Researchers are about to rewrite the history of cetaceans!

Along the Coast of Victoria. However, in the county of Wadawurrung, fossils discovered in Jan Juc revealed the existence of a new species of whale, baptized Janjucetus dullardi. Similarly, Described for the first time in the Zoological Journal of the Linnean Societythis species was identified from a partial skull. Furthermore, including the bones of the ear and the teeth, uncovered in 2019 by RossRoss Dullard, a resident of the seaside resort, who donated it to the Victoria Museums.

A flax whale… carnivorous – Researchers about rewrite history cetaceans!

For them paleontologistspaleontologists Victoria museums, Janjucetus dullardi illuminating the early evolution of BalensBalens (Mysticeti). Meanwhile, Today. Furthermore, these marine giants, such as the common rorqualcommon rorqualthe Rorqual BlueRorqual Blue And the Rorqual Franc, researchers about rewrite history cetaceans! are among the largest animals that have ever lived, sometimes reaching more than 30 meters long per 100 tonnes. In addition, They feed on plankton and small fish.

But that has nothing to do with Janjucetus dullardi. In addition, This specimen was barely more than 2 meters away, and adults probably did not exceed 3.5 meters, the size of a large dolphin. Similarly, But behind this modest template hid a formidable predator: slender body, fast swimming, eyeseyes forward -oriented and sharp teeth. Consequently, A hunt closer to that of a shark than that of its modern cousins.

Janjucetus Dullardi, a new species of whale described by scientists from the Victoria Museum Research Institute. Furthermore, © Museums Victoria. Meanwhile, Youtube

As Ruairidh Duncan, doctoral student at the Research Institute of Museums Victoria and Monash University, explains, the first bladder whales separated from tooth whales about 30 researchers about rewrite history cetaceans! million years ago, keeping characteristics still visible today: enlarged and flattened jaws, and unique infraorbit plates forming the floorfloor fromorbitorbit. Furthermore, Now these features are well found in Janjucetus dullardi.

His colleague, Dr. Erich Fitzgerald. principal conservative in paleontology of vertebrates, specifies that at the first examination, the fossil did not seem to have these characteristics. But a careful study of skullskull revealed a key element: a cranial floor bone presenting the swollen shape specific to all flashes. unlike the fine crest observed in tooth cetaceans and to echolocationecholocation. « There is no doubt about what we see here “, He concludes.

A rare representative of mammalodontidae

The first whales descend from terrestrial mammals which. more than 50 million years ago, ventured into the old seas of our researchers about rewrite history cetaceans! planet. Janjucetus dullardi belongs to a group today extinguished. the mammalodontidae, which only lived at the time oligoceneoligocenebetween 30 and 23 million years old.

This fossil is the third species of mammalodontidated identified in Victoria. only the fourth in the world, the last having been discovered in New Zealand (New Zealand). It is also the first specimen of this group to keep the teeth. structures of theinner earinner earkey elements to understand how these primitive whales nourished, moved and interacted with their environment.

It is also the second species attached to the genus Janjucetusnamed after the seaside resort where the fossils were found. The first, Janjucetus hunderidescribed in 2006 by Erich Fitzgerald, measured about 3 meters and also lived in the middle of the oligocene. The researchers noted a notable difference: the upper teeth of Janjucetus dullardi have a pronounced researchers about rewrite history cetaceans! crest, absent from Janjucetus hunderi. « This type of anatomical difference goes beyond normal variation within the same species. and rather corresponds to a distinction between two close but very distinct species “Explains Erich Fitzgerald.

The age of Janjucetus dullardi is estimated between 26. 27 million years old, while that of Janjucetus hunderi covers a wider period. “” They may have existed simultaneously. or they could constitute what is called a chronoese, where an animal evolves into another », says Ruiridh Duncan. Erich Fitzgerald never shakes: ” To confirm this, you will have to discover more Janjucetus fossils. »

Exploit all the potential of fossils

Researchers have dismissed the hypothesis that the difference in dentition observed in Janjucetus. dullardi could correspond to a simple growth phase. In these first whales, thee-maile-mail mineralized very early, and fossils show that they only had one generation of teeth. In other researchers about rewrite history cetaceans! words, no temporary dentition replaced by permanent teeth as in humans. “” Ten million years earlier, their ancestors had milk teethmilk teeth »Raplolle Rory Duncan.

Understanding this transition is essential, underlines Erich Fitzgerald. It could shed light on the evolution of flashes. explain why most modern dolphins have a large number of teeth, all of similar shape and size, a rare characteristic in the rare characteristic in mammalsmammals.

But the question remains open: ” We do not yet have fossils necessary to answer them “, Specifies Erich Fitzgerald. To progress. it would be necessary to find a fossil specimen of a whale with primitive baleen or an early ancestor of echolocalizing dolphins, capturing this pivotal moment where a young man loses his milk teeth while the permanent teeth begin to push.

Each new fossil of Janjucetus Bring an additional part researchers about rewrite history cetaceans! to the puzzle of the evolution of cetaceans. But many questions remain unanswered: what steps have really led these predators to today’s giants? The next discoveries could still rewrite history.