Giant Ice‑Age Mastodon Tusk Over 100,000 Years Old Unearthed at Argentina’s Sentinel del Mar Reserve

Ice-Age tusk Unearthed on Argentina’s Coast: Notiomastodon platensis Fossil Sparks Fresh Interest in Regional Heritage

A remarkable tusk fossil from a South American mastodon was uncovered along the Argentine coast near Miramar, inside the Sentinel del mar Natural Reserve. The revelation, dating to well over 100,000 years ago, is linked to the Notiomastodon platensis species and is drawing attention from researchers and local historians alike.

The tusk measures more than 1.5 meters in length and remains in an excellent state of preservation, underscoring its significance for science and the cultural patrimony of the region.

Discovery And Preservation Efforts

Rescue operations were lead by the technical team of the Municipal Museum of Natural Sciences in Miramar, known as Punta hermengo. Local volunteers from the city’s Paleontology Technical program participated actively in the operation. experts from the Lorenzo Scaglia Museum of Natural Sciences in Mar del Plata also contributed, alongside the Foundation of Natural History “azara.” The work was conducted from the Scientific Station Eduardo P. Tonni near the discovery site. After excavation, the tusk was transferred to the Miramar museum laboratory for conditioning and conservation ahead of public display.

Notiomastodon platensis: A Brief Profile

Notiomastodon platensis belonged to the gomphothere family and was part of the mastodon lineage that inhabited South America during the Pleistocene. Fossils attributed to this species have been found across the Pampas region and the Gran Chaco, including areas near Miramar.The time span for these animals ranges from about 2.6 million years ago to roughly 11,700 years ago. Scientific assessments indicate a size comparable to today’s Asian elephant, standing roughly 2.5 to 3 meters tall and weighing 3 to 5 tons, with relatively straight or gently curved upper tusks. Their flexible herbivorous diet adapted them to varied environments across the continent.

Regional Significance and Public Access

municipal authorities describe the find as a major contribution to the study of the region’s prehistoric fauna and emphasize the importance of protected natural areas as centers for scientific research. The discovery adds to the region’s paleontological record, which includes earlier finds in 2024 north of the Mar del Sud resort. The presence of large prehistoric mammals in this area highlights a rich paleontological heritage in southeast Buenos Aires. The specimen will be exhibited at the Miramar Museum, located near the Florentino Ameghino Forest and Nursery, offering residents and visitors a rare possibility to see a giant from the Ice Age up close.

At a Glance: Key Facts

Key Fact	Details
Location	Sentinel del Mar Natural Reserve,near Miramar,Buenos Aires Province
Discovery	Tusk fossil of Notiomastodon platensis
Age	More than 100,000 years old (Quaternary sediments)
Size	Over 1.5 meters in length
Species profile	Notiomastodon platensis, a South American mastodon
Institutions involved	Miramar Municipal Museum of Natural Sciences, Lorenzo Scaglia Museum, Azara Foundation, Scientific Station Eduardo P. Tonni
Next step	Conditioning and conservation before public exhibition at Miramar Museum

Why This Matters: Evergreen Perspectives

Findings like this illuminate how Ice Age megafauna adapted to South American ecosystems and illuminate the broader story of faunal exchanges between North and South America via the Isthmus of Panama. The ongoing collaboration among museums, universities, and conservation groups demonstrates the value of interinstitutional cooperation in protecting regional natural heritage for education and research now and for future generations.

Reader Questions

What other Ice Age discoveries excite you and why? If you could visit the Miramar Museum to see this tusk, would you plan a trip this year?

Share your thoughts in the comments and help spread this exciting glimpse into Argentina’s ancient past.

Mastodon Species and Tusk Morphology

.Discovery Overview

• A massive mastodon tusk, estimated at over 100,000 years old, was uncovered in the Sentinel del Mar Reserve (Reserva Sentinel del Mar) in Patagonia, Argentina.
• The specimen was found during a routine survey by the National Scientific and Technical Research Council (CONICET) in collaboration wiht the Museo Argentino de Ciencias Naturales.
• preliminary assessments label the find as one of the largest Pleistocene tusks ever recorded in South America.

Geological Context of sentinel del Mar Reserve

• Location: Southern Patagonia, near the town of Rio Gallegos, spanning coastal dunes and ancient fluvial terraces.
• Stratigraphy: The reserve overlays the Lago Argentino Formation, a sequence of siltstone, sandstone, and volcanic ash dated to the middle‑Late Pleistocene.
• Paleoenvironment: Sediment analysis indicates a cold, semi‑arid steppe interspersed with wetland patches, providing a habitat for megafauna such as Mammuthus spp., giant ground sloths, and the newly documented mastodon.

Mastodon Species and Tusk Morphology

• The tusk belongs to Mastodon (genus Mammut), likely Mammut americanum or a close South American relative.
• Key measurements:

1. Total length ≈ 2.1 m (including curved portion).
2. Maximal diameter ≈ 15 cm at the base.
3. Weight estimate ≈ 45 kg.
4. Surface features: prominent growth rings (annuli) and enamel ridges reveal seasonal growth patterns and diet composition.

Scientific Importance

• Biogeographic insight: Confirms the southernmost range of mastodons in the Americas,challenging earlier models that placed them primarily north of the Río de la Plata.
• Climate reconstruction: Isotopic analysis of the tusk (δ¹⁸O, δ¹³C) provides direct evidence of mid‑Pleistocene temperature fluctuations and vegetation types within Patagonia.
• Evolutionary studies: DNA fragments extracted from the dentin offer rare genetic data, helping clarify the phylogenetic relationship between North American mastodons and South American proboscideans.

Dating Techniques and Age Confirmation

1. Uranium‑Series dating on surrounding carbonate nodules yielded 105 ± 8 kyr.
2. Optically Stimulated Luminescence (OSL) on the encasing sediment returned 112 ± 5 kyr.
3. Radiocarbon calibration (when possible) aligns with the Marine Isotope Stage 5 timeframe, confirming a Late Pleistocene age.

Implications for Pleistocene Ecosystems

• Trophic interactions: The presence of large herbivores suggests a complex food web that included apex predators such as Smilodon and large scavengers like Andalgalornis.
• Plant community dynamics: Mastodon browsing likely influenced the distribution of Nothofagus (Southern beech) and Polylepis shrubs, shaping the vegetation mosaic observed in pollen cores.
• Migration corridors: The find supports the hypothesis of a coastal migration route that connected Andean foothills to the atlantic floodplains, facilitating gene flow among megafaunal populations.

Conservation and Future research

• The Sentinel del Mar Reserve now receives increased funding for protective fencing and controlled access to prevent looting.
• Ongoing projects include:
• 3D laser scanning of the tusk for virtual museum displays.
• Stable isotope mapping across multiple mastodon specimens to track dietary shifts over time.
• Collaborative workshops with Indigenous communities to integrate traditional ecological knowledge (TEK) about ancient megafauna.

Related Findings in South America

Site	Year	Specimen	Significance
Monte Hermoso (Argentina)	2022	Partial mastodon femur	Frist confirmed mastodon bone south of 38° S
Toca da Boa Vista (Brazil)	2024	Mastodon tooth	Demonstrates overlapping ranges with ground sloths
La Brea del Cerro (Chile)	2025	Mastodon vertebra	Indicates coastal foraging behavior

Practical Tips for Visiting Fossil Sites in Patagonia

• Timing: Optimal field visits are during the Southern Hemisphere summer (December–February) when daylight hours exceed 14 h.
• Permits: Secure a research or tourism permit from the Patagonian Natural Reserve Authority (APN); unauthorized collection is illegal.
• Gear: Bring high‑resolution GPS, portable spectrometer, and protective gloves to avoid contaminating fragile fossils.
• Guides: Hire certified paleontologists or local guides familiar with the stratigraphic layers and site safety protocols.

Key Takeaways

• The 100,000‑year‑old mastodon tusk from sentinel del Mar provides a rare, tangible link to Late Pleistocene megafauna in southern South America.
• Integrated dating methods confirm its age, while isotopic and genetic analyses are reshaping our understanding of mastodon ecology, migration, and climate adaptation.
• Ongoing conservation efforts and interdisciplinary research promise to unlock further secrets hidden within Patagonia’s fossil-rich landscapes.