Date:

Fossil primate shakes up history of strepsirrhines

Fossils discovered in Tunisia challenge several hypotheses concerning the origin of tooth-combed primates (Malagasy lemurs, Afro-Asian lorises and African galagos).

The fossils are of a small primate called Djebelemur, which lived around 50 million years ago. They were discovered by a French-Tunisian team from the Institut des Sciences de l’Evolution in Montpellier (CNRS/Université Montpellier 2/IRD) and the Office National des Mines (ONM) in Tunis. According to the paleontologists, Djebelemur was probably a transitional form leading to the appearance of tooth-combed primates. However, according to genetic data, these primates appeared at least 15 million years earlier. Djebelemur therefore challenges the hypotheses put forward by molecular biology. The work, which has just been published in Plos One, makes it possible to reconstruct a chapter in the evolutionary history of this lineage. In addition, it may help to refine genetic models.

- Advertisement -

Tooth-combed primates, also called strepsirrhines, comprise lemurs and lorisiforms (small primates which include lorises and galagos). In these primates, the anterior teeth of the lower jaw take the form of a comb. This is mainly used for grooming, but also, in some species, for procuring the natural gums that make up part of their diet.

A key question debated by primatologists concerns the time when strepsirrhine primates first appeared. Recent genetic data dates the origin of lemurs and lorises to the onset of the Tertiary period, just after the disappearance of the dinosaurs (approximately 65 million years ago). Some molecular biologists even believe that divergence of the two groups occurred 80 million years ago. However, paleontological data does not corroborate these hypotheses: the oldest known lorisiform fossil dates from a mere 37 million years ago. Could this simply be due to a gap in the fossil record? The fossils discovered by the Institut des Sciences de l’Evolution in Montpellier (CNRS/Université Montpellier 2/IRD) and the ONM in Tunis suggest otherwise: it is the genetic models that may need to be revised.

Discovered in the sediments of a former lake in Djebel Chambi National Park, Tunisia, the approximately 50 million-year-old fossils belong to a small primate called Djebelemur (lemur of the Djebel). This was a tiny animal weighing scarcely 70 g. It was most certainly nocturnal, a predator of insects and a tree-dweller. Some of its morphological characteristics suggest that it was a distant relative of lemurs, galagos and lorises. However, although it did not yet have such a specialized toothcomb, it exhibited a tooth structure that had already been transformed, an early stage of the anterior dentition of today’s strepsirrhines.

Djebelemur thus appears to be a transitional form, pre-dating the lorisiform-lemuriform divergence. Therefore, tooth-combed primates probably did not originate as early as molecular biologists have claimed. This is likely to have occurred less than 50 million years ago, the age of the Djebelemur fossil.

- Advertisement -

This is not the first time that genetic data disagrees with paleontological data. For many groups of mammals, geneticists tend to put forward earlier dates of origin than those provided by direct observation of the fossil record. Molecular biology increasingly seeks to refine its models by constraining them with fossil data. In the case of the origin of tooth-combed primates, Djebelemur could prove to be a significant milestone making it possible to reset the molecular clock and improve estimates of divergence dates derived from molecular phylogenies.

Header Image : © Laurence MESLIN / CNRS, Institut des Sciences de l’Evolution de Montpellier (ISE-M). Djebelemur martinezi, artist’s reconstructions based on life-history traits inferred from the study of new fossil remains.

Contributing Source : CNRS (Délégation Paris Michel-Ange)

- Advertisement -
spot_img
Mark Milligan
Mark Milligan
Mark Milligan is multi-award-winning journalist and the Managing Editor at HeritageDaily. His background is in archaeology and computer science, having written over 8,000 articles across several online publications. Mark is a member of the Association of British Science Writers (ABSW), the World Federation of Science Journalists, and in 2023 was the recipient of the British Citizen Award for Education, the BCA Medal of Honour, and the UK Prime Minister's Points of Light Award.
spot_img

Mobile Application

spot_img

Related Articles

Traces of Bahrain’s lost Christian community found in Samahij

Archaeologists from the University of Exeter, in collaboration with the Bahrain Authority for Culture and Antiquities, have discovered the first physical evidence of a long-lost Christian community in Samahij, Bahrain.

Archaeologists uncover preserved wooden elements from Neolithic settlement

Archaeologists have discovered wooden architectural elements at the La Draga Neolithic settlement.

Pyramid of the Moon marked astronomical orientation axis of Teōtīhuacān

Teōtīhuacān, loosely translated as "birthplace of the gods," is an ancient Mesoamerican city situated in the Teotihuacan Valley, Mexico.

Anglo-Saxon cemetery discovered in Malmesbury

Archaeologists have discovered an Anglo-Saxon cemetery in the grounds of the Old Bell Hotel in Malmesbury, England.

Musket balls from “Concord Fight” found in Massachusetts

Archaeologists have unearthed five musket balls fired during the opening battle of the Revolutionary War at Minute Man National Historical Park in Concord, United States.

3500-year-old ritual table found in Azerbaijan

Archaeologists from the University of Catania have discovered a 3500-year-old ritual table with the ceramic tableware still in...

Archaeologists unearth 4,000-year-old temple complex

Archaeologists from the University of Siena have unearthed a 4,000-year-old temple complex on Cyprus.

Rare cherubs made by master mason discovered at Visegrád Castle

A pair of cherubs made by the Renaissance master, Benedetto da Maiano, have been discovered in the grounds of Visegrád Castle.