Snake evolution

Snake evolution is the history of the lineage that produced modern snakes from their ancestors and diversified them into living and extinct forms. It includes changes in body plan, ecology, and relationships among snake groups.

Snake origins: The emergence of snakes as a distinct lineage from their squamate ancestors. This focused question asks when and from what ancestral lineage snakes first evolved.
Snake skull evolution: The evolutionary changes that made the snake skull highly flexible and capable of wide gapes. Skull mobility enabled snakes to handle prey wider than their own heads.
Squamate phylogeny: The hypothesized evolutionary relationships among lizards, snakes, and other squamates. Snake origins depend on where snakes branch within the squamate family tree.
Dinilysia: An extinct, large-bodied snake from the Late Cretaceous of Argentina, known from a well-preserved skull and skeleton. Its terrestrial anatomy helps test whether early snakes were land-dwelling.
Snake fossil record: The preserved fossil evidence documenting the evolutionary history of snakes. Its gaps make the timing and sequence of early snake transformations difficult to establish.
Najash: An extinct Cretaceous snake from Argentina, known from fossils that preserve substantial hind limbs. Its anatomy offers direct evidence about early snake evolution and terrestrial origins.
Snake jaw mechanics: The coordinated movements of snake jaw bones during prey capture and swallowing. The distinctive jaw apparatus is a major functional outcome of snake evolution.
Vertebral column: The series of vertebrae that supports the trunk and protects the spinal cord in vertebrates. Vertebral counts and shapes help distinguish snake fossils and trace body evolution.
Pachyrhachis: An extinct Cretaceous snake from marine deposits in the Middle East, with small hind limbs. It provides a prominent fossil example of a snake retaining external limbs.
Cretaceous Terrestrial Revolution: A broad ecological transition in the Cretaceous during which land ecosystems and flowering plants diversified. The timing of snake diversification is studied alongside this major terrestrial ecological change.

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