NAT. HIST. BULL. SIAM Soc. 51 (1): 37 -6 7， 2003 GLIMPSES INTO FOSSIL ASSEMBLAGES OF THAILAND: CORAL PERSPECTIVES Henri Fontaine 1， Sirot Salyapongstl ，and Varavudh Suteetho rn2 ABSTRACT Foss i1 co ra1 s 釘 e widespread in 百 ai1 and. They belong to many geologic a1 interv a1 s，企 om Ordovician Ordovician to Quatemary. Th ey been have studied actively during the last 20 ye 紅 S. 恒leyare better better knO Wll， even 白ough some 陀 search still needs to be carried out; for instance ，Triassic co ra1 s ，which oc 四 r in abundance at many loc a1 ities of 百凶land ，remain inadequately known. Carboniferous ，Permian and Triassic corals are widespread 泊Th ai1 and. De vonian and Jurassic cor a1 s are in abundance in restricted areas. Or dovician and Silurian co ra1 s 紅 er 3I官 and remain poorly poorly knO Wll. Cretaceous corals are absen completely t. In τ'h ailand ，the study of cor a1 s is the study study of a long history. One c組 observe Ii ving cor a1 s as well as m 釦 y groups of fossil cor a1 s. Corals Corals provide important information on past environments and help to reconstruct pa1 eogωgraphy; 由ey a1 so provide information on the ages of the rocks in which 出eyare included. included. In this paper ， two De vonian 10c a1 ities 3I官 mentioned the for frrst time; 由ey were discovered discovered in January 2∞ヨ. Key Key words: Tabulata ，Rugosa ，S 釘omatoporoids ，Scleractinia ，Ordovician ，S i1 urian ，De vonian ， Carboniferous ，Permian ，Tri 蹴 ic ，Jurassic ，Quatemary. 問 TRODUCTION In In Th ailand ， corals are widespread both in the sea and on the land. In出 e sea 出ey 出丘 ve 泊 warm water and offer diverse and remarkable shapes. Th ey build up fasc 泊a白19 landscapes. landscapes. Coral reefs ， the “rainforests of the sea" for some au 血ors ， are well developed 泊官lai1 and. 百ley form very complex and very diverse ecosystems. 司自biological diversity includes includes commercially important species ， such as fishes ， providing liveliliood to many people 泊百ailand. On land ，corals are dis 凶buted all over 白e coun 町. Th ey are fossils included 泊 rωks 佃 d are commonly easy of access to everybody ，but 出.ey 釘 e not prominent and do not attract immediate attention. 百ley 訂 'e also associated with diverse other fossil species species of plants and animals. Limestone Limestone rich in corals ，especially Permian limestone widespread in Thai1 and ， has been used to produce wonder 白1 marble. Corals 紅 'e visible on m 佃 Y walls of Bangkok ， along along several s佐'eets. However ， because of the tropical climate ， the good polish of the marble marble slowly disappears and the details of the coral structure become oblitera 低d. Nowadays ， many people prefer granite which is more resi 包tant to weathering. In side houses and hotels ， 18 18 a1 1ee de la Chapelle ， 92140 Clanart ，France. E-mail: henri-fontain e@ wanadoo. 仕 2Geologic a1 Survey ， De partment of Min er a1 Reso 町 'ces ， Rana VI Road ，Bangkok 10400 ，百 ail 釦 d Received Received 11 March 2002; accepted 30 October 2002. 37 38 38 HENRI FONTAINE ，SIROT SALYAPONGSE AND VARAVUDH SUTEETHORN m 訂 ble is well protected. Beautiful corals 釘 'e splendidly preserved and adom m 組 y kinds of of marble pieces (see Figs. lA-B). Before Before travelling about and visiting the cor a1 rock exposures ， one should know some characteristics characteristics of the corals. Th e prim 訂 y pu 叩ose of this paper is to provide general information information on the fossil corals of Th ailand. ENVIRON 恥lliNT Corals 訂 e exclusively marine ，sessile organisms which grow as solitary individuals or exhibit exhibit a colonial mode of growth. Most of the colonial corals are restricted to w 紅 m ， shallow shallow and clear sea water. They 訂 e sensitive to temperature ，depth ，s a1 inity ，nutrient supply supply and illumination. Locally ， they build up reefs.τ 'h ey are generally found at depths of of less th 佃 50m ，組d may be exposed to routine wave energy. Although well adapted to environments ， they can be severely damaged by cyclones. A small climatic ch 加 ge may result result in heavy losses. M 叩 y corals are characterized by narrow thermal tolerances ， and are not not cosmopolitan in dis 位ibution. Th ey have limited ability to acclimatize or adapt to the effects effects of climate change. Hence they 訂 ea growing concem of scientists studying present coral coral reefs ，afraid that coral adaptation cannot keep pace with increasing sea temperatures. Mortality Mortality of reefs has been suggested recently in some areas of the world because of bleaching bleaching outbreak ，possibly due to global warming (for instance ， see DENNIS ， 2002). Coral Coral bleaching occurs when coral expels from its body the symbiotic zooxanthellae so important important to its life ， probably because these algae b配 ome toxic to the cor a1 at higher temperatures. temperatures. Mass coral bleaching has been estimated to have destroyed about one-sixth of of the world's coral colonies during the last m 司or occu 町 ence in 1998; 18 percent of reefs were were damaged in Southeast Asia. Despite this severe event ， recovery is occuring. It is difficult difficult to predict what proportion of bleached coral will die. There is much debate over whether whether coral c叩 adapt to increasing temperature ， but so far ，there is little evidence of thermal thermal adaptation. Such adaptation may be too slow to be noticed by observers. In τ 'h ailand in in the Phuket 訂 'ea ， sea temperatures increased at a rate of more than 20 per 100 years between between 1981 and 1999 (BURKE ET AL. ， 2002). The corals of 出e past lived in similar conditions as today. Wh ere they are abundant and and highly diverse in rocks ，they 訂 e often associated with many other thermophilic benthic organisms. organisms. A w 紅 m climate during the Permian is evidenced in West Cambodia near the Th ai border by the accumulation of bauxite. Green a1 gae occur with the cor a1 s and indicate shallow shallow sea depth. Using geochemistry ，it is possible to get some information on the temperatures temperatures of the seas of the past and to confmn 白at corals are commonly good indicators of of warm climates (YASAMANOV ， 1980). Cor a1 s 紅 'e useful in deciphering paleoclimates because because of their environmental sensitivity; they can constrain paleogeographic reconstructions. reconstructions. For instance ，fossil corals of Peninsular Th ailand are different from those of of Central and East Thailand; they show a lower diversity ，especiallY during the Carboniferous Carboniferous and the Permian. These differences fit with the propos a1， by geologists (BUNOPAS ，1981) ，that Th ailand occupies and straddles two different continent a1 blocks Over the past 530 million years (Ma) ， the seas have invaded parts of Th ailand many times. times. Environments were not at all times and places favourable to cor a1 s. For 泊stance ， when sea water was loaded with sand in some areas ，cor a1 s were killed by the sand moving G Ll MPSES INTO FOSS IL ASSEMB LAGES OF TH A IL AND 39 Figur e 1. A ，B . Va se (1 2.5 C I1l hi gh) l1l acl e of Permi an li l1l es tone co ntainin g a fa sc icll lat巴 co ra l (P se lld ollll oll gia) . On on巴sicl 巴， co rallir es are p巴rp endi clll ar 10 th e sllr face of th 巴 po t. On th e oth 巴r sicl e，th 巴 co rallit es are obli qll 巴 to all1l ost parall el to thi ss urfa ce . Th 巴 S 巴pta are of two ord ers，long ancl sh or t. Th 巴 co lu l1l 巴Il a is v isibl e in the C 巴nt 巴r of th 巴 cora llit 巴 b G Ll MPSES IN TO FOSS IL ASSE MBL AGES OF TH A IL AND 4 1 FigUl 巴s 3A-F. Tablll ata in th e fi elcl ancl in th in s巴cti ons. A: Kilm er ia probl emali ca Man sll y.V 巴ry pec lI li ar coral w ith an ope rclI llI lll of one 10 lhr ee convex plal eS (se 巴 Fo ntain e 巴1 al. 1994 ， p. 49-5 0). Sa lllpl 巴 T 3352 fro m B an Na C hal ianga long lh e road frolll Lalll Na rai 10 Ph elch ab lln. Thi s type 01' co ral is rar e in Thailand. It ap par entl y occ llr s al lWO olh er loca lili es: n巴ar Wat Thalll W lI a Da eng (160 04'24"N ，1 0 I o26'00"E) ancl al Khao Thalll Yai betwee n LOlll sak ancl Na lll Nao. B: Beclcl ecl lilll es ton 巴 ofL a巴III Ph ap Pha in Sur at Thani Provinc e，ri ch in Sillopora ，a bran chin g Tab lllala C: C: Pr olom icil e /i llia af f. 1I/ ll11i lO bul α la Yabe & I-Iayasak a; sa mpl e T519 fr olll Khao Thalll Na lll Ban g，20 klll sO llth of Ph e lchablln. D: P ro lo /'ll ic il elillia simp lex Z h ao & C h巴n; sa mpl e T 3728 lll fro lll Khao C hak C han along th e r oa cl fro lll 1くhok Salllro ng to Takfa . E: P l'O lomicilel illi a CI 乱 .¥'s ilil eca Z h ao & C hen; sa lllp le T253 1 fr olll Phll Ph a Khao 巴aS l of Ban Phia ，Lo ei Pro vin ce.