1.4 Million-Year-Old Footprints Indicate Extinct Hominid, Paranthropus boisei, Was Larger Than Expected

Researchers studying 21 tracks left by ancient hominins in the Kenyan area of Koobi Fora have determined that these footprints were made by Paranthropus boisei. These hominins inhabited the region at the same time as bipedal humans.

Unexpected characteristics of the individuals

According to scientists' calculations, the size and weight of these massive Australopithecines from Koobi Fora significantly exceeded the indicators determined based on the bones of representatives of this species. The research results were presented in the journal Proceedings of the National Academy of Sciences.

Context of ancient hominin findings

Recently, there has been a growing number of studies dedicated to the footprints of ancient hominins, which are sometimes preserved for millions of years. The most famous similar finds are associated with Tanzania, where numerous foot and paw prints belonging to presumed ancestors of Homo—Afar Australopithecus (Australopithecus afarensis) and other hominins who walked through volcanic ash about 3.66 million years ago—were discovered in Laetoli back in the 1970s.

Analysis of the Laetoli tracks showed that Afar Australopithecines, including Lucy, were already confidently walking upright. A more recent discovery concerned findings specifically from the Kenyan formation of Koobi Fora. In 2024, an article was published reporting the presence of tracks of both bipedal humans (H. erectus) and Paranthropus boisei in one area, which presumably coexisted in East Africa about 1.5 million years ago, traversing the same territory within an interval of only a few hours or days.

Details of excavations in Koobi Fora

Kevin Hatale from Chatham University and the Max Planck Institute for Evolutionary Anthropology, together with colleagues from Kenya and the USA, shared data on further investigations in the Koobi Fora formation, but in another location—GaJi10. Initial small excavations were conducted in this section in 1978–1979, resulting in the discovery of seven ancient hominin tracks and 82 paw prints of other animals, including birds and large horned animals, as well as hippos. Additional excavations carried out in 2016 and 2023 allowed for the discovery of another 14 hominin tracks and numerous prints of other creatures.

According to the authors, two of the seven hominin tracks recorded in the 1970s were damaged, but they were carefully documented with photographs and casts. Ultimately, scientists analyzed all 21 tracks and concluded that they likely belonged to eight different individuals. The characteristics of the prints indicate that they are probably the tracks of Paranthropus boisei, who lived in this area approximately 1.43 million years ago.

Conclusions on social behavior

A deeper analysis of the tracks led to unexpected conclusions. If these tracks truly belonged to Paranthropus, calculations showed that several large individuals, presumably males, moved slowly along the bank of an ancient lake at a speed of about one to two kilometers per hour. This suggests a social structure for these hominins, implying peaceful coexistence of males in one group.

The most striking finding was the comparison of the estimated height and body mass of these individuals with data obtained from bones. The authors refer to 2017 statistics, according to which the average height of known Paranthropus boisei at that time was 131.1 centimeters (ranging from 116 to 161.3 centimeters). However, estimates made from the Koobi Fora tracks ranged from 130.6 to 180.9 centimeters, with four individuals exceeding 161.3 centimeters. The average body mass of Paranthropus in the 2017 study was estimated at 36.6–52.5 kilograms (depending on the methodology). For the individuals from Koobi Fora, however, scientists calculated a weight between 39.8 and 74.6 kilograms, with six out of seven individuals exceeding 52.5 kilograms.

Alternative hypotheses

Despite the scientists' inclination to believe that Paranthropus boisei left the tracks 1.43 million years ago in Kenya, other versions were considered. The first hypothesis suggests that the tracks could belong to bipedal humans, which would imply variability in foot structure among members of the genus Homo, about which researchers currently have no data. The second alternative version is that another unknown paleoanthropological and archaeological species of ancient hominins existed in East Africa during that period, although this idea is considered least likely due to the well-studied nature of the region.

Comparison with other finds

Other species of Paranthropus were also found in Southern Africa. Recently, a small representative of this genus was reported, whose bones were found in Swartkrans. This individual, P. robustus, lived between 2.3 and 1.7 million years ago, and its height apparently barely exceeded a meter, while its body mass was about 27 kilograms.

Paleontologists have presented a description of the oldest representative of the carnivorous marsupial family (Dasyuridae). This species, named Miyumba chrisdickmani, inhabited the state of Queensland about 18.24 million years ago, at the beginning of the Miocene.

Characteristics of the new species

Miyumba chrisdickmani was a very small mammal, weighing approximately between 23 and 33.5 grams. It hibernated and fed on insects and various invertebrates. According to data published in the journal Australian Zoologist, scientists had previously been unable to find reliable representatives of Dasyurids in geological layers older than 5.3 million years.

The Carnivorous Marsupial Family

The family Dasyuridae includes about 70 species, existing or extinct in the past, and is found in Australia, as well as on the islands of Tasmania and New Guinea. Known representatives include Tasmanian devils (Sarcophilus harrisii), spotted quolls (Dasyurus), and antechinus mice (Antechinus). Larger and medium-sized species of this group feed on carrion and vertebrates, while smaller species specialize in hunting insects and other invertebrates.

Discovery in Queensland

According to modern scientific models, this group of Dasyurids appeared in the early Miocene, around 18 million years ago. However, in fossil records, its representatives only appear for the first time in the early Pliocene, about 5.3 million years ago. A team of paleontologists led by Timothy Churchill from the University of New South Wales managed to describe the first undisputed representative of Dasyurids from pre-Pliocene deposits.

Jaw Study

The focus of the scientists was seven samples of lower jaws containing teeth—premolars and molars. These finds were discovered at the UNESCO World Heritage site of Riversleigh, located in northwestern Queensland, Australia. The age of these remains has been determined to be 18.24 million years, corresponding to the early Miocene. Churchill and his staff concluded that the owner of these jaws belonged to a previously unknown species and genus in the order of carnivorous marsupials, based on the structure of the molars. Additional analysis allowed it to be classified within the family of carnivorous marsupials as a clade that is sister to all other members of the family. The new species has been named Miyumba chrisdickmani. The genus name comes from the Australian word waanyi, which denotes the area around Riversleigh, and the specific epithet is dedicated to ecologist Christopher Dickman for his contribution to the study of modern dasyurids.

Ecological Niche and Evolution

Calculations showed that M. chrisdickmani weighed only 23.3–33.5 grams, comparable to the smallest extant carnivorous marsupials, such as antechinus mice and sminthopsis mice (Sminthopsis). The authors suggest that representatives of this species lived in the humid tropical forests covering northern Australia in the middle and early Miocene, and judging by their size, hunted insects and other invertebrates, resembling modern New Guinean marsupial mice (Murexia).

Revision of Evolutionary Concepts

By integrating M. chrisdickmani into the evolutionary scheme of the order of carnivorous marsupials, Churchill and his co-authors also established that another presumed pre-Pliocene representative of the Dasyurid family, Mayigriphus orbus, indeed belongs to this group. This species lived in Riversleigh in the early late Miocene and, like M. chrisdickmani, was very small, weighing about 20 grams. It is assumed that M. orbus was an early representative of the subfamily Sminthopsinae, which is adapted to arid open landscapes.

New Chronology of Origin

Thanks to the discoveries of M. chrisdickmani and the recognition of M. orbus as a member of the family, previous ideas about the origin of Dasyurids have been corrected. According to the updated reconstruction, Dasyurids appeared at the end of the Oligocene or beginning of the Miocene, approximately 23.2 million years ago, five million years earlier than previous estimates. Initially, these species inhabited humid tropical forests, but later some of their descendants managed to adapt to other environments, including deserts and savannas.

Other Paleontological Finds

In the context of paleontology, three new fossils of Obdurodon insignis—a toothed ancestor of platypuses—were also described. These finds were made in the Namba formation of South Australia during the Late Oligocene and date back to about 25 million years ago. Analysis of the scapulocoracoid showed that O. insignis likely closely resembled extant platypuses and possessed good swimming skills. Researchers believe that these animals inhabited a large lake or lake system alongside many freshwater inhabitants, including small dolphins. The results of this study were also published in the journal Australian Zoologist.