Liopleurodons can drop these if you are able to kill them in 5 seconds or less, this is due to their teleporting animation which lasts 5 seconds.

If you approach it as a human you have 6 seconds as the liopleurodon is neutral so it has to get mad at you and do its aggression animation first before it is able to do its teleport animation

If you approach it as a tame you have 5 seconds as like any other water giant they are aggressive to all underwater tames

Ways to prove this: (from easiest to hardest)

1. Use a mosa or any other underwater tame with really high melee damage and victim item collection turned on then kill it

2. Lure it to the surface using ammonite rage debuff then put 6-8 c4 on it, then light it ip and it should die instantly, you can then look inside its corpse and screenshot the loot including the megalodon teeth for aura

3. Get a tek rifle then go ham at it until it dies

Note: if you kill the liopleurodon by hand, you also need to collect the loot within the 5 seconds you used to kill the liopleurodon too. So if you killed the liopleurodon in 3 seconds, you only have 2 seconds to grab the loot before the corpse/item cache diseappears