What does the early presence of specialized marine birds like Waimanu indicate about their environment?

Answer

Robust food webs supported specialized predators

The existence of large, highly specialized birds like Waimanu shortly after the mass extinction event indicates that the marine food web was already stable and productive. This allowed the environment to support large, warm-blooded, predatory divers, suggesting that the pressures driving evolutionary specialization in the marine environment were intense and immediate.

What does the early presence of specialized marine birds like Waimanu indicate about their environment?
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