Endangered venomous mammal predates the dinosaurs, study shows

MAY 3, 2016

by Susanna Pilny

Scientists have discovered that a modern venomous mammal—which has been described as a "giant rat with Freddy Krueger claws"—actually predates the dinosaurs.

The mammal, which is called the Hispaniolan solenodon, can only be found on (you guessed it) the island of Hispaniola, which includes Haiti and the Dominican Republic. It grows to be about a foot (30 cm) long, and is currently endangered thanks to the introduction of cats and dogs on the island—although it has been around for some 78 million years, having diverged from other living mammals at that time, according to the scientists.

An ancient mammal with an impressive track record

"It's just impressive it's survived this long," said co-first author Adam Brandt, a postdoctoral researcher at Illinois, in a statement. "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."

Researchers from the University of Illinois and the University of Puerto Rico came to this conclusion after completely sequencing the DNA of solendons’ mitochondria—the part of the cell frequently referred to as its “powerhouse,” which comes complete with its own separate DNA.

Not that getting this DNA was easy—because of their endangered status, solenodon DNA is hard to come by. The team actually had to collect samples by laying on the ground and waiting for the venomous critters to crawl across their bodies. After it all was collected, the researchers then analyzed the samples two different ways in order to sequence the mitochondrial genome—both of which came up with completely identical results.

Then, an expert at Texas A&M used the genes to estimate when solendons diverged from other mammals, which resulted in the date of 78 million years.

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