Some whales are won. You might not know to see them, but their skulls are actually incredibly odd. This mysterious feature helps with echolocation, the way whales work outside where things are making sounds and sensing how they reflect back.
But this robustness is not present in all whales. My coworkers and I recently did research to find out why and when the victorious whale began to develop in a different way to its symmetrical cousins. We now know that the skulls of whiskey whales appeared about 30 million years ago, and that they have become even more heterogeneous, as we know today that organisms have evolved in modern species.
To understand how Vicky whales got that way, we need to look at how they lived and were adapted in the past. Fortunately for us, the whale fossil record has been so remarkably represented that scientists have also called the whale a “posterchill of evolution”. Complete skulls and skeletons stretch back to early whales dating back 50 million years, and more fossils have been spent throughout whale history, from living animals that we know today.
With this record, we can see that the whale’s nostrils have moved from the tip of their snout to the top of their head, an evolutionary strategy for easy breathing on the surface of water. And the skull of the whale with teeth (which technically includes dolphins, as well as species such as the sperm whale) has become more erased, with bones on one side at different locations, on the other.
It is caused by a mass of fatty tissue, called “melon”, which is used for toothed whales. The watermelon and soft tissue required for watermelon are located on the jagged whale on the top left side of the skull, giving them a bulbous forehead and the bones below the skull are also skewed to the left. As the toothed whales evolved, their skull became winekier.
But why do all whales have this winkiness? The whale was previously called “antiquarian” (literally meaning “ancient whale”). They evolved from walking on land to becoming completely aquatic in a relatively short 8 million years.
We know that archaeosect fossils have viscous rostrums (or muzzle). This can be the deformation of fossils or a feature that helps archaeologists to find out which direction is coming from underwater.
Then, about 39 million years ago, whales turned into two groups: those with teeth in their mouths, known as “odontosetes, and baleans (known as rows of bristles) allowing whales to filter food from water “. mysticetes “.
At some point, toothed whales developed whiskey skulls and echolocation. However, mystics, including large cylinder whales (such as blue whales), diverted a completely different evolutionary path. They developed baleen and filter feeding and skulls, which are more symmetrical than both archaic and toothed whales.
We wanted to understand why and when this happened. So to track the asymmetry in the development of whale skulls, we produced 3D scans of 162 skulls, 78 of which were fossils. By mapping this miraculous shape change in the skull across the whale family tree, we can precisely track when it first appeared in evolutionary history and in which families it evolved.
Based on the analysis of these skulls, naso-facial asymmetry (winekynes) developed about 30 million years ago. This was after the transition from archaeologists to modern whales, and after the split between Odontocetes and mystics. Around the same time this oddity was visible, these early toothed whales were developing high frequency hearing and complex echolocation.
We also confirmed that there was little cranial asymmetry in the nasal-facial region of the early ancestors of living whales and was likely not able to echolocate. As such, it is likely that baleen whales have never been able to eclogate.
Most surprising is that this asymmetry has reached its highest levels in some specific animals such as sperm whales and narwhals and other species that live in deep or extreme environments.
This suggests that animals living in these complex environments, including river dolphins in burgu, icy, wasted waters, and shallow, marshy rivers, have developed a different kind of echolocation potential, such as more diverse and discrete Helping them navigate through sound displays. Hunting, with it the bones around the nose and face have become more contrasted.
This evolutionary path of toothed whales becomes more heterogeneous, suggesting that their skulls and more soft tissues may continue to receive winekirs as their echolocation technique becomes more specialized.
These findings remind us not only of the complex evolutionary paths that cetaceans have known as the spectacularly adapted iconic ocean dwellers we still know today, but also that despite living with some of the largest animals What ever existed, there is still much for us to know about them.