In a series of rock layers a geologist finds fossilized shellfish and bony fish in layers that are 1.0 m and 1.5 m deep. however, in a layer that is 2.0 m deep, he finds fossils of a lizard-like dinosaur and a fern-like tree.
which explains his findings?

a) the continent shifted to a polar region
b) the ancient sea dried up and became land
c) an astroid hit the area, causing the dinosaurs to become extinct
d) the ancient land area was invaded by the sea

for your time!