Pala¨ontol Z DOI 10.1007/s12542-013-0206-0 RESEARCH PAPER Shark faunas from the Late Jurassic—Early Cretaceous of northeastern Thailand Gilles Cuny • Romain Liard • Uthumporn Deesri • Tida Liard • Suchada Khamha • Varavudh Suteethorn Received: 13 August 2012 / Accepted: 9 January 2013 Ó The Author(s) 2013. This article is published with open access at Springerlink.com Abstract A revision of the freshwater shark fauna from this is the oldest occurrence of the genus Heteroptychodus, the Phu Kradung Formation in NE Thailand allows the and suggests a Thai origin for this genus, which may have recognition of a new species of Acrodus, which represents replaced Acrodus in the Thai freshwater palaeoecosystems. the youngest occurrence of the genus and confirms its Together with Acrodus, the presence of Lonchidion sp. A displacement in freshwater environments after the Toar- suggests some European affinities for the shark fauna from cian. The rest of the shark fauna includes teeth of Hybodus the Phu Kradung Formation. sp., aff. Hybodus sp., hybodontid dermal denticles, Jia- odontus sp., Lonchidion sp. A, Lonchidion sp. B, Het- Keywords Southeast Asia Á Mesozoic Á Khorat eroptychodus cf. H. kokutensis and dorsal fin spines. The Group Á Hybodontiformes Á Freshwater sharks presence of Jaiodontus and of unusual hybodontid dermal denticles suggests a Jurassic age for most of the Phu Kurzfassung Die Revision der Su¨ßwasser-Haifauna von Kradung Formation, whereas the presence of Heterop- der Phu Kradung Formation in NO-Thailand fu¨hrt zur tychodus suggests an Early Cretaceous age for the top of Identifikation einer neuen Art von Acrodus, die den ju¨ng- the Formation. However, the age of the Phu Kradung sten Nachweis dieser Gattung darstellt und ihre Verdra¨n- Formation is still uncertain, with contradictory signals gung in Su¨ßwasser-O¨ kosystemen nach dem Toarc coming from palynology, detrital zircon thermochronology besta¨tigt. Die weitere Haifauna beinhaltet Za¨hne von and vertebrate palaeontology. In any case, it appears that Hybodus sp., aff. Hybodus sp., dermale Dentikel von Hybodontiden, Jiaodontus sp., Lonchiodon sp. A, Lonchi- odon sp. B., Heteroptychodus cf. H. kokutensis und dorsale G. Cuny (&) Flossenstachel. Das Vorkommen von Jiaodontus und von The Natural History Museum of Denmark, ungewo¨hnlichen hybodontiden dermalen Dentikeln deutet Øster Voldgade 5-7, 1350, Copenhagen K, Denmark e-mail: [email protected] auf ein jurassisches Alter fu¨r den gro¨ßten Teil der Phu Kradung Formation hin, wa¨hrend der Nachweis von Het- R. Liard Á T. Liard eroptychodus ein unterkretazisches Alter fu¨r den obersten Sirindhorn Museum, Sahatsakhan, Kalasin 46140, Teil der Formation andeutet. Allerdings bleibt das Alter der Thailand e-mail: [email protected] Phu Kradung Formation unsicher, da palynologische Da- ten, detritale Zirkone und die Wirbeltierpala¨ontologie T. Liard e-mail: [email protected] widerspru¨chliche Resultate ergeben. Allerdings du¨rfte dies auf jeden Fall den a¨ltesten Nachweis von Heteroptychodus U. Deesri Á S. Khamha Á V. Suteethorn darstellen und somit einen thaila¨ndischen Ursprung dieser Palaeontological Research and Education Centre, Gattung andeuten, die Acrodus in den Su¨ßwasser-O¨ ko- Mahasarakham University, Mahasarakham 44150, Thailand systemen Thailands verdra¨ngt haben mag. Zusammen mit e-mail: [email protected] Acrodus deutet das Vorkommen von Lonchiodon sp. A auf S. Khamha einen europa¨ischen Einfluss auf die Haifauna der Phu e-mail: [email protected] Kradung Formation hin. 123 G. Cuny et al. Schlu¨sselwo¨rter Su¨dost-Asien Á Mesozoikum Á established, although the uppermost part is sometimes Khorat-Gruppe Á Hybodontiformes Á Su¨ßwasser-Haie considered a separate formation, the Waritchaphum For- mation (Mouret 1994; Philippe et al. 2004). All of the sites Insitutional abbreviations listed below are located in the upper part of the Phu Kra- SM Sirindhorn Museum, Sahatsakhan, Kalasin dung Formation (Fig. 1). Province The material described in the present work comes from PRC Palaeontological Research and Education Centre, eight localities (Fig. 2). Due to the Department of Mineral Mahasarakham University Resources’ policy of protecting fossiliferous sites, the exact locations of the outcrops cannot be provided in this article. For scientific purposes, their GPS coordinates can be obtained on request from the Sirindhorn Museum. Phu Noi Introduction is located in Kham Muang District in Kalasin Province. This site encompasses three fossiliferous layers inside a Since 1990, the Khorat Group (Late Jurassic—Early Cre- complex palaeochannel sequence and its associated drain- taceous in age) has yielded rich assemblages of freshwater age system (Fig. 3): hybodont sharks, which were recovered from three for- • A light grey conglomeratic sandstone layer at the base mations (from bottom to top): the Phu Kradung, Sao Khua of the palaeochannel, which yielded shark teeth and and Khok Kruat Formations (Cuny et al. 2007). The dermal denticles, scales and teeth of actinopterygians, assemblages from the Sao Khua and Khok Kruat Forma- fragments of lungfish toothplates and turtle shells, tions are well known and show a high level of endemicity crocodile teeth and many indeterminate bone frag- (Cuny et al. 2006, 2008, 2010), whereas the Phu Kradung ments. This layer is referred to here as PNA. Formation has so far yielded mostly fragmentary remains • A series of siltstone and mudstone higher up in the that have proven difficult to interpret (Cuny et al. 2007). In palaeochannel, approximately 10 m above the basal 2008, the discovery of a new locality in Kalasin Province, conglomeratic sandstone, which have yielded hybodont Phu Noi, led to the discovery of shark teeth in conglom- teeth, dermal denticles and finspines, as well as eratic sandstones of the Phu Kradung Formation, the actinopterygian, turtle, crocodile and dinosaur fossils. preservation of which was better than at any other sites This layer is referred to here as PNB. discovered in this formation so far. This new material • A greyish siltstone inside the proximal floodplain facilitated the reappraisal of the whole of the shark faunas deposit. This layer is referred to here as PNC, and is from the Phu Kradung Formation and allowed a better situated approximately 400 m WSW of PNB. It has understanding of their composition. yielded hybodont dermal denticles, numerous Lepi- dotes-like scales and some fragments of crocodiles and dinosaurs. Geological setting The second site, Khok Sanam, is also located in Kham The Phu Kradung Formation is the most basal formation of Muang district. It consists of bluish and purple siltstones the Khorat Group (Racey and Goodall 2009). Its thickness that outcrop over a surface of 200 m2. The bluish siltstone varies from 1,200 m in the basin centre to around 500 m on yielded hybodont teeth and finspines, scales of actinop- its southern flanks (Racey 2009). It consists of fluvial terygians, toothplates of lungfishes as well as turtle, croc- sandstones, siltstones and mudstones, and is dated as either odile and dinosaur remains. Late Jurassic based on fossil vertebrate evidence (Buffetaut Sang Khae is the third site located in Kham Muang et al. 2001; Buffetaut and Suteethorn 2007; Tong et al. district. It consists of green and purple siltstones that out- 2009a) or Early Cretaceous on the basis of palynology crop over a surface of 100 m2, but only a thin, 5 cm thick, (Racey and Goodall 2009) and detrital zircon thermo- green layer has yielded hybodont teeth, various actinop- chronology (Carter and Bristow 2003). The Formation can terygian scales, isolated teeth and jaw fragments, fragments be divided into a lower and an upper part, with sandstones of turtle shells, a possible lepidosaurian jaw fragment, and tending to be more common in the upper than in the lower crocodile teeth. part (Sattayarak 1983; Racey et al. 1996). The lower part Phu Nam Jun (Kuchinarai district, Kalasin province) has corresponds to a lake margin, whereas the upper part cor- yielded a single shark tooth, recovered from greenish to responds mostly to meandering river environments under a reddish siltstones, which yielded many complete semiono- probable two-season semi-arid/humid climate (Mouret tiform fishes as well as a lungfish (Cavin et al. 2003b, 2007; 1994; Racey et al. 1996; Racey 2009). However, a lower Cavin and Suteethorn 2006). The tooth was found in a plaster and an upper member have not yet been officially jacket containing Lepidotes buddhabutrensis specimens. 123 Shark faunas from the Late Jurassic Fig. 1 Left: composite log of the upper part of the Phu Kradung two sites. Right: distribution of the different taxa in the sites of the Formation. The upper part, zone 1, corresponds to the upper two- Phu Kradung Formation included in the present study. XJ indicates thirds of Mouret’s (1994) Waritchaphum Formation and encompasses genera normally unknown in the Cretaceous, whereas Xc indicates four sites. The middle part, zone 2, is approximately 500 m thick and genera normally restricted to the Cretaceous.The exact position of encompasses the lower third of the Waritchaphum Formation. The Kham Phok, NBL32 and Sang Khae in the log cannot be ascertained, lower part, zone 3, is approximately 100 m thick and encompasses whereas the one of Wang Din So is highly speculative Kham Phok is situated north of the village of Ban Kham fishes, an incomplete crocodile tooth, as well as many Phok, Khamcha-i district, Mukdahan province. The shark unidentifiable small bone fragments. This site is referred to teeth were recovered from a reddish siltstone level with here as NBL32. sandy to microconglomeratic lenses, which was surface The last locality, Wang Din So, is a disused quarry collected. The site has yielded a large fossil turtle as well as (Wang Thong district, Phitsanulok province). The remnant a theropod tibia (Buffetaut and Suteethorn 2007; Tong of the front of the quarry is made of a 15 m high cliff et al. 2009b). Fragments of hybodont finspines as well as consisting of a coarse grey sandstone surmounted by a teeth of actinopterygians, crocodiles and theropod dino- 6-m-high series of intercalating grey siltstones and sand- saurs were also recovered.