Echidna

Echidna most probably.

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... selection theory within the Galapagos group of islands. Australia has some very unique flora and fauna a good example of this is the Platypus and Echidna these are what are called Monotremes they are egg laying mammals the only 2 egg laying mammals in the world, Australia's fauna have developed ...

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You're falling into the trap of homologous and analogous structures. Just because echidnas have spines, doesn't mean they evolved from porcupines. Similarly, just because dolphins have dorsal fins, doesn't mean they evolved from Tuna. Some humans have genetic anomalies ...

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