Rescue workers said the bodies - 52 children, 33 women and 7 men from Niger were found near the Algerian border.
Many of the bodies were in an advanced state of decomposition, and some had been partly eaten by wild animals.
They were buried in a mass grave, close to where they died.
Authorities said 19 of the group reached Algeria by foot and were returned to Niger.
Two survived after walking the 50 mile trek back to Arlit, a mining down in Niger, and it was there that the alarm was raised.
Niger is ranked by the United Nations as the least developed country on earth. Every year thousands risk their lives by crossing through Northern Niger into North Africa and across the Mediterranean into Europe.
Most of those who make the perilous journey on ancient open-topped trucks are young African men in search of work.
Rescuers said the doomed convoy of women and children was puzzling.
Almoustapha Alhacen who lives in Arlit, a mining down approximately 50 miles from where the bodies were found, was alerted after survivors reached the town on foot. He said:
This is extremely difficult and the most horrible thing I have ever see.
These are women and children; they were abandoned and left to die.
We found them scattered over a large area, in small groups. Some were lying under trees, others exposed to the sun. Sometimes we found a mother and her children, some of the bodies were children alone.
They were left there for so long that their bodies are decomposed.