The Fossil Record
Whale fall fossils from the late Eocene and Oligocene (34-23 MYA) in Washington and from the Pliocene in Italy include clams that also inhabited non-chemosynthetic environments. Chemosynthetic-only animals do not appear until the Miocene (23 to 5 MYA) in California and Japan. This may be because the lipid content of early whale bones was too low.
The discovery of the limpet Osteopelta in an Eocene New Zealand turtle bone indicates that these animals evolved before whales, including possibly inhabiting Mesozoic (251-65 MYA) reptiles. They may have survived in seeps, wood-falls and vents while waiting out the 20 million year gap between the reptiles' extinction and whales' emergence. Another possibility is that these fossils represent a prior, dead-end evolutionary path, and that today's whale fall animals evolved independently.
Read more about this topic: Whale Fall
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