Chondrichthyan and osteichthyan fauna from the middle Miocene deposits of Palasava, Kutch, India: implication for paleoenvironment and paleobiogeography

The Neogene of Kutch, India is well known for its rich marine and terrestrial vertebrate assemblages. However, the data of piscean fauna from the middle Miocene of India is very scarce. We report here additional chondrichthyan and osteichthyan remains from the middle Miocene deposit of Chhasra Formation, Palasava site, Kutch, Gujarat, India. The elasmobranchs include Carcharhinus Blainville, 1816 ( C. brevipinna (Müller & Henle, 1839), C. falciformis (Müller & Henle, 1839), C. cf. leucas , C. aff . perezi , Carcharhinus sp.), Negaprion Whitley, 1940 ( Negaprion sp.), Aetobatus Blainville, 1816 ( Aetobatus sp.), Myliobatis Cuvier, 1816 ( Myliobatis sp.), Dasyatis Rafinesque, 1810


INTRODUCTION
The Miocene deposits of Kutch, India is well known for its diverse fossil assemblages comprising of foraminifers, molluscs, chondrichthyan, teleostean, reptilian and mammalian remains (Wynne 1872;Lydekker 1876;Venkatappaya 1955; Sahni & Mishra 1975; Sahni & Mehrotra 1981;Bhandari et al. 2009Bhandari et al. , 2015Bhandari et al. , 2018;;Kulkarni et al. 2010;Patnaik et al. 2014;Kapur et al. 2019;Singh et al. 2019Singh et al. , 2020;;Sharma et al. 2021;and references therein).Recent, geological field work conducted in the middle Miocene (c. 14 ± 2 Ma, Kapur et al. 2019) deposits of Chhasra Formation at Palasava localities of Kutch, Gujarat, India have yielded teeth of elasmobranch, teeth, bones and spines of teleosts.The Palasava village of Kutch, Gujarat India is also known to report diverse mammalian taxa such as Sanitherium Meyer, 1865, Sivameryx Lydekker, 1878,   The sharks and batoids from the early and late Miocene marine sediments of India are very common (Sahni & Mehrotra 1981;Ralte et al. 2011;Tiwari & Ralte 2012;Sharma 2013;Sharma & Patnaik 2013, 2014;Sharma et al. 2021;and references therein).However, the record of chondrichthyan and osteichthyan faunas from the middle Miocene deposits of India and their systematic study is very meager and our understanding of their taxonomic diversity and faunal relationships is poor.The present paper documents certain chondrichthyan and osteichthyan fauna from the middle Miocene Palasava locality.The collected gnathostome remains and their associated faunas have been used here for paleoenvironmental and paleobiogeographic assessment.Faunal correlation of sharks and batoids from the middle Miocene deposits of western coast of India with some coeval deposits of America, Europe and Indo-Pacific region has also been reassessed.

GEOLOGICAL SETTING
The Kutch basin of Gujarat, India is well known for metazoan fossils ranging in age from the Mesozoic to Pleistocene ( Biswas 1992;and reference therein).Neogene deposits of Kutch are divisible into three formations: Khari Nadi, Chhasra and Sandhan formations (Biswas 1992).The Geological Survey of India (2012) classified the Neogene rocks of the Kutch as Khari Nadi Formation (Oligocene to lower Miocene age), Gaj Formation (lower Miocene to middle Miocene age) and Sandhan Formation (Pliocene age) (also see Fig. 1).The Gaj Formation is equivalent to the Chhasra Formation of Biswas (1992).Lithologically, the Khari Nadi Formation overlying the Maniyara Fort Formation (Oligocene) has a conformable contact with the younger Gaj/Chhasra Formation.The Khari Nadi Formation is dated as early 43 +/− 0.05 Ma, see, Gradstein et al. 2004) and has a weak erosional unconformity with the underlying Oligocene Maniyara Fort Formation (Catuneanu & Dave 2017;Sharma et al. 2021).The Gaj/Chhasra Formation comprises mainly of olive green shale, gypseous shale and claystone with alternations of thin argillaceous limestone beds and disconformable upper contact with the younger rocks of Sandhan Formation (?Miocene-Pliocene) (Biswas 1992) (also see Fig. 1B-E).The Chhasra Formation, named after the Chhasra village, was earlier dated as early Miocene (Burdigalian) by Biswas (1992).However, based on the mammalian assemblages at the Palasava site, it is reassigned to middle Miocene (Langhian-Serravallian; c. 14 ± 2 Ma) age for the ossiferous sedimentary succession (Kapur et al. 2019).The Sandhan Formation is comprised of clay with concretions, pelleted rock, siltstone, parallel to cross-laminated sandstone beds intermittent with conglomerate beds comprising of calcareous nodules, agate pebbles, very coarse sand and mudclasts.

MATERIAL AND METHODS
The specimens described here were collected in-situ from the field and were also recovered from the maceration of bulk samples of approximately 500 kg from Palasava fossil site (23°26'23.60"N,70°59'2.31"E)Rapar Taluka, District Kutch, Gujarat state in western India (Fig. 1).The Palasava fossil site is located around 6-7 km east of Palasava village, Taluka Rapar, District Kutch, Gujarat State, western India (Fig. 1A).The maceration technique follows Sharma et al. (2021).The dried macerated residues were sieved through mesh sizes ranging from 74 to 595 μm and were seen under Leica Stereozoom Microscope (ASPO 9) for picking the microvertebrate remains.The collected fossils were studied and photographed under a Leica M205C Stereozoom Trinocular Microscope housed at BIOPS Lab, Central University of Punjab, Bathinda.The tooth terminology of elasmobranch follows Cappetta (2012).The described specimens are deposited at the BIOPS Lab., Department of Geology, Central University of Punjab Bathinda-151401 (India) and Department of Geology, Panjab University, Chandigarh under the catalogue numbers: BIOPS/CUP/KP and PUKPS.
referred speCimens.-One isolated upper tooth under the specimen number PUKPS-784.
desCription Specimen PUKPS-782 is a small size tooth, crown is triangular in shape, distally inclined, both the mesial and distal cutting edges are finely serrated (Fig. 2A-C).The serration is slightly coarser towards the median portion of the cusp.The lingual face of the tooth is convex while the labial face is slightly flattened towards the apex, convex at the median portion and slightly concave towards the base of the crown.
The mesial edge of the cusp is distally inclined and the distal edge forms a nearly vertical notch to the heel.The crown of the tooth is curved lingually (Fig. 2C).The root is bilobate, wider than the height, with a prominent median groove that separates each lobe and the base of the root is nearly straight to slightly concave.

desCription
The specimens PUKPS-781, 782, 783, 785 and 786 are triangular in shape, crown broader at the base and narrowly pointed towards the apex.The mesial cuttings are straight to slightly convex and arched distally.The distal cutting edge is straight and nearly perpendicular to the basal margin (Fig. 2D-R).Both the mesial and distal cutting edges bear strong serrations which are slightly coarser towards the base and also separated from the coarsely serrated heels by a shallow angular notch (Fig. 2D-R).The lingual faces are convex while the labial faces are flattened, the crown base of the teeth are compressed labio-lingually (Fig. 2D, E, G, H, J, K, M-P).The basal margins of the teeth are curved upward at the lingual side and are nearly straight and horizontal at the labial side.The specimen PUKPS-786 shows a gap in serrations at the median portion of the mesial cutting edge (Fig. 2P-R).The serrations at the basal part of tooth of specimen PUKPS-785 are not clearly visible due to abrasion and worn out (Fig. 2M, N). desCription Specimen PUKPS-787 is a small tooth having a broad and triangular crown, cusp is erect and slant apically (Fig. 2S-U).
Tooth is partially worn out, but the serrations at both mesial and distal cutting edges are still visible.The serrations at both the cutting edges are coarser towards the heel.The mesial cutting edge is uneven or weakly sigmoid and extend towards the heel without showing any distinctive notch.The distal cutting edge is nearly straight to slightly concave, and separated from the heel by a shallow distal notch.The lingual face of the crown is convex while the labial face is flat (Fig. 2S).
The neck in between the crown base and the root is curved upward in the lingual view and nearly straight or slight curved in the labial view.The root is high, broad and bilobate, basal part of the root is arched upward (Fig. 2U).(Sahni & Mehrotra 1981).Carcharhinus leucas is considered a circum-tropical epipelagic shark which is well adapted to tropical waters, rivers, and coastal lakes below 30 m depths (Compagno 1984(Compagno , 1988;;Pimiento et al. 2013).
Carcharhinus perezii -Compagno, 1984: 492. referred  desCription Specimen PUKPS-795 is a lower tooth having narrowly erected, high, pointed and symmetrical crown.The specimen is worn out, root is broken and ill preserved.The cutting edges are ornamented with uniformly fine serrations and which are absent on the heel (Fig. 3A-C).The labial face is flat and the lingual face is convex (Fig. 3C).The crown of the tooth is lingually curved and again recurved labially towards the apex (Fig. 3C).Root is thin, its basal part is concave and a median nutritive groove divides the root into two lobes.The height of the crown is 6.72 mm, height of the root is 3.46 mm, width of the root is 8.3 mm and total height of the tooth is 10.18 mm.The specimen PUKPS-796 is of moderate size poorly preserved upper tooth, crown is erect and sub-triangular in shape.Both the mesial and distal cutting edges are coarsely serrated and the serrations continue up to the heel of the teeth.However, serrations are either very week or totally disappear toward the apex.Mesial cutting edge is sinuous, convex at the middle and recurved mesially towards the apex, and the distal cutting edge is convex (Fig. 3D-F).Labial face of the teeth is nearly flat and lingual face is curved (Fig. 3F).The crown height is 5.59 mm, and the total height of the tooth is 8.23 mm.
remArks Species level identification of lower teeth of Carcharhinus is very difficult and it is also a much debated subject (Kent 1994;Naylor & Marcus 1994;Purdy et al. 2001;Pimiento et al. 2013) desCription The specimens PUKPS-797-800 are small size teeth, crown is triangular in shape and broader towards the base.The labial faces of the teeth are flat and lingual faces are convex.The mesial cutting edges are slightly inclined distally with pointed apex.The cutting edges bear no serration and are smooth and extend onto the heels (Fig. 3G-R).The mesial edges are straight to slightly curved and the distal edges are straight.PUKPS-799 is having a nearly perpendicular distal cutting edge (Fig. 3M, N).The basal margins of the teeth are curved on the lingual side and nearly straight on the labial sides.Roots are low, bilobate, broad and have a slightly curved to nearly straight base, central foramen is present in the median portion of the root.The crown height of the teeth ranges from 4.1-5.05mm, root width from 7.48-8.04mm and the total height of the teeth from 7.5-8.41mm.desCription The specimen BIOPS/CUP/KP-35 is an incomplete tooth, medium sized and crown is rectangular to hexagonal in shape.The surface of the crown is flat and ornamented with shallow pitted tubercles (Fig. 3Y).The crown is low and slightly overhanging on the labial side, and the root is separated from the crown by a shallow trench running along the tooth length (Fig. 3Z).The lingual face of the crown presents a slightly oblique shelf.The root of the tooth is totally under the crown and it is also ornamented with small rectilinear furrows.(Sahni & Mehrotra 1981;Sharma 2013;Sharma & Patnaik 2013).Teeth of the genus Myliobatis and Rhinoptera closely resemble to each other and their precise identification is quite difficult (Gillette 1984).Teeth of Myliobatis are characterised by higher crown, more angular occlusal surface, and a thicker lingual cingulum (Laurito & Valerio 2008;Perez et al. 2017) and differ from those of Rhinoptera in having a significant interlocking design and asymmetrical feature and greater width/length ratio (also see Gillette 1984; Kocsis et al. 2018;Sharma et al. 2021).The presence of lingual shelf and less angular crown deemed fit to assign the present specimen under the genus Myliobatis.desCription Specimen BIOPS/CUP/KP-36 is a medium size tooth and strongly curved lingually.The crown is wider at the median portion of tooth.The surface of tooth crown is highly abraded and the root boundary is not distinct (Fig. 3BB).The labial face/side of the crown is ornamented with ridge and trench (Fig. 3CC).The root of the tooth is extremely extended lingually and is dorso-ventrally flattened.Specimen PUKPS-803 is strongly curved lingually and broken on the lateral side of teeth (Fig. 3DD, EE).In occlusal view, the crown surface is flat and crown is wider at the median portion of the tooth.The labial side of the crown is straight and the lingual side is nearly curved at the margin.The crown and the root of the tooth are separated by a trench running along the length of the tooth, root is extended lingually.Specimen PUKPS-804 differ from the tooth morphology of BIOPS/CUP/KP-36 and PUKPS-803.The crown surface of the tooth is curved and ornamented with small pits, the crown height is maximum in the median region of the file (Fig. 3FF-HH).The root is arched lingually and it consists of alternate grooves and laminae.The root is higher than the crown.A small ridge line runs in between the crown and root (Fig. 3GG) and on the labial side, the root penetrates the crown face (Fig. 3HH).teeth in the present specimens deem fit to assign it as Aetobatus.Earlier, Aetobatus sp. had been reported from the early Miocene Khari Nadi Formation of Kutch, (Sahni & Mishra 1975;Sharma et al. 2021); Miocene of Bhuban Formation of Mizoram (Tiwari & Ralte 2012) and late Miocene of Baripada Beds (Ghosh 1959;Mondal et al. 2009;Sharma & Patnaik 2013).Teeth of the Aetobatus are also known from the early Miocene France (Goedert et al. 2017), Switzerland (Jost et al. 2016) desCription Specimen PUKPS-804 is a small tooth having a high, symmetrical and angular crown margin and is wider than long in occlusal view.The lateral portion of the specimen PUKPS-804 is broken (Fig. 3II-KK), the lingual and labial faces are slant.The labial and lingual faces of the tooth are ornamented with wrinkles.The crown of the tooth is slightly overhanging towards the labial side and it is also separated from the root by a shallow trench (Fig. 3JJ).The specimen is having nine root lobes and each lobe is separated by an alternating groove (Fig. 3KK).BIOPS/CUP/KP-37 is a small tooth, crown is low, hexagonal in shape, slightly asymmetric in occlusal view, and the root is slightly extended lingually (Fig. 3LL-NN).The crown surface is flat with reticulated ornamentation.The lingual face of the crown has a slightly oblique shelf (Fig. 3KK).The labial face of the crown is overhanging the root (Fig. 3NN) and crown is slightly thicker on the mesial side compared to the distal sides (Fig. 3NN).On the lingual side, the crown and root boundary is separated by a ridge running along the entire length of the tooth.The root is as high as the crown and shows a polyaulacorhizid vascularisation type represented by eleven parallel laminae separated by deep nutritive grooves in basal view (Fig. 3NN).

remArks
The present specimen PUKPS-804 is comparable with Rhinoptera sherborni White, 1926 in having width, asymmetrical, hexagonal shape crown in occlusal view, presence of prominent ridge separating the crown and root at lingual side of the tooth.However, it differs from the later in having a thinner crown, and a highly inclined labial face of the crown.BIOPS/CUP/ KP-37 is differentiable from Rhinoptera studeri and Rhinoptera raeburni in having thinner and asymmetric crown.The incomplete preservation and scarcity of the specimens makes it difficult for a precise identification up to the species level and hence been assigned here as Rhinoptera sp.Dasyatis rugosa (Probst, 1877) (Fig. 4A-C) desCription Specimen BIOPS/CUP/KP-38 is a small size tooth, a broad and prominent transverse crest divides the crown into lingual and labial faces (Fig. 4A-C).The labial and lingual visors are semi-circular to sub-angular in shape.The labial face of the crown presents wrinkles like reticulated ornamentations and a prominent narrow and extended labial median hollow.The labial visor is smooth in basal views and labial part of the root is depressed (Fig. 4C).The lingual face of the crown is flat to slightly concave and a median lingual ridge is weakly developed.The root is bilobate, robust, lingually projected, each lobe separated by a wide furrow (Fig. 4C).The basal face of the root is flat and triangular in shape.desCription Specimen BIOPS/CUP/KP-39 is a small size female tooth, crown is higher than root, globular to rhombic in shape, fairly angular (Fig. 4D-F).The median transverse crest is prominently broad and high which lowers quickly towards the latero-posterior side.The labial face of the crown possesses a crescent shape median labial hollow depression (Fig. 4E) ornamented with irregular reticulations of ridge and furrow (Fig. 3E).BIOPS/ CUP/KP-40 represents a male tooth (Fig. 4G-I).The transverse crest is high, pointed lingually, smooth, forms a broad V-shape, the marginal angle of the crown is sharp and angular.The labial visor is smooth, angular in shape in basal view and meets the lingual visor at a marginal angle.Order MYLIOBATIFORMES Compagno, 1973 Family dAsyAtidAe Jordan, 1888 Genus Himantura Müller & Henle, 1837 Himantura menoni Sahni & Mehrotra, 1981 (Fig. 4J-R) Himantura menoni Sahni & Mehrotra, 1981: 83, pl desCription Specimens BIOPS/CUP/KP-41, 42, 43 are small teeth and high crowned rhombic in shape in occlusal view (Fig. 4J-R).
The crown of the tooth is divided into labial and lingual zones by the presence of a prominent transverse crest.The labial face of the crown is convex, shallow, a median hollow is present, crown enameloid is ornamented with wrinkles (Fig. 4K, L, Q).The lingual face of the crown is concave and a prominent median lingual ridge is present.However, the labial faces of the crowns are ornamented by irregular pits and wrinkles (Fig. 4J, K, M, N, P, Q).The labial visors are wide and nearly semi-circular to subangular in outline, and the lingual visors are narrow and angular.Median lingual ridge separates the lingual faces into two equal parts which are smooth and concave.The roots of the teeth are strong, lingually arched, bilobate and each root lobe is separated by a deep median groove (Fig. 4J, L, M, O, P, R).Labial part of the root is depressed, while the basal face of the root is nearly flat and triangular in shape.
remArks in the labial face of the crown (Fig. 4LL-OO).Labial faces of the crowns present a deep depression along the transverse crest, and reticulated folded ornamentation of enameloid is present at the labial margin (Fig. 4LL, OO).The lingual face of the crown is slightly concave, and median lingual ridge is absent (Fig. 4KK, NN).Root is small, bilobate and a wide and deep groove is present in between the two lobes, that is lingually projected.The basal face of the root is flat and triangular in shape.

remArks
The present record is the first report of fossil remains of Taeniurops from Miocene deposits of India.desCription The specimens BIOPS/CUP/KP-52, 53 are poorly preserved, small sized teeth having high crown, rhombic to asymmetric, reticular shape (Fig. 4QQ-VV).The labial faces of the crown are ornamented with small pits in occlusal views (Fig. 4RR, UU).The thick labial and lingual visor are ornamented with irregular ridge and furrows running nearly vertical (Fig. 4QQ-VV).The face is curved and absence of median lingual ridges.Root of the tooth is small, weak, divided by a shallow nutritive groove (Fig. 4TT).desCription The teeth are classified into four morphotypes based on morphological variations.
Morphotype 1 (Fig. 5A, B) BIOPS/CUP/KP-54 is globular in shape, elongated and distally curved towards the apical crown.In lateral view, the tooth is terminated distally with blunt and short hook.In occlusal view, the masticatory area is depressed and bounded by two small lateral cusps (Fig. 5B).The central part of the masticatory area is uneven and ornamented with a shallow crest and furrow.
Morphotype 2 (Fig. 5D, E) BIOPS/CUP/KP-55 is partially broken.The tooth terminates distally in a blunt well-marked hook.The masticatory area is bounded by well-developed crests on either side and is ornamented with another row of crests in the central part.
Morphotype 3 (Fig. 5E, F) BIOPS/CUP/KP-56 is anteroposterioly compressed, trapezoidal in shape and elongated.In occlusal view, the crown surface is oval in outline.In lateral view, the crown is slightly curved.The masticatory surface is strongly oblique to the longitudinal axis of the crown.
Morphotype 4 (Fig. 5G-J) BIOPS/CUP/K-57 and 58 are short, cylindrical in shape and have a circular crown.The grinding surface of the teeth is fully exposed with slightly depressed medially on the crown surface.The lateral margin of teeth is slightly constricted at the median portion of teeth.desCription Specimen BIOPS/CUP/KP-59 (Fig. 5K, L) is a medium size tooth, tricuspidate, subcylindrical in shape, and labiolingually compressed.At the crown, the three cusps are aligned and the middle one is more elongated and prominent.In the basal section, the teeth present a central pulp cavity.

remArks
The present specimen resembles characids reported from the late Miocene of Baripada.Bed, Orissa (Sharma & Patnaik 2013) and the Lower Oligocene and Miocene of the Arabian Plate (Otero 2001) by having tricuspidate cusps, subcylindrical in shape, labio-lingually compressed, and the middle cusp is more elongated than the two lateral cusps.However, the limited fossils do not allow more precise taxonomic allocation.
LoCAtion And horizon.-Middle Miocene greyish coarse sandstone gravelly lag bed of Chhasra Formation at Palasava site, Kutch, Gujarat.
desCription Specimens BIOPS/CUP/KP-60, 61, (Fig. 5M-Q) represent pectoral spines which are highly damaged and preserve only the proximal part with three articular processes (dorsal, ventral and axial processes).The dorsal process (or condyle) is semi-circular in shape with fine striations developed on their surface.The ventral process is greatly reduced and located opposite to the dorsal process.The axial process is also reduced and slightly pointed.Serrations and denticles are absent on the lateral margins.Specimen BIOPS/CUP/KP-62, 63, 64 (Fig. 5R-W) are the dorsal spines, characterised by a well preserved articular head, a medium to moderately large rounded articular foramen, and slightly curved and compressed.A wide groove is developed which is continuous throughout the length of the spine.Serrations or denticles are absent on the lateral margins of all the spines.remArks BIOPS-60 and 61 differ from the clariid by having an axial process.Gayet (1987) described that clariid spines do not exhibit any form of axial process and the condyle represents only a quarter of circle.The pictoral spines of ariid are also devoid of any surface ornamentation (Hora 1939;Singh et al. 2019), whereas the condyle surfaces of the present specimens are marked by the striations.BIOPS-60 and 61 are attributed to the pectoral spine of bagrid by the presence of striations on condyle, the presence of three articular processes and the absence of serrations or denticles on the shafts (Sahni & Khare 1977;Gayet 1987;Otero & Gayet 2001;Singh et al. 2019).BIOPS-62, 63 and 64 are closely similar to bagrid dorsal spines (Gayet 1987;Parmar & Prasad 2012;Singh et al. 2019), having a well preserved articular head, a medium to moderately large rounded articular foramen, slightly curved and compressed and devoid of serrations or denticles on the desCription The present spines are broken off and no distal and proximal parts are preserved.They are dorso-ventrally convex, and are ornamented with striations on both sides.The posterior denticles are prominent with well-developed, whereas the anterior denticles are absent (Fig. 5X-AA).The denticles are conical in shape and are closely spaced.The shafts are wider towards the proximal end and narrower towards the distal end.desCription The present teeth are pointed, conical in shape, bulging towards the base.Most of the teeth surfaces are ornamented with weak wrinkle and longitudinal serration (Fig. 5DD-GG), whereas some have smooth surfaces (Fig. 5BB, CC, HH, II).
The tooth referred to BIOPS-70 is large and straight, whereas BIOPS-67, 68 and 69 are small and apically curved.

DISCUSSION fAunAL Composition And pALeoenvironment
The middle Miocene Palasava section of Kutch, India has yielded a diverse faunal assemblage comprising of elasmobranchs, teleosts, chelonians, crocodiles, snakes, birds and mammals (Kapur et al. 2019) (also see Fig. 6).The mammalian fauna (11 families, nine genera and nine species) is the most diverse, followed by the batoids (three families, eight genera and ten species) and teleosts (three families, genera and species unidentified), crocodiles (two families, two genera and two species), turtles (two families, three genera and species unidentified), birds (two families, genera and species unidentified), sharks (one family, two genera and seven species), snake (one family, one genus and one species) (also see Fig. 6A, B).The fish fauna (sharks, batoids and teleosts) of Chhasra Formation with a total of seven families, ten genera and 17 species is quite diverse (also see Fig. 6A,  B).  (Pimiento et al. 2013;Carrillo-Briceño et al. 2016b).Carcharhinus leucas is also considered to be adapted to freshwater conditions (Compagno 1984;Cook et al. 2010).Carcharhinus brevipinna is mainly found in warm temperate to tropical areas in the Atlantic, Mediterranean and Indo West Pacific (Compagno 1984;Reiner 1996;Burgess 2009;Perez et al. 2017) et al. 2014).Negaprionodon sharks mainly inhabit estuarine and intertidal through offshore waters at depths of 92 m in the Atlantic and the Pacific Ocean (Compagno 1984;Kent 1994).Among the Negaprion, N. brevirostris frequently inhabit mangrove environments and coral reefs, but occasionally can be found in the open ocean near surface waters for migration purposes and occur in tropical and temperate, estuarine and marine waters generally at depths of 0-92 m (Compagno 1984;Kent 1994;Compagno et al. 2005).Negaprion is commonly adapted to warm waters (Cappetta 1987) and mainly feeds on actinopterygians, small shark, squid and octopus, etc. (Compagno 1984).Among the batoids, Myliobatis and Taeniurop are known to inhabit brackish and marine open sea environments (Compagno 1984;Carrillo-Briceño et al. 2016b).Aetobatus, Dasyatis, Himantura, Pastinachus and Pristis are mostly found in shallow shelves, shallow estuaries, lagoons and fresh water (Compagno 1984 The osteichthyans of Palasava comprising of Cyprinidae, Bagridae, Characidae and Channidae are commonly found in freshwater river and brackish water conditions (Nelson 2006).The present ecology of these extant taxa shows that they live in freshwater and brackish water conditions throughout Africa and Asia (also see Roberts 1975;Mo 1991).Among the extant freshwater teleosts, cyprinids including carps, barbs and loaches are the most common and occur essentially in lakes and rivers (McClelland 1839;Daniels 2000).Bagrids dwell in diverse habitats such as upland streams, large river channels and seasonal floodplain lagoons (Winemiller 1996).Channids inhabit a variety of freshwater conditions ranging from lakes, ponds, rice paddies, swamps, and peat swamp forests, to large rivers, creeks, and hill streams (Rüber et al. 2020).Records of elasmobranch, teleosts, and various mammalians, reptiles and birds (Fig. 6A) (Kapur et al. 2019) suggest a warm and humid, tropical to sub-tropical environmental condition in the middle Miocene (c. 14 ± 2 Ma).The teleosts described above are found mostly in freshwater and sometimes in brackish water (Nelson 2006).The present piscean fauna associated with other marine and terrestrial vertebrate remains from this section suggest a coastal, marginal marine, near shore littoral to neritic environment of deposition with the influence of freshwater riverine system.have allowed the migration of sharks from eastern Pacific to Indo-Pacific Ocean through the Mediterranean sea (Fig. 6B).
The present elasmobranch assemblage from the middle Miocene deposits of the western coast of India still shows a good similarity index with their counterparts of Mediterranean Sea namely, France (33%), Portugal (27%), Spain (19%) and Hungary (40%).As compared to the similarity data of early Miocene fauna, the middle Miocene data shows a slight decline in the similarity index.However, this similarity may be attributed either to the diversification of Indian fauna from the remnant water of the Tethys Sea (also see Sahni & Mehrotra 1981;Mondal et al. 2009;Sharma & Patnaik 2014) or intermittent migrations of a marine fauna between Mediterranean and Indian Ocean during some short-term reopening of the Tethyan Seaway around 15-14 Ma (Harzhauser et al. 2007; and references therein), before a permanent closure of the seaway took place.Such a permanent land bridge would have permitted the migration and diversification of terrestrial fauna across Africa and Eurasia (also see Rögl 1999;Harzhauser et al. 2007;Patnaik 2016;Kapur et al. 2019).However, a higher faunal affinity has been observed with Eastern Pacific-Panama (50%); Indo-Pacific-Japan (41%), South Korea (24%) and Caribbean Sea-Lesser Antilles (24%), Eastern Atlantic-Poland (43%) (also see Gillette 1984;Karasawa 1989;Portell et al. 2008;Yun 2020) (Table 1; Fig. 7).A closer faunal similarity of middle Miocene Palasava fishes with those from Japan, South Korea, Lesser Antilles and Panama (also see Gillette 1984;Karasawa 1989;Portell et al. 2008;Yun 2020) might point towards a gradual shift in migration path through the Pacific Ocean to Indo-Pacific region (Fig. 7).Such a shift coincides with the Neogene worldwide invasion of large Carcharhinidae through other possible gateways of open Panama isthmus and/or South African strait which would have promoted the diversification of Indo-Pacific marine groups (Briggs 1999;Adnet et al. 2007).
The teleosts belonging to Cyprinidae, Bagridae, Clariidae and Channidae inhabited both Africa and Asia in the Miocene (Nelson 1994(Nelson , 2006;;Singh et al. 2019).The dispersal history of different taxa of teleost families between Eurasia and Afro-Arabia is linked to the connection and separation of landmasses (Patterson 1993;Doadrio 1994;Nelson 2006).The extant cyprinids represent the most diverse family of bony fishes in Eurasia and Africa (Nelson 2006), and fossil cyprinids have also been reported from Asia (Li et al. 1983;Tiwari et al. 1991;Lee 2004;Chang & Chen 2008;Parmar & Prasad 2012;Sharma et al. 2015;Singh et al. 2019), Europe (Gaudant & Rousset 1979;Cavender 1991;Gaudant et al. 2002) and Afro-Arabic Plate (Otero 2001).However, the family is widely considered to have originated in China (Briggs 1999;Gaudant et al. 2002).Their dispersal can be correlated with the first Tertiary land connection between the Afro-Arabia and Asia ( Rögl & Steininger 1983;Adams et al. 1983;Thomas 1985).Miocene bagrids and clariids have also been reported from many localities of Asia, Europe, Afro-Arabia (also see James & Slaughter 1974;Thomas 1981;Frostick & Reid 1986;Stewart 2001;Otero & Gayet 2001;Parmar & Prasad 2012;Argyriou et al. 2015;Singh et al. 2019).Although they are since the Palaeogene times in both Asia and Afro-Arabia, their dispersal history could not be resolved as there was no terrestrial connection between the two continents before (Otero & Gayet 2001).The snakehead (channids) fishes were restricted to tropical south Himalayan regions such as Baluchistan, Pakistan, India and Nepal (Böhme 2004) during the early Miocene.After this, they expanded rapidly into subtropical Western Eurasia and have been recorded from many localities of Western Eurasia during 17.5-13 Ma (Böhme & Ilg 2003;Böhme 2004).But, these fishes were absent in the southern parts of Western Eurasia (Mediterranean region, Eastern Europe and Arabia), Eastern Eurasia (Mongolia, China and Japan), and Africa during 17.5-13 Ma.At the beginning of late middle Miocene, they disappeared from Western Eurasia and were restricted to central and south Asia approximately between 13-8 Ma (Böhme 2004).However, a species level identification of the assemblage is required to evaluate any fresh-water connection between Afro-Arabia and Southwestern Asia during the Miocene.The ichthyofauna described above and other associated marine and terrestrial vertebrate remains from middle Miocene (c. 14 ± 2 Ma) suggest a coastal, marginal marine, near shore littoral to neritic environment of deposition with the influence of freshwater riverine system.The integration of the flora and fauna from Palasava points towards the presence of a warm, humid/wet, tropical to sub-tropical environmental conditions during the middle Miocene.
The elasmobranchs described above show a good similarity index with their counterparts in the Mediterranean Sea suggesting a short-term reopening of the marine pathway during Langhian.However, a much higher faunal affinity with those of Eastern Pacific indicates a gradual shift towards migration between Pacific Ocean and Indo-Pacific region once a permanent landbridge was established.
fig. 1. -A, Map of India showing the study locality (represented by rectangular box); B, geological map of Kutch (GSI, 2012); C, stratigraphic column of the Palasava locality (after Kapur et al. 2019); D-F, field photograph of middle Miocene Chhasra Formation as exposed at the Palasava section.

remArks
The teeth of the genus Aetobatus are distinguished from those of Rhinoptera in having lower crown, oblique root lobe which are extremely extended from the crown (Sharma & Patnaik  2013; Sharma et al. 2021; and references therein).Strongly curved and extreme extension of root at the lingual side ofSingh N. A. et al.
remArks BIOPS/CUP/KP-65 and 66 differed from the pectoral spines of ariid, e.g.Arius Valenciennes, 1840 from Baripada Beds of Miocene(Hora 1939) and Arius sahni Khare, 1976 from middle Eocene Subathu Formation of Beragua Coal Mine, Jammu and Kashmir (Khare 1976) by having denticles on posterior margin.A bagrid spine reported byGayet (1987) from the lower-middle Eocene Kuldana Formation, Pakistan (Gayet 1987) also differs from BIOPS/CUP/KP-65 and 66 in having both anterior and posterior dentitions.The present specimens compare well to those of clariid such as Clarias batrachus (Linnaeus, 1758) and C. falconeri Lydekker, 1886(Sahni & Khare 1977)  reported from the Middle Siwalik deposits of Ladhyani and Lehri-Sarail, Himachal Pradesh on account of having denticles on the shaft and the presence of longitudinal striations on both dorsal and ventral surfaces.However, C. batrachus and C. falconeri are characterised by their minute denticles on the anterior margin, whereas the denticles on the shaft of BIOPS/CUP/KP-65 and 66 are present only on the posterior margin.Because of all these differences and lack of diagnostic features, it is difficult to assign these spines to any family.Order PERCIFORMES Bleeker, 1859 Family ChAnnidAe Fowler, 1934 Channidae indet.(Fig. 5BB-II) referred speCimens.-Several teeth under the specimen numbers BIOPS/CUP/KP-67, 68, 69, 70.LoCAtion And horizon.-Middle Miocene greyish coarse sandstone gravelly lag bed of Chhasra Formation at Palasava site, Kutch, Gujarat.
The crown-root boundary is convex.The crown height of the tooth is 2.45 mm, width of the root is 6.76 mm and the total height of the tooth is 4.44 mm.
(Sahni & Mehrotra 1981)evipinna (Müller & Henle, 1839) is distinguished from other Carcharhinus taxa in having a short cusp with a lingually curved crown (Perez et al. 2017).The upper teeth of C. brevipinna are closely similar to C. limbatus, however it differs in having a shorter cusp, asymmetric crown and finer serration at teeth shoulder (Perez et al. 2017).The upper teeth of C. limbatus are differentiable from C. brevipinna in having coarser serrations at the heels especially at the distal heel (see, Perez et al. 2017).The differentiation of the present specimen into upper or lower tooth is very difficult.However, we prefer to describe it as upper tooth of C. brevipinna, which is often slightly broader (also see Perez et al. 2017).The present specimen resembles to those of C. brevipinna reported from the late Miocene of Lago Bayano, Panama (Perez et al. 2017) in having a shorter and more asymmetric crown, lingually curved towards the apex and extended root.Previously, dermal denticle of C. brevipinna had been reported from the late Miocene deposit of Baripada beds as C. maculipinnis(Sahni & Mehrotra 1981).This is the first report of C. brevipinna from the Miocene sediments of Kutch, India.Carcharias (Prionodon) falciformis Bibron in Müller & Henle, 1841: 47.Carcharhinus falciformis -Purdy et al., 2001: 151, fig.53b-f.
The roots are bilobate, slightly thicker at the lingual side, base of the lobes are nearly curved to straight and each lobe is divided by a shallow nutritive groove.The crown height ranges from 5.76-4.03mm,width of the root is 12.29-6.7 mm and the total height of the tooth is 9.85-6.87mm.LoCALity And horizon.-Middle Miocene (Langhian age) greyish coarse sandstone gravelly lag bed of Chhasra Formation at Palasava site, Kutch, Gujarat.
(Sahni & Mehrotra 1981)erez et al. 2017;Perez et al. 2017)rhinus taxa in having a gap in serrations between the apex and the base of teeth on the mesial cutting edge, the straightness of the mesial cutting edge and narrowed crown with a notch on both cutting edges(Purdy et al. 2001; Marsili et al. 2007;Perez et al. 2017).However, extant species of C. falciformis can have variable morphology including the absence of serration gap and more distally inclined crown(Purdy et al.  2001).The absence of noticeable serration gap at mesial cutting edges of the present specimens corresponds to upper lateral teeth (also see Purdy 1990).Teeth of C. falciformis are comparable with those of Carcharhinus amboinensis (Müller & Henle, 1839)(Bass et al. 1973;Naylor & Marcus 1994; Koscic et al. 2018)in having broader crown base, angular, distally placed notch, perpendicular distal cutting edges, and horizontal root base but it differs from the later in the presence of a shallow notch on the mesial cutting edge.Carcharhinus falciformis has been reported from the early Miocene ofMalta, Venezuela (Ward & Bonavia 2001;  Carrillo-Briceño et al. 2016b) and late Miocene of Borneo, Panama(Pimiento et al. 2013;Perez et al. 2017; Koscic et al.  2018).Earlier, C. falciformis was reported from late Miocene Baripada Beds of Orissa, late Miocene Piram Beds and (?) middle Miocene deposits of Gogha coast of Kathiawar(Sahni & Mehrotra 1981).The present specimens are the first report of C. falciformis from the Miocene sediments of Kutch, India.Genus Carcharhinus Agassiz, 1843Carcharhinus cf.leucasMüller & Henle, 1839(Fig.2S-U)Carcharhinus leucas Müller & Henle, 1839: 42.Chondrichthyan and osteichthyan fauna COMPTES RENDUS PALEVOL • 2022 • 21 (43) referred speCimen.-One isolated upper tooth, specimen number PUKPS-787.
The height of the crown is 6.35 mm, width of the root is 13.26 mm and the total height of the tooth is 11 mm.
The serrations at both edges are coarser toward the base of the crown.The distal cutting edge is separated from the coarsely serrated heel by a shallow distal notch, whereas the coarsely serrated mesial cutting edge extends up to the mesial heel without having any notch.The root is thin, bilobate, median nutritive groove is present; the root is as wide as the heel of the crown and the basal part of the root is straight.
remArksThe present specimen is ill preserved, partially worn out and broken at the apex and hence proper identification up to species level is difficult.The present specimen is different from C. pricus (Schultz 1977; Karasawa 1989; Szabó & Kocsis 2016) and C. egertoni (Sharma & Patnaik 2014) in having broad crown and thicker root.Teeth of the genus Carcharhinus have earlier been reported from lower Miocene of Kutch (Patnaik et al. 2014), and middle Miocene of Kutch (Kapur et al. 2019), late Miocene of Baripada Beds (Sharma & Patnaik 2014; Sharma et al. 2021), late Miocene of Kutch (Bhandhari et al. 2015), Miocene deposit of Bhuban Formation, Mizoram (Ralte et al. 2011).referred speCimens.-One isolated anterior lower tooth under the specimen number PUKPS-795 and one upper tooth under the specimen number PUKPS-796.LoCALity And horizon.-Middle Miocene (Langhian age) greyish coarse sandstone gravelly lag bed of Chhasra Formation at Palasava site, Kutch, Gujarat.
(Sahni & Mehrotra 1981;Mondal et al. 2009;;brevirostris and N. Eurybathrodon were reported from the late Miocene of Baripada Beds in the eastern coast of India (Sharma & Patnaik 2014) and from the lower Miocene Bhuban Formation ofMizoram (Ralte et al. 2011).This is the first record of Negaprion sharks from the middle Miocene of Kutch.Extinct species Bhuban Formation,Mizoram (Ralte et al. 2011)in having a broad and triangular shape crown in PUKPS-801, however the absence of serration at the cutting edges of tooth and poor nature of preservation makes it difficult to diagnose them as belonging to Carcharodon.Certain sharks of the family Carcharhinidae have been earlier reported from the Miocene deposits of India including the Kutch and Saurashtra, Gujarat in the western coast of India(Sahni & Mehrotra 1981;Patnaik et al. 2014; Sharma et al. 2021), Baripada Beds, Odisha in the Eastern Coast of India(Sahni & Mehrotra 1981;Mondal et al. 2009; Sharma & Patnaik 2014; andreferences therein) and Bhuban Formation, Mizoram (Ralte et al. 2011).speCimens.-Isolated teeth BIOPS/CUP/KP-35.LoCAtion And horizon.-Middle Miocene greyish coarse sandstone gravelly lag bed of Chhasra Formation at Palasava site, Kutch, Gujarat.
(Cappetta 1987;rybathrodon(Cappetta 1987; Purdy et al.  2001) is considered to be analogous with the extant species Negaprion brevirostris(Pimiento et al. 2013)based on similarity of the teeth morphotypes.The present specimens are differentiable from Negaprion brevirostris in having broader and shorter crown instead of tall and narrow crown in the later.Teeth of the genus Sphyrna having a deep distal notch are also easily distinguishable from the present specimen.Negaprion sharks are also reported from the late Miocene of Lago Bayano Panama (Perez et al. 2017 as N. brevirostris), early Neogene of Western Venezuela (Carrillo-Briceño et al. 2016b as N. eurybathrodon).referred speCimens.-Two isolated upper teeth under the specimen numbers PUKPS-801, 802.LoCALity And horizon.-Middle Miocene (Langhian age) greyish coarse sandstone gravelly lag bed of Chhasra Formation at Palasava site, Kutch, Gujarat.remArks The present specimens are incomplete and highly worn out and difficult for proper taxonomic allocation.The specimens are comparable to Carcharodon taxa reported from the Miocene, COMPTES RENDUS PALEVOL • 2022 • 21 (43) referred
Kocsis et al. 2018; they are devoid of pointed transverse crest that bend towards the rear side (also seeKocsis et al. 2018; Sharma et al. 2021).Teeth of the genus Himantura were earlier reported from middle to late Eocene of Egypt (Underwood et al. 2011), Morocco and Pakistan (Case & Earlier teeth of the genus Pastinachus have been reported from Tapar sites of the late Miocene deposits of Kutch, India (Sharma et al. 2021).The present report is the first record of Pastinachus from the middle Miocene deposits of India.The lateral teeth of the Pastinachus are characterised by their thick, large robust size, rhombic to hexagonal shape, and presence of a salient bulge on the labial face of the crown (Herman et al. (Andrianavalona et al. 2015) been reported from the late Miocene Tapar locality of Kutch, India(Sharma et al. 2021), late Miocene of Baripada Beds of eastern India as Dasyatis menoni(Sahni & Mehrotra 1981; Sharma & Patnaik  2013)which was later re-assigned to the genus Himantura(Andrianavalona et al. 2015).The present teeth resemble COMPTES RENDUS PALEVOL • 2022 • 21 (43) referred speCimens.-Two isolated upper lateral teeth under the specimen numbers BIOPS/CUP/KP-44, 45, and upper symphysial teeth under the specimen numbers BIOPS/CUP/KP-46, 47, 48, 49.grooves.The basal face of the root is flat and sub triangular to semicircular in shape.In specimens BIOPS/CUP/KP-48 and 49, the roots are small, elongated and lingually arched, bilobate and the diverging lobes are separated by wide and deep grooves (Fig. 4EE, HH).(Sahni & Mehrotra 1981; Sharma & Patnaik 2013; Sharma et al. 2021) to Pastinachus kebarensis (also see Adnet et al. 2019; Sharma et al. 2021).Previously, teeth of Pastinachus were reported from the early Miocene of Libya (Argyriou et al. 2015), the Neogene of Taiwan as Dasyatis sp. by Uyeno (1978) (also see Cappetta & Cavallo 2006; Cappetta 2012), from the Miocene deposits of Borneo (Kocsis et al. 2018).Earlier Pastinachus sp. has also been reported from the late Miocene of Baripada Beds in the eastern coast of India as Dasyatis sylvestris (also see Sahni & Mehrotra 1981; Sharma & Patnaik 2013).Fossils of Pastinachus sp. have been described from shallow marine fossil-bearing deposits of Djebel el Kébar (Merzeraud et al. 2016).The species of Pastinachus aquitinicus has been reported from France, Lisbon Province, Portugal and Alachua County, Florida, United States (also see Leriche 1942; Zbyszewski 1949; Cahuzac et al. 2007; Gagnaison 2017).teeth, crowns are broad, high and acute (Fig. 4KK-PP).The crown is divided into lingual and labial parts by a sharp transverse crest.The labial and lingual visors of the crown join at sharp marginal angles; labial margins are less arched than the lingual margins.An elongated transverse hollow is present Singh N. A. et al.
(Villafaña et al. 2020)Villafaña et al. 2020)ransversal edge and an occlusal face that is quite concave(Cappetta & Gayet 2013;Villafaña et al. 2020).It is also separable from the teeth of Dasyatis in having distinct depression in the labial visor which is bordered by a sharp crest(Cappetta & Gayet 2013;Villafaña et al. 2020).The present specimens represent female teeth as they lack the male diagnostic characters of having highly pointed crown.Besides, this male teeth have strong cuspidate and lingually oriented cusps(Villafaña et al. 2020).
(Otero et al. 20091822)reported from the LaSingh et al. 2019)ary Lukundol Formation of Nepal(West et al. 1988)and to Barbus sp. reported from the Oligocene-Miocene of Switzerland and France(Gaudant et al. 2002).Because of sharing similar features with different genera of cyprinid, the allocation of this specimen to a particular genus is impossible.BIOPS/CUP/KP-55 also has welldeveloped crest on the tooth edge and the presence of another row of crest on masticatory area attributes to the pharyngeal teeth of cyprinid(Tiwari et al. 1991; Parmar &  Prasad 2012;Singh et al. 2019).BIOPS 56 compares well to Labeo by having a laterally flattened crown, oblique occlusal surface and slightly enlarged crown teeth distally(Otero et al. 2009) but differs on account of having an anteroposteriorly narrow crown.However, the present specimen can be assigned to cyprinid without doubt based on its trapezoidal shape, anteroposteriorly narrower, laterally flattened and broader occlusal surface(Tiwari et al. 1991; Kotlia & Mathur (1997)are closely similar to the channid reported from the Upper Siwalik deposits of SuraiKhola,  Nepal (Kotlia & Mathur 1997)and lower Siwalik beds of Jammu (Parmar & Prasad 2012) by having conical shape, pointed apical part, thin enameloid layer and striations on the crown as well as at the base.BIOPS-67, 68 and 69 also compare well to recent Channa Scopoli, 1777 such as C. stratus Day, 1878 (synonym of Ophicephalus striatus Day, 1878) and C. mullius F. Hamilton, 1822 described byKotlia & Mathur (1997)on account of having curved apex and base with wrinkles and striations, but the recent Channa sp. is characterised by being anteriorly narrower and posteriorly broader, unlike the present specimens.Because of sharing of the above mentioned tooth morphological features except for being anteriorly narrow and posteriorly broad, the present specimens are attributed here to Channidae.
Singh N. A. et al.
(Compagno 1984;traube 2019;Villafaña et al. 2020) by the families Carcharhinidae, Myliobatidae, Dasyatidae and Pristidae.The shark assemblage is dominated by the genus Carcharhinus, comprising C. brevipinna, C. falciformes and C. leucas which are mostly circum-tropical in distribution, except for C. perezi which is mainly restricted to the Caribbean Sea (also seeCompagno 1984;Pollerspöck & Straube 2019;Villafaña et al. 2020).Carcharhinus sharks are considered to be adapted to a wide range of habitats ranging from inshore to offshore environment, from tropical, subtropical to temperate climate(Compagno 1984; Cappetta 2012; Sharma et al.
(Underwood et al. 2011)erwood et al. 2011)uch as Himantura or Pastinachus, have also been reported from estuaries and fresh water(Kocsis et al. 2018).The record of Pastinachus associated with certain mammal bones from Tunisia is considered to have been deposited in a forestland (Dartevelle & Casier 1943; Adnet et al. 2010; Murray et al.  2010), close to coastal environment from the early late Eocene of Egypt (Murray et al. 2010), shallow marine inshore(Adnet  et al. 2010;Underwood et al. 2011), shallow and macrotidal environments between dune or channel bar sets(Underwood et al. 2011).Pastinachus is considered as amphidromous, resting on shallow-water inshore sandflats and frequently venturing far into estuaries and freshwaters (Adnet et al.

table 1 .
-Faunal similarity (Dice' similarity) of early and middle Miocene elasmobranch of Kutch, India and other early and middle Miocene deposits of Mediterranean and Indo-Pacific regions.The data of early Miocene elasmobranch of Kutch, India are from Sharma et al. (2021) and references therein.Middle Miocene faunal similarity between the Kutch fauna and other middle Miocene deposit of Mediterranean and Indo-Pacific regions COMPTES RENDUS PALEVOL• 2022 • 21 (43)