The discoveries were made during an expedition to the Los Amigos Biological Station in the remote Madre de Dios region of southeastern Peru, according to a news release on the university's website.
The biologists have detailed their rare sightings in a journal article published Thursday in Amphibian & Reptile Conservation.
What are the creepy details?
Like most of the keep-you-up-at-night images, video of the dinner-plate-sized tarantula dragging the softball-size mouse opossum was captured during one of the team's nighttime surveys.
"During their night surveys, team members walk slowly through the forest with flashlights and headlamps, in single file, scanning the forest and listening intently," the release said.
One night, Michael Grundler and two other students "heard some scrabbling in the leaf litter."
"We looked over and we saw a large tarantula on top of an opossum," said Grundler, a co-author of the paper. "The opossum had already been grasped by the tarantula and was still struggling weakly at that point, but after about 30 seconds it stopped kicking."
Maggie Grundler, Michael's sister, pulled out her cellphone and started shooting video of the encounter.
Later, an opossum expert from the American Museum of Natural History confirmed that the video was the "first documentation of a large mygalomorph spider [tarantula] preying on an opossum."
"We were pretty ecstatic and shocked, and we couldn't really believe what we were seeing," Grundler said in the release. "We knew we were witnessing something pretty special, but we weren't aware that it was the first observation until after the fact."
Tarantulas don't typically feed on opossum, according to arachnologist Rick West, who wasn't a member of the research team.
"Tarantula predation on vertebrates is not a common thing, but it does happen. They are opportunistic feeders and they'll take whatever they can subdue," West told National Geographic. "In the South American rainforest, I've found that some of the larger tarantulas prey often on frogs, and that was reflected in this article."
Among the other sightings, the researchers captured video and photos of battles between spiders, frogs, snakes, scorpions, and more.
Watch what happens when a tarantula encounters a baby opossum | Science Newsyoutu.be