How do you eat a skip full of food every day without ever chewing? How do you walk on tiptoes when you’re the length of four London buses? How do you have sex when you weigh 70 tons? While the answers to these three questions is probably “with great difficulty”, scientists are tackling such improbable questions after uncovering what is undoubtedly the biggest dinosaur excavation of all time.

In the spring of 2014, a lone farmer scanned his land, looking for a lost sheep. He thought there was something odd about the rocky ledge his grizzled old sheep was perched on. Dinosaur finds aren’t uncommon in the area but the outcrop was huge – could it really be a bone? He called in the scientists. When they determined that the ledge was in fact the 8ft thigh bone of a dinosaur, this sleepy Argentinian farm became the most important dinosaur dig site for more than 100 years.

Facebook Twitter Pinterest The Titanosaur replica at the American Museum of Natural History in New York. Photograph: Spencer Platt/Getty Images

Since its discovery, an international team of biologists, Hollywood model makers, a BBC film crew and palaeontologists, led by Dr Diego Pol and his colleagues from the Museum of Paleontology Egidio Feruglio in Argentina, has worked tirelessly and after 40,000 hours’ work, the results are astounding. The team discovered that not only was this giant herbivore a new species but it was the largest dinosaur ever, dwarfing its closest competitors. What’s more, the team found that seven of these animals actually died in the exact same spot, across at least three different occasions, approximately 101.6 million years ago.

This new dinosaur belongs to a group known as the sauropods, the long-necked, big-bodied beasts usually found roaming around in herds in the background of Hollywood dinosaur blockbusters. If you’ve seen Dippy at the Natural History Museum in London, then you’ll know what a sauropod is. Within this fascinating group of large herbivorous dinosaurs, however, a subsection is known as the titanosaurs and, as the name suggests, these are the real giants – the ones that literally shook the ground. They followed on from the extinction of smaller sauropods, such as the better-known diplodocids and brachiosauridae, and were found across the world. South America is especially rich in titanosaur fossils and already, true giants such as Puertasaurus and Argentinosaurus have been unearthed there.

Facebook Twitter Pinterest David Attenborough with a giant titanosaur’s 8ft-long thigh bone. Photograph: Robin Cox/BBC

Describing any new species can be a delicate subject, so introducing the largest dinosaur to both the scientific community and the wider world will be a huge task. Everyone wants their giant dinosaur to hold the title of “biggest” and, with multiple methods for assessing size to choose from, the team needed to be certain of what they’d found. Body size estimations can vary according to the technique used and on how much of the skeleton is retrieved. Estimates for the previous biggest dinosaur, Argentinosaurus, are based on fewer than 20 bones and Puertasaurus size estimates on just four vertebrae.

The difference with this newly discovered titanosaur is that much of the skeleton has been found. From the seven individuals, 223 bones have been recovered to date, allowing Pol and his team to use multiple methods to develop a reliable size estimate. Their results show that this dinosaur was 37m in length and weighed 70 metric tons, making it the largest animal ever to walk the face of the planet.

These dinosaurs had to sustain this incredible weight on four specially adapted column-like legs. They were so big they probably used the heavy musculature running from their thighs to halfway down their tails to gain momentum for walking. What’s more, in order to survive the stresses and fractures that could easily result from such extreme weights, these animals not only evolved to reduce the toes in their forelimbs, forcing them to walk on horseshoe-shaped stumps of reduced metacarpal bones, they walked on tiptoes, with huge fleshy pads cushioning the impact as they moved.

Weighing as much as up to 15 African elephants, this new species of dinosaur hasn’t even been named yet and although we still can’t fully explain why seven animals were found together, the 80 or so giant serrated carnivore teeth from an unknown killer found alongside the bones hint at a murderous end for these gentle giants. However, as a lifesize replica skeleton is unveiled at New York’s American Museum of Natural History, this super-size discovery is set not only to inspire a new generation of dinosaur fans but will stoke the fires of scientific debate for years to come.

Ben Garrod is an evolutionary biologist based at Anglia Ruskin University who appears in Attenborough and the Giant Dinosaur, BBC1, Sunday 24 Jan at 6.30pm