Mosasaur: The T-rex of the seas

At the time when the famous Tyrannosaurus rex was roaming the lands of Earth, there was another, lesser-known predator species lurking throughout the world’s oceans, the mosasaur. At one point in the distant past, however, mosasaurs were less-than-fierce land-dwellers.

A new study documented the evolutionary process of the mosasaurs. The findings suggest that, at one point, the mosasaur’s ancestors were land-locked creatures with very limited swimming abilities. Eventually, the creatures evolved into a slim, sea snake-like form more suited for swimming, and from there evolved into a predator of the open seas.

In order to track the evolution of the mososaurs, researchers looked at four different mososaur fossils. One such fossil researchers took at look at was the Dallasaurus, one of the earliest form of the mososaurs that was still largely built for living its life out on land.

To help fill in the gaps of the mososaurs’ evolutionary process, researchers looked at modern animals to help understand how mososaurs evolved from land-dwelling creatures to predators of the seas. Johan Lindgren, lead researcher at Lund University, hypothesizes that the mososaurs developed a two-lobed, crescent tail similar to sharks. The mososaur’s new-and-improved tail, among other improvements, made it a faster and more efficient swimmer.

Fast forward a few million years later, and the mosasaurs were starting to get bigger – up to 56 feet long, researchers suggest. At around the same time the mosasaurs started getting bigger, the smaller (22 feet) ginsu sharks had disappeared from the oceans. There’s no hard evidence to suggest that the mosasaurs were responsible, but the timing makes it a likely scenario.

Along with the majority of dinosaurs, the mosasaurs were wiped out during the Cretaceous-Tertiary extinction event roughly 65.5 million years ago.

Thanks, Christian Science Monitor