Fossil Record
This is, geologically-speaking, rather a young group, having evolved from the Late Paleocene in the Cenozoic Era.
The group is represented in the fossil record from shells of those groups within the clade that mineralized. These shells are a major contributor to the carbonate cycle, making up as much as 12% of global carbonate flux. However the low stability of their aragonitic shells means that few end up being preserved in sediments, these being in shallower waters of the tropical oceans.
Read more about this topic: Sea Butterfly
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