25 million years ago the biggest land mammals of all time, the indricotheres, stalked the Earth. Up to seven metres tall and weighing 15 tonnes, adults were too big to be eaten by any predator of the time. Only in the first few years of its life was indricotheres vulnerable. The programme follows the fate of a calf from his traumatic birth to see whether it can survive droughts, killer hogs and hyaenodon - a predator the size of a rhino with jaws that could crush a rock.

Take a look back at many of the most fascinating science stories of 2017, a year full of stunning advancements in individual fields of study, from astronomy to biology, geology to history – when we piece these discoveries together we see the year in a new light.

Take an express journey to the edge of the universe as the filmmakers use computer-generated animation to build on images captures by the Hubble Telescope. The animation and story telling absolutely wonderful. Beginning on planet Earth, viewers are hurtled into the deepest reaches of space. There are no stops on this flight, and along the way the mysteries of the universe come alive as we examine the history and science of distant celestial.

Moving on to the Late Eocene period 36 million years ago and mammals have prospered and are now the largest creatures on land and sea. This is an era of animals like andrewsarchus, the biggest mammal carnivore ever to walk on land, and the brontotheres, small-brained herbivores. It is in the sea, however, that the most monstrous mammals of all can be found. We follow the fate of a female basilosaurus, a huge serpent-like early whale, but nothing like the gentle filter feeding whales of the 21st century. Four times the length of the great white shark, with jaws to match, she is every inch a killer.

The series takes place after the extinction of the dinosaurs 65 million years ago and recreates animals of the Cenozoic with computer-generated imagery and animatronics. The first episode starts 49 million years ago, when Earth has fully recovered from the dinosaur extinction and is covered in a mysterious forest. This is a time that the world has almost forgotten - Germany was a hot sweaty jungle, birds ruled the earth and preyed on miniature horses and whales walked on land.

David Attenborough concludes his epic history of the evolution of flight with an exploration of the highly advanced fliers that dominate our skies today – the extraordinarily diverse skills of the birds, and the sonar-guided precision of the bats. He encounters some of our planet’s most remarkable fliers – from peregrine falcons dive-bombing starlings over Rome, to hummingbirds hovering in the cloud forests of Ecuador. In a spectacular finale, he visits Gomantong cave in Borneo to witness the mass exodus of a million bats.