Fossilized footprints discovered in the Botucatu Formation across São Paulo, Paraná, and Santa Catarina prove that large mammals roamed alongside dinosaurs 130 million years ago, according to a study published in the Journal of South American Earth Sciences. Researchers from five Brazilian institutions authored the paper, which was released in August, challenging long-held assumptions about the size and ecological role of Mesozoic mammals.
Botucatu Formation Footprints Reveal Surprising Mammalian Size
The largest fossilized tracks reach up to 11.4 centimeters in length and 13.4 centimeters in width, according to the research team. Based on these measurements, scientists calculate that the animal measured approximately 1.55 meters in length. This dimension far exceeds expectations for mammals sharing habitats with dinosaurs prior to their extinction, presenting a stark contrast to traditional views of early mammals as tiny, hidden creatures.
“The animal would be, for the researchers, similar to a large dog, with some rat-like features,” the study notes regarding the morphological characteristics of the tracks. The spacing between each footprint measures 40 centimeters, giving paleontologists a reliable metric to reconstruct the creature’s stride and body proportions.
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Morphological Evidence and Dietary Hypotheses
Researchers confirmed the mammalian origin of the tracks based on their distinct shape, which resembles enlarged mammalian footprints rather than the known patterns left by dinosaurs or crocodiles. While researchers cannot pinpoint the exact species, the combination of size, shape, and spacing rules out reptilian locomotion.
Although the footprints do not contain direct evidence of the animal’s diet, the research team proposes that the creature likely functioned as an omnivore. Scientists suggest it may have preyed on smaller mammals, invertebrates, and even small dinosaurs, occupying a much higher rung on the food chain than previously theorized.
Institutional Collaboration Behind the Discovery
The published study represents a collaborative effort among researchers from several Brazilian universities. Contributors include the Universidade do Estado de Minas Gerais (UEMG), the Universidade Federal do Rio Grande do Norte (UFRN), the Universidade do Estado do Rio de Janeiro (UERJ), the Centro Universitário SATC (UniSATC), and the Universidade Federal de São Carlos (UFSCar).
Despite the significance of the findings, the authors emphasize that major questions remain unanswered because no skeletal remains have been recovered. While a footprint allows for accurate size estimations, it cannot reveal the shape of the skull, teeth, or skeletal structure necessary for formal taxonomic classification.
Frequently Asked Questions
What is the Botucatu Formation?
How big was the mammal that left the tracks?
Researchers estimate the animal measured about 1.55 meters in length, with footprints reaching up to 11.4 cm long and 13.4 cm wide, comparable in body size to a large dog.
When did this animal live?
The footprints date back approximately 130 million years to the Mesozoic era, a time when dinosaurs dominated global ecosystems.
Why are these footprints significant?
They challenge the traditional scientific view that Mesozoic mammals were exclusively small creatures trying to avoid larger predatory dinosaurs.
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