Sea dragons (Mosasaurophioidea)

Mosasaurophioideans(also known as "sea dragons") are aquatic reptiles constituting the clade Mosasaurophioidea. There are around 210 living species, with 80 extinct species. The species are divided into three groups. The first one is Icthyophia (fish snakes), which contains over 70 species with only 10 extinct species. The second is the Thalassosauria (true serpents), which consists out of 60 species and the same amount of extinct species as the icthyophids. The last group is the Cetophia (giant serpents), which is the largest group, consisting out of 110 living species and 30 extinct species, this group has many species that are either filter-feeders or carnivores.

Because there were no whales, mosasaurs, plesiosaurs, or ichthyosaurs on Chaoterra, these animals were great at exploiting these unoccupied niches. Like sharks, many species are countershaded (a darker color on top and a lighter color on the bottom). They have multiple body shapes, from being similar to their ancestors, to looking alot like a shark.

Reproduction
Unlike their relatives and ancestors, most mosasaurophioideans are ovoviviparous, meaning that they carry their eggs inside their bodies until they hatch. They also show some form of parental care like crocodiles do, this parental care also goes on until their baby is about 4 years old.