The Triassic world-wide: Madagascar
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The Indian-Australian-Antartic part of Gondwana started its separation from the African-South American part at the beginning of the Lower Triassic along a rift zone that dates back to the Permian. The resulting graben structures that reached from southern South Africa to what is today India formed a large basin with mainly terrigenous sedimentation. Most of the basin sediments belong to the Karroo Formation. The name derives from the Karroo Basin in South Africa, but important outcrops are also found in Madagascar (which was still part of India during that time). Synsedimentary nodules from the Karroo Formation of northern Madagascar contain astonishingly well-preserved specimens of a Lower Triassic fresh water fish fauna as well as remains of reptiles and amphibians.

Reptile

Barasaurus sp.

Remains of Barasaurus are comparably abundant. Due to the preservation in nodules, mostly trunk fragments are found. Furthermore, most of the bones were dissolved. It's not uncommon that the stomach region still contains gastroliths (lower picture). Those are small pebbles that were swallowed by the carnivorous reptiles to support food digestion by breaking up larger or harder food particles.

Lower Triassic (Karroo Formation), Madagascar
Fish in nodule

Australosomus merlei (PRIEM)

Lower Triassic (Karroo Formation), Anaborana (Madagascar)
Fish in nodule

Ecrinesomus dixoni WOODWARD

Lower Triassic (Karroo Formation), Anaborana (Madagascar)
Fish in nodule

unidentified

Lower Triassic (Karroo Formation), Anaborana (Madagascar)
Crustaceans

unidentified

Because of their thin armour and the bad conditions for preservation within the porous sediment, remains of crustaceans are most often badly preserved.

Lower Triassic (Karroo Formation), Anaborana (Madagascar)
Scale length, if not otherwise stated: 1 cm.