The brand-new specimen, a partial hand-and-foot(manus-pes)print set, goes back to the Eocene date, some 55 million years earlier.

Identified T-373, it was gathered from the Fossil Hill Formation on King George Island’s Fildes Peninsula.

This paleontological website is so abundant in maintained plants, plumes and animal traces that it is secured as an Antarctic Specially Protected Area.

“Although the earliest mammalian or mammal-like footprints date from the Late Triassic, an impressive boost in the variety and abundance of their record happens towards completion of the Mesozoic, together with direct proof in the kind of teeth and skeletal remains,” stated Dr. Héctor Mansilla-Vera from the Instituto Antártico Chile at the Museo Colección Paleontológica de Antártica y Patagonia and his coworkers from Chila and Argentina.

“Following the Cretaceous-Paleogene mass termination occasion, the fossil record of land mammals, consisting of bones, teeth, and ichnological proof, such as footprints, ends up being considerably more plentiful around the world.”

“The mammalian fossil records from South America, which are phylogenetically connected to those from the Antarctic continent, plainly contrast with the much scarcer record documented there.”

“The total land-mammal fossil record from Antarctica is represented primarily by separated teeth and, to a lower degree, by skeletal remains.”

“Notably, all these products are limited to Eocene-Oligocene layers on Seymour (Marambio) Island, West Antarctica, highlighting the strong geographical predisposition of the Antarctic Paleogene mammalian record in a continent where terrestrial mammals are now completely missing.”

The T-373 print itself is little– about the size of a big coin– however its shape uses ideas to who made it.

The specimen reveals 3 rounded toe pads set up in an arc, a triangular heel pad, and no claw marks, functions constant with a cat-sized mammal strolling on its toes.

Utilizing a formula that approximates body mass from footprint location, the authors determined that the animal weighed just about 1.3 kg.

These shapes and size carefully match a group of extinct South American predators called sparassodonts, pouched, weasel-like mammals connected to opossums that prevailed in Patagonia throughout the exact same age.

“T-373 represents the natural cast of a little, partly maintained manus and pes imprint, identified by a rounded triangular metapodial pad impression, a minimum of 3 circular digit impressions organized in an anterior arch, and a digitigrade posture,” the paleontologists stated.

“The approximated body mass for the T-373 trackmaker lines up specifically with the size variety of little Hathliacynidae sparassodonts, e.g., Pseudonotictis“

No fossilized bones or teeth from a sparassodont have actually ever been discovered in Antarctica.

The scientists argue the footprint is the greatest proof yet that these animals crossed into Antarctica over a land bridge that when linked the continent to South America, before the 2 landmasses wandered apart and Antarctica’s environment turned freezing.

Previously, palentologists thought the only land predators in Antarctica’s Eocene forests were little forefathers these days’s falcons and flightless fear birds.

The brand-new discover recommends mammals likewise inhabited a predatory specific niche because community, including a formerly unidentified layer to the Antarctic food web.

“The T-373 footprint makes up the very first direct ichnological proof of a land mammal in the Eocene environments of Antarctica,” the researchers concluded.

“The discovery supports the concept that these endemic South American predators had actually reached high southern latitudes by the early Paleogene.”

“It even more fine-tunes the restoration of the trophic structure of the West Antarctic community by exposing a more intricate food web incorporating herbivores, little mammals, birds, and now a mammalian peak predator within a transitional seaside environment.”

The discovery is reported in a paper released this month in the journal Polar Biology

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H. Mansilla-Vera et al2026. Mammal tracks from the Eocene of Antarctica. Polar Biol 49, 101; doi: 10.1007/ s00300-026-03539-1