Scientists built a comprehensive record of big mammals that survived more than 6,000 years ago in the Nile Valley, thanks to animal depictions in ancient Egyptian artifacts.

Published in the Proceedings of the National Academy of Sciences journal, the new scientific study enumerated 37 species of big-bodied mammals found in Egypt, of which only eight of them remain at present. The mammals recorded from the late Predynastic Period, which is before 3100 BC, and are no longer existent in Egypt are elephants, giraffe, lions, oryx, wild dogs and hartebeest.

Based on the new evaluation of said record, the scientists say extinctions of species have led to an increasingly less stable ecosystem. Local extinctions of mammal species brought about a constant decline in the stability of animal communities in Nile Valley.

Formerly a graduate student in University of California, Santa Cruz (UCSC) and presently a postdoctoral fellow in Santa Fe Institute, Justin Yeakel says the previously rich and diverse community of mammals is "very different now."

"As the number of species declined, one of the primary things that was lost was the ecological redundancy of the system. There were multiple species of gazelles and other small herbivores, which are important because so many different predators prey on them," says Yeakel, first author of the study Collapse of an ecological network in Ancient Egypt. "When there are fewer of those small herbivores, the loss of any one species has a much greater effect on the stability of the system and can lead to additional extinctions."

This study started in 2010, the year Yeakel and co-author Nathaniel Dominy went to visit San Francisco for Tutankhamun exhibition and was amazed by the artwork and animal depictions. Dominy was formerly UCSC’s anthropology professor but now part of Dartmouth.

UCSC paleontologist and co-author Paul Koch helped the team to develop an approach when making use of records to evaluate the consequences of such changes in the occurrences of species.

Said study also has its basis on compiled records by the zoologist Dale Osborne. His book in 1998 titled The Mammals of Ancient Egypt offers a detailed picture of the historical animal communities of the region as based on paleontological and archaeological evidence and historical records.

Yeakel says Osborne’s book allowed them to apply ecological modeling techniques in order to study the possible consequences of such changes in the ecological system.

The study also says the latest major shift in mammalian communities was around 100 years ago.