Phuket mar. biol. Cent. Res. Bull. 75: 13–18 (2018) Phatthalungoceras srisuki A NEW GENUS AND SPECIES OF TRIASSIC NAUTILOID CEPHALOPOD (CEPHALOPODA, ORTHOCERATOIDEA, ORTHOCERATIDAE) FROM EASTERN PENINSULAR THAILAND Kittichai Tongtherm 1 and Jaruwat Nabhitabhata 2 * 1 Department of Biology, Faculty of Science, Prince of Songkla University, Hatyai, Songkhla 90112, Thailand 2 Excellence Centre for Biodiversity of Peninsular Thailand (CBIPT), Faculty of Science, Prince of Songkla University, Hatyai, Songkhla 90112, Thailand *Corresponding author: Email: [email protected], [email protected]INTRODUCTION The eastern part of peninsular Thailand geologically belongs to the Shan-Thai or Sibumasu microplate or terrane (DMR, 2001; 2014). Khao Ok-Thalu or Khao Thammalai in Phatthalung province (Changwat Phatthalung; 07º37´N, 100º 05´E) is one of several isolated limestone monadnock scattered in the Quaternary plain of the Phatthalung area. The hill is about 2 km in length with a 245 m peak above sea level and is located at the 100º longitude line, about 2 km northeast of Amphoe Muang Phatthalung, (Fig. 1). The marine carbonate rocks in the area belong to the Chaiburi Formation, which are of Early to Late Triassic age based on micropaleontological evidence (Ampornmaha, 1995; Sardsud, 2001; Sardsud et al., 2017). Khao Ok-Thalu belongs to the lower/middle/upper member of the Chaiburi Formation, the Chiak Limestone Member, which consists of laminated mudstone and bioclastic mudstone. These strata strike N10°W and dip 55- 60°E (DMR, 2001; 2014; Sardsud, 2001). Fossils of radiolarians, ostracods, gastropods and echino- GHUPV IRXQG LQ WKLV PHPEHU DUH ¿OOHG ZLWK FOHDU calcite cement, and geopetal fabrics (Ampornmaha, 1995; Sardsud, 2001). Conodonts date this member as Early Anisian to Late Carnian (Sardsud, 2002; Sardsud et al., 2017). Cephalopod fossils in Thailand are known from only a few localities. In peninsular Thailand, nautiloids have been recorded only from Ordovician Silurian, Carboniferous and Triassic strata (Tongtherm et al ., 2016a; b; 2017). Moreover, previous records of Anisian Triassic orthocerids elsewhere are relatively rare. The present specimen of this nautiloid fossil was collected from Khao Ok-Thalu, Phatthalung province (Changwat Phatthalung), peninsular Thailand as an outcrop fossil by Mr. Paladej Srisuk. MATERIALS AND METHODS One specimen of nautiloid fossil was collected from Khao Ok-Thalu, Phatthalung province (Changwat Phatthalung), peninsular Thailand (07 o 37´N, 100 o 05´E) (Fig. 1), by Mr. Paladej Srisuk on 2 September 1973. The systematic terminology of morphology and measurements generally follows Teichert et al. (1964). The description of nautiloid specimens was made using the following abbreviations for shell dimensions: Pl = Phragmocone length, Paw = Phragmocone anterior width, Ppw = Phragmocone posterior width, Nc = Number of chambers, Cl = Chamber length. The type specimen is deposited in Palaeontological Research and Education Centre, Mahasarakham University (PRC), Thailand, with SUH¿[HG FDWDORJXH QXPEHU 35&6+0.2 7KDL ZRUGV XVHG LQ WKH WH[W DUH .KDR PHDQV PRXQWDLQ or steep hill, Muang means city and Changwat means province. ABSTRACT: Phatthalungoceras srisuki gen. et sp. nov. (Orthoceratidae) has been collected from Khao Ok-Thalu, Chaiburi Formation, Triassic Strata in Phatthalung province, in eastern peninsular Thailand and is described as a new genus and species based on the characteristics of the internal mold of the phragmocone. The new genus is distinguished from other family members by its elliptical cross section of the conch as well as suborthochoanitic septal neck and free endosiphuncular deposit. Ornamentation is absent. Keywords: new genus, new species, Triassic, nautiloid, Thailand.
Transcript
Phuket mar. biol. Cent. Res. Bull. 75: 13–18 (2018)
Phatthalungoceras srisuki A NEW GENUS AND SPECIES OF TRIASSIC NAUTILOID CEPHALOPOD (CEPHALOPODA, ORTHOCERATOIDEA, ORTHOCERATIDAE) FROM
EASTERN PENINSULAR THAILAND
Kittichai Tongtherm1 and Jaruwat Nabhitabhata2*
1 Department of Biology, Faculty of Science, Prince of Songkla University, Hatyai, Songkhla 90112, Thailand
2 Excellence Centre for Biodiversity of Peninsular Thailand (CBIPT), Faculty of Science,Prince of Songkla University, Hatyai, Songkhla 90112, Thailand
The eastern part of peninsular Thailand geologically belongs to the Shan-Thai or Sibumasu microplate or terrane (DMR, 2001; 2014). Khao Ok-Thalu or Khao Thammalai in Phatthalung province (Changwat Phatthalung; 07º37´N, 100º 05´E) is one of several isolated limestone monadnock scattered in the Quaternary plain of the Phatthalung area. The hill is about 2 km in length with a 245 m peak above sea level and is located at the 100º longitude line, about 2 km northeast of Amphoe Muang Phatthalung, (Fig. 1). The marine carbonate rocks in the area belong to the Chaiburi Formation, which are of Early to Late Triassic age based on micropaleontological evidence (Ampornmaha, 1995; Sardsud, 2001; Sardsud et al., 2017). Khao Ok-Thalu belongs to the lower/middle/upper member of the Chaiburi Formation, the Chiak Limestone Member, which consists of laminated mudstone and bioclastic mudstone. These strata strike N10°W and dip 55-60°E (DMR, 2001; 2014; Sardsud, 2001). Fossils of radiolarians, ostracods, gastropods and echino-
calcite cement, and geopetal fabrics (Ampornmaha, 1995; Sardsud, 2001). Conodonts date this member as Early Anisian to Late Carnian (Sardsud, 2002; Sardsud et al., 2017). Cephalopod fossils in Thailand are known from only a few localities. In peninsular Thailand,
nautiloids have been recorded only from Ordovician Silurian, Carboniferous and Triassic strata (Tongtherm et al., 2016a; b; 2017). Moreover, previous records of Anisian Triassic orthocerids elsewhere are relatively rare. The present specimen of this nautiloid fossil was collected from Khao Ok-Thalu, Phatthalung province (Changwat Phatthalung), peninsular Thailand as an outcrop fossil by Mr. Paladej Srisuk.
MATERIALS AND METHODS
One specimen of nautiloid fossil was collected from Khao Ok-Thalu, Phatthalung province (Changwat Phatthalung), peninsular Thailand (07o37´N, 100o05´E) (Fig. 1), by Mr. Paladej Srisuk on 2 September 1973. The systematic terminology of morphology and measurements generally follows Teichert et al. (1964). The description of nautiloid specimens was made using the following abbreviations for shell dimensions: Pl = Phragmocone length, Paw = Phragmocone anterior width, Ppw = Phragmocone posterior width, Nc = Number of chambers, Cl = Chamber length. The type specimen is deposited in Palaeontological Research and Education Centre, Mahasarakham University (PRC), Thailand, with
or steep hill, Muang means city and Changwat means province.
ABSTRACT: Phatthalungoceras srisuki gen. et sp. nov. (Orthoceratidae) has been collected from Khao Ok-Thalu, Chaiburi Formation, Triassic Strata in Phatthalung province, in eastern peninsular Thailand and is described as a new genus and species based on the characteristics of the internal mold of the phragmocone. The new genus is distinguished from other family members by its elliptical cross section of the conch as well as suborthochoanitic septal neck and free endosiphuncular deposit. Ornamentation is absent.
Keywords: new genus, new species, Triassic, nautiloid, Thailand.
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Figure 1. Type locality; Khao Ok-Thalu, Changwat Phatthalung, Peninsular Thailand: 1. Phukhaothong Dolomite, Khao Khuha-Sawan; 2. Chiak Limestone Member, the eastern zone of Khao Ok-Thalu; 3. Specimen
RESULTS
Order Orthocerida Kuhn, 1940Family Orthoceratidae M’Coy, 1844
Phatthalungoceras gen. nov.Fig. 2
Tienoceras sp. A; Tongtherm et al
Tienoceras sp. A; Tongtherm et al
Type species: Phatthalungoceras srisuki sp. nov., designated herein.
Material examined Holotype: PRC-SKM-KO-151, Phragmocone internal mold, Phragmocone length 16.97 mm, Chaiburi Formation, Triassic (Anisian), Khao Ok-Thalu, Changwat Phatthalung, Peninsular Thailand, 07o37´N, 100o05´E, collector P. Srisuk.
Phatthalungoceras srisuki a new genus and species of Triassic nautiloid cephalopod
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lateral acute angle absent; cameral deposit present, on mural, episeptal and connecting ring; siphuncle
deposit free; suture 1 saddle on dorsum, 2 on ventrum.
Etymology. The name is an arbitrary combination of Phatthalung province (Changwat Phatthalung), the type locality, in combination with the Latin
Remarks. Phatthalungoceras shares many characters of the genus with the Permian Tienoceras but
conch which is lenticular with acute-angular lateral sides in Tienoceras (Chao, 1954; p. 36, pl.
Tienoceras to
was not well preserved. T. lenticulare is the only species of the genus. We suggest that Tienoceras should belong to the Order Orthocerida Kuhn, 1940, Superfamily Orthocerataceae, Family Ortho-ceratidae, based on its orthochoanitic to subortho-choanitic phragmocone and the free endosiphuncular deposit. Such characteristics are also presented in Phatthalungoceras. It is notable that the two
Tienoceras is
1954; Teichert et al., 1964) and Phatthalungoceras is from Triassic strata.
Phatthalungoceras srisuki sp. nov. Fig. 2
Material examined. As for description of genus.
Description. Phragmocone fragment, orthoconic longicone, 4 chambers preserved, length 16.9 mm, conch depressed, ornament absent; cross section width anterior 5.7 mm, posterior 4.5 mm, dorsum
deposit free; suture one dorsal saddle, 2 ventral saddles with 1 median lobe.
Measurements and counts. Pl. 19.7 mm, Paw 5.7 mm, Ppw 4.5 mm, Nc 4 chambers, Cl 2.9 mm.
Etymology. The name ‘srisuki’ (Latin for “Srisuk”) commemorate the type-specimen collector, Paladej Srisuk, Palaeontological Research and Education Centre, Mahasarakham University.
Remarks. The characters that distinguish Phatthalungoceras srisuki from the similar species T. lenticulare have already been discussed on the basis of their generic characters.
DISCUSSION
Phatthalungoceras srisuki and species described from peninsular Thailand. Occurrence of orthocerid nautiloids from Triassic
in this region, the mainland of Southeast Asia.
ACKNOWLEDGEMENTS
The authors would like to thank the Palaeon-tological Research and Education Centre, Ma-hasarakham University, Thailand, for the loan of
Faculty of Science, Prince of Songkla University for their assistance in the laboratory work. Our warmest thanks are dedicated to Dr. Janek von
Research, University of Vienna. This work was
Promotion and National Research University Project
Commission and ASEA-UNINETS research grant, University of Vienna. Also thanks to the late Dr.
with the English language corrections.
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Figure 2. Phatthalungoceras srisukiof the phragmocone with suture on the posterior; 2a. and 2b. cross section of anterior view of the phragmo-
5b. ventral view of the phragmocone with suture on the anterior; 5c. posterior view of the phragmocone with central siphuncle; 5d. cross section in posterior; 5e. and 5f. segmented siphuncle and suborthochoanitic septal neck at the posterior. Scale bar = 10 mm.
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REFERENCES
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Sardsud, A. 2001. Preliminary report on geological survey for standardization of Chaiburi Formation, Changwat Phatthalung. In:
Sardsud, A. 2002. Triassic conodont faunas and zonation in the Chaiburi Formation from the Phattalung area, peninsular Thailand. In:
stratigraphy of the Chaiburi Formation in peninsular Thailand; the early to late Triassic carbonates succession evidence in Shan-Thai Terrane. In: A. Sardsud, K. Khaowiset, D. Saesaengseerung, K. Tongtherm, M. Katthasema, T. Pengtha and I. Chanpheng (eds.). Program and abstract, the 16th th
and D.E.N. Zeller. 1964. Treatise on Invertebrate Palaeontology, Part K Mollusca 3: Cephalopoda-
of America and University of Kansas Press, Kansas. 519 pp. Tongtherm, K., J. Nabhitabhata, P. Srisuk and D. Tannayopas. 2016a. New records of nautiloid cephalopods fossils (Cephalopoda: Orthocerathoidea and Nautiloidea) from Eastern Peninsular Thailand. In: S. Piromwarakorn and S. Maipae (eds.). Proceedings of the Fourth National Marine Science Symposium. Prince of Songkla University, Songkhla. pp. 313–328. Tongtherm, K., J. Nabhitabhata, P. Srisuk, T. Nutadhira and D. Tannayopas. 2016b. New records of nautiloid and ammonoid cephalopod fossils in peninsular Thailand. Swiss J. Palaeontol. 135(1):Tongtherm, K., J. Nabhitabhata, P. Srisuk and T. Nutadhira. 2017. New records of nautiloid cephalopod
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Manuscript received: 10 January 2017Accepted: 9 January 2018
