Suds versus nanoparticles and more reader feedback

The bipedal Butcher

 In “Fearsome croc dominated northern Pangaea” (SN: 4/18/15, p. 16), Ashley Yeager introduced Carnufex carolinensis, also known as the Carolina Butcher. This ancestor of crocodiles reigned as a top predator more than 200 million years ago in what later became North America.

Some readers questioned the illustration that accompanied the story, showing the ancient reptile balancing on its hind limbs.