In one corner of Patagonia, the fossil of a tiny tooth just changed history. With barely Three millimetersThis piece revealed that mammals coexisted with dinosaurs in the south, solving a mystery that has intrigued science.
The analysis was published in a prestigious scientific journal Scientific reports, She was rescued in a province Chubut It allowed us to define, for the first time and unambiguously, the existence of… Polysalicylate In this region, as shown from Conisit.
The diversity of lifestyles from the past continues to amaze in Patagonia. Now, the focus is on Polysalicylatean extinct group of mammals that evolved around 170 million years. Until this discovery, there were only clear records of its existence north america, Europe and AsiaBut certainties remained about their presence in the south of the planet.
He explained: “These mammals diversified and spread on a planet completely different from the one we know today, with a warmer and more humid climate and ecosystems dominated by conifers and cycads, which are plants similar to palm trees, ginkgos and ferns; and a very diverse fauna, the most famous representatives of which are dinosaurs and flying reptiles.” Javier N. Guelfoa researcher at the institution and first author of the study.
The multiple tubercles had a skull shape that predicted what rodents have today: ever-growing incisors, space between them and the rest of the teeth, and molars with multiple rows of cusps. This structure allows for functions such as crushing seeds, breaking shells, and chopping vegetables.
The main fossa is the upper molar only 3 mmwere found in the excavation campaign conducted in Chubut Between 1997 and 1998. The piece was kept in a bag of unanalyzed sediment for nearly twenty years, until it was reviewed in a laboratory. Investigation revealed that this tooth contains three rows of aligned cusps, a feature exclusive to polystyrenes.
“What this analysis revealed was an upper molar with three rows of aligned cusps that reliably confirm the presence of… Polytuberculosis in south america At the same time they indirectly confirm the hitherto doubtful identity of the earlier records. Galvo.
The study was also conducted Francisco Guin (Conset) and Nahuel Vega (National Atomic Energy Commission, CNEA), used computed tomography technology to reconstruct the sample in 3D without damaging it. The new mammals have been named Notopolytheles Joelis. “Notopolytheles” means “southern polytuber” and “joelis” honors Joel CarinoThe team reported that it was the student who was able to identify the piece under a magnifying glass.
Until this finding, the presence of MTB in the Southern Hemisphere had been a matter of debate. It is possible that the previously found “plagiolacoid” teeth belong to other groups, such as the Gondwanathrians.
“One reason to question this is that plagioalacoid teeth appear to have evolved independently between different groups of present-day mammals.” Since there is no other possible evidence that it lived here, opinions are divided: some maintain that it actually corresponds to polymniotes, and others, on the other hand, attribute it to other mammals called gondwanatherians. Galvo.
Molly Notopolytheles Joelis It not only confirms its origin, but also presents an unusually long root and marked differences in the height of the cusps, providing new morphological elements not recorded among its Northern Hemisphere relatives.
The result indicates that these mammals They coexisted with dinosaurs and flying reptiles in the Patagonian ecosystemincorporating the same biodiversity that characterized the region during the period Cretaceous period.
The presence of multituberculates in south america and Australiain addition to indirect evidence in AntarcticaIt indicates that these mammals moved across the supercontinent Gondwana Before the partition of the continent. This discovery strengthens the idea of ancient biogeographical connections and integrates with other fossil records, such as monotremes, allowing us to rethink the evolution of southern mammals.
The character of the paleontologist also stands out in the work. Rosendo PascualWho died in 2012, and he was the one who managed the collection campaign in which the fossil was found. Pascual defended the hypothesis of the existence of multiple tubercles in Patagonia: “Our knowledge of the evolution and biogeography of these forms forms a story that still has many chapters to review and others to write. They conclude that this history, forged in the shadow of the great dinosaurs, is being reconstructed today from tiny teeth that reveal a complex and extraordinary past.
The discovery was published in Scientific reports It represents an inevitable reference for future studies on the prehistoric fauna of Patagonia (Guelfo, J.N., Gwen, F.J. and Vega, N.A., 2025). A tiny fossil tooth reveals new aspects of life in the age of dinosaurs and expands understanding of mammalian lineages that persisted for millions of years in the Southern Hemisphere.