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. It was originally named as an African species of Brachiosaurus (B. brancai), but this has since been moved to its own genus. Giraffatitan was for many decades known as the largest dinosaur but recent discoveries of several larger dinosaurs prove otherwise; giant titanosaurians appear to have surpassed Giraffatitan in terms of sheer mass. Also, the sauropod dinosaur Sauroposeidon is estimated to be taller and possibly heavier than Giraffatitan.
Most size estimates for Giraffatitan are based on the specimen HMN SII, a subadult individual, but there is evidence supporting that these animals could grow larger; specimen HMN XV2, represented by a fibula 13% larger than the corresponding material on HMN SII, would have measured around 23–26 metres (75–85 ft) long and weighed about 40–48 metric tons (44–53 short tons).
In 1906, mining engineer Bernhard Wilhelm Sattler, while travelling, noticed an enormous bone jutting out of the ground at the Tendaguru (the "steep hill") near Lindi, in what was then German East Africa, today Lindi Region, Tanzania. In early 1907, his superior Wilhelm Arning in Hannover received a report on the find. Arning again informed the Kommission für die landeskundliche Erforschung der Schutzgebiete, a commission in Berlin overviewing the geographical investigation of German protectorates.[3] The German secretary of state of colonies, Berhard Dernburg, at the time visited German East Africa accompanied by the industrialist Heinrich Otto. Otto had invited the paleontologist Professor Eberhard Fraas to join him as a scientific advisor.[4] In the summer of 1907, Fraas, already for some months travelling the colony, received a letter from Dr Hans Meyer in Leipzig urging him to investigate Sattler's discovery. On 30 August, Fraas arrived by steamer at the coastal town of Lindi.[5] A five-day march brought him to the Tendaguru, where he could confirm that the bones were authentic and dinosaurian.[6] Soon Sattler joined him with a team of native miners who uncovered two large sauropod skeletons which were transported to Germany.[7] Ultimately, these would become the holotypes of the genera Tornieria and Janenschia.
Fraas had observed that the Tendaguru layers were exceptionally rich in fossils. After his return to Germany he tried to raise enough money for a major expedition. He managed to attract the interest of Professor Wilhelm von Branca, the head of the Geologisch-Paläontologische Institut und Museum der Königliche Friedrich-Wilhelm Universität zu Berlin.[8] Von Branca considered it a matter of German national pride that such a project would succeed.[9] He involved the well-connected pathologist David von Hansemann.[10] Von Hansemann founded a Tendaguru Committee headed by Johann Albrecht, the duke of Mecklenburg. Soon it became fashionable to join this committee which counted a large number of prominent German industrialists and scientists among its members. Many of their rich friends donated considerable sums.[11] To lead the expedition, von Branca sent out one of his curators, Werner Janensch,[12] and one of his assistants, Edwin Hennig.[13] Both men arrived in Dar es Salaam on 2 April 1909.[14]