After playing this game since almost the beginning, I have watched this pattern.
Level 20 is the overall level used to create most dinos, especially the higher ranked dinos.
Also Ludia seems to be notorious for introducing new dinos that require using a dino that most players will not have had any reason to level up or collect DNA for. This is their way of keeping people at bay from automatically being able to create new dinos and allows them to sell incubators with that needed dino DNA.
So to all players, concentrate on levelling all of your dinos to level 20. This will ensure that unless it takes absolutely new dinos to create new releases, you will be at the point with every dino to at least start creating new dinos almost instantly.