A python embryo turns its leg cells into a pair of penises. Researchers now believe that signals from the embryonic gut trigger the development of the penis in many different species.
Patrick Tschopp/Harvard Medical School/Department of Genetics
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Patrick Tschopp/Harvard Medical School/Department of Genetics
David Roberts says the Cyber-Enhanced Working Dog harness will allow humans to monitor dogs' physical and emotional states remotely, such as in search and rescue operations.
Becky Kirkland/North Carolina State University
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Becky Kirkland/North Carolina State University
The Smithsonian's Jon Blundell scans the fossilized foot bone — the metatarsal — of the Wankel T. rex to help create a digital 3-D image of the long-dead dinosaur.
Nikki Kahn/The Washington Post
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An adult spotted lanternfly is seen, its wings spread to show a colorful hind wing. The invasive pest has sparked a quarantine in Pennsylvania.
Holly Raguza/Pennsylvania Department of Agriculture
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Holly Raguza/Pennsylvania Department of Agriculture
"Even as a paleontologist, I imagine them fighting, I imagine them roaming around; they still fuel my imagination." - Jack Horner
James Duncan Davidson/TED
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A puppy waits at an adoption event in Miami last year. The city is now considering a ban on the sale of puppies in retail pet stores. Cities and towns in several states have passed similar bans, aimed at cracking down on substandard, large-scale puppy breeders.
Wilfredo Lee/AP
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P22, a 4-year-old male mountain lion known as the "Hollywood Lion," is known to traverse the hills in and around Los Angeles. He is seen here recaptured by the National Park Service in March after being exposed to rat poison.
AP Photo/National Park Service
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It's a bull market for cattle: prices are climbing across the U.S. In Tulsa, Okla., stockyards reported selling 4,500 head of cattle at record prices in a single day's sale last week.
Charles Osgood/AP
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In the northwestern United States, this crayfish would be just a friendly bit of local fauna. But in Scotland, it's an invasive species wreaking havoc on trout streams.
Ari Shapiro/NPR
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