Jakarta –
Crocodiles have a habit of peeking at the surface of the water. This habit is often interpreted as stalking prey. Crocodiles, which are carnivorous animals, are considered dangerous if they are close to humans. But what is the actual reason why crocodiles often do this?
A study conducted by a team of International Paleobiology experts succeeded in solving this puzzle. The researchers found that the ancestors of modern crocodiles that lived in the sea did not evolve like whales and dolphins. This prevents crocodiles from diving to great depths.
History of the Thalattosuchian Ancestors of Modern Crocodiles
This research published in Royal Society Open Science today explains that Thalattosuchians who lived during the time of the dinosaurs stopped exploring the deep sea because of their large snout sinuses.
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Meanwhile, whales and dolphins (cetaceans) evolved from land mammals to fully aquatic mammals in a period of around 10 million years. During this time, their bone-encased sinuses shrink and they develop sinuses and air sacs outside their skulls.
This reduces the pressure buildup during deeper dives, allowing them to reach depths of hundreds (dolphins) and thousands (whales) of meters without damaging their skulls.
Previously, Thalattosuchians who lived during the Jurassic and Cretaceous periods were divided into two groups. The first group, Teleosauridae, which was shaped like the modern gharial crocodile, probably lived in coastal waters and estuaries. Meanwhile, Metriorhynchidae has a slender body with fin-like limbs and a tail and is thought to be able to live in the sea.
Research on Crocodile Ancestors
Researchers from the University of Southampton, the University of Edinburgh and other institutions wanted to see whether thalattosuchians had made similar sinus adaptations to whales and dolphins on their evolutionary journey from land to sea.
To find out the answer, the research team used computed tomography, a special type of scanning, to measure the sinuses of 11 thalattosuchian skulls, 14 skulls of modern crocodile species, and six other fossil species.
The results of the study showed that the accuracy of the sinuses of the braincase decreased as the Thalattosucian’s adaptation to aquatic life increased. This is similar to the changes that occur in pauses and dolphins.
Researchers suggest that this decline occurred due to various factors, such as their buoyancy, diving ability and how they feed. Not only that, the researchers also found that when Thalattosuchians became fully aquatic, the sinuses on their snouts would expand more when compared to their ancestors.
“The decline of the braincase sinuses in Thalattosuchia mirrors the decline that occurs in cetaceans, reducing during the semi-aquatic phase and then reducing further as they become fully aquatic,” explained Dr. Mark Young, lead author of the research, is from the University of Southampton.
“Both groups also developed extracranial sinuses. However, while the sinus system of cetaceans helps regulate pressure around the skull during deep diving, the extensive snout sinus system of metriorhynchids prevents this from deep diving,” he said.
“This is because at greater depths, the air in the sinuses becomes compressed and causes discomfort, damage, or even collapse of the snout due to its inability to withstand or equalize the increased pressure,” Young said.
In contrast to other animals that experience this difficulty, whales and dolphins have efficient kidneys so they can filter salt from sea water. Reptiles and seabirds rely on salt glands to remove salt from their systems.
Dr. Young and his colleagues believe that the larger and more complex snout sinuses of metriorhynchids could have helped clear their salt glands, similar to how modern marine iguanas work.
“The main problem for animals with salt glands is ‘build-up’, where the salt dries out and blocks the salt drains. Modern birds shake their heads to avoid this, while marine iguanas sneeze to expel the salt,” Dr Young said.
“We think the dilated sinuses in the metriorhynchidae help excrete excess salt. Birds, like the metriorhynchidae, have sinuses that come out of the snout and pass under the eyes and when their jaw muscles contract, it creates a booming sound-like effect in their sinuses. For the metriorhynchidae, when the sinuses experienced this effect, it compressed the salt glands within the skull and created a sneezing-like effect, similar to modern marine iguanas.”
This study shows how major evolutionary transitions take place and are shaped by a species’ anatomy, biology, and evolutionary history.
“It is very interesting to discover how ancient animals, such as thalattosuchia, adapted to life in the sea in their own unique way showing similarities and differences with today’s cetaceans,” said Dr. Julia Schwab, one of the authors of the paper from the University of Manchester.
Dr Young concluded: “Thalattosuchia became extinct in the Early Cretaceous period, so we will never know for sure whether, given more evolutionary time, they could have merged further with modern cetaceans or whether the need to mechanically drain their salt glands was an insurmountable barrier. bypassed for further aquatic specialization.”
(pal/pal)
Crocodiles: The Sneaky Surface Peekers of the Water World
So, you thought crocs were just laying around like that friend who’s never ready to leave the house? Well, it turns out they have a hobby—one that involves a bit of stealth and strategy. Yes, these lumbering beasts have a knack for peeking at the surface of the water, and while some of you might assume they’re just practicing their synchronized swimming skills, they’re actually on the prowl. But let’s dive deeper (pun intended) into the reason behind their behavior.
Scientists and researchers from the exciting world of International Paleobiology—sounds like a cocktail party, doesn’t it?—decided to take a look under the hood of our scaly friends. And they discovered something rather peculiar: modern crocodiles haven’t followed the swimming success story of whales and dolphins. You know, those mammals that transitioned from land lubbers to the kings of the ocean in about a mere 10 million years. Talk about a glow-up!
The Ancient Sea Kings: Thalattosuchians
Meet the Thalattosuchians, the ancient ancestors of today’s crocodiles who once roamed the earth when dinosaurs were still sending each other anniversary cards! These fascinating creatures are thought to have abandoned the deep sea exploration gig due to their large snout sinuses. And here we thought that your average crocodile just had sinus issues like your Uncle Jeff after a night out.
According to recent research published in the Royal Society Open Science, while Thalattosuchians were groovin’ in the sea, they couldn’t quite match the adaptation skills of their cetacean buddies. Whales and dolphins, for instance, shed some sinus weight allowing them to dive deep without risking a very expensive skull repair.
The Science of Snouts and Sinuses
Thank goodness for modern technology, right? Researchers from the University of Southampton and the University of Edinburgh decided to strap on their lab coats and delve into the skulls of not just Thalattosuchians, but also modern crocodile species and some fossilized guests at the party. They used computed tomography to unveil the secrets lurking in that big toothy grin.
What did they find? Oh, just a simple correlation between decreased braincase sinuses as Thalattosuchians transitioned to an aquatic lifestyle. Sounds complicated? Well, think of it like this: the more they tried to adapt to water, the less room there was for air in their heads. It’s like trying to fit your entire life’s belongings into an overnight bag—something’s gotta give!
But that’s not the only twist in this tale. Researchers postulated that the extensive sinus systems in Thalattosuchians didn’t just help them breathe; they may have played a role in regulating salt. Yes, this means they might have a special skill set for managing the ocean’s salty gifts—a sort of evolutionary recycling program.
Wild Theories and Sneezing Crocs
Dr. Mark Young, one of the lead authors, dropped some knowledge bombs about how the sinuses could have created some sort of sneezing reaction—similar to what marine iguanas do to expel salt. That’s right, these ancient reptiles might’ve put on quite a show, sneezing in the ocean like they were part of a bizarre aquatic comedy act!
According to Young, this discovery helps us understand not just how Thalattosuchia adapted to the changing waters, but how these processes reveal that animals are, in fact, incredible problem solvers. It’s a bit like watching someone learn to swim while also trying to juggle. Hilarity ensues!
Final Thoughts: The Crocodile Enigma
Thalattosuchia went extinct in the Early Cretaceous period, so the mystery remains: would they have evolved into the sleek swimming machines we now associate with dolphins? Or was their biology a roadblock they could never overcome? It’s one of nature’s unsolvable mysteries that would make even Sherlock Holmes raise an eyebrow.
Whatever the conclusion, the spirited history of crocodiles and their ancient cousins reminds us that evolution isn’t just survival of the fittest, but also about adapting and evolving in the weirdest and wildest ways. So the next time you see a crocodile peeking out from the water, remember—it’s a curious reminder that our world is as bizarre as it is fascinating!
(pal/pal)
Sive snout sinuses found in metriorhynchids, a group of Thalattosuchians, might have played a critical role in their ability to manage excess salt while living in marine environments. These sinuses likely functioned to help expel excess salt, akin to how modern marine iguanas expel salt through sneezing. So, while they may have looked a bit odd, these adaptations were keystones for survival in salty seas.
Comparative Evolution: Crocs and Cetaceans
Now, every good evolution story needs a twist, and this one is no different! Unlike Thalattosuchians, cetaceans took a different route. They evolved from terrestrial mammals into aquatic creatures over a stunningly rapid million-year marathon. Their structural changes—like shrinking the bone-encased sinuses and developing air sacs outside the skull—enabled them to dive deep without risking injury from crushing pressure. So while modern crocodiles may float gracefully near the surface, their ancestors were once scaling the depths of the ancient seas.
Dr. Mark Young, the study’s lead author, articulated this contrasting evolutionary path by explaining how both cetaceans and Thalattosuchians adapted their sinus structures, albeit in opposing directions. “While cetaceans have evolved mechanisms for pressure regulation during deep dives, the large snout sinuses in Thalattosuchians hinder their ability to dive,” he noted. Their anatomical features, while unique to their ecological niches, ultimately determined their fates in the ever-changing tapestry of evolution.
What This Means for Our Understanding of Evolution
The findings from this research offer fascinating insights into evolutionary biology. They show how various factors—like buoyancy, feeding habits, and environmental pressures—shaped the anatomy and ecological strategies of these ancient reptiles. “It’s intriguing to learn how both ancient and modern species adapted to their surroundings, displaying both similarities and unique adaptations,” remarked Dr. Julia Schwab, a co-author of the study.
The study serves as a vivid reminder of how evolution is not a linear pathway toward improvement, but rather a complex web of adaptations that allow different species to thrive in their specific environments. In the case of the Thalattosuchians, their inability to dive deeply may have ultimately limited them, leading to their extinction during the Early Cretaceous period. Thus, while crocodiles of today might seem quite ordinary as they lounge around, their ancestors tell tales of ancient oceans, evolutionary gambles, and a complex past that remains just beneath the surface.
the journey of understanding Thalattosuchians enhances our perspective of evolutionary transitions and the diverse strategies life can utilize to adapt to ever-changing conditions. As researchers delve deeper into these ancient lineages, we continue to discover the many ways life on Earth has shaped itself to forge a path through time.
