109 million people face another day of poor air quality as smoke from blazes in Ontario drifts over the US

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Tens of millions of Americans are enduring another day of smoky skies, irritated eyes and bad air quality, as Canadian wildfire smoke spread again over huge swathes of the US, affecting about 109 million people across the midwest, mid-Atlantic and north-east.

The pungent wildfire blanketed cities such as Chicago and Detroit, where residents on Friday were warned to stay indoors and reduce activity levels after the air quality index reached a “hazardous” 361, according to the government website AirNow.

Skeleton judged to be one of the largest and most complete ever unearthed was excavated on a ranch in South Dakota

A vast, fossilized Tyrannosaurus rex nicknamed Gus sold at Sotheby’s in New York on Tuesday for $50.1m with fees (£37.4m) to a phone bidder – making it the most valuable dinosaur fossil sold at auction.

It also sold well above a pre-sale estimate of $20m to $30m (£15m to £22.4m).