The Fossil Who Bridges Crocodile's Changes to the Dolphins

riorinaldy (45)in #esteem • 7 years ago

Paleontologists have discovered Jurassic-tailed fossils that they believe to be missing links between two parts of an ancient crocodile family.

The Jurassic Period (Jura) is the second segment of the Mesozoic Era. This period of time occurred from 199.6 to 145.5 million years ago, following the Triassic Period and before the Cretaceous Period. The period in which Pangea's super-continent began to break.

Reptiles are the dominant animal life forms during the Jurassic Period. Some of the largest animals that ever existed were dinosaurs that lived during the Jurassic Period. Some of them grow over 30 meters long and weigh more than 100 tons.

At that time, although dominated by dinosaurs, it was also the era of the first small mammals to appear on Earth. During this primeval period marine life was very diverse. There are various types of animals, some of which are the ancestors of modern crocodiles.

During the Jurassic period, ancient crocodiles have two basic forms which each have a number of species. One group looks like a "harness" because of the thick skin typical of dinosaurs and has limbs to walk on land. Others, have tail fins and fish wings, not armor. So, in other words, a group looks like a crocodile we know today and one more like a dolphin.

According to British scientists, several species of crocodiles that lived during the dinosaur era evolved into dolphins.

For this study, scientists examined the 180-million-year-old fossil from a creature called Magyarosuchus fitosi. The giving of this name is based on the honor of the amateur collector who finds it, Attila Fitos. The specimen, discovered in 1996 from the mountains of north-western Hungary, was then sent to a museum in Budapest, where it has remained for more than two decades.

The crocodile specimen of the Jurassic era has a large backbone, about five meters long, has large, pointed teeth to catch prey. When found the fossil is not in intact form but consists of several pieces of pelvis, jaw, and spine.

As the paleontologists watch these fossils, they feel awkward with one of the strange-looking spines. Further observations revealed that it was part of the tail fin.

"With an estimated body length of 4.67-4.83 meters M. fitosi is the largest known metriorhynchoidnon-metriorhynchid," wrote the study, published online in the PeerJ journal.

This fossil has two distinct characteristics that are also seen in each group of crocodiles. His whole body was coated with hard skin and had a tail fin like found on dolphins or whales.

"The combination of maintaining a heavy armor on the back and abdomen and having a hypocercal tail is unique, highlighting further ways of marine adaptation to the uncertain Metriorhynchoidea."

"These fossils provide a unique insight into how crocodiles began to evolve into dolphins and killer shapes like whales more than 180 million years ago," said Dr. Mark Young, of the School of Geosciences University of Edinburgh, said in a statement.

"The presence of both armor and tail highlights the incredible diversity of Jurassic crocodiles," he added.

Quoted from Popular Science (17/5), according to Andrea Cau, a vertebrate paleontologist and blogger based in Giovanni Capellini Geological Museum, Italy - who was not involved in the study - the discovery of M. fitosi not only helps researchers reconstruct how this type of reptile it adapts to a fully marine lifestyle, but also provides a better picture of the geological history of metriorhynchoids.

"The fossil record of Eastern Europe is less well known than elsewhere, such as Western Europe which is the best documented area for this extinct crocodile species," Cau explains.

This new discovery helps illustrate how the diversity of crocodyliforms in the Jura era spread.

Ancient crocodiles dominate the oceans and coastal Jurassic periods. One recent study proves that reptiles appear earlier than previously thought, at least 163 million years ago.