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
Famous quotes containing the words fossil and/or record:
“The earth is not a mere fragment of dead history, stratum upon stratum like the leaves of a book, to be studied by geologists and antiquaries chiefly, but living poetry like the leaves of a tree, which precede flowers and fruit,—not a fossil earth, but a living earth; compared with whose great central life all animal and vegetable life is merely parasitic.”
—Henry David Thoreau (1817–1862)
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—Fred G. Gosman (20th century)