Approximately 66 million years ago, the end-Cretaceous extinction event drastically altered Earth’s biodiversity. However, the implications for marine fish remain a topic of debate due to gaps in the fossil record. A recent study conducted by paleontologists reveals a collection of marine fish fossils from the 62.2 million-year-old Quraya 3 site in Egypt’s eastern desert, shedding light on this transition. These discoveries include the earliest known fossil skeletons of horse mackerel, moonfish, and pipefish, which are relatives of seahorses.

“The fossil record is limited, and there exists a substantial 10 million-year gap,” stated study lead author Sanaa El-Sayed, a doctoral candidate at the University of Michigan.

“While we know asteroids impacted marine environments, it remains unclear how these events shaped the ocean’s inhabitants, particularly modern fish species.”

“This site is remarkable in addressing when, where, and which species existed in modern oceans just a few million years post-dinosaurs.”

At the Quraya 3 site, El-Sayed and her colleagues identified fossils from 21 distinct fish species spanning nine orders.

“Most of these fish are percomorphs, a dominant group in today’s oceans, yet relatively rare during the dinosaur era,” noted co-author Professor Matt Friedman, director and curator of the University of Michigan Museum of Paleontology.

“This discovery reinforces the theory that a biological crisis tied to the end-Cretaceous mass extinction led to the loss of certain fish types, allowing modern-looking fish groups to flourish soon after.”

The “Patterson Gap,” named after the paleontologist who studied it, identifies the fossil-poor section of the record before and following the mass extinction at the end of the Cretaceous.

This gap obscures our understanding of how fish species were affected by extinction events.

“This early Cenozoic gap raises two critical questions,” added Professor Friedman.

“First, did the fish we traditionally associate with extinction at the end of the Cretaceous truly not continue into the Paleogene period? Or were they simply overlooked due to poor records?”

“Second, when did recognizable modern groups actually emerge?”

“This gap represents an extensive timeframe in which the details remain unclear, frustratingly coinciding with one of Earth’s most intriguing historical periods.”

“Our remarkable findings provide insights into this critical epoch.”

“We found numerous preserved skeletons; however, the species long believed extinct were absent.”

“Our research indicates that their absence likely reflects genuine extinction occurring around the end-Cretaceous event, rather than simply a record deficiency.”

“Moreover, this site offers concrete evidence that many modern fish groups were established quite early in the evolutionary timeline.”

The research team also contemplated the broader implications of their findings in the context of the fossil record following the end-Cretaceous mass extinction.

Upon comparing their findings with data from additional fossil deposits, they noted that most percomorphs discovered shortly after extinction events predominantly thrived in tropical regions.

Conversely, fewer percomorphs appeared at high latitudes, becoming more common only significantly later.

“An intriguing geographic pattern emerges regarding how contemporary fauna evolved,” Friedman said.

“It appears they predominantly developed in tropical regions, later dispersing to higher latitudes as climatic conditions changed.”

“As we enhance our fossil record, these conclusions will be put to further rigorous testing.”

These significant findings are published in this week’s edition of Scientific Progress.

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Sanaa El-Sayed et al. 2026. The Rise of Modern Marine Fishes Caught in Lagerstätte during the Early Paleocene. Scientific Progress 12(23); doi: 10.1126/sciadv.aec8978