhura pond locality are not Late Jurassic in age but Miocene. We wrote this paper (Fürsich et al, 2023) because of the far-reaching conclusions that have been drawn from the molluscan fauna at that locality, in particular with respect to the evolution of turritellid gastropods and the evolution of drilling predation by naticid gastropods.…”

“…According to the new coordinates of the locality given by Das et al (2023), our section (Fürsich et al, fig. 2) is in fact approximately 200 m away along strike, exhibits a similar bed geometry, and thus can be assumed to represent the same stratigraphic unit.…”

Drilling predation on Early Jurassic bivalves and behavioral patterns of the presumed gastropod predator—evidence from Pliensbachian soft-bottom deposits of northern Germany

“…The oldest occurrence of the family Naticidae has been considered to be from the Early Cretaceous (Kase and Ishikawa 2003; Klompmaker et al 2016). Naticids recently reported from the Upper Jurassic of Kutch, India (Das et al 2019) are now considered as Miocene in age (Fürsich et al 2023). During the Paleozoic, the gastropod family Platyceratidae produced drill holes and lived as an epifaunal parasite on blastoids, crinoids, and brachiopods (Baumiller et al 1999; Baumiller and Gahn 2002; Thomka and Brett 2021).…”

“…Although there is a substantial amount of drill-hole record from the Cretaceous onward (Huntley and Kowalewski 2007; Rojas et al 2017), the record is quite scarce in the Triassic (i.e., Fürsich and Jablonski 1984; Newton et al 1987; McRoberts and Blodgett 2000; Klompmaker et al 2016; Tackett and Tintori 2019) and in the Jurassic (i.e., Sohl 1969; Bromley 1981; Harper et al 1998; Kowalewski et al 1998; Harper and Wharton 2000; Aberhan et al 2011; Bardhan et al 2012; Karapunar et al 2020a,b; Saha et al 2021; see also Fürsich et al 2023). Different hypotheses have been proposed to explain the rarity of drill holes in the Mesozoic fossil record: low diversity of drilling organisms (Kowalewski et al 1998; Huntley and Kowalewski 2007), low sampling intensity and poor preservation (Huntley and Kowalewski 2007), and taphonomic bias (Harper et al 1998).…”