Archaeologists have discovered two lost cities in the deep jungle of Honduras, emerging from the forest with evidence of a pyramid, plazas and artifacts that include the effigy of a half-human, half-jaguar spirit.

The team of specialists in archaeology and other fields, escorted by three British bushwhacking guides and a detail of Honduran special forces, explored on foot a remote valley of La Mosquitia where an aerial survey had found signs of ruins in 2012.

Chris Fisher, the lead US archaeologist on the team, told the Guardian that the expedition – co-coordinated by the film-makers Bill Benenson and Steve Elkins, Honduras and National Geographic (which first reported the story on its site) – had by all appearances set foot in a place that had gone untouched by humans for at least 600 years.

“Even the animals acted as if they’ve never seen people,” Fisher said.