New Fossil Discovery Could Resolve Controversy Surrounding Spinosaurus Sailback Features

Artist's interpretation of Spinosaurus mirabilis

Artist’s Interpretation of Spinosaurus mirabilis

Credit: Dani Navarro

The fascinating debate surrounding the dinosaur Spinosaurus continues: was it an exceptional swimmer capable of diving to catch prey or a “hell’s heron” that snatched giant fish from shallow waters? Recent fossils of a new species, Spinosaurus mirabilis, discovered approximately 1,000 kilometers inland, may provide clarity, asserting that it resembled a sandpiper, as suggested by Paul Sereno from the University of Chicago.

The discussion of Spinosaurus lifestyles among paleontologists is ongoing, characterized by distinctive features such as large sails, massive claws, wide feet, and crocodilian jaws. Previous depictions in the 2025 BBC series Walking with Dinosaurs presented them as aquatic hunters.

In 2019, local guides led Sereno’s team to a remote Niger desert, where they unearthed a fragment of jaw bone identified later as belonging to a type of spinosaur. The COVID-19 pandemic delayed their return to the site.

During their second expedition, researchers discovered about ten Spinosaurus bones. Remarkably, they observed large crests atop the skulls and unique sails along their spines shortly after their initial find.

Sereno stated, “This was a shining moment because we recognized it as a new species of Spinosaurus that would significantly enhance our understanding of these dinosaurs.”

Named Spinosaurus mirabilis, this species is estimated to have roamed the Earth around 95 million years ago, growing to lengths of about 10 to 14 meters, comparable to the renowned Spinosaurus aegyptius. Sereno warned, “You wouldn’t want to be close to this animal; it could take you down in about three seconds.”

Similar to Spinosaurus aegyptius, this new species possessed a noticeable crest, though its crest was significantly larger—potentially reaching at least 40 centimeters in height for larger individuals. Researchers believe that, comparable to modern crowned birds such as the guinea fowl, these crowns were likely covered with a keratin sheath, standing at least 50 centimeters high.

https://www.youtube.com/watch?v=C9DW4EgJ0zg" title="Spinosaurus Discovery

The delicate crest probably served not as a weapon but as a visual display. “It likely boasted bright colors,” Sereno remarked. “It signals, ‘I’m here, I’m healthy.’

The significant sails of the Spinosaurus might also have been utilized for visual signaling. Sereno suggests it raised questions about their purpose in mating and territorial protection. “Such environments, like beaches and riverbanks, enhance visibility, allowing animals to spot rivals and mates over long distances,” he explained.

Crested Skull of S. mirabilis

Credit: Keith Ladzinski

Modern sandpipers, like the great blue heron, exhibit similar display characteristics, reinforcing the migration theory posited by Sereno. When comparing various animals based on the proportions of their jaws, necks, and hindlimbs, spinosaurids were found adjacent to heron-like species.

Although Spinosaurus struggled to swim efficiently due to its large sails, it could dive to depths of about 10 feet (3 meters) as an adult, according to Sereno.

Evidently, most spinosaur fossils have been discovered near oceans, while S. mirabilis thrived far inland. Sereno notes, “No marine predator weighing over a ton has entered freshwater habitats.” The absence of major freshwater predators, like river killer whales, supports the idea that these creatures were adaptations, similar to modern herons.

Sereno mentions, “This study validates the consensus developed regarding these animals. They aren’t super swimmers or deep divers; rather, they resemble herons and storks, foraging through shallow waters for their primary diet of fish.”

David Horn from Queen Mary University of London remarked, “The unique crest suggests a new species, and variations in jaws and teeth further solidify this point.”

Mark Witton at the University of Portsmouth, UK, emphasized that the lengths of the legs indicate Spinosaurus was capable of efficient movement, countering claims of a predominantly aquatic lifestyle.

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Source: www.newscientist.com

Rediscovered After 50 Years: The Return of a Long-lost Sailback Shark

Adult Female Sailback Hound Shark

Jack Sagumai et al. (2025)

A rare species of shark has been rediscovered in Papua New Guinea, nearly half a century after its last sighting.

The Sailback Hound Shark, known for its unusually large dorsal fin (Gogolia filewoodi), was first recorded by researchers in 1973. A pregnant female was captured in Astrolabe Bay, near the Gogol River, and this marked the only known instance of the species for many years.

Jack Sagumai and his team from the World Wildlife Fund Pacific gathered fisheries data from local communities, aimed at supporting the national action plan for sharks and rays. In March 2020, they were pleasantly surprised when they stumbled upon images of several small sharks close to the mouth of the Gogol River, all featuring the characteristic dorsal fin.

Initially, five of these sharks were identified as female. In 2022, another fisherman in the vicinity caught a male. Collaborating with William White from the Commonwealth Scientific and Industrial Research Organization in Australia, the team verified that these creatures were indeed the long-lost sailback houndsharks.

“When we heard that this species was so elusive, it was frustrating,” Sagmai said.

This marks the first scientific documentation of the species in over 50 years, though fishermen in Astrolabe Bay claim they regularly encounter these sharks. They report sightings near the mouth of the Gogol River while fishing primarily for drums, according to Sagmai.

“It appears to favor deeper waters and tends to associate with other fish when feeding near the river mouth,” he noted.

As these sharks are only located in a small area, they may represent a “micro-inhabiting” species with a very limited range in Astrolabe Bay.

“Alternatively, they may have once had a broader distribution across regions like Indonesia and Papua New Guinea,” suggested David Ebert from San Jose State University in California. This region also hosts similar micro-inhabiting species, such as bamboo and epaulette sharks.

Sagumai noted that information regarding the Sailback Hound Shark’s biology and population size remains sparse. Currently, two deceased specimens are housed at the University of Papua New Guinea, and the team plans to collaborate with researchers in Australia and Florida to conduct a DNA analysis of the sharks.

“These efforts will establish genetic baselines for future monitoring and inform conservation strategies,” he added.

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Source: www.newscientist.com