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Sarabosaurus dahli: A newly discovered mosasaur species provides incredible evolutionary insights

Diving deep into the past, a research team has discovered an ancient mosasaur fossil. Further analysis revealed it to be a new species, Sarabosaurus dahli. They found it in the rugged gray shale badlands of the National Park Service Glen Canyon National Recreation Area.

This recent archaeological breakthrough in southern Utah has brought a 94-million-year-old secret to the surface. Dr. Barry Albright is a faculty member at the University of North Florida. He made this fascinating discovery, along with a research team from the Bureau of Land Management (BLM).

Mosasaurs were originally land dwelling creatures

Mosasaurs were unique creatures. They were reptiles adapted entirely for marine life. Mosasaurs roamed the oceans while their dinosaur cousins reigned on land.

The genesis of this discovery traces back about 11 years. Scott Richardson, a dedicated volunteer trained under Dr. Albright.

He tirelessly scoured the land for remnants of organisms that once inhabited the vast seaway spanning across the heart of North America. This was during the Late Cretaceous Period, approximately 84 to 95 million years ago.

In March 2012, Richardson stumbled upon a treasure trove of ancient history. Small skull fragments and vertebrae, the vestiges of an early mosasaur, lay scattered across a large shale slope.

As Dr. Albright elucidates, “During the time the Tropic Shale was being deposited, about 94 million years ago, mosasaurs were still very small, primitive, and in the early evolutionary stages of becoming fully marine adapted. For these reasons, their fossils are extremely rare and difficult to find.”

How Sarabosaurus dahli was discovered

Over the next two field seasons, a joint team from the BLM and the National Park Service painstakingly recovered nearly half of the specimen. This amount proved sufficient to identify the ancient creature.

The research team, captained by BLM Paria River District paleontologist Dr. Alan Titus, consisted of BLM staff and volunteers. Among them was volunteer Steve Dahl.

His dedication to the project led to his being immortalized in the species name, Sarabosaurus dahli. This name translates to “Dahl’s reptile of the mirage”.

The name encapsulates both the bygone seaway this creature swam through, and the desert mirages associated with the region’s intense summer heat.

New mosasaur, Sarabosaurus dahli, is a monumental discovery

“Mosasaurs from younger rocks are relatively abundant, but mosasaurs are extremely rare in rocks older than about 90 million years,” explained Dr. Titus. “Finding one that preserves so much informative data, especially one of this age, is truly a significant discovery.”

These oldest mosasaurs were diminutive, just about 3 feet long. Yet, they evolved into massive, lizard-like marine predators. Mosasaurs ruled the oceans during the later stages of the dinosaur era.

Originally, their land-bound ancestors resembled the present-day Komodo Dragon. However, over time, their sea-faring descendants developed sleek bodies, fin-like limbs, and tails designed for swift navigation through water.

In contrast to its primitive predecessors, Sarabosaurus boasted a significant evolutionary advancement. It had developed a new system to pump blood into its brain.

According to Dr. Michael J. Polcyn of the University of Utrecht, Netherlands, and Southern Methodist University, Dallas, “Sarabosaurus sheds light on long-standing questions regarding the relationship of some early branching mosasaurid species, but also provides new insights into the evolution and antiquity of a novel cranial blood supply seen in a particular group of mosasaurs.”

This pivotal discovery propels our understanding of the mysterious past. It also sheds light on the intriguing world of these ancient marine reptiles. This is truly a giant leap forward for science.

The results of this transformative research have been freshly published in the journal Cretaceous Research. Image credit: ANDREY ATUCHIN

More about mosasaurs

Mosasaurs were large, carnivorous marine reptiles that lived during the Late Cretaceous period. This period spanned from around 92 to 66 million years ago.

These fascinating creatures are known for their adaptation to marine life. They evolved from land-dwelling, lizard-like ancestors. Here’s what we know about them:

Size and Appearance

The size of mosasaurs varied, with the smallest species measuring about 3 feet long and the largest, such as Mosasaurus hoffmannii, reaching lengths of up to 50 feet or more.

Mosasaurs had elongated, streamlined bodies with powerful, paddle-like limbs and a long, strong tail that helped them navigate and accelerate in the water. They also had large, robust skulls equipped with strong jaws and sharp teeth, perfect for their predatory lifestyle.


Mosasaurs exhibited a number of fascinating adaptations for life in the sea. They had a double-hinged jaw and a flexible skull (similar to snakes), which allowed them to swallow their prey whole. Some mosasaurs also had a second set of teeth on the roofs of their mouths.

 These creatures evolved from land-dwelling lizards and, over time, their limbs transformed into flippers, their tails became more like those of sharks, and they developed the ability to give live birth in the water.

Diet and Hunting

Mosasaurs were apex predators in their oceanic ecosystems, preying on a variety of marine life, including fish, squid, and other marine reptiles. Some larger species may have also fed on smaller species of mosasaurs.

Their hunting techniques are believed to have been similar to those of modern-day killer whales, isolating a member of a school of fish or a pod of squids and attacking with speed and power.

Distribution and Habitat

Mosasaurs were a global species, with fossils found on every continent, indicating that they inhabited a wide range of marine environments, from shallow nearshore waters to the open ocean.

Discovery and Extinction

The first mosasaur fossils were discovered in the Netherlands in the late 18th century, and they have since been found worldwide.

Mosasaurs went extinct during the K-T event (the Cretaceous–Paleogene extinction event) about 66 million years ago, which is also well-known for causing the demise of the dinosaurs.

Relation to Modern Animals

Mosasaurs are not dinosaurs but are more closely related to modern-day monitor lizards and snakes. Their closest living relatives are thought to be the Komodo dragon and the closely-related Gila monster.

Overall, mosasaurs were fascinating, well-adapted creatures that dominated the oceans of the Late Cretaceous period. Their fossils continue to provide valuable insights into life on Earth millions of years ago.

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