In the museum of natural history in Berlin stands the tallest mounted skeleton in the world. It is Giraffatitan brancai, formerly known as Brachiosaurus brancai. Its head towers 14m above the ground, and it isn't even a fully grown adult. For most of the 20th century, people thought its full-sized relatives were the largest animal to ever walk on land. Now we know there's even larger species, like Argentinosaurus or Sauroposeidon. How could these animals become so ridiculously big? And why is this one standing in Berlin, when it was found in Africa? The first question can be answered by biology. The second by the study of imperialism.

In the late Jurassic period, what is nowadays known as Tanzania was a subtropical coastal plain and home to all the species seen in the OP picture: Giraffatitan, Dicraeosaurus and Kentrosaurus. In the early 20th century, what is nowadays known as Tanzania was known as German East Africa. It became the victim of the colonial ambitions of the German Empire, staking out its claim for a "place in the sun", ruthlessly grabbing the parts of Africa that had not yet been claimed by the British Crown, the French, the Belgian or the Portuguese. After the area had been occupied and an extractive economy put into place, a mining prospector, Bernhard Wilhelm Sattler, came across a giant bone sticking out of the hills in Tendaguru in 1906. Soon, an expedition sponsored by industrialist Heinrich Otto set out to discover how rich the hills were in fossils. A massive excavation began, carried out by native miners led by chief supervisor Boheti bin Amrani. 230 tons of fossils were excavated from the land, then carried to the next port on people's backs. Wikipedia casually drops this sentence: "The expedition initially employed about 160 native porters as beasts of burden could not be used because of the danger posed by the tse tse fly." It was too dangerous for horses. But using black people was apparently fine. And more than a century after that, the fossils these people dug up and carried across dirt roads to be packed in crates, are still standing in Berlin, as a debate about restitution of cultural goods taken in colonial contexts begins to take shape.

So that's how these bones were discovered. But how was it possible for sauropods like Giraffatitan to get so enormously large? After all, the largest mammals are all aquatic. A blue whale is almost twice as heavy as a fully grown Giraffatitan likely was, but it doesn't have to support its own body weight. It could only get as heavy as that after returning to an ocean life. Turns out sauropods had some highly evolved bird-like features already, like pneumatized bones. Their bones are partially hollow and filled with air sacs connected to their highly specialized lungs. This helps birds to be light enough for flight, and they provided a relatively lightweight frame for the long-necked dinosaurs. The necks are another advantage they have over mammals. A giraffe neck is close to the maximum of what's physiologically possible. Because like all mammals, they only have seven vertebrae in their neck. They're just ridiculously long. Giraffatitan had more than 20 neck vertebrae. And that giant neck allowed it to graze with ease. This graphic shows the feeding range, the area that the animal could reach with its mouth without moving its body. It becomes pretty clear why sauropods got longer and longer necks during the next 80 million years of evolution: it was just a very energy-efficient way of feeding, where they could remain in one place and strip away all available vegetation before moving on. Just like capitalism, they just kept constantly expanding their reach. Until the meteor came.