Halisaurus auriculatus lived approximately 70 million years back throughout the early Maastrichtian age, the last age of the Cretaceous duration.

The types came from Halisaurinae, a subfamily of normally little-to medium-sized mosasaurs.

“The Halisaurinae are a subfamily of Mosasauridae identified by reasonably little size, and primitive jaw and tooth morphology,” stated Ain Shams University paleontologist Ahmed Ali Shaker and his associates.

“Halisaurines have actually traditionally been among the rarest and least recognized groups of mosasaurs.”

“Currently, the group makes up eleven types, designated to the genera Eonatator Halisaurus Phosphorosaurusand Pluridensand variety stratigraphically from the Santonian to the uppermost Maastrichtian.”

“Fossils of Halisaurinae are now understood worldwide in North and South America, Africa, Asia, and Europe, especially in the low latitude seas surrounding Africa.”

“Discoveries of this group ended up being crucial in comprehending the variety and advancement of mosasaurs, showcasing adjustments that assisted these reptiles thrive in the oceans of the Cretaceous duration.”

Halisaurus auriculatusremains were discovered in 2024 in the Dakhla Shale, near the town of Teneida in the Dakhla Oasis in Egypt’s Western Desert.

The fossil consisted of a partial skull, jaw bones, and various vertebrae and limb bones, all protected in 3 measurements.

The specimen was connected with scattered components of bony fishes, turtle shell pieces, and plesiosaur vertebrae.

According to the research study, Halisaurus auriculatus is identified by abnormally long, slim jaws lined with more than 20 teeth on each side, together with an extremely customized ear structure unlike any seen before in this household of reptiles.

These functions indicate a fast-biting however fairly weak jaw, coupled with specialized hearing that might have assisted the animal hunt little victim such as fish and squid in dim light, whether in the evening or in much deeper water.

Especially, Halisaurus auriculatus was discovered in the very same rock layer and basic location as another mosasaur, Halisaurus hebaeexplained by a few of the exact same scientists in 2023.

The 2 types vary significantly in skull and jaw anatomy, leading the research study authors to recommend that the 2 animals divided up the offered food resources instead of contending straight– a phenomenon called specific niche partitioning.

Halisaurus auriculatus is identified from the coeval Halisaurus hebae by long, slim jaws, a high tooth count and special expertise of the quadrate,” they stated.

“These recommend adjustment for a quick bite however low bite force, and possibly expertises of the acoustic device for undersea hearing.”

“These functions recommend expertise on little victim and specific niche partitioning in between halisaurines in the animals.”

“Halisaurines were a varied part of the Tethys and Atlantic in the Maastrichtian, highlighting their eco-friendly significance within Late Cretaceous marine environments.”

The findings appear online in the journal Acta Palaeontologica Polonica

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A.A. Shaker et al2026. A brand-new types of halisaurine mosasaurid from the Upper Cretaceous of Egypt. Acta Palaeontologica Polonica 71 (3 ): 589-604; doi: 10.4202/ app.01310.2025