Medieval shoe found in vulture nest reveals centuries-old secrets in European mountain caves

The species disappeared from southern Spain over 70 years ago. In a Sept. 18 press release, the University of Granada (UGR) said the vultures' nests "are true natural museums, preserving traces from hundreds of years ago."

During his field work, researcher Sergio Couto and his team found a complete esparto sandal - made from esparto grass native to the Mediterranean region - in the nests. The medieval shoe dates back to the late 13th century.

The researcher also found a fragment of tanned, painted leather that "resembl[ed] a mask," per the university, along with an 18th-century piece of basketry and a crossbow arrow.

The vultures' dwellings also held ropes, horse tack and thousands of bone fragments and eggshells.

The discoveries were made between 2008 and 2014; they were not released to the public until now. 

Of the 2,483 artifacts recovered, a whopping 2,117 were bone fragments. 

More than 9% of the remains "were of human origin … including 25 esparto-fiber items, 72 leather pieces, 11 made of hair and 129 textile fragments," UGR said in a statement.

"In addition, the eggshell remains provide a unique opportunity for comparative toxicological studies - vital for understanding pesticide exposure and the local extinction history of the bearded vulture. This information is key to the species' recovery in Europe."

UGR credited the stable temperature and humidity conditions of the caves for preserving the artifacts "in excellent condition."

Archaeologist Marja-Liisa P. Grue told Fox News Digital the shoes had been "in moist and oxygen-deprived masses for hundreds of years."