Swiss J Palaeontol (2016) 135:23–56 DOI 10.1007/s13358-015-0101-2 Systematics, endemism and phylogeny of Indian proplanulitins (Ammonoidea) from the Bathonian–Callovian of Kutch, western India 1 1 Rakhi Dutta • Subhendu Bardhan Received: 25 February 2015 / Accepted: 28 August 2015 / Published online: 8 December 2015 Ó Akademie der Naturwissenschaften Schweiz (SCNAT) 2015 Abstract Spath (1931) described five genera namely Si- Bathonian of Kutch (Roy et al. 2007). Procerites was a vajiceras Spath, Obtusicostites Buckman, Hubertoceras European genus and perhaps gave rise to Proplanulites in Spath, Kinkeliniceras Buckman and Cutchisphinctes Spath the Boreal Europe. We here envisaged that Sivajiceratinae from the Upper Bathonian and entire Callovian of Kutch, and the European Proplanulitinae show evolutionary con- western India and included 33 species within them. He vergence of some characters since they evolved from a grouped these genera within the subfamily Proplanulitinae common ancestral stock. of the Boreal Province. But however the palaeobiogeo- graphic distributions of the Kutch forms suggest that they Keywords Sivajiceratinae Á New subfamily Á Kutch Á were restricted within the Indo-Madagascan Province. Middle Jurassic Á Palaeobiogeography Á Evolution Callomon (1993) expressed doubts about the phylogenetic affinity of Kutch genera and inferred that proplanulitins of Kutch were unrelated to Boreal Proplanulites and consti- Introduction tute an endemic lineage. In the present study, we made a thorough systematic revision of proplanulitin taxa of Kutch The Bathonian of Kutch, western India, witnessed sudden in the light of intraspecific variability and sexual dimor- migration of many ammonite genera from different pro- phism. Our study reveals that Spath’s (1931) work suffered vinces as soon as the Kutch Basin opened up (Roy et al. from excessive and subjective splitting. Many species 2007). Macrocephalitins, for example, invaded from the described by him were nothing but variants of a single, West Pacific Province (Indonesia) and underwent a spec- variable, biological species. The genus Hubertoceras was tacular radiation of many endemic genera/species during considered as the microconch of Obtusicostites. Cutchis- Late Bathonian–Early Callovian times (Spath 1931). Five phinctes was excluded as it appears to be unrelated. We genera namely Sivajiceras Spath, Obtusicostites Buckman, finally described two species within each genus, Siva- Hubertoceras Spath, Kinkeliniceras Buckman and jiceras, Obtusicostites and Kinkeliniceras from the Callo- Cutchisphinctes Spath were described by Spath (1931) vian. We grouped these Kutch genera within a new from the Upper Bathonian to entire Callovian successions subfamily Sivajiceratinae which is distinct from the exist- of Kutch. All these genera were new records in Kutch and ing subfamily Proplanulitinae. The oldest genus Sivajiceras grouped within the subfamily of Proplanulitinae of the evolved from contemporary Procerites during the Late Boreal Province. Since their first description, the new genera were continuously referred to as proplanulitins although their paleobiogeographic occurrence was restric- & Rakhi Dutta ted to the Indo-Madagascan Province and not a single [email protected] species of the Boreal genus Proplanulites has been recor- Subhendu Bardhan ded from Kutch or neighbouring regions. It was Callomon [email protected] (1993) who first expressed doubts about the phylogenetic 1 Department of Geological Sciences, Jadavpur University, affinity of Kutch genera and predicted that a detailed study Kolkata 700032, India would one day reveal that Kutch proplanulitins are entirely 24 R. Dutta, S. Bardhan unrelated to the Boreal forms and constitute an endemic Geological setting lineage. In the present study, we revisited Kutch’s the so-called The origin of the Kutch Basin was related to the frag- proplanulitins. Our study included type material archived mentation of Gondwana during the Late Triassic to Early in the Geological Survey of India, Kolkata; The Natural Jurassic. The exposed Jurassic sediments range in age from History Museum, U.K. and numerous additional specimens the Bajocian to Tithonian (Biswas 1982, 1991; Roy et al. collected by us from different sections in the mainland of 2007;Fu¨rsich et al. 1994, 2013) and were deposited during the Kutch Basin with precise stratigraphic information. We repeated episodes of marine transgression and regression studied the group in the light of new information on (see Biswas 1991; Mukherjee 2007). The fossiliferous intraspecific variability and sexual dimorphism within a Bathonian–Callovian sediments are exposed best in the biological species. The concept of sexual dimorphism was mainland of Kutch, particularly in Jara, Jumara, Keera and not in vogue during the time of Spath (1931). The detailed Jhura in the NW of Bhuj, the principal district town of systematic revision led to synonymising many of the Kutch as well as in Ler-Fakirwadi, south of Bhuj (Fig. 1). Spath’s species into a single species. Dimorphism has been These areas form domal outcrops (Mitra et al. 1979) due to established in most of the species. These revised endemic subsequent tectonic activity and offer excellent sections. genera were assigned to a new subfamily Sivajiceratinae n. All type specimens of the present new subfamily come subfam. We excluded another genus Cutchisphinctes from different localities of the mainland of Kutch (Waagen described by Spath (1931) because it shows strong 1875; Spath 1931) (Fig. 1). In our extensive and repeated resemblance to the subfamily Pseudoperisphinctinae, more field surveys, we collected additional specimens mainly specifically to Choffatia. from Jumara and Keera. The Middle and Upper Bathonian Roy et al. (2007) made an attempt to establish the sediments belong to the Patcham Formation while Callo- evolutionary relationship between the older Procerites vian sediments are grouped into the Chari Formation which was found in the Bathonian of Kutch and the con- (Mitra et al. 1979). The Patcham Formation in mainland is temporaneous Sivajiceras, the type genus of the new sub- exposed only in Jumara and the Chari Formation is well family Sivajiceratinae. We will reiterate their view exposed in many localities within mainland (Fig. 1). The regarding the origin of the Sivajiceratinae in the following biostratigraphy of Patcham and Chari formations are and provide detailed evidence. We will try to explain the delineated by many workers in a series of previous studies stunning similarities between the Boreal Proplanulites and (Mitra et al. 1979; Datta 1992; Roy et al. 2007). The the taxa from Kutch. depositional environment of the Patcham Formation was a Fig. 1 Geological map of Kutch showing the major localities (solid squares) from where fossils of the Sivajiceratinae have been collected (modified after Biswas 1977;Fu¨rsich and Pandey 2003) Systematics, endemism and phylogeny of Indian proplanulitins (Ammonoidea)… 25 carbonate ramp on the epicontinental shelf. The Upper Systematic palaeontology Bathonian sediments in Jumara consist mainly of greenish to grey shale intercalated with shelly and white limestone Abbreviations Specimen numbers bear the following of varying thickness (Roy et al. 2007). The depositional repository institutional prefixes: NHMUK—Natural His- milieu of the Chari Formation was a shelf environment. tory Museum, United Kingdom; GSI—Geological Survey The lower part of the Chari Formation is Early Callovian in of India; Kolkata; JUM—Jadavpur University Museum- age and includes mostly shale-limestone association Kolkata (where all additional specimens are archived). * in (packstone or wackestone). The Middle Callovian beds are front of the publication year in the synonymy list for the dominantly siliciclastic and represent a shoaling upward name-giving citation. v—in the synonymy list in front of phase (Datta 1992;Fu¨rsich and Oschmann 1993). The the publication year indicates the specimens which were Upper Callovian beds are composed of an alternation investigated in the present study. [M] and [m] designate between greenish grey shale, occasionally gypseous with macroconch and microconch, respectively. The following secondary gypsum and white fossiliferous limestone. letters are used to indicate shell parameters: D—diameter Dominantly, argillaceous facies in the Chari Formation of the shell; U—diameter of the umbilicus; W—width of were deposited in the outer ramp formed within the Kutch the whorl; H—height of the whorl from the umbilical embayment (Fu¨rsich et al. 2004). The sediments were margin; P—number of primary ribs per half whorl; S— deposited below storm wave base in low-energy number of ventral ribs (secondary plus intercalatory ribs) environment. per half whorl; RW—rib width of the shell; RS—rib space The stratigraphic distributions of the studied genera of the of the shell. SP—Sivajiceras paramorphum; OO—Obtu- Sivajiceratinae n. subfam., Procerites and other important sicostites obtusicosta; KA—Kinkeliniceras angygaster; ammonite species reported from the two studied localities KK—Kinkeliniceras kinkelini, K—Keera and J—Jumara. (Jumara and Keera) are shown in Figs. 2 and 3. The strati- Superfamily Perisphinctoidea Steinmann, 1890 graphic distribution of these genera is shown in Fig. 4 Family Perisphinctidae Steinmann, 1890 against the regional biostratigraphic background. Subfamily Sivajiceratinae nov. subfam. Type genus: Sivajiceras Spath, 1930 Materials and methods Diagnosis: Shell large and evolute. Depressed