I wanted to bring to your attention a possible group that I came up with for the "Future of the World" project.
Agkistrodon subtimalus, or simply the Crowned Striker, evolved into various species over the next few million years. This species becomes the ancestor of a new group called Maurosodontoidae, meaning "black tooth", because most species in this group have evolved black fangs. Maurosodontoidea becomes very diversified and develops into two new subfamilies; Makrysrynchosinae, meaning "long snout", and Syntomirynchosinae, meaning "short snout". These groups differ in size, build and niche; Members of Makrysrynchosinae are smaller and more agile, with the largest being 4 meters (13 feet long), and have teeth build for gripping and holding on the prey rather than tearing flesh, therefore would be better equipped for eating fish, lizards, mammals, other snakes and various small creatures. Members of Syntomirynchosinae, however, are some of the largest species in the entire family, the largest growing up to 10 meters (33 feet) long, and have teeth built for tearing and rending flesh, and could easily feed on large herbivores, such as the Scutosquama, and can scavenge the kills of other predators, and may even devour other predators, such as members of the Theriosauria.
These two different groups have similarities, however. Like their ancestor, these creatures have various, and sometimes elaborate, horns or crests, and they're often more prominent in males, with females having smaller horns or crests, or not having any at all in some species. Also like their ancestor, these groups are endothermic, and can control their own body heat, with some species able to remove their own signature, a good design for not being detected by prey or other predators. They also inherited the multiple pairs of fangs and the neurotoxin of their ancestor. This is nonexistent in the larger species, however, because they can easily kill with sheer force and constriction, rather than venom.