| Not exactly what you’re asking but whales used to be land mammals. > It is believed that modern-day whales evolved from land-based animals about 55 million years ago. These land-based mammals are believed to be hoofed mammals, sharing a common ancestry with even-toed ungulates such as the cow and the deer. > Evolution of Whales
Whales started their journey as all other organisms have, as single-celled bacteria. An evolutionary picture of the whales can be broken down as follows: - 3.8 billion years ago: The first single-celled organisms appeared (Bacteria) - 3 billion years ago: Viruses (also single-celled organisms) became present - 2 billion years ago: Eukaryotic cells are present. These are cells that contain organelles, or tiny organ-like structures - 1.5 billion years ago: Eukaryotic cells evolved three ways. These cells evolved into the ancestors of plants, animals, and fungi - 900 million years ago: The first multicellular structures became present - 800 million years ago: The animal strain of organisms undergoes its first split and continues into basic marine organisms such as sponges - 540 million years ago: The first chordates or animals with backbones are present - 530 million years ago: The first true vertebrate or boned organism is present - 500 million years ago: Animals first started exploring the land - 417 million years ago: Lungfish became present. Lungfish are the first organisms to breathe both on land and in the water with both lungs and gills - 397 million years ago: The first tetrapods or four-legged species are present - 340 million years ago: Amphibians branch off from the other tetrapods - 310 million years ago: The remaining tetrapods split into what will be reptiles, birds and dinosaurs, and mammals - 200 million years ago: A mass extinction occurred and warm-blooded proto-mammals developed - 140 million years ago: Placental mammals also known as eutherians are present - 105-85 million years ago: The placental mammals split into four major groups, including laurasiatheres, which will contain the whale species. - 65 million years ago: The greatest extinction event so far wipes out the dinosaurs providing more potential for mammals to colonize the planet - 50 million years ago: Artiodactyls pakicitus, a mammal, resembling a wolf and tapir mix with cloven hooves begins evolving into what we know as whales - 47 million years ago: Early forms of whales live in shallow seas, returning to land to mate and give birth - 35-45 million years ago: The first fully aquatic whale is present (Basilosaurus) Modern-day whales are believed to have moved into the oceans around the Tethys Sea, now the Mediterranean Sea and Asia. https://northamericannature.com/how-did-whales-evolve/ |