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November 13, 2025 — A new study published Nov. 12 in the journal Current Biology reveals that mosasaurs—the top marine predators of the Cretaceous—could lunge at speeds up to 15 miles per hour, outrunning the explosive burst of a great white shark. The research, led by Rutgers University paleontologist Kiersten Formoso, overturns a century-old assumption that these ancient reptiles were slow, inefficient swimmers.
Instead of sculling through the water like giant eels, mosasaurs used stiff bodies and powerful tail fins to launch themselves after prey. That explosive acceleration may have made them some of the most fearsome hunters ever to swim the seas.
When the first well-preserved mosasaur skeletons were unearthed in the late 1800s, their flippered limbs made it clear they were marine animals. But their long, vertebral columns showed none of the tail specializations seen in sharks or dolphins. Many paleontologists assumed these reptiles swam by undulating their entire bodies, much like crocodiles or eels. That style generates heavy drag in water, especially at large sizes, so mosasaurs were long dismissed as sluggish and inefficient.
The view shifted in the 2010s. Anatomists re-examined mosasaur skeletons and found that many had fairly rigid bodies. One landmark study showed that at least some mosasaurs had shark-like, bilobed tail fins. This new body plan suggests a much more efficient form of propulsion—the difference between pushing off a pool wall and starting from a dead tread.
“They were probably much more efficient and dynamic swimmers than previously thought,” Formoso said.
Formoso, a functional morphologist, wanted to know exactly how much power those tails could generate. She and her colleagues combined fossil measurements with mathematical modeling to simulate the forces of a mosasaur lunge.
They measured skeletons from two mosasaur families. From the long-tailed lineage, they examined the fearsome Tylosaurus proriger and the smaller, agile-looking Platecarpus. From the short-tailed group, they studied Plotosaurus—measured while hanging from the ceiling of the Natural History Museum of Los Angeles County—and an undescribed species of Mosasaurus, the genus that gave the family its name.
The team also digitally scalable their measurements to represent the largest mosasaurs: the humpback-whale-sized Tylosaurus rex and Mosasaurus hoffmannii. Their models suggest that a single flick of the tail from a 45-foot-long Tylosaurus rex could produce a lunge of roughly 23 feet per second, or about 15 mph.
By comparison, a great white shark—the largest living predatory shark—can manage a burst of about 11 mph (16 feet per second), enough to catapult itself out of the water after seals. The mosasaur's acceleration would have been a game-changer in the Cretaceous ocean.
The study reveals more than just raw speed. It shows how tail shape dictated predation strategy. Long-tailed mosasaurs like Platecarpus and Tylosaurus could flex their tail fins more deeply before snapping back, storing elastic energy and releasing it in short, violent bursts. That made them perfect ambush predators, lurking near the seafloor in shallow seas before rocketing upward to seize large fish, plesiosaurs, and even smaller mosasaurs.
Short-tailed mosasaurines, including Mosasaurus and Plotosaurus, had a different approach. Their tails couldn't produce the same explosive lunge—maxing out at roughly 13 to 16 feet per second—but they were more efficient for sustained cruising. This allowed them to patrol open-ocean waters in search of prey over long distances, much like modern tunas, mako sharks, and swordfish.
“People really underestimate the scariness of a forward lunge,” Formoso said. “Getting caught in the lunge of one of these mosasaurs would be like getting hit by a car, or even a bus.”
The two tail designs fit neatly with earlier observations of skull shape and tooth wear. Long-tailed mosasaurs have V-shaped snouts and wear patterns suggesting they bit into large, struggling prey—consistent with ambush attacks. Short-tailed forms have heavier, more robust snouts, perhaps suited for grasping fast-moving or slippery prey.
Mike Polcyn, a mosasaur expert at Southern Methodist University who was not involved in the study, said the new results support a longstanding idea: the long-tailed lineage was the first to become giant predators in shallow seas, using ambush tactics to dominate those waters. That competitive push likely forced the short-tailed lineage into deeper environments, where a more energy-efficient, pursuit-based hunting style was advantageous.
“That sustained swimming performance as a pursuit predator instead of an ambush predator might have ultimately led to the demise of Tylosaurus in favor of the large Mosasaurus,” Polcyn said.
Amelia Zietlow, a paleontologist at the History Museum of the Castle in Wisconsin, praised the research. “It’s a valuable contribution to how we understand mosasaurs as once living, breathing animals,” she said.
Formoso’s method could be applied far beyond the four species in this study. Other extinct predators, such as the giant-toothed Prognathodon and the shell-crushing Globidens, are natural candidates. The same approach may even help scientists learn about elusive modern animals, such as sei whales, which are difficult to observe in the wild but well represented in museum collections.
“They’re large predators, so they’re very important components of their respective ecosystems,” Formoso said. “Understanding how they operate is really cool.”
As paleontologists continue to refine their modeling tools, the picture of mosasaur life becomes sharper. Far from being slow, dwindling relics, these marine reptiles were dynamic, powerful hunters—each equipped with a specialized tail and a unique strategy for surviving in the competitive oceans of the Cretaceous.
