Original: One of the earliest known terrestrial ( land-dwelling ) gastropods is Maturipupa which is found in the Coal Measures of the Carboniferous period in Europe , but relatives of the modern land snails are rare before the Cretaceous period , when the familiar Helix first appeared .
Simplified: One of the earliest known terrestrial ( land-dwelling ) gastropods is Maturipupa which is found in the Coal Measures of the Carboniferous period in Europe .