Lophostoma (lit. "crested mouth") are the first clade of terrestrial animals.
Lophostomes employ passive respiration, with two spiracles each leading to a lung and heart. They have eight legs composed of pure muscle, along with six feeding arms and two eye-stalks with three eyes on each. These eyes are reflector eyes, meaning that they are great at detecting movement but are poor at getting a clear image.
Like their tentaclostoma ancestors, lophostomes eat, excrete waste, and sexually reproduce through their mouth, the only orifice in their bodies. Large-bodied lophostomes have retained the shell of their ancestors (which acts as their primary form of support), although it is comprised of lighter and more flexible material.
The lophostomes are the most diverse clade of terrestrial animals, as they include the highly diverse malacoformes, and were present for 20 million years prior to the arrival of the osteopods.
Lophostomes have developed internal fertilization, with male lophostomes employing a "cloacal kiss" to transfer gametes into the female. Fertilized eggs are then kept in the female's oviduct until they develop a waterproof casing, after which they are deposited on land.
Like osteopods, lophostomes complete the majority of their development before they hatch.
There are two major branches of the Lophostoma evolutionary tree:
- Malacoformes: Small bodied-creatures, analogous to terrestrial arthropods.
- Diplostoma: Larger creatures, notable for their improved digestive system and the development of flying animals.