July 28, 2011
In North America, the Morrison Formation is a famous and fossil-rich slice of time; its rock contains the bones of some of the quintessential dinosaurs. Apatosaurus, Allosaurus, Stegosaurus and more—the Morrison represents the heyday of Jurassic dinosaurs. A less similar but less famous site represents the Late Jurassic world. The fossil sites of Tendaguru, in Africa, preserve dinosaurs similar to, yet distinct from, their North American counterparts.
Paleontologists Wolf-Dieter Heinrich, Robert Bussert and Martin Aberhan just reviewed the history and significance of Tendaguru in Geology Today. In 1906, a German mining engineer made the fortuitous discovery of dinosaur bones near Tendaguru Hill in Tanzania. News made it back to Germany, and after an initial expedition in 1907, Berlin’s Museum of Natural History launched a major effort to uncover the area’s dinosaurs between 1909 and 1913. The result? Over 225 tons of dinosaur bones from one of the most productive fossil sites in all of Africa.
The Jurassic dinosaurs of the Tendaguru sites have often been seen as a rough equivalent to those of the Morrison. Big, long-necked sauropods, such as Dicraeosaurus, Tornieria and Giraffatitan (formerly Brachiosaurus), were numerous and a prominent part of the dinosaur fauna. There was also the spiky stegosaur Kentrosaurus, the ornithopod Dysalotosaurus and a host of poorly known predatory dinosaurs, including Elaphrosaurus and an Allosaurus-like theropod.
Frustratingly, no complete, articulated dinosaur skeletons were ever found at Tendaguru, but the sites preserve some intriguing fossil features. For one thing, the early 20th century expeditions found bonebeds of Kentrosaurus and Dysalotosaurus. They were once thought to represent mass deaths when herds of dinosaurs were killed en masse by local flooding, though, as Heinrich and co-authors point out, the bonebeds could have been created by dinosaurs becoming stuck in the mud and dying over a relatively longer period of time. The fact that the articulated feet of big sauropod dinosaurs have been found in an upright position hints that some of these huge dinosaurs also became mired and died—life alongside the Jurassic lagoon could be dangerous.
But one of the most curious aspects of the Tendaguru dinosaurs is that they are so similar to those found in North America’s Morrison Formation. After all, Giraffatitan was previously described as a species of Brachiosaurus—a dinosaur found in Jurassic North America—and problematic big theropod remains from Tendaguru have been attributed to Allosaurus, not to mention the presence of stegosaurs and other dinosaurs on both continents. Whereas the Tendaguru dinosaurs were once thought to be nearly equivalent to those of North America, a different picture has emerged in which the dinosaurs of Tanzania were similar to those found in the Morrison Formation, but actually belonged to different genera. Nevertheless, the close correspondence between the two raises the question of why very similar dinosaur communities independently came to exist on two different continents. Paleontologists will have to dig deeper to find out.
Heinrich, W., Bussert, R., & Aberhan, M. (2011). A blast from the past: the lost world of dinosaurs at Tendaguru, East Africa Geology Today, 27 (3), 101-106 DOI: 10.1111/j.1365-2451.2011.00795.x
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