Scientists discover new turtle that lived alongside 'Lucy' species
Holotype skull of the extinct mud terrapin species Pelusios awashi. Graphic by Brenton Adrian/ASU
Shell pieces and a rare skull of a 3-million-year-old freshwater turtle are providing scientists at Arizona State University with new insight into what the environment was like when Australopithecus afarensis, the species that includes the famous “Lucy” — lived.
The fossils of the newly named Pelusios awashi came from several turtles and were uncovered across several sites, including the well-known “First Family” hominin location. The area is located in Ethiopia’s Hadar Formation, where numerous early hominin ancestor fossils have been discovered.
“The fossils were stored in the Hadar collections at the National Museum of Ethiopia in Addis Ababa and were recovered during expeditions in the late 20th century,” said Brenton Adrian, an affiliated graduate student at ASU's Institute of Human Origins and School of Human Evolution and Social Change.
“I was prepared to look at turtle fossils, so I was able to determine that this was probably something new. I was able to start right away with descriptions and get the photos I would need for the figures.”
Based on the research, Adrian said P. awashi was about 42 centimeters long, similar to the width of a medium-sized laptop. The prehistoric turtle had a broad, powerful upper jaw, suggesting it likely fed on hard-shelled prey like snails and crustaceans. This type of crushing diet, known as durophagy, is also seen in some modern African turtles.
Isotopic data from animal fossils and sediments at the Hadar Formation indicate savanna landscapes 3 million years ago, with freshwater rivers and variable flooding, abundant aquatic vegetation and a climate wetter than that of modern Ethiopia.
Along with human ancestors like A. afarensis, this turtle was living among crocodiles, and one shell fragment had distinct crocodilian tooth marks. While there is no evidence so far that A. afarensis ate these turtles, other early hominin sites show that later species sometimes collected and consumed terrapins.
“I’m glad people made the effort to collect these specimens, and it’s particularly exciting that the new species adds to our understanding of Pliocene paleoecology in eastern Africa,” Adrian said. “I hope to work on more of the turtles from these sites.”
Adrian has worked with scientists at ASU and beyond to identify five other new species of turtles and two Miocene carnivoran species from Kenya during his academic career.
Several scientists with the Institute of Human Origins and the School of Human Evolution and Social Change participated in the research about P. awashi, including: Associate Professor Christopher Campisano, President’s Professor Emeritus Kaye Reed and Professor Denise Su.
"A new species of the mud terrapin Pelusios offers insights into early hominin habitats at the Pliocene Hadar Formation of Ethiopia” was published in Scientific Reports.
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