Text: According to Michael Lee of the University of Sydney and Michael Caldwell of Chicago's Field Museum, the 100-million-year-old fossil, christened Pachyrachis problematicus (problematic thick-ribbed animal) in the late 1970s, is a proto-snake with two legs.
Entailment: The 100-million-year-old fossil has been identified as a proto-snake with two legs by two experts in the field.
Contradiction: The 1-million-year-old fossil has been identified as a proto-snake with two legs by two experts in the field.