Laje do Coringa is not a graveyard of articulated skeletons. It is a concentration of hundreds of isolated bones and teeth, tumbled and broken, exposed in the Alcântara Formation of the São Luís-Grajaú Basin. Wave action has done most of the damage and continues to do it. That makes the site both extraordinarily productive and extraordinarily frustrating: material erodes out constantly, and it erodes away just as constantly. The paleontologist Elaine Machado has called the key discovery here an accident, well-preserved specimens being rare in a place where the tide works on everything that surfaces. The rock dates to the Cenomanian stage of the Late Cretaceous, sometime between 100.5 and 93.9 million years ago.

In 1999 the site gave up a pair of fused premaxillae - the front of an upper jaw - from an enormous predator. Alexander Kellner and colleagues formally described it in 2011 as Oxalaia quilombensis, from the holotype MN 6117-V, with a maxilla fragment, MN 6119-V, referred to the same animal. It was a spinosaurid: the long-snouted, crocodile-jawed lineage that includes Spinosaurus. Kellner's team estimated a skull around 1.35 metres long and a body of 12 to 14 metres weighing five to seven tonnes, which would make it the largest theropod known from Brazil. Some of its details are genuinely odd. The palatal surface of the premaxillae is sculptured, and it carried two replacement teeth per socket, which is unusual among theropods. The naming was deliberate and local. Oxalaia honours the orixá Oxalá; quilombensis honours the quilombos - communities founded by people who escaped slavery - including the one that still lives on the island where the fossil was found.

The status of Oxalaia is not settled, and honesty requires saying so. In 2020 Smyth and colleagues argued it was nothing more than a junior synonym of Spinosaurus aegyptiacus, the distinguishing features attributable to variation between individuals rather than between species. Subsequent analyses between 2021 and 2023 pushed back, finding diagnostic differences in the shape of the snout and the position of the nostril sufficient to keep the genus standing. For now the name holds, but it holds on a pair of jaw bones from a bed the sea is actively destroying, which is a thin foundation for any taxonomic argument. More material would settle it. The tide is not cooperating.

What surrounds Oxalaia in the deposit is as interesting as the animal itself. The Alcântara Formation has produced the giant coelacanth Mawsonia gigas, rays and sawfishes and a range of other fish, pterosaurs, diplodocoid and titanosaur sauropods, a large carcharodontosaur, noasaurids and dromaeosaurs - along with conifers and ferns from the vegetation. The environment was tropical and heavily forested, set within a broader arid-to-semi-arid landscape with strongly alternating rainfall. Nearly all of it matches the fauna of Morocco's Kem Kem beds of the same age. That correspondence is the point: 95 million years ago these were not two continents but one shoreline. South America and Africa were still parting, and the animals had not yet noticed. Cajual is a fragment of Gondwana that happens to sit in a Brazilian bay.

Cajual is inhabited. A small quilombola community lives there, part of a much larger pattern: the municipality of Alcântara, which contains the island, holds over two hundred quilombola settlements - the greatest concentration in Brazil. They took root as the colonial cotton and sugar economy collapsed and landowners walked away from the territory. Their situation since has been contested. The construction and expansion of the Alcântara Launch Center on the mainland displaced more than three hundred families from thirty-two communities in the 1980s, and the Inter-American Court of Human Rights subsequently ruled against Brazil, ordering compensation and the restoration of territory; in September 2024 President Lula signed decrees advancing quilombola land titling in the area. The dinosaur that made the island scientifically famous carries their name in its own. It is a rare case of a species epithet pointing at the living people of a place rather than past them.