This 27 June 2019 video says about itself:
CNN: Inside a Crimean cave was a gigantic ancient mystery just waiting to be uncovered: a bird so large that it weighed nearly as much as an adult polar bear.
Giant birds once roamed Madagascar, New Zealand and Australia. The latest fossil find, an intriguing fossilized femur, was recently found in Taurida Cave on the northern coast of the Black Sea. It was discovered along with other fossils, including bison bones, that helped researchers date the now-extinct giant bird to between 1.5 million and 2 million years ago.
When the first early human ancestors arrived in Europe, they might have encountered these birds. The researchers think the bird probably reached the Black Sea region by crossing Turkey and the Southern Caucasus.
From Gizmodo.com, 26 June 2019, by George Dvorsky:
Ancient Bird Weighed Nearly 1,000 Pounds but Could Still Haul Ass Like an Ostrich
Paleontologists working in Crimea have uncovered evidence of the largest bird ever found in Europe. Standing taller than an elephant and weighing nearly 1,000 pounds, this enormous bird could still run at a fast pace when threatened.
Big birds have been discovered in Eurasia before, but nothing quite on this scale. In fact, the only birds that really compare are the extinct elephant birds of Madagascar and the extinct moas of New Zealand. The research paper associated with the discovery—published today in the Journal of Vertebrate Paleontology—claims it’s the biggest bird ever found in the northern hemisphere.
Assigned the name Pachystruthio dmanisensis, this animal’s nearly complete femur was found within the Taurida cave network of Crimea. This lone bone, dated to around 1.8 million years ago, was found alongside other animal remains, including a mammoth, bison, and some large carnivores.
Intriguingly, this time period coincided with the introduction of early humans to the region. A similar collection of fossils was previously uncovered at a nearby site in Dmanisi, Georgia, which happens to be the oldest hominin site outside of Africa. Consequently, these large birds “might have been a source of meat, bones, feathers, and eggshell for early hominin populations,” wrote the authors in the new study, which was led by Nikita Zelenkov from the Russian Academy of Sciences.
That early humans may have hunted these birds is a distinct possibility. Recent evidence suggests humans hunted elephant birds in Madagascar around 6,000 years ago.
“When I first felt the weight of the bird whose thigh bone I was holding in my hand, I thought it must be a Malagasy elephant bird fossil because no birds of this size have ever been reported from Europe. However, the structure of the bone unexpectedly told a different story,” said Zelenkov in a press release. “We don’t have enough data yet to say whether it was most closely related to ostriches or to other birds, but we estimate it weighed about 450 kg (992 pounds). This formidable weight is nearly double the largest moa, three times the largest living bird, the common ostrich, and nearly as much as an adult polar bear.”
Zelenkov’s team used a well-established formula, which took various measurements of P. dmanisensis’s femur, to estimate body mass. Further analysis pointed to a flightless bird that stood 11.5 feet (3.5 meters) tall.
Due to the femur’s long and slim shape—which bore a striking resemblance to the modern ostrich—it’s likely this creature was able to move fast. “Pachystruthio dmanisensis was a good runner, which may be explained by its coexistence with large carnivoran mammals,” the authors wrote in the study. And by large carnivores, the researchers weren’t kidding; the femur was found alongside the remains of giant cheetahs, giant hyenas, and saber-tooth cats.
As to why this creature evolved such a big size, the researchers said it likely had something to do with the arid environment in which it lived. Its large mass and efficient metabolism meant it could make better use of the low-nutrition foods found in the open steppes.
Christopher Torres, a graduate student of integrative biology at the University of Texas at Austin, said this report is “super exciting” for a lot of reasons.
“It expands known occurrences of gigantic birds into a new hemisphere,” he told Gizmodo. “It highlights a third case of gigantism among a rather closely related group of birds that also includes elephant birds and moa. Conventional thought was that birds could afford to lose flight and get really large only if there were no terrestrial mammals to compete with or hide from. This new report of giant birds coexisting with large mammals is forcing us to rethink those assumptions,” said Torres, who wasn’t affiliated with the new research.
To which he added: “This report raises some fascinating evolutionary and ecological questions that I cannot wait to see answered.”