Researchers in Brazil have uncovered a new fish fossil dating back roughly 252 million years, found just 50 kilometers (31 miles) from the largest impact crater in South America.
The specimen, named Leolepis matogrossensis, comes from the Corumbataí Formation in the state of Mato Grosso and marks the first nearly complete Paleozoic ray-finned fish ever recorded in that region.
The study, led by Valéria Gallo of the Department of Zoology at the State University of Rio de Janeiro, appears in the Journal of South American Earth Sciences.
The fossil measures about 150 millimeters (5.9 inches) long and was preserved in reddish siltstone. That rock formed at the bottom of a shallow megalake during the late Permian period, as the region dried out under increasingly arid conditions.
Ganoid scales and cone-shaped teeth set species apart
A geologist named Léo Adriano de Oliveira found the specimen in 2005 near the town of Alto Garças. The genus name honors his discovery. The fossil is now kept at the Universidade Federal do Mato Grosso under the catalog number UFMT-353.
The study mentions that the fish had a torpedo-shaped body covered in roughly 50 rows of thin, glossy scales with jagged back edges. Its jaw held small, cone-shaped teeth, and its skull bones were arranged in a pattern researchers had not seen before.
These features set it apart from other ancient fish species already known from Brazil. To figure out where Leolepis fits on the fish family tree, the team ran a detailed comparison against dozens of related species.
The results placed it as the closest relative of a genus called Paramblypterus, with another Brazilian fish, Angatubichthys, sitting at the base of the same group. Together, the three species now form an expanded version of the family Paramblypteridae.
Ancient fish fossil survived near Brazil’s largest impact crater
The location of the find adds another layer of interest. The Araguainha Dome, the crater in question, formed when a large asteroid struck the region around 251.5 million years ago, roughly the same time as the mass extinction event that wiped out most life on Earth at the end of the Permian period.
Gallo and her colleagues note that the impact likely did not disturb the exact rock layer where the fish was buried, since that layer sat deep underground at the time of the collision. However, the researchers found that rock layers closer to the crater rim show clear signs of disturbance from the same event.
The team says the discovery adds valuable evidence to a limited fossil record from this period in South America. Most previous finds from the region consist of scattered scales or bone fragments rather than complete specimens.
Researchers hope that future digs in the Paraná Basin will turn up more examples of Leolepis or related species, helping scientists better understand what life looked like just before one of the planet’s most severe extinction events.
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