Paleontologists in Egypt have stumbled upon an extraordinary fossil haul: nearly 500 fish frozen in time. The site, called Qreiya 3, shows which fish thrived after the extinction and hints at how modern marine ecosystems started to take shape.
The fossils, dating back 62.2 million years, include more than 20 species of ray-finned fish spread across nine larger groups. As explained by the National Geographic Explorer Sanaa El-Sayed, a paleontologist at Mansoura University, the moment they realized how well-preserved the fish were, they knew they had found something special. The findings, published in Science Advances, offer a window into the early Paleocene oceans, a period that has long been missing from the fossil record.
Understanding how ocean life bounced back after the Cretaceous-Paleogene extinction has been tricky. While land fossils show the rise of mammals, birds, and plants, marine recovery remained murky. According to Hesham Sallam, also at Mansoura University and co-author of the study, Qreiya 3shows not just who survived, but who moved in and diversified in the empty niches left behind.
Percomorphs Dominate Early Oceans
The biggest story at Qreiya 3 is the rise of percomorphs, a group that today includes everything from tuna and seahorses to anglerfish. According to Sanaa El-Sayed, percomorphs were around before the extinction but weren’t all that common.
“Qreiya 3 provides one of the clearest views yet of how modern marine ecosystems emerged,” adding that the location “reveals that many fish groups important in today’s oceans were present only four million years after the extinction of the dinosaurs,” said Hesham Sallam.
At Qreiya 3, though, they appear everywhere, hinting at a big evolutionary boom as these fish explored new forms and lifestyles. Fossils include tiny reef-dwellers as well as needle-toothed predators, showing early experiments in survival and hunting.
One particularly exciting find was a predatory percomorph related to modern tuna and mackerel. As El-Sayed explained, its teeth helped identify it and made it the oldest known relative of these fast swimmers. These fossils also help fill a 10-million-year gap in the record of bony fish evolution, known as the Patterson Gap, named after British paleontologist Colin Patterson.
oceans bounced back unevenly
Even though Qreiya 3 shows thriving fish communities, recovery wasn’t uniform everywhere. Based on the research, fossils from other parts of the world show that some regions kept older, more ancient fish for longer, while tropical zones may have been the first to assemble fish faunas that look more like what we see today. The pattern makes sense after a global disaster, some places bounce back faster than others.
Elizabeth Sibert, a paleontologist from Woods Hole Oceanographic Institute, who wasn’t involved in the study, said that:
the site is exciting because it provides “fossil evidence for fish communities during what was a critical time.” She added that the site gives scientists something solid to study during a period that was largely missing from the record.
Parallels With Terrestrial Evolution
The percomorph boom in the oceans mirrors what happened on land.El-Sayed pointed out that, just like tiny placental mammals and beaked birds expanded into new roles after the extinction, certain fish groups flourished, rapidly diversifying and taking full advantage of the empty ecological niches left behind by the mass die-off.
These early expansions helped set the stage for the ecosystems we see today, both on land and under the sea. Excavations at Qreiya 3 are far from finished. Sallam noted that the fossils uncovered by the study team so far represent only a small fraction of what could be hidden beneath the desert sands.
“What we are publishing now is only the beginning of the story,” said Sallam. “This study is an initial synthesis from a much broader research effort. Many important specimens are still under preparation and study, and we expect this site to continue transforming our understanding of how modern marine fish faunas became established in the wake of the K–Pg extinction.”
