Creatures that crossed an ocean to find India

Subject : Geography

Section: Physical Geography

Context: A species of bat and a primitive lemur(IUCN: Endangered) have been found in Gujarat’s Vastan lignite mine.

Many life forms in Madagascar have affinities to lineages found in India (3,800 km away) rather than Africa (413 km). This posed a ‘difficult enigma’ to naturalists.
Zoologist Philip Sclater was perplexed by the presence of lemurs, their relatives, and their fossils in Madagascar and India, but not in nearby Africa or the Middle East.

Continental drift

In plate tectonics, the large rocky plates that we stand on float on molten subterranean rocks and move 2-15 cm per year relative to each other. A landmass called Gondwana, split into two 165 million years ago — one containing what is now Africa and South America, the other comprising India, Madagascar, Australia and Antarctica.
Around 115 million years ago, Madagascar and India together broke free. Around 88 million years ago, India moved northward, dropping a few parcels of land along the way to form Seychelles. It joined the Eurasian mass 50 million years ago giving rise to the Himalayas and South Asia that we are familiar with.
Around 115 million years ago, it was the dinosaurs that ruled. Many life forms had not even evolved. Supporting the Gondwana breakup, dinosaur fossils found in India and Madagascar are closely related, and do not resemble species found in Africa and Asia. Fragments of Laplatosaurusmadagascarensis have been found in both India and Madagascar.

Molecular clocks

A powerful technique, the molecular clock, is used to estimate the time when two forms of life diverged from each other.
It is based on the observation that evolutionary changes in the sequence of an RNA or a protein molecule occur at a fairly constant rate.
The difference in the amino acids of, say the haemoglobin of two animals can tell you how long ago their lineages diverged. Molecular clocks corroborate well with other evidence, such as the fossil record.

India’s pivotal position

India occupies a pivotal position in the distribution of life forms in Asia, Madagascar and Africa. Gondwana creatures moved out of India. Others crossed over to stay. For example, Asian freshwater crabs( Gecarcinucidae) are now found all over Southeast Asia but their most recent common ancestor evolved in India. The frog family, Sooglossidae, is found only in India and the Seychelles
In India, we have the lorises, which are the closest extant relatives of the lemurs. These are shy, nocturnal forest dwellers, with large, appealing eyes. They are also believed to have survived oceanic rides from Africa.
They are mostly found in the Northeastern States (slow loris)(IUCN: Endangered), and where Karnataka, Kerala and Tamil Nadu meet (slender loris)(IUCN: Endangered).