EARLY TRIASSIC (DIENERIAN) CONODONTS FROM NORTHERN THAILAND AND THEIR BEARING ON THE EVOLUTION OF MULTIELEMENT APPARATUSES Norman M. Savage Geological Sciences, University of Oregon, Eugene, Oregon 97403, USA Michael J. Orchard Geological Survey of Canada, Vancouver, BC, V6B 5J3, Canada Apsorn Sardsud Department of Mineral Resources, Bangkok, Thailand Petra Lutat Palaeontological Research Centre, Mahasarakham University, Thailand 44150

Location of the Phrao field area in northwest Thailand

Fossil locality west of Phrao, northwest Thailand

Narong and Supatta in their garden

Narong and Supatta’s very full garden with almost no remaining exposure

Bed PR-48 at the Phrao locality PR-48

Beds 50, 51 and 52 at the Phrao locality PR-50 PR-51 PR-52

Spe c. 1a 1b 1c 2a 2b 2c 3a 3b 3c 4a 4b 4c P 1 elements from Bed PR-48, Phrao section, northwest Thailand. a, lateral, b, aboral, c, oral views

5a 5b 5c 6a 6b 6c 7a 7b 7c 8a 8b 8c P 1 elements from Bed PR-48, Phrao section, northwest Thailand a, lateral, b, aboral, c, oral views

9a 9b 9c 10a 10c 10b 11a 11b 11c 12a 12b 12c P1 elements from Bed PR-48, Phrao section, northwest Thailand a, lateral, b, aboral, c, oral views

Neospathodus sp. A. Bed PR-50, Phrao section, northwest Thailand, possible apparatus.

Neospathodus sp. B. Bed PR-50, Phrao section, northwest Thailand, possible apparatus. P1 P2 M S1 S2 S3 S4 S0

Fused cluster from Bed PR-51, upper and lower views. Consisting of ?S3, S4, S1, plus an S2 and a P1.

Representative P1 elements

Bed PR-51. Neospathodus concavus

Bed PR-51. Neospathodus aff. concavus

Bed PR-51 Neospathodus chaohuensis

Bed PR-51. Neospathodus ex gr. chii

aaaa a aa a aa A B Neospathodus dieneri A, Morphotype 1, B, Morphotype 2

A B Bed PR-48. Hindeodus parvus A, Side view B, Oral view

DMR Field Group: Chan, Dr. Apsorn Sardsud, New, and Oan

Conclusions Preliminary work suggests this Phrao locality comprises several horizons with important Dienerian apparatuses. The key to understanding the evolution of multielement Lower Triassic conodonts lies in Dienerian collections. The Neospathodus dieneri Sweet 1970 group were amongst the first species from Neogondolella ancestors in the early Induan and represent the major rootstock for many Olenekian conodonts. The faunas include two morphotypes of N. dieneri, plus fewer specimens of N. chii, N. concavus, and ?N. chaohuensis, all recently described from Induan- Olenekian boundary beds at Chaohu, China (Zhao et al., in press). The faunas also contain rare specimens of Neogondolella carinata and Hindeodus parvus, species that have been regarded as casualties of the end- Griesbachian extinction. The abundant Thailand material adds to our understanding of the evolving apparatuses of the Early Triassic but at this preliminary stage in the work it is difficult to confidently differentiate the apparatuses.

Thanks are extended to: Narong and Supatta for allowing access to their garden and permitting us to collect rock samples, and The Geological Survey Division of the Thailand Department of Mineral Resources, Bangkok, and the Palaeontological Research Institute, Mahasarakham University for financial and logistic support, and the drivers, field assistants, and technicians.