Diplostoma (lit. "double mouths") are a clade of Lophostoma consisting of all large-bodied Anthostomes. They are notable for their development of a through gut.
First appearing around the year 4175ma, Diplostomes represent the clade from which large-sized lophostomes evolved from, in contrast to the small-bodied Malacaformes. The Diplostomes were the first group of large-bodied terrestrial animals. However, the emergence of the Ostepods (which brought many species to extinction) and the reduction of atmospheric oxygen (which resulted in the reduction of their maximum size) have seen the Diplostomes taking a much smaller role in the ecosystem.
However, they have persisted into the modern day, having representatives among all of the terrestrial biomes. While less adaptable than the Osteopods, some Diplostomes have nevertheless evolved unique adaptations to overcome their anatomical disadvantages.Their eyes consist of muscular turrents, which are much shorter than the ancestral eyestalks but can still be swiveled back and forth to increase their field of vision. Diplostomes have begun the transition to K-selection, with the size of broods lowering to less than 200.
The most notable trait of the Diplostomes is their evolution of a through gut: while they still possess one orifice, their gut has developed separate canals for ingesting food and excreting waste, increasing digestive efficiency.
Diplostoma is the larger of the two branches of Lophostoma in terms of body size, which they owe to their superior digestive system. However, they are unable to reach the sizes of the Osteopods due to their lack of internal support structures: the largest species of Diplostoma measured only 2 meters in length, and atmospheric oxygen levels have since declined to the point where such a size is impossible.
- Placostraca: Generalist herbivores with thick shells
- Stenostraca: Largely carnivorous, with various reductions of the ancestral shell
- Biblaridion stated that he intended to show Diplostomes evolving to aquatic environments in Part 7, but was forced to cut them due to time constraints.