Fossil Belonged to Tail of Massive Herbivore in Uzbekistan

(CN) — A new analysis of 90-million-year-old dinosaur remains has revealed a first-of-its-kind sauropod from Uzbekistan. 

Researchers found that a single tail vertebra, discovered in 1997, belonged to a dinosaur they have now dubbed Dzharatitanis kingi. PLOS One published the research Wednesday.

The fossil is the first in a subclass of sauropod dinosaurs, called rebbachisaurids, to come from Asia: It turned up in Dzharakuduk, Uzbekistan, in the Upper Cretaceous Bissekty Formation. 

Sauropods were giant, long-necked, long-tailed herbivores, among the largest Earth-walking creatures ever to have lived. Diplodocus, from a North American branch of the family, is one of the most abundant species in present-day Colorado. 

Another famous sauropod is the behemoth titanosaur, which is likely the largest dinosaur discovered to date. 

Titanosaur remains had been discovered before in Uzbekistan, and researchers initially believed that the fossilized tail bone now ascribed to Dzharatitanis kingi had belonged to that breed of dinosaur. 

Alexander Averianov, a researcher at the Russian Academy of Sciences in Saint Petersburg, explained how the new research overturns old assumptions about the fossil. 

“Its reinvestigation shows that it actually belongs to Rebbachisauridae,” he wrote in an email, “the family of diplodocoid sauropods never found before in Asia.”

The discovery also marks the second sauropod group identified in the collection of nonavian dinosaurs from the Bissekty Formation, the other being a novel titanosaur species found in the Upper Cretaceous rock layer. 

The species is named after geologist Christopher King, a colleague and friend of the researchers who died in 2015. King “did much of the work on the geology of Cretaceous strata in Central Asia,” the study authors wrote. 

Averianov said the sample from Uzbekistan is one of the youngest of its group in the fossil record. Other fossils from the group have been found in South America and Europe. 

What makes Dzharatitanis kingi unusual is the structure of its skeleton. The configuration of bone plates on its neural spine is unique, but it is also similar to European fossils in the same group. 

To better understand the evolutionary development of the group of dinosaurs, the researchers conducted a phylogenetic analysis. This allowed them to place the sample from Asia in the context of sauropod evolution, and migration, over time. 

Similarities between Asian and European findings, for example, suggest that ancestors of European rebbachisaurids dispersed at some point to Asia from Europe. 

They would have taken a land bridge that crossed over the Turgai Strait — also known as the West Siberian Sea — because most of Europe in Cretaceous times was isolated from Asia.  

Averianov explained that findings like this point to the idea that the fossil record remains incomplete. 

“The rare taxa have little chances to get into the fossil record and we are serendipitous to find this fossil of a very rare animal,” Averianov said. 

“Possibly rebbacisaurids were more widely distributed in Asia,” he added, “but were not abundant and their fossils were not preserved or found.”

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