Imagine having to swim in a river or lake one day only to encounter a massive creature in the water with teeth as large as those of a Tyrannosaurus rex. Sounds like the plot to a Hollywood creature feature, right? Believe it or not, such a terrifying animal did indeed inhabit the Earth's waters millions of years ago.

Researchers in Madagascar have unearthed a giant, prehistoric creature that had massive teeth similar to those of the T. rex. Known as the Razanandrongobe sakalavae, or "Razana" for short, the animal is believed to be an ancient ancestor of crocodiles. Its discovery provides the next step to filling in the 74-million-year-long gap in the evolutionary history of crocodiles.

Apex Predator

The remains of the Razana was first discovered on Madagascar more than a decade ago. While scientists believed the creature was most likely a predatory species from the Jurassic period, they had a difficult time pinpointing its exact placement in the evolutionary tree.

As far as its features go, the Razana had traits similar to those of crocodylomorphs, a group of animals that includes crocodiles and their prehistoric relatives. It also shared traits with theropods, a group of dinosaurs that includes the fearsome T. rex.

In a study featured in the journal PeerJ, an international team of researchers re-examined the Razana fossils. They also looked at five cranial fragments that were recovered from the same site in Madagascar where the crocodilian remains were found. It is believed that the two sets of fossils may have come from the same taxon.

The research team found that the remains are those of a crocodylomorph belonging to the Notosuchia suborder. These creatures were said to have roamed the Earth during the Cretaceous period. Fossils of Notosuchia crocodylomorphs have been found in different parts of the world such as in Africa and Asia. Some have also been recovered in Europe and South America.

What was confusing, however, is that the evolutionary lineage of Notosuchia crocodylomorphs may have begun far earlier in history. Scientists believe it happened between 174 to 163 million years ago during a period known as the Middle Jurassic. Unfortunately, there are no available fossil evidence to support this evolutionary history, which is why it is referred to as a "ghost lineage".

Nortosuchia Suborder

For the Razana, the researchers established its placement in the evolutionary tree in the Nortosuchia suborder. They believe that this group of creatures may have even been the oldest and largest crocodylomorph suborder in the planet's history. It is likely that the Razana may have also predated other members of the Nortosuchia suborder by about 42 million years.

The lack of enough evidence makes it difficult to determine how large the Razana may have been exactly. The researchers estimate that the creature was likely larger than the Sarcosuchus, another crocodile-like animal known to reach up to 39 feet long. It may have also dwarfed the 34-foot-long Purussaurus, which lived in South America some eight million years ago.

Study co-author Cristiano Dal Sasso pointed out the Razana may have even given the T. rex and its theropod relatives a run for their money as the dominant creatures on the food chain. The size of the ancient crocodile's teeth indicate that it fed on hard animal tissues such as bone. With such a powerful bite, it is likely that the Razana was one fearsome apex predator during its time.

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