EARLY TRIASSIC (DIENERIAN) CONODONTS FROM NORTHERN THAILAND AND THEIR BEARING ON THE EVOLUTION OF MULTIELEMENT APPARATUSES

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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 10400
• Petra Lutat
• Palaeontological Research Centre, Mahasarakham
  University, Thailand 44150

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Location of the Phrao field area in northwest
Thailand
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Fossil locality west of Phrao, northwest Thailand
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Narong and Supatta in their
garden
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Narong and Supattas very full garden with almost
no remaining exposure
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PR-48
Bed PR-48 at the Phrao
locality
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PR-50
PR-51
PR-52
Beds 50, 51 and 52 at the Phrao
locality
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Spec.
1a
2a
3a
4a
1a
1b
2b
3b
4b
1c
2c
3c
4c
P1 elements from Bed PR-48, Phrao section,
northwest Thailand. a,
lateral, b, aboral, c, oral views
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7a
8a
5a
6a
7b
8b
5b
6b
5c
6c
7c
8c
P1 elements from Bed PR-48, Phrao section,
northwest Thailand a,
lateral, b, aboral, c, oral views
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9a
10a
11a
12a
9b
10b
11b
12b
9c
10c
11c
12c
P1 elements from Bed PR-48, Phrao section,
northwest Thailand a,
lateral, b, aboral, c, oral views
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Neospathodus sp. A. Bed PR-50, Phrao section,
northwest Thailand, possible apparatus.
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M
S3
S2
P1
S4
S1
S0
P2
Neospathodus sp. B. Bed PR-50, Phrao section,
northwest Thailand, possible apparatus.
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Fused cluster from Bed PR-51, upper and lower
views. Consisting of ?S3, S4, S1, plus an S2 and
a P1.
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Representative P1 elements
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Bed PR-51. Neospathodus concavus
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Bed PR-51. Neospathodus aff. concavus
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Bed PR-51 Neospathodus chaohuensis
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Bed PR-51. Neospathodus ex gr.
chii
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a
a
a
a
a
a
a
a
a
a
A
B
Neospathodus dieneri A, Morphotype 1,
B, Morphotype 2
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B
A
Bed PR-48. Hindeodus parvus A, Side view
B, Oral view
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DMR Field Group Chan, Dr. Apsorn Sardsud,
New, and Oan
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Conclusions Preliminar
y 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.
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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.

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