This Famous Fossil May Not Belong to Any Known Human Species

The legendary “Little Foot” fossil may be an entirely new human ancestor.

An international team of scientists led by researchers from La Trobe University in Australia and the University of Cambridge is questioning how one of the most complete early human fossils has been classified. Their new findings suggest the specimen may not belong to any known human ancestor species, opening the possibility that it represents an entirely new one.

The Discovery of “Little Foot”

The fossil was discovered in 1998 in South Africa’s Sterkfontein Caves and later given the nickname “Little Foot.” For years, it has been widely accepted as a member of the Australopithecus genus. This group includes early human relatives that walked upright and lived in South Africa between about 3 million and 1.95 million years ago.

Ronald Clarke, the paleoanthropologist who led the excavation and analysis of the skeleton over a 20-year period, originally identified Little Foot as Australopithecus prometheus when the fossil was publicly unveiled in 2017. Other researchers disagreed, arguing that it belonged instead to Australopithecus africanus, a species first described in 1925 by Australian anatomist Raymond Dart and already known from Sterkfontein and other South African sites.

New Research Challenges the Classification

In a peer-reviewed study published in the American Journal of Biological Anthropology, a research team led by La Trobe University adjunct Dr. Jesse Martin reached a different conclusion. After closely examining the fossil, the researchers found that Little Foot does not share a defining set of features with either Australopithecus prometheus or Australopithecus africanus. This suggests the fossil may belong to a previously unknown species.

“This fossil remains one of the most important discoveries in the hominin record, and its true identity is key to understanding our evolutionary past,” Dr. Martin said.

“We think it’s demonstrably not the case that it’s A. prometheus or A. africanus. This is more likely a previously unidentified, human relative.

“Dr. Clarke deserves credit for the discovery of Little Foot, and being one of the only people to maintain there were two species of hominin at Sterkfontein. Little Foot demonstrates in all likelihood he’s right about that. There are two species.”

Why Little Foot Is So Important

Known formally as StW 573, Little Foot remains the most complete ancient hominin skeleton ever discovered. Despite its importance, Dr. Martin’s team is the first to publicly challenge its species identification since the fossil was introduced to the scientific community in 2017.

“Our findings challenge the current classification of Little Foot and highlight the need for further careful, evidence-based taxonomy in human evolution,” Dr. Martin said.

Dr. Martin, who is an adjunct at La Trobe University and a postdoctoral research fellow at Cambridge, will continue this work with students from La Trobe. Their next goal is to determine exactly which species Little Foot belongs to and how it fits into the broader human family tree.

Broader Implications for Human Evolution

The study was supported by an Australian Research Council grant led by Professor Andy Herries at La Trobe University. Professor Herries emphasized the fossil’s value for understanding early human diversity and how ancient human relatives adapted to different environments across southern Africa.

“It is clearly different from the type specimen of Australopithecus prometheus, which was a name defined on the idea these early humans made fire, which we now know they didn’t. Its importance and difference to other contemporary fossils clearly show the need for defining it as its own unique species.”

Reference: “The StW 573 Little Foot Fossil Should Not Be Attributed to Australopithecus prometheus” by Jesse M. Martin, Luca Morris-Obst, A. B. Leece, Stephanie Baker, Andy I. R. Herries and David S. Strait, 29 November 2025, American Journal of Biological Anthropology.
DOI: 10.1002/ajpa.70177

The research was conducted through collaboration among institutions in the United Kingdom, Australia, South Africa, and the United States.

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