The Elements of Evolution (10-1) Rangeomorphs


Rangeomorphs were a frondose animal, standing tall while attached to the seafloor by a holdfast, though some lay flat. Rangeomorphs were among the earliest large organisms: some grew to 2 meters tall, though others were only a few centimeters. Their soft bodies were fractal branches unlike any other complex macrobe.

Rangeomorphs could rapidly shape-shift: growing into a long, tapered column if the seawater above them had an elevated oxygen level or food flow. As filter feeders, rangeomorph frond size and shape were responsive to nutrient availability and uptake.

Rangeomorphs sent out waterborne propagules to reproduce in distant areas. Plants later imitated this technology with stolons.

Rangeomorphs were adaptively optimal for the low-competition, high-nutrient conditions of Ediacaran oceans. With the Cambrian explosion in animal diversity (from 541 MYA), fundamental changes in ecological and geochemical conditions led to their extinction. ~ English paleobiologists Jennifer Hoyal Cuthill & Simon Conway Morris