Phuket mar. biol. Cent. Res. Bull 74: 1–12 (2017)

NEW RECORDS OF NAUTILOID CEPHALOPOD FOSSILS FROM

Kittichai Tongtherm1, Jaruwat Nabhitabhata2*, Paladej Srisuk3, Thammarat Nutadhira4

1Department of Biology, Faculty of Science, Prince of Songkla University, Hatyai, 90112, Thailand 2Excellence Centre for Biodiversity of Peninsular Thailand (CBIPT), Faculty of Science, Prince of Songkla University, Hatyai, Songkhla 90112, Thailand 3Palaeontological Research and Education Center, Mahasarakham University, Kantarawichai, Mahasarakham 44150, Thailand 4Natural History Museum, Kampangwittaya School, La-ngu, Satun 91110, Thailand *Corresponding Author: Jaruwat Nabhitabhata E-mail: [email protected], [email protected]

ABSTRACT: Sixteen taxa of nautiloid cephalopods were recorded based on fossils from Ordovician, ?Silurian-Devonian, Carboniferous and Triassic strata in Peninsular Thailand. The fauna comprised Nautiloid gen. et sp. indet. I, Nautiloid gen. et sp. indet. II, Nautiloid gen. et sp. indet. III, Nautiloid gen. et sp. indet. IV, Ormoceras bayfieldi Stokes, 1836, Orthocerida gen. et sp. indet., Orthocerataceae gen. et sp. indet. I, Orthocerataceae gen. et sp. indet. II, Orthocerataceae gen. et sp. indet. III, Orthocerataceae gen. et sp. indet. IV, Michelinoceratinae gen. et sp. indet., Chidleyenoceras sp. indet., Tainocerataceae gen. et sp. indet., Trigonoceratidae gen. et sp. indet., Aipoceratidae gen. et sp. indet. and Nautilaceae gen. et sp. indet. Although most of the studied taxa were indeterminate species due to poor preservations of specimens, all taxa are new records for Thailand.

Keywords: new records, nautiloid cephalopod, fossil, Thailand.

INTRODUCTION Thailand, including 20 taxa from Peninsular Thailand (Tongtherm et al., 2016). Peninsular Thailand is situated in the southern The first record of nautiloid cephalopod fossils part of Thailand with Paleozoic and Mesozoic was Actinoceras sp. from Ordovician strata in Nakhon rocks being distributed along a north-south axis Si Thammarat Province, in the eastern part of the (Fig. 1). The stratigraphic successions are found in peninsula (Brown et al. 1951). Kobayashi (1958) the Phuket Mountain range and and Pitakpaiwan et al. (1969) described a new Mountain range (Wongwanich et al., 2002; Cocks taxon, Armenoceras chediforme Kobayashi, 1958 et al., 2005). The Ordovician Rocks are deep-water from , . facies of shales and limestones, distributed in the Pitakpaiwan et al. (1969) reported four species lower part of the peninsular (Wongwanich et al., of Ordovician nautiloids from western, central to 1983; DMR, 2013). The rocks of the Late Silurian , from to Nakhon to Early Carboniferous are shallow-water facies Si Thammarat Province. Teraoka et al. (1982) of sandy marl, black shale, calcareous siltstone reported the Ordovician Endoceroid sp. from Satun and nodular limestones with uncertain age (Wong- Province (southern Thailand). Stait and Burrett wanich et al., 2002; DMR, 2001; 2013). The (1984) reported seven Ordovician nautiloids from carbonate formations of Triassic rocks occur only western and southern Thailand, including a new in Phattalung Province (Ampornmaha, 1995; Sardsud, taxon, Machuroceras nakamense Stait and Burrett, 2001). The nautiloid fossils were recorded from 1984 from Nakhon Si Thammarat Province. The the Ordovician to Triassic strata in Thailand. nautiloid with the oldest age in Thailand is Currently, 27 taxa of nautiloids are recorded in Endoceratidae gen. et sp. indet. from stromatolitic 2

Phuket mar. biol. Cent. Res. Bull limestones of Lower Ordovician strata in Tarutao Specimens were from eleven localities in Island, (Stait and Burrett, 1984). Peninsular Thailand (Fig. 1, Table 1). The first Ingavat-Helmcke (1994) reported five species of three localities were on the Gulf of Thailand coast: Ordovicain and Silurian nautiloids from northern 1) Khao Phanomsherd (KPC; N 08o 09´, E 99o 51´), to southern Thailand. Ishibashi et al., 1994 cited Ron Phibun District, Nakhon Si Thammarat Province, after DMR, 2006) described a new Middle with Rung Nok Formation, Thung Song Group, Permian taxon, Siamnautilus ruchae Ishibashi et Lower Ordovician (Arenigian) Strata (Wongwanich al., 1994 from Province, . et al., 1983, 1990; DMR, 2001, 2013); 2) Khuan DMR (2006) reported three species of Ordovician Kruad (KN; N 07o 70´ E 99o 85´), Si Banphot and Permian nautiloids from northern to southern District, Province, with indeterminate Thailand. Ridd et al. (2011) recorded the first strata of Silurian to Devonian (DMR, 2001); and nautiloid of the , Michelinoceras 3) Khao Ok-thalu (KO; N 07o 37´ E 100o 5´), Muang micheline (Barrande, 1866) from Permian to Triassic District, Phatthalung Province with Phukhaothong Strata, Province. Tongtherm, et al. (2016) Dolomite, Chaiburi Formation, Lampang Group, recorded two Ordovician nautiloids, Sactorthoceras Early to Middle Triassic (Anisian) (Ampornmaha banestanensis Evans, 2006 from Satun Province 1995, Sardsud, 2001). Localities 4‒6 were on the (western part of the peninsular) and Mediganella Andaman Sea coast (western part) of the peninsular magna Teichert and Glenister, 1952 from Nakhon in La-ngu District, Satun Province, Rung Nok Si Thammarat Province and four Triassic nautiloids, Formation, Thung Song Group, Lower Ordovician including Michelinoceras sp. A, Tienoceras sp. A, (Arenigian) (Wongwanich et al., 1983, 1990; DMR, Syringoceras barrandei (Hauer, 1847) and Juvavi- 2001, 2013). Locality 4 was in a private rubber onautilus heterophyllus (Hauer, 1849) from Phatthalung plantation (N 06° 91´ E 99° 77´). Locality 5 was Province, eastern part of Peninsular Thailand. Khao Junungnui (N 06o 95´ E 99o 79´). Locality 6 was Khao Dang (N 06° 54´ E 99° 46´). The seventh MATERIALS AND METHODS to ninth localities were in La-ngu District, Satun Province, Upper Ordovician deposits, including in A total of 59 specimens of nautiloid fossils the Pa Kae Formation, Thung Song Group (Wong- were studied. The terminology used in describing wanich et al., 1983; DMR, 2001). Locality 7 was morphology, morphometric measurements and the canal bank behind Ban Tha-rae (N 06° 56´ E indices essentially followed Arkell et al. (1957) 99° 46´). Locality 8 was Khao To-ngai (N 06° and Teichert et al. (1964). 50´ E 99° 46´). Locality 9 was Khao Noi (N Materials are from 3 sources. 1) The Palae- 06° 97´ E 99° 77´). The tenth to eleventh localities ontological Research and Education Center, were in also in La-ngu District, Satun Province, but Mahasarakham University (PRC, PRC-SHM), with Lower Carboniferous strata where deposits Mahasarakham Province (northeastern Thailand). were the Pa Samed Formation, Thong Pha Phum The specimens were collected by the third author Group (Wongwanich et al., 1983, 2002; DMR, 2001). (PS) from southern Thailand during 1973–1974 as Locality 10 was Khao Kuanthang (N 06o 96´ E 99o unidentified outcrop fossils. 2) The collections of 76´). Locality 11 was Khao Banhan (N 06° 93´ E the Natural History Museum, Kampang Wittaya 99° 79´). School (KPNHM), Satun Province (southwestern All voucher specimens have been catalogued Thailand), collected by the fourth author (TN) by KT and JN and afterwards, deposited in the during 2004‒2012. 3) in situ records from the field reference collections of PRC and the KPNHM. survey (ISI-LN-ST) in Peninsular Thailand by KT Thai word used in the text is Khao (= Mountain). (Kittichai Tongtherm), JN (Jaruwat Nabhitabhata) and TN (Thammarat Nutadhira). 3

New records of nautiloid cephalopod fossils from Thailand

Figure 1. Localities considered in the present study in Peninsular Thailand: Nakhon Si Thammarat Province (1 locality); Phatthalung Province (2 localities); Satun Province (8 localities) (modified from: DMR 2001). 4

Phuket mar. biol. Cent. Res. Bull

Table1. Localities and stratigraphy considered in the present study in Peninsular Thailand (Wongwanich et al., 1983, 1990, 2002; Ampornmaha, 1995; Sardsud, 2001; DMR, 2001, 2013).

Province District Locality Member Formation Group Period

Nakhon Si Ron Phibun Khao Rung Nok Thung Song L. Ordovician Thammarat Phanomsherd Phatthalung Si Banphot ?Khuan Kruad ?Silurian- Devonian Muang Khao Ok-thalu Phukhaothong Chaiburi Lampang L. to M. Triassic Phatthalung Dolomite

Satun La-ngu Rubber Rung Nok Thung Song L. Ordovician plantation Khao Junungnui Rung Nok Thung Song L. Ordovician

Khao Dang Rung Nok Thung Song L. Ordovician

canal behind Ban Pa Kae Thung Song U. Ordovician Tha-rae Khao To-ngai Pa Kae Thung Song U. Ordovician

Khao Noi Pa Kae Thung Song U. Ordovician

Khao Kuanthang Pa Samed Thong Pha L. Carboniferous Phum Khao Banhan Pa Samed Thong Pha L. Carboniferous Phum

RESULTS N 06° 50´ E 99° 46´, collector T. Nutadhira; PRC- SHM-KN-003, phragmocone length 13.7 mm, Nautiloid gen. et sp. indet. I ?Silurian-?Devonian, ?Khuan Kruad, Si Banphot (Fig. 2a, b) District, Phatthalung Province, N 07o 70´ E 99o 85´, collector P. Srisuk; KPNHM-025, phragmocone Material examined: 14 specimens; ISS-LN-ST-001 length 150.0 mm, Pa Samed Formation, Thong and 002, phragmocone length 111.0‒180.0 mm, Pha Phum Group, Lower Carboniferous, Khao Rung Nok Formation, Thung Song Group, Lower Kuanthang, La-ngu District, Satun Province, N Ordovician, private rubber plantation, La-ngu 06o 96´ E 99o 76´, collector T. Nutadhira; PRC- District, Satun Province, N 06° 91´ E 99° 77´, collector SHM-KO-112, 124, 149, 150, 152, 155 and 156, T. Nutadhira; ISS-LN-ST-007, phragmocone length phragmocone length 9.5‒43.0 mm, Phukhaothong 40.0 mm, Pa Kae Formation, Thung Song Group, Dolomite Member, Chaiburi Formation, Triassic, Upper Ordovician, canal bank behind Ban Tha-rae, Khao Ok-thalu, Phatthalung Province, N 07o 37´ E La-ngu District, Satun Province, N 06° 56´ E 99° 100o 5´, collector P. Srisuk. 46´, collector T. Nutadhira; ISS-LN-ST-008 and 009, phragmocone length 80.0‒190.0 mm, Pa Kae Description: Phragmocone fragment, orthoconic Formation, Thung Song Group, Upper Ordovician, longicone, slender, length 9.5‒190.0 mm, width Khao To-ngai, La-ngu District, Satun Province, anterior 4.9‒60.0 mm, 31.6‒52.1% of length, 5

New records of nautiloid cephalopod fossils from Thailand posterior 2.6‒42.0 mm, 22.1‒27.2% of length, Remarks: The chamber length of Nautiloid gen. shell wall not preserved; chambers distant, length et sp. indet. I of 32.0‒62.5% of width was larger 2.1‒20.0 mm, 32.0‒62.5% of phragmocone width, than Nautiloid gen. et sp. indet. II, Nautiloid gen. 2‒12 chambers preserved; cameral deposit free; et sp. indet. III and Nautiloid gen. et sp. indet. IV siphuncle central, stenosiphonate, diameter 1.1‒4.0 mm, 10.9‒25.0% of phragmocone width.

Figure 2. a, b Nautiloid gen. et sp. indet. I; PRC-SHM-KN-003, lateral view; c, d Nautiloid gen. et sp. indet. II; PRC-SHM-KPC-001, lateral view; e, f Nautiloid gen. et sp. indet. III; PRC-SHM-KPC-004, lateral view; g, h Nautiloid gen. et sp. indet. IV; PRC-SHM-KO-322, lateral view; i–k Ormoceras bayfieldi Stokes, 1836; ISS-LN-ST-044, (i) lateral view, (j, k) crytochoanitic septal neck; l, m Orthocerida gen. et sp. indet.; PRC-SHM-KPC-005, lateral view; n, o Orthocerataceae gen. et sp. indet. I; PRC-SHM-KPC-017, lateral view; p, q Orthocerataceae gen. et sp. indet. II; PRC-SHM-KPC-019, lateral view. 6

Phuket mar. biol. Cent. Res. Bull

Nautiloid gen. et sp. indet. II District, Nakhon Si Thammarat Province, N 08o (Fig. 2c, d) 09´ E 99o 51´, collector P. Srisuk.

Material examined: 8 specimens; PRC-SHM- Description: Phragmocone fragment, orthoconic KPC-001, 013 and 016, phragmocone length longicone, slender, length 11.1‒26.6 mm, width 8.3‒45.7 mm, Rung Nok Formation, Thung Song anterior 11.3‒17.6 mm, 42.4‒66.1% of length, Group, Lower Ordovician, Khao Phanomsherd, posterior 10.1 mm, 38.0% of length, surface an- Ron Phibun District, Nakhon Si Thammarat Province, nulated transverse, width 1.1‒1.8 mm, 9.9‒10.3% N 08o 09´ E 99o 51´, collector P. Srisuk; ISS-LN- of phragmocone width, cross section circular; ST-003 & 004, phragmocone length 50.0‒400.0 chamber dense, length 1.8‒4.0 mm, 17.2‒22.7% mm, Rung Nok Formation, Thung Song Group, of phragmocone width, 4‒12 chambers preserved; Lower Ordovician, private rubber plantation, siphuncle marginal, eurysiphonate, expanded, La-ngu District, Satun Province, N 06° 91´ E 99° segmented, diameter 4.6 mm, 43.3% of phragmocone 77´, collector T. Nutadhira; KPNHM-033, phrag- width. mocone length 260.00 mm, Rung Nok Formation, Thung Song Group, Lower Ordovician, Khao Remarks: The characteristic of transverse annulated Junungnui, La-ngu District, Satun Province, N surface of Nautiloid gen. et sp. indet. III was absent 06o 95´ E 99o 79´, collector T. Nutadhira; ISS-LN- in Nautiloid gen. et sp. indet. I, Nautiloid gen. ST-005, phragmocone length 60.0 mm, Pa Kae et sp. indet. II and Nautiloid gen. et sp. indet. IV. Formation, Thung Song Group, Upper Ordovician, canal bank behind Ban Tha-rae, La-ngu District, Nautiloid gen. et sp. indet. IV Satun Province, N 06° 56´ E 99° 46´, collector (Fig. 2g, h) T. Nutadhira; ISS-LN-ST-006, phragmocone length 130.0 mm, Pa Kae Formation, Thung Song Group, Material examined: 1 specimen; PRC-SHM-KO-322, Upper Ordovician, Khao To-ngai, La-ngu District, phragmocone length 16.0 mm, Phukhaothong Satun Province, N 06° 50´ E 99° 46´, collector Dolomite Member, Chaiburi Formation, Triassic, T. Nutadhira. Khao Ok-thalu, Phatthalung Province, N 07o 37´ E 100o 5´, collector P. Srisuk. Description: Phragmocone fragment, orthoconic longicone, subslender, length 8.3‒400.0 mm, width Description: Phragmocone fragment, crytoconic anterior 8.2‒70.0 mm, 17.5% of length, posterior longicone, slender, length 16.0 mm, width anterior 2.0‒44.0 mm, 11.0% of length, shell wall not 7.0 mm, 43.8% of length, posterior 5.5 mm, 34.4% preserved; chambers dense, length 1.4‒5.3 mm, of length; lirae presented, S-shape, thin, dense; 8.8‒28.6% of phragmocone width, 6‒54 chambers siphuncle central, stenosiphonate, diameter 1.0 mm, preserved; cameral deposit free; siphuncle central, 16% of phragmocone width. stenosiphonate, diameter 1.0 mm, 14.3% of phrag- mocone width. Remarks: The crytoconic longicone phragmocone of Nautiloid gen. et sp. indet. IV was unique. Remarks: The chamber length of Nautiloid gen. et sp. indet. II was much shorter than that of Nau- Subclass Actinoceratoidea Teichert, 1933 tiloid gen. et sp. indet. I (8.8‒28.6 vs. 32.0‒62.5% Order Actinocerida Teichert, 1933 of phragmocone width). Family Ormoceratidae Saemann, 1853 Ormoceras bayfieldi Stokes, 1836 Nautiloid gen. et sp. indet. III (Fig. 2i, j, k) (Fig. 2e, f) Ormoceras bayfieldi; Foerste, 1924. pl. 3, figs. 1 Material examined: 2 specimens; PRC-SHM- A, B, text fig. 1 KPC-004 & 015, phragmocone length 11.1–26.6 mm, Rung Nok Formation, Thung Song Group, Material examined: 1 specimen; ISS-LN-ST-044, Lower Ordovician, Khao Phanomsherd, Ron Phibun phragmocone length 136.00 mm, Rung Nok 7

New records of nautiloid cephalopod fossils from Thailand

Formation, Thung Song Group, Lower Ordovician, episeptal thick, hyposeptal thin, connecting ring Khao Dang, La-ngu District, Satun Province, N thin, cylindrical; siphuncle marginal, expanded, 06° 54´ E 99° 46´, collector T. Nutadhira. segmented, eurysiphonate, diameter 6.4 mm, 32.0% of phragmocone width, endosiphuncular deposit free. Description: Phragmocone fragment, slightly crytoconic longicone, slender; length 136.0 mm, Remarks: The siphuncles of present specimens width anterior 36.0 mm, 26.5% of length, posterior were well preserved. 21.0 mm, 15.4% of length; chambers dense, length 6.0 mm, 21.1% of phragmocone width, 20 chambers Superfamily Orthocerataceae M’Coy, 1844 preserved; septal neck crytochoanitic, recumbent, Orthocerataceae gen. et sp. indet. I length 2.0 mm, 7.0% of phragmocone width; septum (Fig. 2n, o) one-third of chamber length, adnation area short, width 1.5 mm, 5.3% of phragmocone width; brim Material examined: 1 specimen; PRC-SHM-KPC-017, narrow, width 1.5 mm, 5.3% of phragmocone width; phragmocone length 37.4 mm, Rung Nok Formation, siphuncle central, expanded, segmented, eurysi- Thung Song Group, Lower Ordovician, Khao phonate, diameter 11.0 mm, 38.6% of phragmocone Phanomsherd, Ron Phibun District, Nakhon Si width; deposit annulosiphonate, width 6.0 mm, Thammarat Province, N 08o 09´ E 99o 51´, collector 10.5% of phragmocone width. P. Srisuk.

Remarks: The phragmocone etc length of present Description: Phragmocone fragment, orthoconic specimen was much longer than the holotype longicone, length 37.4 mm, slender, width anterior reported by Foerste (1924) (136.0 vs. 60.0 mm), 5.4 mm, 14.4% of length, posterior 4.4 mm, 11.7% but the siphuncle diameter indices were similar of length, cross section circular; siphuncle central, (38.6 vs. 31.4% of phragmocone width). stenosiphonate, diameter 1.1 mm., 21.8% of phragmocone width; endosiphuncular deposit free. Subclass Orthoceratoidea M’Coy, 1844 Order Orthocerida Kuhn, 1940 Remarks: The phragmocone shape of Ortho- Orthocerida gen. et sp. indet. cerataceae gen. et sp. indet. I was slender with a (Fig. 2l, m) width of less than 15% of length. The siphuncle was also slender with a diameter of less than 30% Material examined: 3 specimens; PRC-SHM- of width. KPC-005, phragmocone length 16.4 mm, Rung Nok Formation, Thung Song Group, Lower Orthocerataceae gen. et sp. indet. II Ordovician, Khao Phanomsherd, Ron Phibun (Fig. 2p, q) District, Nakhon Si Thammarat Province, N 08o 09´ E 99o 51´, collector P. Srisuk; ISS-LN-ST-013, Material examined: 2 specimens; PRC-SHM-KPC phragmocone length 60.0 mm, Rung Nok Formation, 019, phragmocone length 16.6 mm, Rung Nok Thung Song Group, Lower Ordovician, Khao Dang, Formation, Thung Song Group, Lower Ordovician, La-ngu District, Satun Province, N 06° 54´ E 99° Khao Phanomsherd, Ron Phibun District, Nakhon 46´, collector T. Nutadhira; KPNHM-001, phrag- Si Thammarat Province, N 08o 09´ E 99o 51´, mocone length 30.0 mm, Pa Kae Formation, Thung collector P. Srisuk; ISS-LN-ST-012, phragmocone Song Group, Upper Ordovician, Khao Noi, La-ngu length 100.0 mm, Pa Kae Formation, Thung Song District, Satun Province, N 06° 97´ E 99° 77´, collector Group, Upper Ordovician, Khao To-ngai, La-ngu T. Nutadhira. District, Satun Province, N 06° 50´ E 99° 46´, collector T. Nutadhira. Description: Phragmocone fragment, orthoconic longicone, length 16.4–60.0 mm, slender; width Description: Phragmocone fragment, orthoconic anterior 14.0–28.0 mm, 46.7–85.7% of length, posterior longicone, length 16.6–100.0 mm, width anterior 5.0–11.0 mm, 18.3–30.4% of length, cross section 8.0–20.0 mm, 20.0–48.1% of length, posterior oval; chambers dense, length 2.0–3.0 mm, 11.0–24.0% 5.2 mm, 5.2–31.2% of length, cross section sub- of phragmocone width, 5–10 chambers preserved, circular; chambers dense, length 1.0 mm, 15.6% 8

Phuket mar. biol. Cent. Res. Bull of phragmocone width, 16 chambers preserved; Khao To-ngai, La-ngu District, Satun Province, siphuncle marginal, broad, eurysiphonate, diameter N 06° 50´ E 99° 46´, collector T. Nutadhira; 2.3 mm, 34.5% of phragmocone width; endosip- PRC-SHM-KO-679 to 682, phragmocone length huncular deposit free. 13.0–41.7 mm, Phukhaothong Dolomite Member, Chaiburi Formation, Triassic, Khao Ok-thalu, Remarks: The chambers of Orthocerataceae gen. Phatthalung Province, N 07o 37´ E 100o 5´, collector et sp. indet. II were dense with a length of about P. Srisuk. 15% of the width. The siphuncle diameter was much larger with diameter of more than 34.5% of Description: Phragmocone fragment, orthoconic width compared to 21.8% in Orthocerataceae gen. longicone, length 13.0–85.0 mm, slender, width et sp. indet. I. anterior 8.0–24.0 mm, 28.2–61.5% of length, posterior 5.0–14.0 mm, 16.4–38.4% of length, Orthocerataceae gen. et sp. indet. III surface smooth, ornament absent; chambers distant, (Fig. 3a, b) length 4.0–9.3 mm, 37.5–88.8% of phragmocone width, 2–13 chambers preserved; connecting ring Material examined: 8 specimens; ISS-LN-ST-010 thin; cameral deposit present, hyposeptal thicker and 018, phragmocone length 30.0–60.0 mm, Pa than episeptal and mural; siphuncle central, broad, Kae Formation, Thung Song Group, Upper stenosiphonate, diameter 2.0 mm, 17.4% of phrag- Ordovician, canal bank behind Ban Tha-rae, La- mocone width. ngu District, Satun Province, N 06° 56´ E 99° 46´, collector T. Nutadhira; ISS-LN-ST-011 and 014, Remarks: The chamber length of 37.8–88.8% of phragmocone length 30.0–85.0 mm, Pa Kae width of this taxon, was much longer compared to Formation, Thung Song Group, Upper Ordovician, less than 20% of Orthocerataceae gen. et sp. indet.

Figure3. a, b Orthocerataceae gen. et sp. indet. III; PRC-SHM-KO-679, lateral view; c, d Orthocerataceae gen. et sp. indet. IV; ISS-LN-ST-016, lateral view; ISS-LN-ST-016; e Michelinoceratinae gen. et sp. indet.; PRC-SHM-KN-002, lateral view; f, g Chidleyenoceras sp. indet.; KPNHM-022, (f) lateral view, (g) suture; h Tainocerataceae gen. et sp. indet.; KPNHM-029, lateral view; i Trigonoceratidae gen. et sp. indet.; PRC- SHM-KO-683, lateral view; j Aipoceratidae gen. et sp. indet.; PRC-SHM-KO-684, lateral view; k Nautilaceae gen. et sp. indet.; KPNHM-026, lateral view 9

New records of nautiloid cephalopod fossils from Thailand

Orthocerataceae gen. et sp. indet. IV Description: Phragmocone fragment, orthoconic (Fig. 3c, d) brevicone, length 15.6 mm, width anterior 6.2 mm, 39.8% of length, posterior 4.6 mm, 29.4% of Material examined: 10 specimens; KPNHM-002, length, whorl section oval; cameral deposit present, 023, 031 and 032, phragmocone length 58.0 mm, episeptal and mural thin, 9.1% of phragmocone Rung Nok Formation, Thung Song Group, Lower width, hyposeptal thick, 13.2% of phragmocone Ordovician, Khao Dang, La-ngu District, Satun width; chambers dense, length 2.9 mm, 53.9% of Province, N 06° 54´ E 99° 46´, collector T. Nutadhira; phragmocone width, 3 chambers preserved; septal ISS-LN-ST-016 and 017, phragmocone length neck orthochoanitic; siphuncle central, segmented, 40.0–120.0 mm, Pa Kae Formation, Thung Song slightly expanded, stenosiphonate, diameter 0.9 mm, Group, Upper Ordovician, Khao To-ngai, La-ngu 15.9% of phragmocone width; endosiphunclular District, Satun Province, N 06° 50´ E 99° 46´, deposit present, parietal. collector T. Nutadhira; ISS-LN-ST-019 to 022, phragmocone length 30.0–105.0 mm, Pa Kae Remarks: The generic character of septal neck Formation, Thung Song Group, Upper Ordovician, length was not preserved. canal bank behind Ban Tha-rae, La-ngu District, Satun Province, N 06° 56´ E 99° 46´, collector T. Subclass Nautiloidea Agassiz, 1874 Nutadhira. Order Barrandeoceratida Flower in Flower and Kummel, 1950 Description: Phragmocone fragment, orthoconic Family Apsidoceratidae Hyatt, 1884 longicone, slender, length 30.0–400.0 mm, width Chidleyenoceras sp. indet. anterior 11.0–70.0 mm, 17.5–36.7% of length, (Fig. 3f, g) posterior 8.0–30.0 mm, 7.5–26.7% of length; chambers distant, length 5.0–30.0 mm, 33.3–48.3% Material examined: 1 specimen; KPNHM-022, of phragmocone width, 4–14 chambers preserved; diameter 50.0 mm, Pa Samed Formation, Thong cameral deposit present, hyposeptal and episeptal Pha Phum Group, Lower Carboniferous, Khao equal thick, 1.3–4.5 mm, mural thin, 1.0–3.0 mm; Banhan, La-ngu District, Satun Province, N 06° siphuncle central, broaded, stenosiphonate, diameter 93´ E 99° 79´, collector T. Nutadhira. 1.8–3.2 mm, 10.7–12.4% of phragmocone width; endosiphuncular deposit free. Description: Phragmocone fragment, tarphycone, diameter 50.0 mm, whorl not overlapped, height Remarks: The Orthocerataceae gen. et sp. indet. 9.7 mm, 19.4% of diameter; umbilicus expanded, IV was similar to Orthocerataceae gen. et sp. indet. diameter 23.5 mm, 47.0% of diameter; chambers I, but the equal thickness of hyposeptal and episeptal distant, length 7.4 mm, 14.7% of diameter; protoconch deposits of the former taxon differed from the circular; suture round, lateral lobe present (L1). different thickness in the latter taxon. The size of present specimens with a wide range represented Remarks: The characteristics of Chidleyenoceras sp. different regions of the phragmocones. indet. were similar to the Ordovician Chidleyenoceras chodleyense (Foerste, 1928) (Teichert et al., 1964) in Family Orthoceratidae M’Coy, 1844 overall. However, species diagnostic characters of Subfamily Michelinoceratinae Flower, 1945 the phragmocone surface and the septal neck were Michelinoceratinae gen. et sp. indet. not preserved in the present specimen. (Fig. 3e)

Material examined: 1 specimen; PRC-SHM-KN-002, phragmocone length 15.7 mm, ?Silurian-?Devonian, ?Khuan Kruad, Si Banphot District, Phatthalung Province, N 07o 70´ E 99o 85´, collector P. Srisuk. 10

Phuket mar. biol. Cent. Res. Bull

Order Nautilida Agassiz, 1874 Superfamily Aipocerataceae Hyatt, 1883 Superfamily Tianocerataceae Hyatt, 1883 Family Aipoceratidae Hyatt, 1883 Tainocerataceae gen. et sp. indet. Aipoceratidae gen. et sp. indet. (Fig. 3h) (Fig. 3j)

Material examined: 3 specimens; KPNHM-027, Material examined: 1 specimen; PRC-SHM-KO-684, 029 and 030, diameter 32.0–50.0 mm, Pa Samed diameter 23.5 mm, Phukhaothong Dolomite Formation, Thong Pha Phum Group, Lower Member, Chaiburi Formation, Triassic, Khao Carboniferous, Khao Banhan, La-ngu District, Ok-thalu, Phatthalung Province, N 07o 37´ E 100o 5´, Satun Province, N 06° 93´ E 99° 79´, collector collector P. Srisuk. T. Nutadhira. Description: Phragmocone fragment; evolute, Description: Phragmocone fragment, evolute, diameter 23.5 mm, whorl section circular, height diameter 32.0–50.0 mm, whorl height 10.0–14.0 8.5 mm, 29.5% of diameter, width 8.4 mm, 35.8% mmm, 20.0–37.5% of diameter; umbilicus closed, of diameter, venter rounded, smooth; umbilicus fairly evolute, 18.0–42.0 mm, 43.9–84.0% of expanded, circular, diameter 11.6 mm, 49.3% of diameter, circular; septum straight; suture lobes diameter; ornamentation smooth; chambers distant, slightly shallow. length 4.3 mm, 51.1% of diameter; cameral deposit free; suture s-shape. Remarks: The identification relied on only characteristics of the umbilicus and septum. Remarks: The identification was based on the absence of ornamentation and the s-shape of Superfamily Trigonoceratidae Hyatt, 1884 suture. Other generic and specific characteristics Family Trigonoceratidae Hyatt, 1884 were not preserved. Trigonoceratidae gen. et sp. indet. (Fig. 3i) Superfamily Nautilaceae de Blainville, 1825 Nautilaceae gen. et sp. indet. Material examined: 1 specimen; PRC-SHM-KO-683, (Fig. 3k) diameter 25.9 mm, Phukhaothong Dolomite Member, Chaiburi Formation, Triassic, Khao Ok-thalu, Material examined: 2 specimens; KPNHM-026 Phatthalung Province, N 07o 37´ E 100o 5´, collector and 028, diameter 31.0‒36.0 mm, Pa Samed P. Srisuk. Formation, Thong Pha Phum Group, Upper Carboniferous, Khao Banhan, La-ngu District, Description: Phragmocone fragment, evolute, Satun Province, N 06° 56´ E 99° 47´, collector T. diameter 25.9 mm, whorl width 18.0 mm, 69.4% Nutadhira. of diameter, whorl section subquadratic, depressed, surface smooth, ornament absent; umbilicus perforate, Description: Phragmocone fragment, involute, deep, circular, diameter 15.0 mm, 83.4% of phrag- diameter 31.0‒36.0 mm, whorl height 16.0‒18.0 mm, mocone diameter, umbilical zone steep angle; cameral 44.4‒58.1% of diameter; umbilicus closed, circular, deposit absent; chambers dense, length 2.3 mm; narrow, 4.0‒7.0 mm, 12.9‒19.4% of diameter; siphuncle ventral. septum sinous.

Remarks: The specimen was identified from Remarks: The identification was based on the characteristics of the whorl section and umbilicus. narrow umbilicus and the sinous septum. The generic characters of phragmocone surface and ornaments were not preserved. 11

New records of nautiloid cephalopod fossils from Thailand

DISCUSSION We also thank staff of the Excellence Centre for Biodiversity of Peninsular Thailand, Department All taxa of the present studies were new records of Biology, and Princess Maha Chakri Sirindhorn of cephalopod fossils from Thailand, although Natural History Museum, Faculty of Science, most specimens were not well preserved and Prince of Songkla University for their assistance consequently indeterminate to genus and species in the laboratory work. Our warmest thanks are levels, except Ormoceras bayfieldi Stokes, 1836. dedicated to Janek von Byern, Core Facility Cell The sixteen taxa in the present study are additions Imaging and Ultrastructure Research, University of new records of Thai cephalopod fauna comprising of Vienna and Alexander Lukeneder (Naturhisto- 6 taxa recently reported by Tongtherm et al. (2016). risches Museum Wien) for their supervision. This The total number of nautiloid taxa is currently 43 work was also supported by the Higher Education in Thailand and 22 (more than 50%) in the Peninsular Research Promotion and National Research Thailand. University Project of Thailand, Office of the Higher Education Commission and ASEA-UNINETS ACKNOWLEDGEMENTS research grant.

The authors would like to thank the Palaeonto- logical Research and Education Center, Mahasara- kham University, Thailand, for loan of specimens.

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Manuscript received: 10 February 2016 Accepted: 24 November 2016