Still, we can only speculate as to the evolutionary significance of 'internal' molecular mechanisms, which are often silent or neutral, whereas we can see, directly and immediately, the profound consequences of these shifts (on snail shells, fish limbs, hen's teeth, and so on) in external phenotypes.
A large turtle, decapitated and its limbs, shell, and entrails removed.
More than 85% of the marsh crabs died in the cages, they report online this week in Ecology, which were littered with broken shells and severed limbs.
Four days into Germany's Spring Offensive, amid the chaos of the British retreat through the Pas-de-Calais region of northern France, a private with the 23rd Middlesex risked life and limb under shell fire to bring back the body of his commanding officer.
"The fossil of one of the world's oldest-known turtle shells with a limb bone, was discovered in clay deposit in a rubbish dump north-west of Krakow, Poland".
He uses a 3-D printer to create plastic shells that fit around the prosthetic limbs, and then wraps the shells in any flexible material the customer desires, be it an old bomber jacket or a trusty boot.
The 35-year-old private in the Army Service Corps had developed a paralysis of his lower limbs after a shell explosion at Ypres in June 1917.
Dr. Wali finished his rounds, examining patients who were paraplegic after being hit in the spine, or who had two, or even three, limbs removed after shells landed on their homes.
Their common name is presumably derived from their ability to draw their head and limbs completely within the shell and close themselves up like a box.
"Go and break through the lines," says Rufus. "And remember while you're out there risking your life and limb through shot and shell, we'll be in here thinking what a sucker you are".
