In Spain, traces of cave bears dating back nearly 30,000 years have been discovered.

People often learn about the existence of ancient animals through their fossilized remains. These can include entire skeletons (although such finds are extremely rare) or fragments of one or two bones. Occasionally, paleontologists also discover soft tissues of ancient species, and sometimes even their mummified bodies preserved in permafrost. For instance, recently, Russian researchers described the mummy of a saber-toothed kitten, which revealed numerous details about the appearance of this extinct cat.

There is another class of fossilized traces that literally consists of these: ichnofossils. These markings reflect walking, running, swimming, nesting, feeding, and other actions, revealing both ecological characteristics and the evolution of movement as the skeleton developed.

Some species known only from such prints are referred to as ichnotaxa. In the Romanian Ursilor Cave (also known as the "Bear Cave"), fossilized bear tracks were discovered in 2011, attributed to the cave-dwelling species (Ursus spelaeus). However, it cannot be said for certain that the tracks were left by the cave bear, which is why the German paleontologist Cajus Diedrich introduced the term Ursichnus europaeus for such markings.

A new set of cave bear tracks was discovered on the Iberian Peninsula — in northern Spain at the Cueva de Honseca (Cueva de Honseca). Strictly speaking, the discovery was reported back in 2021, but it remained unclear to whom the footprints belonged and how old they were. The cave itself, which is 3.6 kilometers long, has been known since the 1970s, so some tracks had already been trampled by tourists. In a recent study, published in the journal Ichnos, Spanish paleontologists described these prints and identified the species that left them.

The researchers identified 16 markings, consisting of three elements: the heel pad, toe prints, and claws. The front paw prints averaged 13 centimeters in length and 14.6 centimeters in width, while the hind paw prints measured 15.6 and 12.5 centimeters respectively. Paleontologists scanned the cave gallery in high resolution (2 ± 1.7 millimeters) and created three-dimensional models based on the bear footprints. In calculating the size of the animal, the specialists compared the data with known ichnotaxa of bears, found, for example, in the French Chauvet cave and other locations.

The main task was to determine which bear left the footprints in the Spanish cave — the brown bear (U. arctos) or the cave bear? The latter has front paw toes that form a rounded arch, the claw marks are smaller than those of the brown bear, and the sole pad is larger. All criteria, as noted by the authors of the article, matched Cajus Diedrich's description, meaning they fit Ursichnus europaeus. This is the first confirmed finding for the Iberian Peninsula, as emphasized by the researchers.

Most of the footprints in the Cueva de Honseca date back 27,000 to 28,000 years (when the animal inhabited Europe before going extinct in the late Pleistocene) and were left by a young predator weighing around 100 kilograms. However, some well-preserved tracks likely belonged to an animal weighing up to 438 kilograms. By the way, it is unclear who is heavier — the brown bear or the cave bear. According to various data, the latter could grow to 500 or 800 kilograms, while the brown bear weighs up to 400-600 kilograms.

“Unfortunately, some tracks were destroyed by enthusiasts who visited the inner parts of the cave carelessly before scientists became aware of their existence. Therefore, one of the goals of such research is to highlight the value of these fossils and promote their preservation,” — noted the article's author, Jesus Rodriguez.