Extinct glyptodonts really were gigantic armadillos, ancient DNA shows
|An illustrated rendition of two glyptodonts |
[Credit: Peter Schouten]
"Glyptodonts in fact represent an extinct lineage that likely originated about 35 million years ago within the armadillo radiation," says Hendrik Poinar of McMaster University in Canada.
"Glyptodonts should probably be considered a subfamily of gigantic armadillos," adds Frederic Delsuc of CNRS in France. "We speculate that the peculiar structure of their unarticulated carapace might have evolved as a response to the functional constraint imposed by the size increase they experienced over time."
|An illustration of a glyptodont [Credit: Artist Carl Buell]|
In the new study, the researchers used a technical trick allowing them to specifically fish Doedicurus mitochondrial DNA out of an extract containing plenty of DNA from other sources. They used RNA baits designed from computationally reconstructed ancestral DNA sequences based on known modern sequences of glyptodonts' living relatives.
Their phylogenetic analysis establishes that glyptodonts are in fact deeply nested within the armadillo crown group, representing a distinct subfamily (Glyptodontinae) within the family known as the Chlamyphoridae, represented today by the dwarf pink fairy armadillo and the giant armadillo, for instance. Molecular dating suggests that glyptodonts diverged no earlier than about 35 million years ago, the researchers report, in good agreement with their known fossil record.
|Melanie Kuch, research assistant, Department of Anthropology at |
McMaster University examines ancient glyptodont specimens
[Credit: McMaster University]
Poinar and Delsuc say they'll continue to explore ancient DNA lifted from numerous other fossil xenarthrans, including giant ground sloths.
Source: Cell Press [February 22, 2016]