The mammals of the future

In this scenario, let's imagine a future Earth characterized by an environment that changed and adapted just like the surviving animals. These changes had been triggered by the mass extinction event at the end of the Holocene, an event that erased majority of the planet's biodiversity. However, a wide range of species somehow managed to survive, including elephants, manatees, dugongs, rhinos, tapirs, cetaceans, otters, skunks, pinnipeds, mongooses, civets, colugos, lemurs, possums, opossums, and platypuses. These are alongside obvious potential survivors like rats, a few bird species, crocodilians, turtles, lizards, snakes, frogs, salamanders, sharks and other adaptable fish, and various invertebrates. Over the subsequent tens of millions of years, leading possibly up to 100 million years into the future, these creatures were not only able to survive but also continue to evolve and diversify. Evolutionary pressures and changing environments drove them to acquire new adaptations and behaviors, and diversify into new families and species. Elephants for instance, evolved into smaller or larger species based on their environment's food availability and climate, with some developing fuzzy coats for colder regions. Similarly, rhinos diversified; some staying as land-dwellers, others becoming semi-aquatic to exploit new ecosystems. Marine mammals like manatees, dugongs, and cetaceans made even greater leaps. With the newfound ecological niches in the marine environment, some evolved to fill roles left vacant by the extinct species, leading to more diverse types of marine mammals, more species of dolphins and whales, and possibly completely new forms of aquatic organisms. Reptiles like the snakes, lizards, and turtles also capitalized on the changes. Their hardiness and generalist traits allow them to survive in a number of different environments, leading to new forms of reptiles, some maybe taking to the skies and others becoming more dominant on land. Of course, a number of animals also took to the trees. lemurs, possums, and opossums found protection against predators in the foliage and therefore diversified into a plethora of tree-dwelling species, further colonizing the world's forests. These tens of millions of years saw an incredible radiation of life, a testament to nature's resilience. Even after a devastating extinction event, life found a way to not only survive but thrive, filling every available niche with a wonder of evolutionary creativity. In the heart of this regained biodiversity, life on Earth was never the same. A unique testament to the powers of evolution, adaptation, and survival of the fittest that rule over the animal kingdom. A new era, defined by the creatures that had not only survived the Holocene extinction but had learned to flourish beyond it.