# Footprints in Brazil's Botucatu Formation point to a 1.55 m mammal from 130 million years ago

- Published: 2026-11-14 07:24 UTC
- Section: Life & Health › Biology & biochemistry
- Tags: Botucatu Formation, Cretaceous mammal footprints, largest Mesozoic mammal, Chelichnopodidae, Brazil fossil tracks, Gondwana desert, Brasilichnium, mammaliaform, Hermínio Ismael de Araújo-Júnior
- URL: https://realtech.media/news/rt-e76c40b133bb7dc3b5b8caba_footprints_in_brazil/

**Authors of a study in the Journal of South American Earth Sciences link the prints to the largest known mammal of the dinosaur era, about twice the size of any known Cretaceous mammal.**

![Footprints in Brazil's Botucatu Formation point to a 1.55 m mammal from 130 million years ago](https://realtech.media/media/2026/11/88cb5d034c3ab410.jpg)
*dailygalaxy.com*

A team including first author Pedro Buck and Hermínio Ismael de Araújo-Júnior has described footprints from the Botucatu Formation in Brazil that they attribute to the largest mammal yet identified from the era of the dinosaurs, according to dailygalaxy.com [1]. The study was published in the Journal of South American Earth Sciences. The tracks are around 130 million years old, and the animal that made them is thought to have been twice the size of any known Cretaceous mammal [1].

The standard picture holds that mammals of that time were shrew- or squirrel-sized. Some did prey on dinosaurs, but only the very smallest ones, about as big as modern birds, were thought to do so.

## What the tracks show

The largest prints are 11.4 centimeters (4.5 inches) long and 13.4 centimeters (5.4 inches) wide. This ratio helped convince the authors that a mammal, not a dinosaur, made them [1]. Their spacing suggests a stride of about 40 centimeters (16 inches).

Using species for which both bones and footprints are known, the team put the trackmaker at roughly 1.55 meters (5 feet) long [1]. Nothing attributed to a dinosaur or crocodile looks like these prints, which resemble scaled-up versions of tracks left by many mammals. The authors have not named the animal, but they assign it to the Chelichnopodidae family of mammal footprints. They note that most vertebrate tracks in the formation were imprinted in low-cohesion sediment, which generally simplifies morphology and erases fine anatomical detail.

Two earlier candidates for the record, Aracoaraichnium leonardii and Brasilichnium anaiti, were reported in 2017 from the same formation. Both likely matched small dogs or large house cats in size. The new trackmaker is closer to a large dog or even a mountain lion.

## Desert setting and missing bones

The region is green today, but 130 million years ago it was a huge desert far from the nearest coastline. When Gondwana broke apart, most of the Botucatu Formation ended up in South America and a small part remained in Africa. Brasilichnium footprints were widespread across the region, including at the newly studied site.

Why a large mammal lived here is not established. Buck told Science that big dinosaurs may have been absent from this desert for reasons that remain unclear, leaving extra niches for mammals.

Body fossils are unlikely to settle the question soon. Araújo Júnior told IFLScience that no mammaliaform body fossils are known from Jurassic or Early Cretaceous rocks in Brazil, and that the Early Cretaceous skeletal record across Gondwana is extremely scarce. He added that conditions preserving footprints in the desert may not have favored bones, and that deposits from friendlier local environments, where carcasses were more likely to be buried, offer better odds.

Tracks cannot reveal diet the way teeth or jaws do. The authors consider the maker an omnivore that may occasionally have preyed on juvenile or small-bodied dinosaurs. Smaller mammals and invertebrates were probably on the menu too, with plants a minor part at most [1].

## Sources

1. [dailygalaxy.com](https://dailygalaxy.com/2026/11/giant-mammal-footprints-brazil)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-e76c40b133bb7dc3b5b8caba_footprints_in_brazil/