The corpses of rare conjoined bats found in Brazil have given scientists a closer look into a phenomenon that has only ever been recorded twice before.
When Marcelo Rodrigues Nogueira, a postdoctoral researcher in biology at the State University of Northern Rio de Janeiro first saw the bat twins, he was “completely astonished,” he wrote in an email to Live Science. “I have handled many bats [in my career], some with very impressive morphological characters (and bats are very special in this respect!), but none [were as] surprising as these twins.” [See Photos of the Rare Conjoined Bats Found in Brazil]
Only two other pairs of conjoined bat twins have been reported in the scientific literature, one in 1969 and another in 2015.
Although it’s not known exactly what causes identical twins to be conjoined, the phenomenon is known to occur when a fertilized egg splits too late. If an egg splits four to five days after being fertilized, two separate identical twins will form. If, however, the splitting doesn’t occur until 13 to 15 days after fertilization, the fertilized egg will only separate partially, and the twins will be conjoined.
The researchers first became aware of the conjoined bats after the animals were donated to the Laboratory of Mastozoology at the Rural Federal University of Rio de Janeiro. No one from Nogueira’s team, which includes embryologists Nadja Lima Pinheiro and Adriana Ventura from the Area of Embryology at the Rural Federal University of Rio de Janeiro, saw the twins right when they were found. Because of this, the scientists, aren’t certain if the twins were stillborn or if they had died shortly after birth.
The bats, found under a mango tree in southeastern Brazil in 2001, are dicephalic parapagus conjoined twins, which means they’re oriented side by side with their whole trunks conjoined. X-rays revealed that the twins’ spines form a “Y” shape, with two separate columns of…