An illustration of the giant teratorn (Argentavis magnificens), an extinct species believed to be the largest flying bird that ever lived. Illustration by Jaime Chirinos, Science Photo Library/Corbis

I thought Quetzalcoatlus is the biggest pterosaur or flying dino? —Vince

This is a great question that came out of a column in which a reader had asked, “How big was the largest flying dinosaur?” It’s not Quetzalcoatlus, but my answer, Changyuraptor yangi, wasn’t right either, says Mark Witton of the U.K.’s University of Portsmouth via email, because that animal was a glider and not a flier.

“The distinction is that fliers—more correctly known as powered fliers—produce their own lift, whereas gliders cannot.” Witton illustrates the distinction by saying it’s the difference between an airplane and a parachute: “They both allow travel through air, but the mechanics are very different.”

Witton says the largest flying dinosaur would be “something like the Miocene giant condor-like bird Argentavis,” with a 23-foot (7-meter) wingspan and 154-pound (70-kilogram) mass. Birds, Witton says, “are a group of dinosaurs in themselves, and many of them—including numerous modern species—surpass Changyuraptor in wingspan and mass.”

Vince is right in that Quetzalcoatlus were, indeed, “the largest pterosaurs, and the largest known flying animals of all time, but dinosaurs they aren’t,” Witton writes. (Related: “New Flying Reptile Found in ‘Unprecedented’ Pterosaur Boneyard.”)

Dinosaurs and pterosaurs are different groups but share a common ancestor in Avemetatarsalia. Nat Geo blogger Brian Switek explains the difference and provides a handy chart showing where the groups split in a 2010 story on Smithsonian.com. Check out Witton’s blog for tons more on pterosaurs. (Related: “New Golden Age for Pterosaurs, Flying Reptiles of the Dinosaur Era.”)

How long does a spider bite [venom] react in the nervous system? —Arocha Musa, Jr., Uganda

This question came to us from an earlier column about which spider bites are most dangerous to humans.

Leslie Boyer of the University of Arizona, Tucson, says that “in most cases, the effects on bitten people are over within a matter of days, and the toxins are probably gone within a day or so after that. Once in a while an unlucky person is sick for a couple of weeks,” but that’s more the healing process than getting rid of the venom itself.

If a bite is treated with antivenin, Boyer says, the venom that’s active against the body “drops very quickly to near zero after a good neutralizing dose,” but, though it’s inactive, it might stay in the body for a while until the immune system works it out.

A parasitic fig wasp drills through a fig fruit. Photograph by Lakshminath Kundanati

Is the zinc in the drill generated from the wasp’s body? Are the wasps born like that? —Jasmin Syedda, U.S.

This question arose from the story “Wasp Bores Into Fruit With Metallic Drill Bit,” which detailed research from earlier this year revealing that female parasitic fig wasps have a zinc-tipped ovipostor, a structure that allows them to “pierce the tough skin of unripe figs” and lay their eggs inside the fruit.

But where does the zinc come from? Study leader Namrata Gundiah said via email that “the fig is a rich source of zinc, among other minerals, and serves as a nursery for the developing larvae of pollinator and parasitoid wasps.” It’s unlikely that the zinc is self-generated by the wasp or that they are born with zinc-tipped ovipositors, and more likely that the zinc is assimilated from the developing fruit in which the wasps themselves develop.

I have so many ants in my yard that new hills spring up all over the place. … I am thinking of driving to Texas and stealing an armadillo. Do you think the armadillo would eat the ants? —Bonnie, Las Vegas, New Mexico

Last week Jim Loughry of Valdosta State University in Georgia answered a reader’s armadillo question; in this follow-up, Loughry says via email that armadillos “do eat ants, but having one as a pet for the sole purpose of eliminating ants is pretty extreme,” and not the best treatment. Loughry’s wife, Colleen McDonough, also of Valdosta State, concurs, saying via email it’s unlikely they’d eliminate all the ants, and would “eat other things as well and then leave.”