Rangeomorphs

Ecology

Rangeomorphs dwelt in shallow to abyssal marine environments, were unable to move, and had no apparent reproductive organs. They may have reproduced asexually by dropping fronds. Since many lived below the lowest level of the ocean where sunlight can penetrate, they could not have survived by photosynthesis. There is no evidence of a gut or mouth. One hypothesis is that nutrients from seawater were concentrated in their bodies by osmosis. Among living organisms, only osmotrophic bacteria live in this way, but the fractal branching tube structure of rangeomorphs gave them an unusual amount of surface area for every unit of body volume. This structure may have made it possible for osmotrophic organisms to grow to large sizes. However, other researchers argue this way of life is implausible, and suggest filter feeding or other mechanisms.