Diego Basin Early Triassic amniotes (Triassic to of Madagascar)

Where: Diana, Madagascar (13.0° S, 49.3° E: paleocoordinates 44.2° S, 42.2° E)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Couches à Poissons et Ammonites Member (Middle Sakamena Formation), Induan to Induan (252.2 - 247.2 Ma)

• "All previously described tetrapod specimens from the Diego Basin have been collected from the 'Couches à Poissons et Ammonites' (Besairie 1971) suggesting that the material described herein also pertains to this horizon, though this cannot be stated with absolute certainty." The "Couches à Poissons et Ammonites" are equivalent to the Middle Sakamena Formation of the Morondava Basin. "Biostratigraphical correlations based on ammonite faunas indicate referral of the 'Couches à Poissons et Ammonites' to the local Gyronitien Stage (Besairie 1971), which is equivalent to the Induan Stage of the Lower Triassic. This conclusion is supported by comparisons between the vertebrate faunas of Madagascar and the African mainland, which suggest that the Middle Sakamena Formation is intermediate in age between the Lystrosaurus and Cynognathus Assemblage Zones (Battail et al. 1987). Palynological data is also consistent with these interpretations (Wescott and Diggens 1998)." (Ketchum & Barrett, 2004. Canadian Journal of Earth Sciences 41:1-8).

•"The presence of Magniestheria truempyi in the same formation (Shen et al., 2002) indicates an Early Smithian (Olenekian, Early Triassic) age by correlation with the well-constrained Triassic strata of the Germanic Basin (Kozur and Weems, 2010)." (Falconnet et al. 2010. Comptes Rendus Palevol 11:357-369)

•Given the conflicting suggestions of an Induan or early Olenekian age, an Induan–Smithian range is given here.

• member-level stratigraphic resolution

Environment/lithology: coastal; sandy claystone and lenticular sandstone

• " [...] shallow-water marine deposits [...]" (Ketchum & Barrett, 2004).
• " [...] sandy shales with intercalated sandstone lenses that contain terrestrially derived detritus [...]" (Ketchum & Barrett, 2004).

Size class: macrofossils

Preservation: mold/impression, concretion

Reposited in the OUM

Primary reference: H. F. Ketchum and P. M. Barrett. 2004. New reptile material from the Lower Triassic of Madagascar: implications for the Permian–Triassic extinction event. Canadian Journal of Earth Sciences 41(1):1-8 [J. Mueller/T. Liebrecht/T. Liebrecht]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 92493: authorized by Johannes Mueller, entered by Torsten Liebrecht on 16.11.2009

Creative Commons license: CC BY (attribution)

Taxonomic list

Reptilia
  -
Reptilia indet. Laurenti 1768 reptile
OUMNH GX 69, 86, 88, 94, 100, 102
 Eosuchia - Tangasauridae
Tangasauridae indet. Haughton 1924 diapsid
OUMNH GX 63, 68, 72, 73, 77, 78, 80, 81, 83, 84, 87, 89 to 93, 98
? Tangasauridae indet. Haughton 1924 diapsid
OUMNH GX 82
Tangasaurinae indet. Piveteau 1926 diapsid
OUMNH GX 64 to 67, 70, 79
Hovasaurus boulei Piveteau 1926 diapsid
OUMNH GX 71, 74 to 76, 85
 Parareptilia - Owenettidae
Barasaurus besairiei Piveteau 1955 parareptile
OUMNH GX 95, 97, 99, 101