Ah, the Early Eocene - back when land connections existed between Antarctica and Australia. Amid mild climates, lush forests and warm waters, the Pakicetus thrived. Picture a creature looking part-wolf, part-crocodile, prowling the prehistoric shores of ancient Pakistan. These ancestors of modern whales had legs for land but hearts for the sea, showcasing the first sign of aquatic adaptations in their elongated bodies and sensory capabilities.

Like its cetacean cousins, Pakicetus had a thickened skull bone known as the auditory bulla, crafted for an underwater soundscape. Yet, it lacked the specialised fat pad that today's whales use to channel sound through ocean depths. Instead, this pioneering species listened through its surroundings like a land mammal, bridging the evolutionary gap between sea-faring giants and their terrestrial ancestors.

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