An artist's rendering of the hypothetical placental ancestor, a small, insect-eating animal with a long, furry tail. The research team reconstructed the anatomy of the animal by mapping traits onto the evolutionary tree most strongly supported by the combined phenomic (physical traits you can see) and genomic data and comparing the features in placental mammals with those seen in their closest relatives.
Credit: Image courtesy of Carl Buell
What do you name the ancestor of almost all living mammals?
According to LiveScience readers, "Ralph" wouldn't be a bad bet.
Ralph topped LiveScience's poll results as of Feb. 21, beating out "Protosorex mammaliensis" and "Little Mama," after scientists announced earlier this month that they'd traced back the features of the hypothetical forerunner to all placental mammals. The animal looks a bit like a modern shrew with a dash of squirrel.
Scientists didn't give this mammal mama a nickname — it is, after all, a composite rather than a real creature. However, the American Museum of Natural History, where much of the research was based, plans to team up with WNYC's Radiolab to host a naming competition for the hypothetical ancestor.
It may seem odd to announce the discovery of an animal that never existed. But the origins of placental mammals — mammals that nourish their young in utero via the placenta, which accounts for nearly all living species — are foggy. The fossil record suggests that mammal diversity exploded after the dinosaurs died out about 65 million years ago at the end of the Cretaceous period, but genetic studies indicate a longer evolution for mammals dating back before the end of the Cretaceous.
The goal of the ancestral mammal project was to marry fossil and genetic evidence, piecing together the DNA and physical changes to trace the lineage back to the beginning, or at least an approximation of the beginning. The result was an insect-eating four-legged creature that weighed less than half a pound. From these humble beginnings arose everything from elephants to bats. The researchers reported their findings on Feb. 8 in the journal Science. [6 Strange 'New' Species Hiding in Museums]
A survey of the researchers involved in the project turned up no consensus on what, if anything, this hypothetical ancestor should be named. Michael Novacek, a study researcher and a paleontologist at the American Museum of Natural History, said that a Latin scientific name wouldn't be appropriate.
"The hypothetical ancestor is not represented by a real specimen, something that is required for Latinized names, or, as they are known in taxonomy, Linnaean names," Novacek wrote in an email to LiveScience.
So much for "Protosorex mammaliensis," the runner-up in the LiveScience poll. Other reader suggestions, contributed via Facebook, included "Timba" after Timon and Pumba from the movie "The Lion King," because "they like grubs, too!" and "yomama" ("obviously").
"These nicknames for the common ancestor are all very creative," said study researcher Maureen O'Leary, a scientist at Stony Brook University in New York. "It's great to see that this animal has inspired so much interest in science and is encouraging people to know about past life on Earth."
Editor's Note: If you have a great naming idea for this shrew-squirrel ancestor, please email Jeanna Bryner at firstname.lastname@example.org.
This article was updated at 12 p.m. EST on Friday to correct the production station of Radiolab.