editorial message - mahasarakham...

Editorial message

In succession of the papers from the 2nd International Conferences on Palaeontology of Southeast Asia (ICPSEA) held at Mahasarakham University and published in our Journal of Science and Technology Mahasarakham University in the year 2010, this volume is a special issue for “Current research on palaeontology in Thailand and nearby countries”. It opens for palaeontologists, who do research in Thailand and nearby countries and for young Thai palaeontologists,the possibility to publish the actual results of their research. There are many institutions that promote and support palaeontological research or education in Thailand: primarily Mahasarakham University and the Palaeontological Research and Education Centre, the Department of Mineral Resources (DMR) and their museums, and the Northeastern Research Institute of Petrifi ed Wood and Mineral Resources (In Honor of His Majesty the King). They all house exhibitions, fossils collections or offer palaeontological education and make palaeontological research possible.

The publications in this volume focus on Mesozoic and Cenozoic vertebrate fossils, e.g. fi shes, dinosaur, turtle, mammals (7 papers) and two further studies about Palaeozoic invertebrate fossils, brachiopods and radiolarians. One paper examines a pedagogic topic. This is of particular interest for primary school students as it is a development education guide to be used in conjunction with a visit to a worth seeing exhibition in Sirindhorn Museum, Kalasin Province.

We believe that this volume is a valuable and useful contribution for palaeontology and for palaeontological education. It is our aim to accumulate palaeontological research in Thailand and nearby countries in the same volume and also encourage young students to start doing research and to continue their research.

Finally, we are grateful to Palaeontological Research and Education Centre, Mahasarakham University for help this volume possible.

Professor Dr. Preecha Prathepha

Editor in chief

Content

Original page

New vertebrate-bearing localities in the Triassic of Thailand ............................................................................ 335 Chalida Laojumpon, Uthumporn Deesri , Suchada Khamha, Athiwat Wattanapituksakul, Komsorn Lauprasert, Suravech Suteethorn, Varavudh Suteethorn

Preliminary note on a small ornithopod dinosaur from the Phu Kradung Formation (terminal Jurassic – basal Cretaceous) of Phu Noi, north-eastern Thailand.................................................... 344

Eric Buffetaut, Suravech Suteethorn, Varavudh Suteethorn, Uthumporn Deesri, Haiyan Tong

Ginglymodian fi shes (Actinopterygii, Holostei) from Thailand: An overview .................................................. 348

Lionel Cavin, Uthumporn Deesri, Varavudh Suteethorn

First discovery of a juvenile Thaiichthys (Actinopterygii: Holostei) from the Late Jurassic - Early Cretaceous of Thailand ...................................................................................... 357 Uthumporn Deesri, Varavudh Suteethorn, Romain Liard, Lionel Cavin

Note on giraffe remains from the Miocene of continental Southeast Asia ....................................................... 365 Yuichiro Nishioka, Rattanaphorn Hanta, Pratueng Jintasakul

Note about new Pleistocene faunal remains from Tham Prakai Phet, Chaiyaphum Province, Thailand ...... 378 Arnaud Filoux, Carole Lespes, Athiwat Wattanapituksakul, Cholawit Thongcharoenchaikit

A revision of Testudo tungia Yeh, 1963 from the Lower Pleistocene Gigantopithecus cave, Liucheng, Guangxi Province, China ...................................................................................................................................... 386

Wilailuck Naksri, Li Lu, Haiyan Tong

Devonian radiolarian faunas in Pai Area, Mae Hong Son Province, Northern Thailand: Paleogeographic implication ................................................................................................................................ 393

Premvadee Sanjit, Nutthawut Wonganan, Yupa Thasod

A new locality of well-preserved silicifi ed Early Permian brachiopods in Loei province, NE Thailand ......... 403 Sakchai Juanngam, Mongkol Udchachon

Development of an education guide for primary school students to be used in conjunction with a visit to dinosaur exhibition in Sirindhorn Museum ................................................................................. 412

Thanasiri Suteethorn

Cover Illustration : Plot of the phylogenetic tree of the Lepisosteiformes against palaeogeography. The upper row shows schematic evolution of the palaeogeographical pattern in the Late Jurassic and in the Cretaceous. The lower row shows the phylogenetic tree included in the palaeogeography.

: See Lionel Cavin, Uthumporn Deesri, Varavudh Suteethorn, Pxx, Figure 1 ; 2014

Original

1 Department of Biology, Faculty of Science, Mahasarakham University, Khantarawichai, Mahasarakham 44150, Thailand.2 Palaeontological Research and Education Centre, Mahasarakham University, Khamrieng, Mahasarakham 44150, Thailand.* Corresponding author: [email protected]

New vertebrate-bearing localities in the Triassic of Thailand

Chalida Laojumpon1*, Uthumporn Deesri1,2 , Suchada Khamha1,2, Athiwat Wattanapituksakul1,2,

Komsorn Lauprasert1,2, Suravech Suteethorn1,2, Varavudh Suteethorn1,2

Received: 30 July 2013; Accepted: 15 October 2013

AbstractThree new vertebrate localities in the Triassic of Thailand are described from the Huai Hin Lat Formation (Carnian to Norian, Late Triassic). They are noteworthy because they contain interesting vertebrate fossils including numerous coprolites, a new record of hybodont shark, rather complete bony fi sh remains, a phytosaur tooth and temnospondyl fragments. The abundance of vertebrate fossils at three new localites is very important for it provides a betterreconstruction of Triassic environments from Thailand and can be a great source of information about the geological history of South East Asia. For this purpose, more excavations are needed.

Keywords: new vertebrate-bearing localities, Triassic, Thailand

IntroductionThe discovery of vertebrate fossils in the Triassic of Thailandstarted when a Thai-French palaeontological team began excavations at several sites of Thailand. Many vertebrate fossils were found, ranging in age from the Late Triassic to the Early Cretaceous, in the continental rocks of the Khorat plateau. However, reports of Triassic fossil ver-tebrates from Thailand are still rather few. Most of the Triassic vertebrate fossils were found in the Huai Hin

Lat Formation, dated from the Late Triassic (Carnian to Norian)1 by palynomorphs and vertebrate assemblages2,3,4

The Nam Phong Formation, palynology suggests that the formation is not older than Pliensbachian (Late Early Jurassic). The numerous remains of Triassic vertebrate fossils that have been found are kept at the Sirindhorn Museum and the Palaeontological Research and Education Centre (PRC), Mahasarakham University. However, most of them have not yet been studied in detail. The biodiver-

Figure 1 Vertebrate fossil localities in the Triassic Huai Hin Lat Formation of Thailand.

Laojumpon et al. J Sci Technol MSU336

sity and evolution of vertebrates as well as the palaeoen-vironment of the Triassic period in Thailand are therefore still very little known. However, in December 2010, the staff of the Palaeontological Research and Education Centre visited Chaiyaphum Province again and found three new localities of vertebrate fossils in the Triassic; Huai Nam Aun, Huai Pha Phueng and Huai Kee Tom. All of them belong to the Huai Hin Lat Formation. Here, we provide a preliminary description of the vertebrate fossils and a geological summary of these three new localities investigated during fi eld trips in 2010-2011.

Previously known localities The Mesozoic sedimentary rocks of Thailand range in age from the Late Triassic to the Early Cretaceous2,3. Sedimentary rocks from the Triassic period consistof the Huai Hin Lat and the Nam Phong Formations. The lowermost unit is the Huai Hin Lat Formation. This formation is composed of fl uvial and lacustrine sand, silt and mudstone deposits associated with volcanic

Figure 2 New localities of vertebrate fossils from this survey A: Huai Nam Aun locality, B: Huai Pha Phueng and C: Huai Kee Tom.

rocks 5; this unit is Upper Triassic (Carnian to Norian)1 on the basis of its palynological contents2,3 and vertebrate assemblages4. These include: a shark denticle6, a tooth of Ferganoceratodus szechuanensis7,8,9, the amphi-bians Cyclotosaurus cf. posthumus and a

plagiosauroid10, and phytosaurs11. All of them were found at an outcrop near Chulabhorn dam, Khonsan district, Chaiyaphum Province. To this should be added the turtle Proganochelys ruchae Broin, 198412 and the archosaur trackways at Tad Huai Nam Yai, near Nam Nao in Phet-chabun Province13,14,15. The Huai Hin Lat Formation is unconformably overlain by the Nam Phong Formation. The Nam Phong Formation consists of continental rocks formed in fl uvial environments (braided and meander-ing channels interbedded with lacustrine or fl oodplain

sequences)3

New localitiesTo the preceding list of localities, we now add three new

localities of vertebrate fossils in the Triassic of Thailand (Figures 1 and 2) including:

1. Huai Kee Tom Gelogical data Huai Kee Tom is a part of Huai Pha Phueng wildlife sanctuary, Khonsan district, Chaiyaphum Province.

Huai Kee Tom is about 10 km away from the Chulaborn dam locality. All of the skeletal elements were found lying

on the surface of the ground. Bone beds were not found during this survey.

Vertebrate Fauna Most of vertebrate fossils from this locality are fragmented. The following vertebrate fossils were

found at Huai Kee Tom: abundant bone fragments, an incomplete archosaur tooth, fragments of turtle shell, and numerous coprolites. Both spiral and non-spiral coprolites were found at this locality. Most of them are rather well

preserve, they are about 10-35 mm in length, fairly smaller than coprolites from the Huai Nam Aun and Huai Pha Phueng localities. Most spiral coprolites from Huai Kee

Tom (Figure 3B-C) are ellipsoidal, ovoid or cylindrical in

New vertebrate-bearing localities in The Triassic of Thailand 337Vol 33. No 4, July-August 2014

shape. The number of coils visible on the surface varies from fi ve to eleven. Inclusions of ganoid fi sh scales are visible on the external surfaces of some specimens. Both the shape and external surfaces of spiral coprolites from Huai Kee Tom are similar to Liassocopros hawkinsi Hunt et al., 200716, which is distributed worldwide from the Late Triassic to the Late Cretaceous16. Concerning non spiral coprolites, the overall shape varies from almost spherical to elongate ellipsoidal. The surface texture is irregular. Several fi sh scales are visible in some areas, suggesting that they were produced by fi sh-eating organisms. The only archosaur tooth from this locality is very poorly preserved, the specimen shows only part of the crown. The surface is rather smooth; numerous denticles also show in lateral view. Ray and Chinsamy (2002)17 suggested that isolated teeth from the Late Triassic-Early Jurassic period should be treated with caution because they could belong to any of the large carnivores present at that time. These include the “thecodonts” (rauisuch-ians, phytosaurs, ornithosuchians and parasuchids) and the theropods (herrerasaurids and ceratosaurs). Conse-quently, the incompleteness of this tooth does not allow identifi cation beyond Archosauria indet.

2. Huai Pha Phueng Gelogical data This locality is part of a stream bed in Huai Pha Phueng wildlife sanctuary (Figure 1). The Huai Pha Phueng locality is about 1 km away from Huai Kee Tom (Figure 2). Sediment in this area consists mainly of brown, gray and black mudstone. Vertebrate fossils were found in several layers of brown and gray laminated mudstone. Vertebrate Fauna Vertebrate fossils from Huai Pha Phueng are a lot of coprolites, a phytosaur tooth and unidentifi ed bony fi shes. Most of them are rather well preserved. Both spiral and non-spiral coprolites, varying in size and shape were found in several layers of Huai Pha Phueng locality. Most spiral coprolites (Figure 3A) are L. hawkinsi, which is also found at Huai Kee Tom locality. However, coprolites from Huai Pha Phueng are bigger than those from Huai Kee Tom locality. The overallshape of non-spiral coprolites from Huai Pha Phueng varies from almost spherical to elongate ellipsoidal. Surface texture is irregular. In addition, the absence of inclusions on their surface suggests that they were not produced by fi sh-eating organisms.

Figure 3 Vertebrate fossils from Huai Kee Tom (B-C: Spiral coprolites) and Huai Pha Phueng locality (A: Spiral

coprolite, B: Bony fish specimen and C: Phytosaur tooth).


A phytosaur tooth from Huai Pha Phueng (Figure 3E) is fairly well preserved. The crown is almost complete whereas the root is missing. It is 9 mm in height. The tooth is conical in shape. The crown shows numerous straight ridges parallel to each other, which become fainter towards the base, and a number of low ridges, which tend to disappear towards the apex. Several characters of this specimen resemble the isolated tooth number HHL1-9.3, which is housed at Sirindhorn museum. Katisat18

suggested that isolated tooth number HHL1-9.3 should be an anterior tooth of a phytosaur. Thus, the tooth from Huai Pha Phueng is probably be an anterior tooth of a phytosaur. Bony fi shes from this locality are very inter-esting and rather well preserved. Few specimens show both the skull and several parts of the body (Figure 3D). Results from a preliminary study by Bumrungsap19 indicated that the bonyfi shes from Huai Pha Phueng are Macrosemiiformes and Semionotiformes. Comparison with vertebrate specimens from the other formation of the Khorat Group suggests that the bony fi shes from Huai Pha Phueng are very different from those from other localities in Thailand19. All the fi sh specimens are now being studied in detail to better understand their taxonomy, evolution and palaeogeography. 3. Huai Nam Aun Locality Gelogical data Huai Nam Aun is situated near the village called Nongyakong (Ban Nongyakong), Khonsan district, Chaiyaphum province (Figures 1 and 2). Sediment in this locality contains various layers of limestone and mud-

stone. The lowest layer of the outcrop consists of dark limestone with chert nodules overlain by dark calcareous mudstones with fossil algae. Finally, the upper part of

the outcrop contains thinly (0.5-2 cm) laminated beds of calcareous mudstone. In these beds, we found a lot of vertebrates fossils, especially coprolites. The lithology suggests that it was deposited in brackish water near a calcium carbonate source (e.g., pond near coastline) with

more or less anoxic conditions during the deposition of the basal layers.

Vertebrate Fauna All vertebrate fossils from this locality were found in calcareous mudstone layers. Huai Nam Aun has produced abundant coprolite material and a lot of skeletal remains including a Hybodus tooth, bony fi sh scales and temnospondyl fragments. Most coprolites from Huai Nam Aun locality (Figure 4K-Q) were preliminarily identifi ed by Laojumpon et al.2012. All of them were subdivided into seven different groups of ichnotaxa including 3 of non-spiral and 4 of spiral type. Most coprolites in this locality are spiral coprolites belonging to L. hawkinsi20 which is distributed from the Late Triassic to the Late Cretaceous of Europe, India and North America. Moreover, we also found Saurocopros bucklandi Hunt et al, 200716 which is abundant in the Late Triassic (Carnian-Norian) and the Early Jurassic16. Concerning non-spiral coprolites, they are very various in size and shape. However, the occur-rence of many bony fi sh scales and bone fragments in several specimens implies that they have been produced by a carnivorous vertebrate20. The most spectacular element from Huai Nam Aun is a shark tooth (Figure 4A) which was found by S.K., because this is the fi rst record of a hybodont shark tooth from the Triassic of Thailand. It is 4 mm labio-lingually and 2 mm high at the level of the main cusp. The tooth shows a high main cusp and two pairs of lateral cus-plets. The crown surface is covered by numerous strong ridges, quite straight, running from the base to the apex of the crown. Although detailed comparisons have not yet been performed, it can be said that the shark tooth from Huai Nam Aun shows similarities with Hybodus. From a palaeobio-geographical and chronological point of view, many Hybodus species were described world-wide on the basis of teeth or more or less complete skeletons. The genus ranges from Middle Triassic to Late Cretaceous21,22. Most of the bony fi sh remains from this local-ity are scales and bone fragments. Fish scales from this locality can be divided into two groups. The fi rst group

(Figures 4B and 4D) is rectangular in outline, rather elongated and almost fl at. The surface is ornamented by numerous densely packed and deep ridges, running along the axis of the scale. Most isolated scales present a socket for the peg and socket articulation


Figure 4 Vertebrate fossils from Huai Nam Aun locality (A: Hybodus tooh, B-D and J: Fish scales, E-I : Temno-spondyl vertebrae and K-Q: Coprolites. All scale bars: 1 cm, except C, J, N, P and Q).


between scales (Figure 4B). Based on the characters above, this group is identifi able as aff.Paleoniscidae. The second group (Figures 4C and 4E) shows a rhombic shape in apical view. The surfaces are rather fl at and smooth. Brito and Gallo, 200223 suggested that semionotid fi sh scales are normally unornamented, slender, and composed of ganoine. Thus this group possibly corresponds to semionotid fi shes. We also found many temnospondyl bones (Figure 4E-H) in this area. Unfortunately, most specimens are very frag-mented. The most complete specimen is an intercentrum. This intercentrum is rather massive, pleurocentra are absent. The outline of the intercentrum is almost circular in anterior and posterior views, the horizontal diameters are about 50 mm in anterior view and 65 mm in posterior view. Both the anterior and posterior surfaces of the intercentrum are rather concave but the posterior articularfacet is more concave. A massive intercentrum and small pleurocentra or an absence of pleurocentra is a character of the vertebrae of Stereospondyli24. In 1981, the amphibian Cyclotosaurus cf. posthumus was found near Chulaborn dam, Chaiyaphum Province10. Chulaborn dam is less than 20 km away from Huai Nam Aun. Thus, the intercentrum from Huai Nam Aun locality probably belongs to Capitosauridae.

Discussions and Conclusion Preliminary surveys in Triassic areas by the staff of the Palaeontological Research and Education Centre (PRC), Mahasarakham University, with the Thai-French palaeon-tological team in 2010-2011 found new three vertebrate

localities at Huai Kee Tom, Huai Pha Phueng and Huai Nan Aun. Although the fossiliferous layer and complete fossils were not found at Huai Kee Tom, the archosaur tooth found at this locality were important evidence in

terms of palaeontology because our knowledge about archosaurs from the Triassic of Thailand is still limited. Only a few scientifi c papers were published so far, such

as the description of two jaw fragments of a phytosaur by Buffetaut and Ingavat11. Thus, Huai Kee Tom may become an important locality for Triassic archosaurs from Thailand in the future and more surveys are needed.

In the case of Huai Pha Phueng, this locality yielded a lot of important data, especially about actinop-terygian fi shes. Numerous actinopterygian fi shes found in this locality are very interesting because most of them are rather complete and can be studied in detail. Many actinopterygian fi shes have been reported from Mesozoic sediments in various parts of Thailand9. Most of them were found in Late Jurassic to Early Cretaceous sediments, whereas from the Triassic there was only one report about actinopterygian fi shes, by Buffetaut, Ingavat and Martin25. Therefore, the actinopterygian specimens from Huai Pha Phueng locality will provide important evidence to increase our knowledge about the evolution and distribution of the Actinopterygii in Thailand during the Triassic. Many interesting specimens were found at Huai Nan Aun locality. The discovery of a tooth of a hybod-ont shark and of abundant spiral coprolites, which are generally produced by sharks or rays26, 27, 28,29 , indicates that Huai Nan Aun is an important locality for the study of chondrichthyan fi shes from the Triassic of Thailand, because only one report about a shark denticle from the Triassic of Thailand has hitherto been published6. Thus this new evidence will help us to better understand the Triassic chondrichthyan fi shes of Thailand. Concerning bony fish remains, although nocomplete specimen was found during this survey of Huai Nan Aun locality, further comparisons will be needed for both the fi rst and second group of isolated scales, because genus-level identifi cation of some palaeoniscid fi shes is possible on the basis of their highly varied scale ornamentation30. Thus the fi rst group can probably be identifi ed at the genus level, whereas the second group, which presents semionotid characters should be compared with semionotid fi shes from other parts of

Thailand, because semionotid scale are widespread in the Mesozoic of Thailand9. Moreover, semionotid scales were discovered in the Triassic of Thailand in 1984, at a rock exposure between Km 105 and 122.5 along the Phitsanulok-Lomsak highway, Phetchabun Province.

All the fi sh scales from that locality were described as Semionotus sp., which is distributed worldwide in the middle Triassic – early Jurassic26. More comparison with


semionotid fi shes from other parts of Thailand should help us increase our knowledge of the evolution ofsemionotid fi shes in Thailand from the Triassic until the Early Cretaceous. The three new localities, Huai Kee Tom, Huai Pha Phueng and Huai Nan Aun, are not more than 20 Km from each other. Our results indicate that the continental Triassic rocks of Thailand, especially in Chaiyaphum Province, contain abundant fossil vertebrate localities. Each locality helps us to understand several topics. Comparisons between specimens from Huai Kee Tom, Huai Pha Phueng and Huai Nan Aun and other localities are still needed to assess their possible relationships with fi nds from other parts of the world, in particular those described from the Triassic beds in China, and more generally to draw conclusions about their palaeobio-geographical signifi cance. Additionally, the abundance of vertebrate fossils at Huai Kee Tom, Huai Pha Phueng and Huai Nan Aun is very important to provide a better reconstruction of Triassic environments in Thailand and can be a great source of information about the geologi-cal history of South East Asia. For this purpose, more excavations are needed.

AcknowledgementsWe would like to thank Wilailuck Naksri, Supassorn Bumrungsap, Thanit Matkhammee, Paladej Srisuk, Jeremy Martin, Jean Le Loeuff, the Thai-French palaeon-tological team and all the people who helped us during fi eld work. We also thank the monks of Wat Tham Wiman Nakin and all the local people from Nong Ya Kong village,

who donated some of the coprolite specimens used in this study. This work was supported by science achievement scholarship of Thailand (SAST), the National Research Council of Thailand (NRCT), the Thailand Research Fund (TRF) and the Palaeontological Research and Education

Centre (PRC).

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Original

1 CNRS, UMR 8538, Laboratoire de Géologie de l'Ecole Normale Supérieure, 24 rue Lhomond, 75231 Paris Cedex 05, France2 Palaeontological Research and Education Centre, Mahasarakham University, Kantharawichai, Mahasarakham 44150, Thailand

* Corresponding author: [email protected]

Preliminary note on a small ornithopod dinosaur from the Phu Kradung Formation (terminal Jurassic – basal Cretaceous) of Phu Noi, north-eastern Thailand

Eric Buffetaut1*, Suravech Suteethorn2, Varavudh Suteethorn2, Uthumporn Deesri2, Haiyan Tong2


AbstractThe lower jaw of a small ornithopod from Phu Noi, a rich fossil locality in the lower part of the Phu Kradung Formation (terminal Jurassic - basal Cretaceous) of Kalasin Province, north-eastern Thailand, is briefl y described. This the best ornithopod specimen hitherto recovered from the Phu Kradung Formation and it shows a combination of characters suggesting that it belongs to a new taxon.

Keywords: Ornithopoda, mandible, Phu Kradung Formation, Late Jurassic, Thailand

IntroductionThe Phu Kradung Formation of north-eastern Thailand contains abundant dinosaur remains, among which mamenchisaurid sauropods are especially well represented1.Sinraptorid theropods have also been found2. Few ornithischian remains have hitherto been reported from the Phu Kradung Formation. They include a stegosaur vertebra3 and a femur of a small ornithopod4. In the present preliminary paper, we report the discovery of a new specimen from the Phu Noi fossil locality, which provides important new evidence about the small ornithopods from the PhuKradung Formation.

Geographical and geological settingThe specimen (Palaeontological Research and Education Centre, Maha Sarakham University, n° PN 13-09)

described below was found in the course of palaeonto-logical excavations carried out by the Palaeontological Research and Education Centre of Maha Sarakham University at Phu Noi, a small hill (as the Thai name indicates) near the village of Ban Din Chi, in Kalasin

Province, northeastern Thailand (see location map in Cuny et al.5). There, the brown, grey and greenish mudstones of the Phu Kradung Formation yield an

abundant and diverse vertebrate fauna, comprisinghybodont sharks5, bony fishes6, turtles, teleosaurid crocodilians, sauropods (including mamenchisaurids), theropods7 (including sinraptorids) and pterosaurs. The age of the Phu Kradung Formation is still relatively uncertain. It was long considered as Late Jurassic, but on the basis of palynological evidence Racey and Goodall (2009)8 consider that most of it belongs to the Early Cretaceous, with the lower part possibly being Late Jurassic. The Phu Kradung Formation probably covers a relatively long time span and in all likelihood the fossil localities it contains are not all of exactly the same age.

According to Deesri et al. (in press)6, the Phu Noi locality

is in the lower part of the Phu Kradung Formation and a Late Jurassic age is likely.

DescriptionThe specimen is a nearly complete small left dentary

(length : 90.30 mm), only the anterodorsal region beingdamaged. Because of this damage to the anterior part, the total number of alveoli in the tooth row is not completely certain. Anterior to the well preserved part of the tooth row, there seems to have been three alveoli,

the anteriormost being smaller than the others and sepa-

Preliminary note on a small ornithopod dinosaur from the Phu Kradung Formation

(terminal Jurassic – basal Cretaceous) of Phu Noi, north-eastern Thailand345Vol 33. No 4, July-August 2014

rated from them by a toothless space. The more posterior alveoli are confl uent. The total number of tooth emplace-ments may have been 13. There is a toothless anterior « spout » between the anteriormost alveolus and the decurved symphysial area. This region must have been partly covered by the predentary. The height of the dentary increases gradually from front to back. The posterodorsal process is not displaced laterally relative to the tooth row, it is posterior to it. Its anterior margin is concave and its posterior margin vertical. There are fi ne striations on the labial face of its tip, probably indicating the contact with the coronoid bone. Laterally to the tooth row, the dentary is convex dorsoventrally, forming a very weak sloping shelf. There are only a few elongate foramina in that area, one of them much larger than the others. Ventrally, the lateral face of the bone curves smoothly into the ventral face. In dorsal and ventral views, the bone is S-shaped, the symphysial region curving medially to meet its right counterpart. In medial view, Meckel’s canal forms a groove along the ventral margin of the bone. This groove becomes narrower anteriorly and extends up to the symphysial area. Its ventral edge is a sharp bony blade. Dorsally to the groove, the dentary forms a smooth vertical surface, which is limited dorsally by a furrow formed by coalescent foramina. In the posterior region, the crowns of two replacement tooth can be seen emerging from that furrow. Three functional teeth are preserved. One is in an anterior position, while the other two are located in the posterior part of the jaw. They are well preserved and show a well-developed ornamentation of ridges

on the enamelled lingual surface. The margins of the laterally compressed crowns bear distinct denticles. The labial faces of the teeth bear no enamel and show wear

facets. The crown of the anteriormost tooth is relatively small and diamond-shaped, the more posterior teeth are larger and fan-shaped, indicating some heterodonty. The ornamented lingual faces do not show a prominent median ridge, and there is no strong basal cingulum.

Visible replacement teeth show similar characters. There are distinct facets on the mesial and distal margins of the

teeth, for the reception of adjacent teeth, which suggests the existence of an incipient dental battery, which was not as developed and did not involve as many successive teeth as those of advanced iguanodontians and hadrosaurs.

Identifi cationThe fan-shaped teeth with a strongly ridged crown indicate that the specimen belongs to an ornithis-chian dinosaur. Among ornithischians, thyreophorans, including stegosaurs and ankylosaurs, have more robustly built mandibles which do not show a well-defi ned and erect posterodorsal process, and their teeth show a strong cingulum not present in the Phu Noi specimen. Basal ceratopsians such as Psittacosaurus, which is known from the Khok Kruat Formation of Thailand9, have a deeper mandible and their teeth show a very strong median ridge, not seen here. The position and shape of the posterodorsal process, the slenderness of the dentary and the teeth lacking a strong cingulum indicate that the Phu Noi mandible belongs to an ornithopod. The Phu Noi ornithopod shows neither the more or less advanced dental battery, nor the laterally displaced posterodorsal process seen in iguanodontids and espe-cially in hadrosaurids. A number of small ornithopod taxa, belonging to more or less basal families (heterodontosau-rids, hypsilophodontids, dryosaurids, etc.) are known from the Jurassic and Cretaceous of various parts of the world, including Asia. The specimen from Phu Noi needs to be compared with these forms. Preliminary comparisons seem to indicate that it shows a distinct combination of

characters (with a rather advanced dentition) and is differ-ent from all hitherto known taxa. This will in all likelihood result in the erection of a new taxon.

ConclusionAlthough some isolated postcranial bones from the Phu Kradung Formation indicated the occurrence of smallornithopods4, the available material was too scanty to

allow an accurate identifi cation. The newly discovered mandible from Phu Noi, which bears several well-pre-served teeth, provides much better evidence about those

Buffetaut et al. J Sci Technol MSU346

ornithopods from the Phu Kradung Formation. Additional comparisons are needed, especially with Asian forms of similar geological age, to establish more precisely its posi-tion among basal ornithopods, but the observations made so far strongly suggest that it belongs to a new taxon. This fi nd improves our knowledge of dinosaur diversity in the Phu Kradung fossil assemblages and testifi es to the pal-aeontological importance of the exceptional Phu Noi site.

References1. Suteethorn S, Le Loeuff J, Buffetaut E, Suteethorn

V, Wongko K. First evidence of a mamenchisaurid dinosaur from the Upper Jurassic–Lower Cretaceous Phu Kradung Formation of Thailand. Acta Palaeon-tologica Polonica 2013; 58 (3): 459–469.

2. Buffetaut E, Suteethorn V. A sinraptorid theropod (Dinosauria: Saurischia) from the Phu Kradung Formation of northeastern Thailand. Bulletin de la Société géologique de France 2007; 178(6): 497-502.

3. Buffetaut E, Suteethorn V, Tong H. The fi rst thyre-ophoran dinosaur from Southeast Asia: a stegosaur vertebra from the Late Jurassic Phu Kradung Forma-tion of Thailand. Neues Jahrbuch für Geologie und Paläontologie Monatshefte 2001; 2: 95-102.

4. Buffetaut E, Suteethorn V, Tong H. Dinosaur assem-blages from Thailand : a comparison with Chinese faunas. In : Lü J, Kobayashi Y, Huang D, Lee YN, eds, Papers from the 2005 Heyuan International Dinosaur Symposium. Beijing: Geological Publishing House 2006; 19-37.

5. Cuny G, Liard R, Deesri U, Liard T, Khamha S, Suteethorn V. Shark faunas from the Late Jurassic - Early Cretaceous of northern Thailand. Paläon-tologische Zeitschrift 2013 DOI 10.1007/s12542-013-0206-0.

6. Deesri U, Lauprasert K, Wongko K, Cavin L. A new species of the ginglymodian fi sh Isanichthys from the Late Jurassic Phu Kradung Formation, northeastern Thailand. Acta Palaeontologica Polonica 2014; 29(2); 313-331.

7. Chanthasit P. New theropod remains from the Phu Kradung Formation of Kalasin Province and a review of Late Jurassic theropod record in Thailand. In: World Conference on Paleontology and Stratigraphy. Nakhon Rachasima: Nakhon Rachasima Rajabhat University 2011, 34.

8. Racey A, Goodall JGS. Palynology and stratigraphy of the Mesozoic Khorat Group red bed sequences from Thailand. In : Buffetaut E, Cuny G, Le Loeuff J, Suteethorn V, eds Late Palaeozoic and Mesozoic Continental Ecosystems in SE Asia. London: Special Papers of the Geological Society 2009; 315: 69-84.

9. Buffetaut E, Suteethorn V, Khansubha S. The ceratopsian dinosaur Psittacosaurus in the Early Cretaceous of Southeast Asia : a review of old and recent fi nds. In:Tantiwanit W, ed Geothai’07 Interna-tional Conference on Geology of Thailand: Towards Sustainable Development and Suffi ciency Economy Bangkok: Department of Mineral Resouces, Bangkok 2007; 338-343.

Preliminary note on a small ornithopod dinosaur from the Phu Kradung Formation

(terminal Jurassic – basal Cretaceous) of Phu Noi, north-eastern Thailand347Vol 33. No 4, July-August 2014

Figure 1 Lower jaw of small ornithopod (PN 13-09) from the Phu Kradung Formation at Phu Noi, in labial (A) and lingual (B) views. Scale bar : 10 mm.

Original

1 Department of Geology and Palaeontology, Muséum d’Histoire naturelle, CP 6434, 1211 Genève 6, Switzerland2 Palaeontological Research and Education Centre, Mahasarakham University, Khamrieng, Kantharawichai, Mahasarakham 44150,

Thailand3 Department of Biology, Faculty of Science, Mahasarakham University, Khamrieng, Kantharawichai, Mahasarakham 44150, Thailand

* Corresponding author: [email protected]

Ginglymodian fi shes (Actinopterygii, Holostei) from Thailand: An overview

Lionel Cavin1*, Uthumporn Deesri2,3, Varavudh Suteethorn2


AbstractIsolated ganoid fi sh scales are not uncommon in Mesozoic deposits of Thailand. Traditionally referred to ‘semionotiform’or Lepidotes-like fi shes, they were not assigned to well-defi ned taxa and are of little use for palaeontologicalreconstructions. During the last fi fteen years, however, the discovery of well-preserved articulated fi sh specimens, with ganoid squamations, allowed us to properly defi ne new taxa, to search for phylogenetic relationships and to address the place of these fi shes in palaeoenvironments. So far two genera and three species of ginglymodians have been named on the basis on material from the Phu Kradung Formation, but at least nine different taxa have been recognized ranging from the Late Triassic to the Aptian. Phylogenetic analyses of Thaiichthys and Isanichthys indicate that they belong, or are closely related, to the Lepisosteiformes. The palaeogeographical distribution of the four known Isanichthys species is restricted to the northern margin of the Tethys during the Middle Jurassicto the basal Cretaceous. The palaeobiogeographical signal of Thaiichthys is more ambiguous, its closest relatives having been found in the early Late Cretaceous of western Gondwana (South America and Africa).

Keywords: Cretaceous, Ginglymodi, palaeobiogeography, phylogeny

IntroductionMesozoic deposits worldwide, both marine and freshwater in origin, have yielded isolated ganoid scales commonly referred to ‘semionotiforms’ or Lepidotes-like fi shes. These scales can generally be distinguished from ganoid scales of non-neopterygian fi shes (the ‘palaeonisciforms’)

because the abdominal fl ank scales usually bear a pair of processes on their anterior margin in complement

to the dorsal process1,2. Their abundance in the fossil record is due in part to their strong mineralization, being constituted of a bony basal plate cover with an enamel layer. Except some research that attempt to identify

the systematic affi nities of isolated scales on the basis of the micro-ornamentation of the enamel layer3,4.5.6, a taxonomical assignment is usually not possible with no

articulated material, in particular if no articulated cranial material is preserved. Relatively complete specimens in anatomical connexion of ginglymodians, however, are known for a long time in various Lagerstätten worldwide, and their study have enabled researchers to propose phylogenetic relationships within the group, and to consider relationships of these fi shes with other actinopterygians. Classically, the Holostei gathered the living Amiiformes and Lepisosteidae, together with some extinct groups. Patterson (1973)7 questioned this concept: he regarded the Holostei as a non-monophyletic group and consid-ered the Semionotidae as Halecostomi, i.e. as closer to teleosts than to gars (Lepisosteidae). Alternatively, Olsen and McCune (1991)8 regarded the Halecomorphi and the

Lepisosteidae as forming a clade with the Macrosemiidae

Ginglymodian fi shes (Actinopterygii, Holostei) from Thailand: An overview 349Vol 33. No 4, July-August 2014

(the Semionotiformes), which is resolved as the sister-group of teleosts. In their scheme, Halecomorphi (Amia and relatives) are located as the sister-group of Semiono-tiformes + Teleostei. During the last decades, however, most molecular phylogenetic studies have resuscitated the Holostei (for instance Venkatesh et al. 20019 , Inoue et al. 200310, Near et al. 201211; Betancur et al. 201312), and this confi guration was subsequently also found in morphological studies, which included fossil taxa13,14. In his review of the Lepisosteiformes Grande (2010)13 proposed a classifi cation, in which the Holostei include the Halecomorphi and a clade called Ginglymodi, which gathers gars together with several extinct taxa. Most recent studies have found the monophyly of Ginglymodi containing the Lepisosteiformes, ‘macrosemiiformes’ and ‘semionotiformes’, but there is still no consensus about the respective composition and relationships of the lat-ter two groups (compared for instance López-Arbarello 20122 with Cavin et al. 201314 and Deesri et al. 201415). An overview of Jurassic and Cretaceous bony fi sh record from Thailand has been published in 20091. However, new discoveries and new analyses of the data have been made during the last years, and a new synthesis is now necessary. Here, we present an overviewof the discoveries of ginglymodians in Thailand, and we

discuss their impact in the evolutionary history of the group within the frame recent phylogenies.

Geological settingThailand consists of two continental blocks or microcon-tinents: the eastern part, on which is located the Khorat Plateau, belongs to the Indochina block, and the western part, including the southern Peninsula, belongs to the ‘Shan-Thai’ or ‘Sibumasu’. The Shan-Thai block has

yielded very few ginglyomodian fi sh remains so far, except scales and fragmentary elements found in the Mab Ching locality in the Khlong Min Formation, Middle or Late Juras-

sic in age1. Most of the ginglymodian remains have been found in the Khorat Plateau in NE Thailand, which contains

non-marine sediments deposited during the Mesozoic. Racey (2009)16 and Racey and Goodall (2009)17 restricteded

the Khorat Group to fi ve formations: the Phu Kradung,

Phra Wihan, Sao Khua, Phu Phan and Khok Kruat forma-tions, in ascending order. Chonglakmani (2011)18 included in Khorat Group the underlaying Nam Phong Formation. Ginglymodians have been found in the Phu Kradung, the Sao Khua and the Khok Kruat formations, as well as in the underlying Late Triassic Huai Hin Lat Formation. The Phu Kradung Formation comprises fl uvial channel sandstone, siltstone and mudstone with intermittent calcretes. The formation was deposited in a mainly lake-dominated fl oodplain cut by meandering and occa-sionally braided river channels. The formation is sandier in its upper part. The age of most of this formation is considered to be Late Jurassic on the basis of recent vertebrate discoveries19,20,21 but the upper part, however, is now regarded as basal Cretaceous in age based on palynological evidence17. Similar ages have been established on the basis of the shark assemblages22. The Sao Khua Formation comprises dominantly fl oodplain deposits including sandstone, siltstone and mudstone, together with common calcretes, and was deposited in a low-energy fl uvial setting comprising meandering channels and extensive fl ood plains. Based on paly-nomorphs, a Berriasian- early Barremian age is sug-gested for this formation17. The Khok Kruat Formation comprises sandstone, conglomerate, siltstone, shale and intermittent palaeosols deposited in a dominantly fl uvial

environment. This formation is considered as Aptian in age on the basis of palynomorphs23 and vertebrates24,25.

The Ginglymodian Thai fossil recordSince thirty years, the Thai-French collaboration team has studied non marine vertebrate fossils from Thailand, ranging in age from the Late Triassic to the late Early Cre-taceous. Bony fi shes have been discovered regularly, and

were mostly represents by isolated ganoid scales referred to semionotid-like fi shes25. From 2002 to 2007, excava-tions were repeatedly conducted in the site of Phu Nam Jun, Tambon Lao Yai, Kalasin Province, a locality discovered some years before by local people26. So far this site

has yielded only bony fi shes, and this discovery triggered specifi c researches on this group of vertebrates. Most of the specimens belong to a ginglymodian fi sh, Thaiich-

Cavin et al. J Sci Technol MSU350

thys buddhabutrensis (Cavin, Suteethorn, Khansubha, Buffetaut & Tong, 2003)27, which was described in detail only recently14. A taphonomical and morphometric study of the T. buddhabutrensis assemblage was published by Deesri et al.28 in 2009. In the meantime, a single speci-men from the Phu Nam Jun site was referred to another ginglymodian, Isanichthys palustris Cavin and Suteethorn, 2006. In 2008, a new site called Phu Noi, situated in the Phu Kradung Formation but located stratigraphically lower than the site of Phu Nam Jun22 has been regularly excavated. A very rich vertebrate assemblage, comprising sharks, turtles, crocodiles and different dinosaurs, has been discovered22. Several ginglymodian specimens were also recovered. Although they show some variability in their skull bone pattern, they have been all referred to a species of Isanichthys distinct from I. palustris, I. lert-boosi Deesri, Lauprasert, Suteethorn, Wongko and Cavin

(2014)15. Isolated discoveries of articulated ginglymodians have been done in other localities from the Phu Kradung Formation. An almost complete specimen was discovered in the Ban Nong Rua site, Wang Nam Khiao District, Nakhon Ratchasima Province, and has been described in a PhD Thesis29. It likely represents a new taxon and its phylogenetic relationships are currently investigated. Two specimens closely related to Thaiichthys have been discovered in localities other than Phu Nam Jun: a specimen referred to Thaiichthys cf. buddhabutrensis was found in the locality of Chong Chat, Non Sung District, Nong Bua Lamphu Province29 and one specimen from

the locality of Kham Phok, Nong Sung District, Mukdahan Province, was regarded as a juvenile of T. buddhabut-rensis30. It should be noticed here that both specimens show differences with individuals from the type locality, but because this species possesses a wide range of

morphological variability, and because only one speci-men from each locality is available, we prefer to avoid erecting new taxa pending the discovery of new material.

Other localities from the Phu Kradung Formation, such as Khok Sanam, Dan Luang, Phu Dan Kaeng, Lam Payang (Phu Klang) and Wan Din So contain smooth ganoid scales, but we are not able so far to determine if they can be referred to one of the taxon from this

Formation known by articulated material (Thaiichthys and Isanichthys) or if they correspond to new taxa.Outside the Phu Kradung Formation, numerous other localities from the Mesozoic of Thailand have yielded isolated ginglymodian remains from different stratigraphic horizons. The locality of Huai Pha Pheng, in the Late Triassic Huai Hin Lat Formation, is one of the rare lo-calities, which has yielded articulated material with the recent discovery of several subcomplete ray-fi nned fi shes. Some of these specimens are probably ginglymodians, but their study is too preliminary to permit well-supported assignations. Other discoveries are mostly isolated scales, rare teeth and skull ossifi cations. Although this kind of preservation precludes the recognition of taxa, we can assess the diversity on the basis of the association of teeth and scales, and on the morphology of the latters. The locality of Mab Ching, in the Khlong Min Forma-tion, has yielded an association of large ganoid smooth scales with a conical tooth, which indicate the occur-rence of a ginglymodian taxon likely different from those of the other localities (Ginglymodi indet. 1 in table 1). Two localities from the Sao Khua Formation (Phu Phan Thong and Phu Wiang) have yielded smooth ganoid scales associated with button-like teeth. This kind of teeth has never been found in the Phu Kradung Formation so far, and it likely indicates the occurrence of another taxon of gingly-modian in this formation (Ginglymodi indet. 2 in table 1). In the Khok Kruat Formation, two kinds of scales have been found in the Khok Pha Suam locality: one kind has a smooth ganoine surface and the other has parallel ridges on the surface. These scales, never found associated with

button-like teeth, indicates the occurrence of two taxa in this locality (Ginglymodi indet. 3 and 4 in table 1). The site of Lam Pao Dam, in the Khok Kruat Formation, has yielded large ganoid scales ornamented with parallel rows of small pits, as well as a large button-like tooth (Gingly-

modi indet. 5 in table 1). The locality of Ban Saphan Hin in the Khok Kruat Formation, Mueang Nakhon Ratchasima District, Nakhon Ratchasima Province, has yielded the

posterior part of an articulated fi sh, as well as numerous isolated skull bones29. We cannot determine so far if these elements correspond to one of the three other taxa pre


sent in other localities of the Khok Kruat Formation, or if they correspond to a new taxon. Thus, at least three gin-glymodian taxa are present in the Khok Kruat Formation. The study of the micro-ornamentation of the enamel surface of these scales is a research in prog-ress29, which should allow assessing more effec-tively the diversity of ginglymodians in each formation.So far ten distinct ginglymodian species can be distin-guished in Thailand ranging from the Late Triassic Huai Hin Lat Formation to the Aptian Khok Kruat Formation. Three species have been named from the Phu Kradung Formation, and a forth is pending. The diversity in the Khok Kruat Formation is apparently also rather important; although the material is not complete enough for erecting new taxa. Strangely enough, the lowest diversity is observed in the Sao Khua Formation, which otherwise has yielded the most diverse tetrapod assemblages31. This paucity is possibly related to taphonomical features of the vertebrate localities that have been excavated in this formation until now. One exception is the locality of Phu Phok (Sakhon Nakhon Province), which is the type locality of the sinamiid Siamamia, a halecomorph fi sh represented by isolated bones and some articulated cranial material32.

Evolutionary historyThe resurrection of Holostei on the basis of morphologi-cal characters, including data from fossil taxa, was fi rst proposed by Grande (2005, 2010)33,13. This clade includes the Halecomorphi and the Ginglymodi, the latter compris-ing the Macrosemiiformes, the Semionotiformes and the Lepisosteiformes. In Grande’s study, the Semionotiformes

consist of the genus Semionotus (represented by S. el-egans (Newberry, 1888)34 only. Cavin (2010)35 proposed a phylogenetic analysis of a set of Mesozoic ginglymodians,

and found that several Cretaceous taxa are stem lepiso-steids, a pattern also found in López-Arbarello (2012)2, although different taxa are placed as stem lepisosteids. In López-Arbarello’s analysis2, the Semionotiformes are monophyletic and gathers genera ranging from the Trias-

sic to the Cretaceous, and includes the Macrosemiidae (which, consequently, lost an ordinal rank as part of the Semionotiformes). Recent analyses14,36,15 recover the

monophyletic Lepisosteiformes, but the taxa placed in the Semionotiformes in López-Arbarello’s study are not resolved as a clade, but are situated in various positions as ‘basal’ ginglymodians. Most of the recent phylogenetic analyses resolve the genera Scheenstia and Lepidotes as basal Lepisosteiformes (Figure 1). Cladistic analyses that include both genera defi ned on the basis of Thai material, Thaiichthys and Isanichthys, indicate 1) that Thaiichthys is a Lepisosteiformes situated as the sister-group of the Western Gondwanian pair Pliodetes and Araripelepidotes14,15, and 2) that Isanichthys, is resolved either in a polytomy with other ginglymodians14,15,36,37 or as basal Lepisosteiformes2,15. It is interesting to note that both Thai genera belong to the Lepisosteiformes (or are closely related to Lepisosteiformes for Isanichthys in some of the studies), a clade containing the living gars restricted now to North and Central America. ‘Lepidotes’ luchowensis Wang, 1974, from the Middle Jurassic of Sichuan, China, and ‘Lepidotes’ latifrons Woodward, 1893 from the Middle Jurassic of UK are included in the genus Isanichthys15. The palaeogeographical distribu-tion of the four species of Isanichthys is broad, but it is concentrated to the northern margin of the Tethys from the Middle Jurassic to the basal Cretaceous (Figure 1). The palaeobiogeographical pattern associated with Thaiichthys is more confuse. This genus appears to be related to a lineage from western Gondwana, which split into the pair genera Pliodetes and Araripelepidotes in the early Late Cretaceous, probably in connection with the opening of the South Atlantic. Because these three genera are freshwater, or possibly brackish for Araripel-epidotes, we suggest that the observed phylogenetic

pattern is related to the fragmentation of Pangea and that the split should be as old as Triassic in age. Vi-cariant events associated with the opening of the South

Atlantic are also observed in other Lepisosteiformes, in particular the split of sister species within both obaichthyid genera, Obaichthys and Dentilepisosteus (Figure 1). It is worth noting that the general patterns proposed here are still weakly supported because their rest on few

taxa and on a weakly supported phylogeny. But they constitute hypotheses to be tested in further studies.


ConclusionGinglymodian fi shes are relatively common in the Me-sozoic sediments of Thailand. Although only two genera and three species have been properly identifi ed so far, new material currently studied and recent fi eld discoveries indicate that much more taxa were present. The knowledge of the Thai ginglymodian fossil record has twofold impacts: 1) It allows to better understand the palaeoecology of the vertebrates assemblages in the Mesozoic of South-East Asia, in particular by showing the existence of ginglymodian fi shes with peculiar posi-tions within the trophic web: Thaiichthys was probably a grazing herbivorous or detritus feeder, while Isanichthys was likely a predator; 2) It contributes to depict the evolutionary history of the ginglymodians as a whole, which were fi shes with a wide variety of morphology, ecology and complex palaeobiogeographical history.

Acknowledgments The authors thank all of the members of the Palaeontolog-ical Research and Education Center (PRC) of Mahasara-kham University, students of Biology Department, Faculty of Science of Mahasarakham University, and especially the members of the staff of Sirindhorn Museum and of the Department of Mineral Resources (DMR) of Thailand who participated to the fi eldworks. The fi eld work was funded by the department of Mineral Resources and the Palaeontological Research and Education Center. UD was supported by the Research in Higher Education Project year 2014/Higher Education Research Promotion (HERP) and National Research University Development in the of-fi ce of the Higher Education Commission. We thank Julien

Claude (ISE-M, Montpellier) for reviewing this article. References

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JA, Davis MP, Wainwright PC, Friedman M, Smith WL. Resolution of ray-fi ned fi sh phylogeny and timing of diversifi cation. PNAS 2012; 109(34): 13698-13703.


12. Betancur-R R, Broughton RE, Wiley EO, Carpenter K, López JA, Li C et al. The tree of life and a new classifi cation of bony fi shes. PLOS Currents Tree of Life. DOI, 10.1371/currents.tol.53ba26640df0ccaee

75bb165c8c26288. 2013.13. Grande L. An empirical synthetic pattern study of

gars (Lepisosteiformes) and closely related species, based mostly on skeleton anatomy. The resurrection of Holostei. Copeia 10. American Society of Ichthyolo-gists and Herpetologists, special Publication 2010; 6 (suppl. 2a): 1-871.

14. Cavin L, Deesri U, Suteethorn V. Osteology and rela-tionships of Thaiichthys nov. gen., a ginglymodi from the Late Jurassic – Early Cretaceous of Thailand. Palaeontology 2013; 56(1): 183-208.

15. Deesri U, Lauprasert K, Suteethorn V, Wongko K, Cavin L. A new species of the ginglymodian fi sh Isanichthys from the Late Jurassic Phu Kradung For-mation, northeastern Thailand. Acta Palaeontologica Polonica 2014; 59(2): 313-331.

16. Racey A. Mesozoic red bed sequences from SE Asia and the signifi cance of the Khorat Group of NE Thailand. In: Buffetaut, E., Cuny, G., Le Loeuff, J. and Suteethorn, V. (eds) LatePalaeozoic and Mesozoic Ecosystems in SE Asia. Geological Society, London, Special Publications 2009; 315: 41-67.

17. Racey A, Goodall J. Palynology and stratigraphy of the Mesozoic Khorat Group red bed sequences from Thailand. In: B Buffetaut, E., Cuny, G., Le Loeuff, J. and Suteethorn, V. (eds) Late Palaeozoic and Mesozoic in SE Asia. Geological Society, London,

Special Publications 2009; 315: 69-83.18. Chonglakmani C. Chapter 6 Triassic. In: Ridd, M.F.,

Barber, A.J. and Crow, M.J. (eds) The Geology of Thailand. Geological Society, London 2011; 137-150.

19. Buffetaut E, Suteethorn V, Tong H. The fi rst thyreo

phoran dinosaur from Southeast Asia, a stegosaur vertebra from the Late Jurassic Phu Kradung Forma-tion of Thailand. Neues Jahrbuch für Geologie und

Paläontologie Monatshefte 2001; 95-102.20. Buffetaut E, Suteethorn V. A sinraptorid theropod

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Formation of northeastern Thailand. Bulletin de la Société Géologique de France 2007; 178: 497-502.

21. Tong H, Claude J, Naksri W, Suteethorn V, Buf-fetaut E, Khansubha S, Wongko K, Yuangdetkla P. Basilochelys macrobios n. ge. and n. sp., a large cryptodiran turtle from the Phu Kradung Formation (latest Jurassic-earliest Cretaceous) of the Khorat Plateau, NE Thailand. In: Buffetaut, E., Cuny, G., Le Loeuff, J. and Suteethorn, V. (eds) Late Palaeozoic and Mesozoic Ecosystem in SE Asia. Geological Society, London, Special Publications 2009; 315: 151-170.

22. Cuny G, Liard R, Deesri U, Liard T, Khamha S, Su-teethorn V. Shark faunas from the Late Jurassic-Early Cretaceous of northeastern Thailand. Paläontolo-gische Zeitschrift. DOI 10.1007/s12542-013-0206-0. 2013.

23. Sattayarak N, Srigulawong S, Patarametha M. Sub-surface stratigraphy of the non-marine Mesozoic Khorat Group, northeastern Thailand. GEOSEA VII Abstracts, Bangkok, 1991; p.36.

24. Cappetta H, Buffetaut E, Suteethorn V. A new hybodont from the Lower Cretaceous of Thailand. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 1990; 11: 659-666.

25. Buffetaut E, Suteethorn V. The biogeographical sig-nifi cance of the Mesozoic vertebrates from Thailand. In: Hall, R. and Holloway, J.D. (eds), Biogeography and Geological Evolution of SE Asia, Backhuys, Leiden 1998; 83-90.

26. Cavin L, Suteethorn V, Buffetaut E, Chitsing S, Lauprasert K, Le Loeuff J, Lutat P, Philippe M, Richter

U, Tong H. A new fi sh locality from the continental Late Jurassic–Early Cretaceous of Northeastern Thailand. Revue de Paléobiologie 2004; 9: 161-167.

27. Cavin L, Suteethorn V, Khansubha S, Buffetaut E, Tong H. A new Semionotid (Actinopterygii, Neop-terygii) from the Late Jurassic–Early Cretaceous of Thailand. Comptes Rendus Palévol 2003; 2: 291-297.

28. Deesri U, Cavin L, Claude J, Suteethorn V, Yuangdet-

kla P. Morphometric and taphonomic study of a ray-fi nned fi sh assemblage (Lepidotes buddhabutrensis,


Semionotidae) from the Late Jurassic-earliest Creta-ceous of NE Thailand. In: Buffetaut, E., Cuny, G., Le Loeuff, J. and Suteethorn, V. (eds) Late Palaeozoic and Mesozoic Ecosystems in SE Asia. Geological Society, London, Special Publications 2009; 315: 115-124.

29. Deesri U. Osteology and scale microstructure of Late Jurassic-Early Cretaceous Ginglymodians from Thailand, Evolutionary, Taxonomical and Palaeogeo-graphical implicantions. PhD Thesis. Mahasarakham University. Thailand. 2013; 266 pp.

30. Deesri U, Suteethorn V, Liard R, Cavin L. First discovery of a juvenile Thaiichthys (Actinopterygii, Holostei)from the Late Jurassic - Early Cretaceous of Thailand. Journal of Science and Technology, Mahasarakham University. In press.

31. Buffetaut E, Cuny G, Le Loeuff J, Suteethorn V. Late Palaeozoic and Mesozoic continental ecosystems of SE Asia, an introduction. Geological Society, London, Special Publications 2009; 315: 1-5.

32. Cavin L, Suteethorn V, Buffetaut E, Claude J, Cuny G, Le Loeuff J, Tong H. The fi rst sinamiid fi sh (Holostei, Halecomorpha) from South-east Asia (Early Cretaceous of Thailand). Journal of VertebratePaleontology 2007; 27(4): 827-837.

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34. Newberry JS. Fossil fi shes and fossil plants of the Triassic rocks of New Jersey and the Connecticut Valley. Monographs of the United States Geological Survey 188; 14: xiv+152 pp., pls. 1-26.

35. Cavin L. Diversity of Mesozoic semionotiform fi shes and the origin of gars (Lepisosteidae). Naturwissen-schaften 2010; 97: 1035-1040.

36. Gibson SZ. Biodiversity and Evolutionary History of Lophionotus (Neopterygii: Semionotiformes) from the Western United States. Copeia 2013; 4: 582–603.

37. Cavin L, Suteethorn V. A new Semionotiform (Actinopterygii, Neopterygii) from Upper Jurassic–Lower Cretaceous deposits of North-East Thailand, with comments on the relationships of Semionotiforms. Palaeontology 2006; 49: 339-353.


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Figure 1 Plot of the phylogenetic tree of the Lepisosteiformes (from Deesri et al. 201415) against palaeogeography. The upper row shows schematic evolution of the palaeogeographical pattern in the Late Jurassic and in

the Cretaceous. The lower row shows the phylogenetic tree included in the palaeogeography. Vicariant events are favoured over dispersal events.

Original

1 Department of Biology, Faculty of Science, Mahasarakham University, Khamrieng, Kantharawichai District, Mahasarakham 44150, Thailand

2 Palaeontological Research and Education Centre, Mahasarakham University, Khamrieng, Kantharawichai District, Mahasarakham 44150, Thailand

3 Department of Geology and Palaeontology, Muséum d’Histoire naturelle, CP 6434, 1211 Genève 6, Switzerland* Corresponding author: [email protected]

First discovery of a juvenile Thaiichthys (Actinopterygii: Holostei) from the Late Jurassic - Early Cretaceous of Thailand

Uthumporn Deesri1,2*, Varavudh Suteethorn2, Romain Liard1 and Lionel Cavin3


Abstract An isolated articulated specimen referred to Thaiichthys buddhabutrensis from the Kham Phok locality, Phu Kradung Formation, is described. It represents the fi rst occurrence of a juvenile ginglymodian found in the Mesozoic of Thailand. The specimen is approximately 15 cm long, 7 cm wide, and lacks the tail. The head is 3.5 cm long, and 4 cm wide. The ossifi cations of the head have no ornamentation, except small pits for the sensory canal. The squamation is composed of articulated ganoid scales with smooth surface. Only the paired fi ns are present. However, we can estimate the posi-tion of the dorsal and anal fi ns by examination of the pattern of the scales along the dorsal ridge and by the position of the unusual shaped anal scale, respectively. The scales show a variety of shape according to their position and some show peg and socket articulations. The size of the specimen is about three times smaller than the common size of the T. buddhabutrensis specimens present in the Phu Nam Jun locality from the Phu Kradung Formation. According to its size and its characteristic, the specimen described herein is referred to a juvenile individual of T. buddhabutrensis.

Keywords: Phu Kradung Formation, Khorat Group, ginglymodian

IntroductionThe well-known fi sh locality of Phu Nam Jun1, from the Late Jurassic to Early Cretaceous Phu Kradung Forma-tion, has yielded numerous ginglymodian fi shes. The largest specimen from this locality, ca. 90 cm in total length, belongs to the genus Isanichthys2, but most of the specimens are referred to Thaiichthys buddhabutrensis3,4

This species has a total length ranging from ca. 40 to 50 cm. In November 2010, a nearly complete fi sh was collected from the Kham Phok locality close to the Kham

Phok village, Nong Sung District, Mukdahan Province, located in NE Thailand on the Khorat Plateau (Figure 1).

Stratigraphically, the Kham Phok area is in the upper part of the Phu Kradung Formation, which is characterized by sandstone beds alternating with silty to claystone. The fi sh remains has been found in a greenish grey silts located just a few centimetres under the surface along the sideways. The specimen itself was enclosed in highly compact calcareous siltstone which was worked with acid and then, because of its size and fragility, me-chanically prepared under a binocular. The preparation was performed in the Palaeontological Research Centre (PRC) and the specimen is now housed in the PRC collec-

tion with the collection number PRC83. After preparation (especially the skull part), the specimen was visible from both sides.

Deesri et al. J Sci Technol MSU358

Figure 1 A: Localization of the Kham Phok locality with outcrops of the Phu Kradung Formation in black; B: The outcrop with the vegetation surrounding; and C: Photograph of the posterior part of PRC83 within the plaster jacket.

Geological settingThe specimen described in the present paper, a small ginglymodian, was found in an outcrop of fl uvial grey

sandy clays of the Phu Kradung Formation near the village of Kham Phok, in the Mukdahan Province, north-eastern Thailand. It was discovered in a greenish grey

lens of siltstone just a few centimetres under the surface, but the specimen itself was enclosed in highly compact calcareous siltstone. The site has also yielded two large cryptodiran turtles5, a tibia of a theropod6 as well as frag-ments of hybodont fi n spines and teeth7. Fragments of crocodile bones, crushing teeth of actinopterygians and

an ornithischian tooth were also found. Other vertebrate

fossils found in a nearby outcrop of the Phu Kradung Formation include a lower jaw of a large crocodilian8, and caudal vertebrae of a Mamenchisaurus-like sauropod6. The Phu Kradung Formation is the basal formation

of the Khorat Group9. Its thickness varies from 1200 m in the basin centre to around 500 m on its South fl anks10. It consists of fl uvial sandstones, siltstones and mudstones

and is dated as either Late Jurassic based on fossil vertebrates evidence5,6 or Early Cretaceous on the basis of palynology9 and detrital zircon thermochronology11.

First discovery of a juvenile Thaiichthys (Actinopterygii: Holostei)

from the Late Jurassic - Early Cretaceous of Thailand359Vol 33. No 4, July-August 2014

The stratigraphic position of the Kham Phok site within the Phu Kradung Formation is diffi cult to determine due to the complex topographic situation of the area, with the presence of rock falls and heavy weathering that prevent any clear positioning. However, it is clearly located inside the upper part of the Phu Kradung Forma-tion, approximately at the same level as the Phu Nam Jun locality, which is located just below a Phra Wihan (Berriasian) sandstone bed.

Systematic palaeontology Super Division Holostei sensu Grande 201012

Division Ginglymodi sensu Grande 201012

Order Lepisosteiformes sensu Cavin, Deesri and Suteethorn 20134

Genus Thaiichthys Cavin, Deesri and Suteethorn 20134

Type species.–Thaiichthys buddhabutrensis (Cavin, Suteethorn, Khansubha, Buffetaut and Tong 2003)3

Figure 2-4 Material PRC83 is a nearly complete fi sh with only unpaired fi ns missing, and with an estimated total length of less than 20 cm. It shows scattered scales in the centre of its squamation, but the dorsal and ventral portions are well articulated. The dermal ossifi cations are

better preserved on the left side; only part of the snout region is crushed, and some bones of the opercular series

are not preserved. Moreover, the circumorbital ossifi ca-tions are slightly shifted. On the right side, dermal bones

are partly in place, but they are mostly destroyed and fragmentary. The skull ossifi cations are smooth without any ornamentation. The nomenclature used in the descrip-

tion follows Grande (2010)12.

DescriptionGeneral features and proportions (Figure 2).– The specimen PRC83 is a small ginglymodian fi sh (ca. 150 mm of estimated standard length), with a proportionally deep body (70 mm of maximum body depth). The head is 35 mm long including the opercular series, and 40 mm deep at the extrascapular level. The skull roof shows a very deep angle with the ventral part, making the general outline triangular in shape. The orbit is relatively small with a longitudinal diameter of 5 mm, which corresponds to a head/orbit ratio of 7. The ossifi cations of the head have no ornamentation, except small pits corresponding to the path of the sensory canals visible on the infraorbitals, der-mosphenotic and the preopercle. This fi sh has a relatively small head compared with the deep squamation; it has a rather steep inclined dorsal outline from the anterior tip to the row of the dorsal median scales. The ventral margin of the squamation is approximately straight except the region between the head and the abdominal region, which shows a concave outline. However, this situation may be due to a preservation bias, as shows the location of the pectoral fi n situated backwards. The insertion of the dorsal fi n is approximately opposite to the pelvic fi n. The dorsal median scales show a unique character: a longitudinal ridge at the centre of the scale with a posterior end seemingly bearing a short spine. There are two large pre-anal scales situated in front of the insertion of anal fi n. The scales at the level of postcranium are in average squarish in shape, with those from the ventral and posterior parts of the body extremely elongated.

Figure 2 The skull and squamation of juvenile Thaiichthys buddhabutrensis, PRC83. A, photograph; B, line drawing.

Deesri et al. J Sci Technol MSU360

Skull roof (Figure 3). The frontal is relatively elon-gated and rectangular, and is slightly broader anteriorly than posteriorly on its preserved portion. Its anterior end bears a constriction at the center and a zig zag posterior suture. At the level of the constriction of the anterior part of the frontal, a slender tube with an open hole is visible, indicating the path of the supraorbital sensory canal. The median suture of the frontal is straight. The length of the frontal is approximately 20 mm long, which is a little more than two times its width. The surface of the bone has no trace of ornamentation. The parietal and the dermopterotic are tightly connected together with a straight suture. The parietal is rather elongated with a smooth surface. The parietal is rectangular in shape, about 2.5 times longer than wide (measured from the shifted right one). The

dermopterotic is relatively small compared to the parietal; it is a small rectangular ossifi cation with several pits for the sensory canal present at its lateral edge. Two pairs of extrascapulars are present, with the medial one much smaller than the lateral one. Because they are crushed and broken, the extrascapulars are rather fragmentary and their shape is diffi cult to estimate: the lateral one shows a large rounded shape with its margin suturing to the posttemporal posteriorly, to the median extrascapular dorsally and to the dermopterotic anteriorly. Their surface is smooth. The lateral extrascapular bears small pits for the path of occipital sensory canal that extends through the posttemporal bone, and the medial extrascapulars bears pits for the supratemporal commissure.

Figure 3 Skull of juvenile Thaiichthys buddhabutrensis, PRC83. A,B; photographs: C,D; semi-interpretative line drawing of the left and right. The shade area corresponds to the broken fracture lines.

First discovery of a juvenile Thaiichthys (Actinopterygii: Holostei)

from the Late Jurassic - Early Cretaceous of Thailand361Vol 33. No 4, July-August 2014

Circumorbital and suborbital series (Figure 3). The circumorbital series is composed of a supraorbital, a large dermosphenotic, and at least four infraorbitals located ventrally and posteriorly to the orbit but the cir-cumorbital ring is seemingly not completely closed. One anterior infraorbital has no contact with the orbit. The fi rst, anteriormost infraorbital is subrectangular in shape with its ventral margin gently curved. The surface of this bone is smooth, with two pits for the infraorbital sensory canal excavated on the anteroventral corner and on the centre of bone. The second infraorbital is approximately rectangular and is longer than deep with its dorsal margin showing a concavity while the other margins are straight. The surface of the ossifi cation is smooth and it bears two pits of the infraorbital sensory canal, one on the centre of the bone and a much smaller second one on the postero-dorsal corner. The third and the fourth infraorbitals on the left side are preserved above the ventral suborbital; they are approximately rectangular with their margin apparently concave, following the shape of the orbit. The fourth in-fraorbital is the smallest circumorbital bone; it is articulated with the adjacent infraorbital ventrally and with the dorsal suborbital posteriorly. The shape of the dermosphenotic is roughly rectangular, with its anterior margin concave, following the shape of the orbit. At its posteroventral cor-ner, there is apparently a deep notch for the opening of a sensory canal. Although the left ossifi cation has shifted a little bit and is lying above the frontal, we can assume that it was located at the posterodorsal corner of the orbit as visible on the other side. It articulates probably with the supraorbital anteriorly, the suborbital posteriorly and the posteriormost infraorbital ventrally. Only one supraorbital

is preserved on this specimen; it is located dorsal to the orbit, and is lying on the ventral half depth of the frontal on the left side. The supraorbital is relatively elongated

and rectangular, but its posterior portion is slightly broader than the anterior one on the preserved portion. There are two suborbitals located in front of the vertical arm of the preopercle. Their shapes are rectangular but the dorsal one is smaller than the ventral one and is slightly longer

than wide, while the ventral one is much larger and it is

deeper than long. The dorsal suborbital articulates dor-sally with the frontal. Jaws. The snout region is very fragmentary. The dentary is apparently present, with its visible part showing a narrow and elongate posterior portion whereas the anterior portion shows a blade-like horizontal part. Unfortunately, we cannot observe any teeth on the bone. Opercular series. The opercular series is better preserved on the left side, with only the preopercle and the opercle visible (Figure 3). The preopercle is a distinctly L-shaped bone (its height is 23 mm and it is 10 mm long) but not on the right side where it is more curved probably because of distortion. The vertical arm is narrow with parallel lateral margins, except the posterior margin at the half depth of the bone which shows a little constriction, making slightly narrower the mid-depth of bone. The ventral arm is quite short with its dorsal margin gently concave and the pos-terior margin gently convex, making a slightly broader angle between the vertical and horizontal arms. There is no tapering dorsally and the ossifi cation ends anteriorly as a blunt spine. A series of pores located in the centre of the bone represent the preopercular sensory canal. The opercle is relatively rectangular in shape, about 1.5 times deeper than wide (9 x 14 mm). The anterior border is straight, while the posterior border is rather convex. The dorsal and ventral margins are not clearly observable as the bone is very damaged but we can assume that they are tapering. The external surface is smooth. Hyoid arch and branchiostegal rays. Because of the poor preservation, the branchiostegal rays are

not visible. The ceratohyal is visible on the right side; it is hourglass-shaped, with its dorsal and ventral margins gently concave. Its anterior portion is smaller than its posterior portion. According to its shape, we regard it as the anterior ceratohyal (Figure 3).

Pectoral girdle. The supracleithrum is visible on the right side; its shape is subrectangular. It sutures with the po

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