The hooked-billed ground phorusrhacid birds of South America and preglacial Antarctica were truly predaceous. Animatronic dinosaur Flightless and ranging from medium to ostrich size, they beat out the predatory marsupials and were the dominant meat eaters of that continent’s Tertiary. It was recently found that they managed to move north over the new Central American land bridge and into the southern states just before the Ice Age. Whether phorusrhacid birds failed in competition with the big cats and dogs that came up the same land bridge, or whether they were already in trouble, is not certain. What is known is that on two continents, for one extended period of time, big dinosaurian ground predators staged a comeback.
Giant penguins made their homes in the southern oceans of the early to mid-Tertiary. These were more looklike than modern penguins, and one species was three times the dimensions of the biggest living species. Bigger yet was the largest of the plotopterids, thd penguin-like pelican relatives of the mid-Tertiary North Pacific. These super penguins and plotopterids are the largest known ocean “dinosaurs.” Their demise may have been at the hands of newly evolving seals.