Giraffatitan

Giraffatitan (name meaning "titanic giraffe") is a genus of sauropod dinosaur that lived during the late Jurassic Period (Kimmeridgian–Tithonian stages) in what is now Lindi Region, Tanzania. Only one species is known, G. brancai, named in honor of German paleontologist Wilhelm von Branca, who was a driving force behind the expedition that discovered it in the Tendaguru Formation.

For many decades, Giraffatitan was thought to be the largest dinosaur ever known, but newer discoveries have shown that some other dinosaurs were even bigger. Giant titanosaurians and the dinosaur Sauroposeidon are now believed to have been larger than Giraffatitan. Most of what scientists know about its size comes from a nearly grown-up but not fully grown individual, but evidence suggests these dinosaurs could grow even bigger.

History of discovery

In 1906, a mining engineer noticed a huge bone sticking out of the ground near Lindi in what was then German East Africa, now the Lindi Region of Tanzania. This discovery was reported to scientists, who later confirmed it was from a dinosaur.

An expedition led by paleontologist Werner Janensch began searching for more fossils in 1909. Over several years, they found many dinosaur bones, including those of a very large species now known as Giraffatitan. These fossils helped scientists learn more about this giant dinosaur that lived millions of years ago.

The most famous skeleton of Giraffatitan is on display in Berlin's Natural History Museum, and it is one of the tallest dinosaur skeletons in the world.

Separation from Brachiosaurus

In 2009, a detailed study showed important differences between Giraffatitan and the North American dinosaur Brachiosaurus. Scientists found many bone differences that led them to recognize Giraffatitan as its own distinct genus. Since then, most researchers have accepted this name for the African dinosaur.

Description

Size

For many years, scientists thought Giraffatitan was the largest dinosaur ever found, and therefore the largest land animal in history. Later, some giant dinosaurs called titanosaurs were found that might have been bigger. But Giraffatitan and another dinosaur called Brachiosaurus are still the largest ones we know well from complete fossils.

All size guesses for Giraffatitan come from a skeleton put together in Berlin. This skeleton includes real bones from a young Giraffatitan called HMN SII. This dinosaur was about 22 metres long and 12 metres tall. Scientists have guessed its weight many times, from as little as 15 tonnes to as much as 78 tonnes. Newer ways to guess weight put it between 23 and 40 tonnes. There is another, even bigger Giraffatitan fossil called HMN XV2, which might have been about 26 metres long and weighed around 40 to 48 tonnes.

General build

Giraffatitan was a sauropod, a type of four-legged, plant-eating dinosaur with long necks and tails. Its body looked a bit like a giraffe, with long front legs and a very long neck. The tail was about a quarter of its total length. It had a tall bony arch in front of its eyes, with a special nose area and teeth that looked like chisels. Its front foot had one claw, and its back feet had three claws.

Skull

Usually, people thought a tall skull shape belonged to Brachiosaurus, but now we think it might really be a feature of Giraffatitan. Scientists have debated where Giraffatitan's nostrils were. Some think they were near the front of the snout, not on top of the head like some people imagined. There has also been talk about whether it had a trunk, but the wear on its teeth suggests it didn’t — the teeth look like they were used for biting and tearing plants, not just grinding them after pulling them off with a trunk.

Classification

When scientists first studied the bones of Brachiosaurus brancai and similar dinosaurs in 1914, they noticed a special feature: a long upper arm bone. This feature was seen in several dinosaurs, including Pelorosaurus and Cetiosaurus. Scientists thought these dinosaurs were closely related.

Later studies used computer programs to understand how these dinosaurs were related. Some scientists suggested that Brachiosaurus and Giraffatitan were not very closely related. In 2009, a scientist named Taylor looked closely at the differences between the two and decided they were different enough to give Brachiosaurus brancai its own name: Giraffatitan. Since then, scientists have continued to study where Giraffatitan fits in the family tree of dinosaurs, and results have changed over time. Some studies say Giraffatitan is closely related to Brachiosaurus, while others place it in a different spot on the family tree.

Paleobiology

The large holes on the top of Giraffatitan's skull were once thought to be where its nostrils were, and scientists believed it might have lived in water like a snorkel. But we now know Giraffatitan lived on land. Its feet were not made for swimming, and water pressure would have made breathing hard.

Giraffatitan's brain was small for its size, about 300 cm³. Some thought a bump above its hip was a "second brain," but it was likely something else called glycogen bodies. The big holes on its skull were not for nostrils on top of its head. Instead, its nostrils were probably at the front of its face, closer to its snout. Some think Giraffatitan might have had a trunk to reach higher leaves, but this is still being studied.

Whether Giraffatitan was warm-blooded or cold-blooded affects how fast it grew and how much it ate. If warm-blooded, it would need to eat a lot each day. If cold-blooded, it would need less food.

Giraffatitan likely ate leaves from the tops of trees. Its neck could not move much to the sides, so it probably fed high up in the trees.

Paleoenvironment

Giraffatitan lived in what is now Tanzania during the Late Jurassic period in a place called the Tendaguru Formation. The landscape there had different kinds of areas, such as shallow sea-like spots, sandy flat areas, and lush inland regions with plants. The climate was warm with rainy seasons and dry times.

Giraffatitan shared its home with many other dinosaurs, including other long-necked sauropods like Dicraeosaurus and Janenschia, as well as plant-eating dinosaurs such as Dysalotosaurus and Kentrosaurus. There were also meat-eating dinosaurs like Allosaurus and flying reptiles called pterosaurs, such as Tendaguripterus. The area was also home to many sea creatures like corals, shellfish, and fish.