There are more than 3,400 species of snakes living in a wide variety of habitats such as water, land and on trees. But, until now, little was known about when and where they evolved. Now a group of researchers led by Allison Hsiang of Yale University has found that the original ancestors of snakes evolved on land, contrary to the popular belief that they first evolved on the sea.
The first snakes had tiny limbs, ankles and toes
The first snakes evolved about 128 million years ago. They were nocturnal predators with tiny hind limbs, toes, and ankles, according to a study published in the journal BMC Evolutionary Biology. Allison Hsiang and her colleagues analyzed fossils, anatomy and genes of 73 different lizard and snake species, some living and some extinct.
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And then they constructed a large family tree to illustrate the major characteristics that have appeared throughout the evolutionary history of snakes. Researchers used morphological and genetic data to figure out how different groups of living snakes are related to each other. Algorithms used in the family tree construction revealed when each trait first arose.
Results suggested that snakes originated in the warm, forest ecosystems of the Southern Hemisphere. Researchers traced their origin to the middle Early Cretaceous period (128 million years ago) in the ancient supercontinent of Laurasia. It’s the same period when several species of birds and mammals appeared on Earth.
Snakes gained Diurnal habits 50 million years ago
Though most ancestral reptiles were active during daytime, ancient snakes were nocturnal. They gained Diurnal habits about 45-50 million years ago with the appearance of Colubroidea family, which currently makes up 85% of the living snake species. Ancestral snakes likely preyed on soft-bodied vertebrate and invertebrate. They were not yet able to manipulate larger prey by using constriction as a form of attack.
Scientists said that snakes were able to occupy a wide range of habitats over their evolutionary history largely because of their skills as “dispersers.