Mysteries of the Ancient Pyramids by Linda Sohner

This book is the third in a series for middle readers that explores ancient sites and cultures. The stories follow the adventures of two best friends, Caroline and Polly. The girls, and Polly's little brother, have the opportunity to visit sacred sites with Caroline's father and his colleagues from the University of Arizona. In this novel, they travel to Mexico to the ancient city of Palenque to explore an archaeological project where they learn about the Mayan culture, language and history. The visitors fall in love with the beauty of the surrounding rain forest. But Caroline and Polly venture too far into the jungle while following a beautiful Mayan bird and get lost during a storm. They spend the night in a small cave where they find a previously unknown ancient burial that could be the most important historical discovery of the decade.