Canada's Unexpected Ostrich Mimic

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American

Where a dinosaur lived is one of the basic details we ask about the terrible lizards. Just like anything with dinosaurs, though, the reality is more complicated than we often appreciate.

The site where a dinosaur’s bones are exhumed isn’t the spot that animal lived, but where it was buried. And even if we broaden our scope to the general area or province, we use modern place names that don’t necessarily reflect the realities of the ancient past. Continents shifted. Seas rose and fell. Mountain ranges were thrust up and eroded back. It’s more change than we can appreciate, making us strain to broaden the scope of our imagination.

An unexpected ornithomimid found in Alberta, Canada made me think about the break between where a particular dinosaur was fossilized and where we can say that a genus or species actually lived. This was one of the ostrich mimic dinosaurs regularly found in Asia and North America, and it turned out to be the sixth distinct ornithomimid found in the Dinosaur Park Formation. But this might not be a new dinosaur. At the moment, at least, it seems to be one that was already found in a place far distant from western Canada.

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In 2011 paleontologist Li Xu and colleagues named a new ornithomimid from Henan Province, China. They called it Qiupalong henanensis, and in that description the researchers noted that their animal closely resembled ornithomimids found in North America. At the time, however, no ornithomimid was known to occur on more than one continent. The forms in Asia were restricted there, just as the species in North America were isolated on that continent.

Here’s where a fossil known as CMN 8902 comes into play. This partial skeleton was uncovered by fossil hunter C.M. Sternberg in 1921 and consisted vertebrae, ribs, parts of the limbs, and elements of the hips. That material didn’t kick up much interest after its discovery, and was categorized as a North American species called Struthiomimus altus in 1972. But now, drawing from that skeleton as well as other referred material, Bradley McFeeters and colleagues argue that the bones represent a species of Qiupalong. If they’re right, this is the first ostrich mimic genus present in both North America and Asia.

The fossils from North America and Asia are separated by time as well as geography, McFeeters and coauthors explain, so the earlier, Canadian Qiupalong may have been a different species. But this offers a new clue as to the interchange of dinosaurs that was going on between the continents during the Cretaceous. The presence of an earlier Qiupalong species in Alberta points to a North American origin for the genus, populations of the dinosaur dispersing into Asia along with horned dinosaurs, tyrannosaurs, and hadrosaurs as falling sea levels opened temporary migratory routes.

So where did Qiupalong live? Paleontologists can follow GPS coordinates to discovery sites that offer a rough idea of where individual animals strutted around. But in a broader sense, this genus has a story spanning two continents and ten million years, populations of the dinosaur expanding and shrinking with the caprices of nature.

Reference:

McFeeters, B., Ryan, M., Schröder-Adams, C., Currie, P. 2017. First North American occurrences of Qiupalong (Theropoda: Ornithomimidae) and the palaeobiogeography of derived ornithomimids. FACETS. doi: 10.1139/facets-2016-0074