Analyzing Extinct Ants in Amber
by AMNH on
Scientists and explorers of every stripe are always on the lookout for the novel—be it a new insight, revolutionary research results, or, in the case of biologists and paleontologists, discovery of new species, genera, or even orders of organisms.
But sometimes you have to look to the old to find the new. Recently, fourth-year graduate student Phillip Barden and Curator and Professor David Grimaldi, his graduate advisor, discerned nine “new” species of extinct ants preserved in Burmese amber (which, by the way, is fossilized tree resin).
Barden, who is a Ph.D. candidate in the comparative biology program at the Museum’s Richard Gilder Graduate School, is not alone in describing new species: more than 30 new species have been described by RGGS students since the program was founded in 2008. Says John Flynn, the dean of the graduate school: “This outstanding rate of naming new species previously unknown to science is a testament to our graduate students’ leadership in expanding discovery, description, and understanding of our planet’s extraordinary biodiversity.”
But while Barden and some of his peers find new animals on field expeditions that take them all over the world, these new amber-ant finds were made inside the Museum, in specimens on loan for research purposes.
These amber-entombed ants are from Kachin State, the northernmost state in Myanmar (Burma), which has been known for its amber from as early as 600 BC in the form of ornate carved pieces. Though ants are hypothesized from DNA evidence to have evolved approximately 120–130 million years ago, the specimens uncovered in this batch of amber are, at about 99–100 million years old, among the oldest found to date.
Using high-resolution X-ray CT scans and light microscopy in the Museum’s imaging laboratory, the researchers were able to discern that these ancient ants resemble modern species anatomically—for instance, they have petioles, a thin body segment between their thorax and abdomen, as well as a gland that, in modern ants, emits antimicrobial fluids. But while living ants have bent or “elbowed” antennae, in these older fossil ants the sections of antennae that emerge from their heads, or “scapes,” are far shorter than those found in living forms. Ants use their antennae, by the way, as sensory organs.
In earlier papers, Barden and Grimaldi described three other new species—and one new genus—also from Burmese amber. Two of these species exhibit tusk-like mandibles, and these ants--one of which is featured in the Museum exhibition Picturing Science—appear to have been quite ferocious, possibly impaling prey with their uniquely expanded mouthparts. Barden says he sometimes gazes at these extinct forms, which look odd to modern eyes, and wonders for a moment: “How did they live?”