Scientists Analyze the DNA of Elusive "Living Fossil" Jungle Squirrel

PeerJ / PeerJ

For millions of years, a mysterious, scaly-tailed squirrel named Zenkerella insignis has made its home in the forests of Central and West Africa. Scientists based most of their knowledge of the creature off fossils and the odd specimen. Now, The Washington Post reports, researchers have finally captured and examined three recently dead Z. insignis specimens, allowing them to study the odd animal’s genome and find its place in the evolutionary family tree. Their findings were published on Tuesday, August 16 in the journal PeerJ.  

Scientists analyzed samples of Z. insignis’s DNA, taken from cheek swabs, and found that the fluffy black critter is in the same family of "gliding" squirrels as Anomalurus and Idiurus. Unlike its relatives, Z. insignis doesn’t have a thin membrane stretching between its fore and hind limbs. However, the squirrels all have tails that are covered in scales near the base. This trait might help them gain traction while climbing up tree trunks.

Villagers on Bioko Island, off Africa’s central west coast, say they capture the strange squirrel once or twice a year. (It reportedly doesn't taste too great, and Bioko's inhabitants call it musulo, which CNN says means "inferior to all squirrels.") But although it’s sporadically spotted on the island, the mammal had long eluded Erik Seiffert, a paleontologist from the University of Southern California who co-authored PeerJ’s Z. insignis study.

Fifteen years ago, Seiffert discovered fossils—including arm and leg bones—of one of the animal’s 37-million-year-old cousins in Egypt's Faiyum Basin. Seiffert wanted to compare them to other bones, but during the course of his research he realized that no other scientists had ever seen Z. insignis alive. Furthermore, only 11 known Z. insignis samples existed, and they were scattered across museum collections.

Despite scant prehistoric evidence, scientists knew more about the squirrel’s ancient ancestors than the present-day mammal itself. In his quest for more knowledge, Seiffert reached out to a colleague, a primatologist named David Fernandez, for assistance. Fernandez now works at the University of the West of England, but before that he was director of the Moka Wildlife Center on Bioko—prime Z. insignis stomping grounds.

Fernandez questioned the villagers about the squirrel, and asked them to save some specimens for him. Sure enough, several Z. insignis were eventually caught in traps, providing Fernandez and Seiffert with an unprecedented look at the scaly-tailed animal.

Z. insignis is considered to be a “living fossil.” It’s existed for the past 49 million years, and hasn’t changed much over the millennia. But despite its ancient past, Z. insignis is still a mystery to those who study mammals. They don’t know what it eats, when it’s active, or whether it thrives in treetops or on the ground. And until recently, researchers had only studied long-dead Z. insignis, and knew little about its basic anatomy. Seiffert, Fernandez, and their colleagues hope to improve their understanding of Z. insignis by sequencing the three specimens’ genomes, analyzing their gut contents, and maybe even spotting one live in the wild.

Z. insignis may be elusive, but rest assured: It isn’t considered endangered yet. The squirrel is thought to live across a vast area of geography, so the International Union for Conservation of Nature (IUCN) has placed it in its “least concern” category,” the Evening Times writes. However, study co-author Dr. Drew Cronin, from Drexel University in Philadelphia, points out that habitat loss and degradation are real, and that greater awareness of Z. insignis is needed to ensure it doesn't eventually succumb to these threats.

[h/t The Washington Post]