Between 1909 and 1913, a field expedition led by Berlin’s Natural History Museum dug a whopping 230 tons of late-Jurassic fossils out of Tanzania’s Tendaguru formation. While nearly 95 percent of the total fossil haul has been prepared and many specimens are on display in museums today, 46 original transport cases and crates from the expedition remained stowed away and unpacked for decades in museum storage.
Now 100 years later, the cases themselves are historical artifacts. To peer inside them non-invasively, researchers used medical computed tomography (CT) scans to reveal the dinosaur bones within, as well as important insights about the colonial-era dig. The results will help scientists prioritize which fossils to unpack and how to prepare them, the researchers write in a paper published in Palaeontologia Electronica.
"It was very exciting for all of us to finally know exactly what was inside the bamboo corsets without having to open them right away," says study author Daniela Schwarz, a paleontologist at Berlin’s Natural History Museum, in a press release. "Until now, there was a lot of uncertainty about how to handle this material, because physical preparation really takes a lot of time, and you also don't want to destroy historical documents of the era."
A Colonial Expedition
Europe first learned of the fossils in 1906, when word reached Berlin that a mining engineer working in the colony of German East Africa, now southern Tanzania, had found bones sticking out of the earth. The site was near a hill called Tendaguru, which translates to “steep hill” in the language of the Mwera people who lived in the area.
The museum launched the German Tendaguru Expedition in 1909, and for four years local workers toiled in the field under German paleontologists to help excavate the formation. Perhaps one of the most productive fossil sites in Africa, the area yielded remains of fishes, lizards, pterosaurs, plants and even early mammals.
But the blockbuster discoveries were dinosaurs from the late Jurassic, including bones from the spike-backed stegosaur Kentrosaurus, the nearly-20-foot-long Elaphrosaurus, giant bone beds of the running dinosaur Dysalotosaurus and the sauropod Giraffatitan brancai (formerly classified as a Brachiosaurus), which once held the title for largest-known dinosaur.
Because of the sheer quantity of material, some fossils shipped off to other institutions, and some remained stored away in the museum’s collections in Berlin. Packing lists detailing the exact contents of the stowed-away cases were lost over the years and some prepared Dysalotosaurus fossils were destroyed in bombings during World War II. This gives meaning to the unpacked fossils today, the researchers say in the paper.
Scanning the Bones
In 2010, paleontologists at the museum decided to see what was in the remaining cases. Teaming up with researchers from the Leibniz Institute for Zoo and Wildlife Research and the Charité hospital, both in Berlin, Schwarz and colleagues imaged the 40 rolled bamboo containers and six wooden crates with a medical CT scanner.
Like how the machine might penetrate soft tissue in the human body to show a broken rib or toe, the CT scans revealed detailed 3D images of bone clusters within the cases.
The paleontologists used the images to determine that many of the bones belonged to Dysalotosaurus, the herbivorous running dinosaur that grew about the size of a kangaroo and of which much of the original fossil material had been lost over the years.
Other cases contained bones from the spiky stegosaur Kentrosaurus and some from Giraffatitan and other unidentified long-necked sauropods (all from the late Jurassic). Containers containing missing skeletal elements of Dysalotosaurus and rarer species from the site will be prioritized for unpacking, the researchers write in the paper.
This virtual documentation will enable other researchers, including historians studying German East Africa and the colonial context of the German Tendaguru Expedition, to study the cases and fossils, along with helping the museum plan what to do with the material.
In recent years, the museum’s ownership of bones from Tendaguru has been challenged, since some public figures want the fossils returned to Tanzania. The Tanzanian government, however, has not requested their repatriation. The government instead focuses on excavating new fossils and promoting contemporary collaboration between German and Tanzanian scientists. The current study is part of a larger effort to reflect upon the Museum’s colonial past, according to a press release.
"It was important to be able to define priorities for the preparation,” Schwarz says in a press release, “and at the same time decide what should be preserved in its original state as a valuable contemporary testimony of this historic expedition under colonial conditions."
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