Ichthyosaurs were marine reptiles that looked like dolphins.
ichthyosaurs
Plesiosaurs were large marine reptiles with limbs shaped like flippers, very long necks and relatively small heads.
plesiosaur
find; discover
Example: If you dig in some backyards you can turn up old bottles.
For more meanings of the phrasal verb turn up, follow the link.
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Belemnites were squid-like animals that looked like cuttlefish and became extinct along with the dinosaurs 65 million years ago.
belemnites
opalised remains of belmenites
Swam is the past tense of the irregular verb swim. Follow the link below to find out more and to listen to some examples.
Ammonites swam in the sea millions of years ago.
more information: swim
Kronosaurus queenslandicus is a sort of large short-necked marine reptile called a pliosaur.
kronosaurus
Something that is broken up is divided into smaller pieces.
The sea ice is breaking up.
Example: The sea ice is breaking up.
For more meanings of the phrasal verb break up, follow the link.
more information: break up