The Tiki Formation is a well-known geological formation located in the Rewa-Gondwana Basin of Madhya Pradesh, India. It is a significant lithostratigraphic unit of the Son-Mahanadi Basin, widely recognized for its rich fossil content and its importance in understanding the terrestrial ecosystems of Gondwana during the Late Triassic to Early Jurassic periods.
Location and Stratigraphy: The Tiki Formation is primarily exposed in the northeastern part of the Son-Mahanadi Basin, within the larger framework of the Indian Gondwana Supergroup. It overlies older Permian formations and is typically overlain by younger Jurassic or Cretaceous units. It is part of a sequence of continental sedimentary rocks that record the rifting and subsequent breakup of the supercontinent Gondwana.
Age: The formation is dated to the Late Triassic (Rhaetian stage) to Early Jurassic (Hettangian stage). This age assignment is primarily based on its distinctive fossil assemblages, particularly the flora and vertebrate fauna, which show strong correlations with other Late Triassic-Early Jurassic continental deposits worldwide.
Lithology: The Tiki Formation is predominantly composed of variegated (multicolored) mudstones, shales, and argillaceous sandstones, often exhibiting reddish-brown, buff, and cream hues. It represents a fluvio-lacustrine (river and lake) depositional environment, characterized by fine-grained sediments laid down in broad floodplains and shallow freshwater bodies. Occasional coarser sandstone lenses indicate fluvial channel deposits.
Paleontology: The Tiki Formation is highly significant for its diverse and well-preserved fossil record, making it a key paleontological site in India.
- Vertebrates: It has yielded important early dinosaur fossils, including sauropodomorphs (e.g., Nambalia, Jaklapallisaurus), as well as rhynchosaurids, temnospondyl amphibians, and various fish species (e.g., Ceratodus). These fossils provide crucial insights into the evolution and diversification of terrestrial vertebrates during a pivotal period in Earth's history.
- Invertebrates: Freshwater bivalve crustaceans, known as estheriids, are commonly found.
- Flora: The formation is noted for its distinctive Dicroidium flora, a characteristic plant assemblage of Gondwana during the Mesozoic. Other plant fossils include conifers, cycads, and ferns, indicating a warm, humid climate with extensive vegetation.
Significance: The Tiki Formation provides a critical window into the paleobiodiversity and paleoenvironments of central India during the Triassic-Jurassic transition. Its fossil content helps reconstruct the paleogeography, paleoclimate, and evolutionary patterns of life on the Gondwanan landmass, contributing significantly to our understanding of early dinosaur radiation and the faunal interchange between different continents during the Mesozoic Era.