Readers ask about Microraptors, an X-ray map of the sky and more

cover of August 15, 2020 issue

Birds of a fossil feather

Four-winged Microraptor, perhaps one of the earliest flying dinosaurs, may have molted just a bit at a time — similar to modern songbirds, Carolyn Gramling reported in “This dinosaur may have shed its feathers like modern songbirds” (SN: 8/15/20, p. 12).

Reader Jan Voelker asked if the dinosaur may somehow be related to the pileated woodpecker.

It’s hard to say just how closely related Microraptor might have been to woodpecker ancestors, Gramling says. Woodpeckers, along with toucans and honeyguides, belong to a biological order called Piciformes. “The evolutionary origins of the Piciformes are still quite murky,” she says. “There just isn’t a whole lot in the fossil record about their ancestors, although there are fossils of modern-looking Piciformes dating as far back as the Oligocene Epoch, which spanned 33.9 million to 23 m­illion years ago.” But Piciformes are members of Aves, the biological class that includes all modern birds and that evolved from small feathered dinosaurs living during the Mesozoic Era, 252 million to 66 million years ago. Microraptor, which lived some 120 m­illion years ago alongside ancient birds, is distantly related to Aves.

Eyes on the sky

A new X-ray map of the entire sky looks deeper into space than any other X-ray map, Maria Temming reported in “This is the most comprehensive X-ray map of the sky ever made” (SN: 8/15/20, p. 30).

Reader Bob Garfield wondered how the image was made. “Is this a composite of a complete, 360-degree image of the sky or is the device looking in one general direction?” Garfield asked.

It’s a composite image of the entire sky, Temming says. “The telescope rotates continually to look at each point in the sky for 150 to 200 seconds on average and then moves on. Scientists stretch out the spherical view of the whole sky into this distended, ellipse-type shape so you can see it all at once on a 2-D surface,” she says.

Old dog, new math

A new formula for converting a dog’s age into human years is based on a comparative study of biological aging in Labrador retrievers and people, Bethany Brookshire reported in “Calculating a dog’s age in human years is harder than you think” (SN: 8/15/20, p. 5).

Reader Sue Jordan wondered how old her 13-year-old dog, a male black Lab and border collie mix, would be in human years according to the new equation.

“He’s around 72 years old in human years,” Brookshire says. “Keep in mind that the study doesn’t apply fully to all dogs, as it was done only in Labrador retrievers.” Collies and Labs might age at different rates. “As scientists do more of these comparisons, they will probably come up with different equations for different breeds,” she says.

“That 72 is a rough estimate; no one can say exactly how old your pup is in human years. But no matter what, I bet he’s great,” Brookshire says.

On the clock

A theoretical universal cosmic clock that may beget time must tick faster than a billion trillion trillion times per second, Emily Conover reported in “The universe might have a fundamental clock that ticks very, very fast” (SN: 8/15/20, p. 9).

Reader Lou Puls wondered if the limitation on the rate at which the f­undamental clock might tick could explain the arrow of time, or the idea that the total entropy (or disorder)

in the universe can only increase over time.

That’s a good question, Conover says. “When I interviewed physicist Martin Bojowald of Penn State for this study, I asked him the same thing. Sadly, he said that, at the moment, there’s no connection. It seems there’s no way to explain the arrow of time with this fundamental clock. At least, not yet,” she says.


The x-axis of the graph in “Agriculture and fossil fuels are driving record-high methane emissions” (SN: 8/15/20, p. 8) was incorrectly labeled. Instead of “metric tons per year,” it should say “million metric tons per year.”