Pachystruthio dmanisensis was a giant cousin of the ostrich that lived in the Pleistocene

Artist's concept of Pachystruthio dmanisensis in its environment (Image Andrey Atuchin)
Artist’s concept of Pachystruthio dmanisensis in its environment (Image Andrey Atuchin)

An article published in the “Journal of Vertebrate Paleontology” reports the identification of an extinct giant bird that lived in the Pleistocene period carried out thanks to the analysis of a fossil discovered in Crimea and other bones. A team of researchers led by Dr. Nikita Zelenkov of the Russian Academy of Sciences named it Pachystruthio dmanisensis attributing it to an existing genus of extinct birds. This is a different conclusion than the one based on the first fossil femur of this species, which in 1990 led other researchers to attribute the species to the genus Struthio, the same as ostriches. However, this animal was much larger given that the researchers estimated that it could be about 3.5 meters (about 11.5′) tall and weigh around 450 kg (about 1,000 lbs).

The first femur attributed to the species in question was discovered in today’s republic of Georgia and in an article (link to the file in PDF format) published in the journal “Acta zoologica cracoviensia” in 1990 the researchers who studied it attributed it to a species they named Struthio dmanisensis, believing that there were similarities not only with today’s ostriches but also with species of the same genus that lived in the Pleistocene period like Struthio oldawayi, which lived in today’s Tanzania and could be a close relative of today’s ostrich.

Last year another fossil femur dating from the early Pleistocene, over 2.5 million years ago, was discovered on the Crimean peninsula. The researchers led by Nikita Zelenkov examined the new fossil and initially thought it was an elephant bird. Instead, after having studied it, they attributed it to the same species that was named Struthio dmanisensis but they compared it with femurs of modern ostriches reaching a different conclusion than the first research. The fossil femurs are much more robust with some features that according to the authors of the new research preclude their assignment to the genus Struthio. Eventually, they considered the assignment to the genus Pachystruthio more correct.

The researchers used empirical formulas to infer some characteristics of Pachystruthio dmanisensis and their estimates indicate that it was about 3.5 meters tall for a weight of around 450 kg, three times as much as an ostrich, almost as much as an adult polar bear. It’s one of the largest birds that ever existed since only elephant birds had similar sizes.

Pachystruthio dmanisensis couldn’t fly but was probably a good runner. At the site in Crimea where the recent fossil of this giant bird was found there were also bones of predators such as giant hyenas and saber-toothed tigers, capable of killing even such a large animal so it’s possible that it needed to be fast to escape those predators.

An interesting possibility is that Pachystruthio dmanisensis was a prey of Homo erectus populations, who were migrating from Africa during the period in which this giant bird lived. There’s no evidence that the two species lived at the same time in that area and more discoveries are needed to get more information on the species that lived in that area. Dr. Nikita Zelenkov explained that last year even mammoth remains were discovered nearby so there may be more of them.

The femur of Pachystruthio dmanisensis discovered last year isn’t the result of a paleontological expedition but a chance finding during the construction of a new highway in Crimea. It’s therefore a lucky case in which work with a completely different purpose also leads to discoveries about the past.

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