To test their model, they need to compare it to exising flightless birds. Build a model for an ostrich, then see how it compares to reality.
If it is close, their ideas on two legged dinosaurs would have more credibility.
https://en.wikipedia.org/wiki/Phorusrhacidae
Supposedly they got up to 700+lbs. They think they might have become these things in modern day:
https://en.wikipedia.org/wiki/Seriema
Who knows, but I wonder how fast something supposedly 7-8 tons and bipedal could run. There’re some folks who speculate that the big therapods might have been plodding scavengers who just chased smaller more mobile and deadly therapods off their kills.
Freegards
Emus win. The Great Emu War of 1932 was a military operation in Australia aimed at reducing the emu population, which was damaging crops in Western Australia. Despite the use of soldiers and machine guns, the operation was largely unsuccessful, with only about 986 emus killed and the population remaining largely unaffected.