14 DAY TRIAL // Recent investigations have shown that ancient seas and oceans were populated by lizards that had fins and which moved through water as easily as sharks do nowadays.
A study published in the journal Nature Communications this past September 10 explains that these creatures, named mosasaurs, started off as land-dwelling lizards.
Hence the fact that, as fossil evidence has shown, their skeletons were not all that different from the ones of present-day reptiles belonging to the same group.
About 98 million years ago, they took to living in shallow pools. In time, they adapted to life in the deep ocean, and became top predators.
Given the fact that adult specimens could grow to measure about 49 feet (15 meters) in length, there is no doubt they had little trouble turning whatever creatures they chanced to come across into their next meal.
As part of the process of adapting to life in the open seas, mosasaurs came to have fins that made it possible for them to navigate this environment as swiftly as sharks and killer whales do nowadays.
Scientists estimate the lizards got their fins roughly 88 million years ago. Until then, they probably swam similarly to eels, i.e. by undulating their bodies.
According to LiveScience, researchers have long suspected that these ancient lizards had fins. Still, it was only when they came across mosasaurs remains that contained imprints of soft tissue that they were able to confirm this theory.
“Here we report an extraordinary mosasaur fossil from the Maastrichtian of Harrana in central Jordan, which preserves soft tissues, including high fidelity outlines of a caudal fluke and flippers,” the researchers write in the Abstract to their paper.
Furthermore, “This specimen provides the first indisputable evidence that derived mosasaurs were propelled by hypocercal tail fins, a hypothesis that was previously based on comparative skeletal anatomy alone.”
The remains that proved the theory that mosasaurs had fins are estimated to be roughly 70 million years old. They belong to a juvenile specimen that measured about 6.5 feet (2 m) in length.
Specialists explain that these lizards went extinct about 66 million years ago. Their demise coincides with that of the dinosaurs.