At first glance, the world's most elusive and mysterious mammal looks like a small, underfed squirrel with a poof of black fur covering a scaly tail. Its DNA, however, paints a more colorful picture, with an evolutionary history virtually unchanged over tens of millions of years.
Called Zenkerella insignis, this remarkable species is one of the world's last living fossils. Back when it first arose, the Arctic was a rainforest, Australia and Antarctica were still connected, and North America's western mountain ranges had yet to rise. As for how its managed to survive for so long, we don't know. In fact, up until recently, all scientists knew was that Zenkerella was really, really good at hiding.
"It's a long lineage that stretches all the way back 50 million years, and we only have one species left that we don’t know anything about," Erik R. Seiffert, professor of cell and neurobiology at the University of Southern California, told The Washington Post. "We don't know when it is active, or what it eats, or if it spends all of its time in the trees or on the ground."
While scientists have known about Zenkerella from both the fossil record and the incomplete remains of 11 poorly preserved museum specimens, the real prize has always been to capture one in the wild. Rumors for decades persisted that Bioko, an island off the west coast of Africa, was home to the species, but not one scientist sent to the region had ever seen one alive or dead.
In 2015, the researchers finally caught a break. David Fernández, a primatologist and conservationist working in Bioko, hatched a plan with Seiffert to enlist the help of local hunters to keep an eye out for Zenkerella in their ground snares. Eight months later, just days before Fernández was set to return to the U.S., a dead Zenkerella was presented to him by village elders.
"He sent me images of the specimen and I could barely contain my excitement," writes Seiffert on his blog. "Indeed, there it was, the first whole-body specimen known for the entire species whose preservation would finally allow us to easily study its DNA, postcranial bones, muscles, brain, gastrointestinal system, etc."
In a paper published in JPeer this week, Seiffert, Fernández and other colleagues detail the DNA results and initial anatomical study of three freshly killed specimens of Zenkerella. They found that while the species has some markers related to other scaly-tailed squirrels, its ancient lineage is unusual enough to merit the creation of the newly formed Zenkerellidae family. It joins an exclusive club of mammals that have survived since the early Eocene epoch, including South America’s colocolo opossum and the African aardvark.
While the dead Zenkerella specimens have been a boon to science, Seiffert is even more determined to study a living, breathing representative. “Zenkerella could be seen as the ultimate Pokémon that scientists have still not been able to find or catch alive,” the USC professor told Red Orbit. He added that research into the new genus is only the beginning, with future field work potentially exposing even more elusive remnants of our ancient world.
"It's fun to think that there might be other elusive mammalian species out there, deep in the rainforests of central Africa that will be new to science,” he said.