By putting together fragments of an ancient skull, scientists have reconstructed the magnificent face of a 330-million-year-old crocodile-like creature called a tadpole, which not only shows off its looks but also its lifestyle. Scientists have known about an extinct species, Crassigyrinus scoticus, for a decade. But since all known fossils of primitive predators are so fragmented, it was difficult to learn more about him. Now, advances in computed tomography (CT) scanning and 3D imaging have allowed researchers to digitally assemble the pieces for the first time, revealing more details about the ancient beast.
Previous studies have shown that C. scoticus is a tetrapod, a four-legged animal related to the first creatures to move from water to land. Quadrupeds began appearing on Earth about 400 million years ago, when the first four-legged mollusks began to evolve from oarfish.
Unlike its relatives, C. scoticus was an aquatic animal. This is either because their ancestors returned from land to water, or because they never landed. Instead, it now lived in coal swamps—wetlands that would turn into coal beds over millions of years—in parts of Scotland and North America.
A new study led by scientists from University College London showed that the animal had huge teeth and powerful jaws. Although its name translates to “fat tadpole,” the study shows that C. scoticus had a relatively straight body and very short limbs, similar to a crocodile or crocodile.
“Crassigirinus was about two to three meters long when it was alive, and that was pretty big for that time,” said study lead author Laura Porro, a lecturer in cell and developmental biology at University College London. “It would probably have behaved like modern crocodiles, hiding under the water’s surface and using its powerful bite to grab prey.” C. scoticus is also adapted for hunting in swampy areas. The new facial reconstruction shows it has large eyes for seeing in turbid water and lateral lines, a sensory system that allows animals to detect ripples in the water.
Although much more is known about C. scoticus, the slit near the front of the animal’s snout still baffles scientists. According to Porro, the gap could mean that C. scoticus has other senses that help it hunt. The creature may have a so-called rostral organ that helps it detect electric fields, Porro said. Additionally, C. scoticus may have a Jacobson’s organ found in animals such as snakes that helps detect various chemicals.
In previous studies, scientists reconstructed C. scoticus with a very long skull similar to a moray eel, Porro said. “However, when I tried to simulate this shape with a digital CT surface, it didn’t work,” Porro explained. “There was no way an animal with such a wide palate and such a narrow skull roof could have had such a head.”
A new study published in the Journal of Vertebrate Paleontology shows that the animal had a skull similar to that of a modern crocodile. The team used CT scans of four individual specimens to reconstruct what the animal looked like and pieced together the broken fossils to reveal its face.
“Once we identified all the bones, it was a bit like a 3D puzzle,” Porro said. “I usually start with the remnants of the meninges, because that would be the core of the skull, and then I would fuse the palate around it.” The team now plans to run biomechanical simulations to test their understanding of C. scoticus and its abilities.
Source: Port Altele
