Dinosaur Tracks in Brazil Found to Have Petroglyph ‘Companions’

A study of a site in Brazil known for its dinosaur tracks has revealed stunning new details about previously unexamined petroglyphs (rock carvings) that cover the very same set of rock formations as the ancient reptilian footprints. This astonishing convergence of paleontological and archaeological evidence is incredibly rare, and it promises to make the site known as Serota do Letreiro (“Signpost Hill” in English) a popular destination for scientists looking to learn more about ancient human culture, dinosaur history, or both.

Ancient Glyph Makers in the Valley of the Dinosaurs

Serrote do Letreiro is located in the state of Paraíba in northeastern Brazil. It consists of three rock outcrops that cover 160,000 square feet (15,000 sq m) of space, all of which feature a combination of dinosaur tracks and rock carvings. The site can be found within the greater confines of Brazil’s Valley of the Dinosaurs (which has been designated as a national monument), just outside the small municipality of Sousa (population 70,000).

The fossilized dinosaur footprints were first observed in the Sousa Basin (the geographical home of the Valley of the Dinosaurs) in the early 20th century. However, it wasn’t until 1975 that paleontologist Giuseppi Leonardi finally organized a team of investigators to visit the region and officially verify the existence of the dinosaur tracks. It was during a 1979 expedition that Leonardi discovered the site of Serrote do Letreiro, and while his focus was naturally on the fossil record, he did make reference in his writings to petroglyphs that were observed there as well. He did not investigate them further, however, and his disinterest was seemingly shared by later visitors to the site.

Ground-level view of the site from Outcrop 1. (Troiano, et al., Scientific Reports 2024)

The newly completed study, which was organized and led by archaeologist and historian Leonardo Troiano from Brazil’s National Historic and Artistic Heritage Institute, sought to correct this baffling oversight, by carrying out a thorough examination of both the fossilized dinosaur footprints and their petroglyph companions.

It is appropriate to refer to the petroglyphs as dinosaur footprint “companions,” since they were intentionally placed adjacent to the fossilized tracks in many instances. They were also carved in an exceedingly careful manner, to make sure the fossils were preserved.

“Despite the profusion of identified petroglyphs, no overlap was observed between these inscriptions and the fossilized footprints,” Troiano and his colleagues wrote in an article about their research published in Scientific Reports. “In none of the cases was it found that the creation of a petroglyph resulted in damage to the existing footprints, suggesting thoughtfulness by the makers.”

The petroglyphs didn’t feature any images of real-life people or animals, but instead consisted of geometrical shapes mixed and matched in various ways. Especially common were carved circles with lines running crosswise or radiating out from the circle center. Notably, the images are similar or identical to petroglyphs that have been found carved into rock faces at other archaeological sites in northeastern Brazil, including engravings that have been found elsewhere in Paraíba and in the neighboring state of Rio Grande do Norte.

Earlier studies had established that the dinosaur prints came from creatures that lived during the Early Cretaceous Period, which dates them to an astonishing 145 to 100 million years before the present. Researchers have identified sauropods (the largest animal to have ever lived), theropods and iguanodontians as among the creatures represented by these fossilized tracks.

(A) Aerial photography of Outcrop 1. (B) Digital sketch-map of the same outcrop, highlighting theropod footprints in white and petroglyphs in dark orange. (Troiano, et al., Scientific Reports 2024)

As for the human petroglyph makers, radiocarbon dating of skeletal remains removed from burials in the vicinity of Serrote do Letreiro show that the region was occupied by indigenous people (specifically by the Kiriri or Carri people) between 7,400 and 600 BC.  It may be possible to link the petroglyphs to a narrower range of dates, the researchers say, once they’ve had time to complete a more thorough analysis of the site using “new methods of direct dating of petroglyphs, such as X-ray fluorescence spectrometry.”

Different morphotypes of tridactyl footprints from outcrop 1, all interpreted as belonging to theropod dinosaurs ( A–F). ( D) and ( F) show footprints in close association with petroglyphs. (Troiano, et al., Scientific Reports 2024)

Contemplating an Unsolvable Historical Mystery

One of the obvious questions this discovery raises is, what were the motivations of the people who chose to carve the geometrical petroglyphs so close to the fossilized footprints?

Petroglyphs found at outcrop 3. ( A) Circle with internal radiating lines; ( B) Aerial photography in which damage to the graphic horizontal panel is visible, affecting an area of high concentration of petroglyphs; ( C) Petroglyphs superficially resembling star icons. Most are lines inside a faded circular outline. Scale bars = 5 cm and 2 m. (Troiano, et al., Scientific Reports 2024)

“Observing such intentionality in the creation of the petroglyphs raises the question of recognition and interpretation of the footprints by the creators of the symbols,” the study authors wrote in  Scientific Reports. “The hypothesis that the makers recognized the footprints as such persists even considering that the contemporary understanding of fossils and their association with dinosaurs was likely unknown to the people who first encountered these footprints.”

People who lived in the region thousands of years ago wouldn’t have known what fossils were exactly, but they probably would have recognized what they saw as either animal footprints that somehow had been embedded in rocks, or lifelike carvings of animal footprints made by their distant ancestors. If they suspected the latter, they might have wondered about the techniques their great, great, great grandparents used to create animal tracks that appeared so authentic.

Regardless of what they thought about the footprints, the glyph makers clearly chose to associate their artworks with them, for reasons that will ultimately be impossible to determine. The activity might have had some sort of spiritual significance, or the glyph makers may have seen the rock outcrops at Serrote do Letreiro as an ancient outdoor art gallery to which they wanted to contribute.

Whatever their ultimate motivations might have been, the work of the glyph makers will now be examined in far closer detail than before, as archaeologists join paleontologists in flocking to a site that will have plenty to offer both.

Top image: Dinosaur tracks in highlight and petroglyphs circled by dashed lines. Source: Troiano, et al., Scientific Reports 2024

By Nathan Falde