After sequencing the mitochondrial genome of the Hispaniolan solenodon, scientists confirmed that the endangered venomous mammal diverged from all other living mammals some 78 million years ago.
The species, Solenodon paradoxus, predates the extinction of the dinosaurs.
“It’s just impressive it’s survived this long,” Adam Brandt, a postdoctoral researcher at the University of Illinois, said in a news release. “It survived the asteroid; it survived human colonization and the rats and mice humans brought with them that wiped out the solenodon’s closest relatives.”
With a long snout and short brown-red fur, the Hispaniolan solenodon looks like a large shrew. Its hairless feet, nose and tail recall those of a possum. The species, sometimes called the Dominican solenodon, is found only on Hispaniola, the island shared by Haiti and the Dominican Republic.
Researchers at the University of Illinois and the University of Puerto Rico used two different methods to sequence the nucleotides that make up solenodon mitochondrial DNA — the kind passed unchanged from mother to offspring — to determine the history of the species’ lineage. Both methods produced the same conclusion, the species diverged from the mammalian tree of life some 78 million years ago.
The timeline fits nicely with studies that suggest the island of Hispaniola was once connected to Mexico and began drifting eastward around 75 million years ago.
Researchers shared the results of their genomic analysis in a paper published this week in the journal Mitochondrial DNA.
“Whether they got on the island when the West Indies ran into Mexico 75 million years ago, or whether they floated over on driftwood or whatever else much later is not very clear,” added lead researcher Alfred Roca, a professor of animal sciences at the University of Illinois.
The Hispaniolan solenodon spent most of the last 78 million years without any natural predators, but is now endangered as a result of habitat loss and predation from cats and dogs brought to the islands by human settlers.