Shortly earlier than a mass extinction ended the Age of Dinosaurs, a reptilian, barracuda-like carnivore with a mouth like a field cutter patrolled the nice and cozy seas that after lined swaths of what’s now North Africa. A lately described fossil of the ocean-dwelling beast reveals that its bite was in contrast to that of any of its kinfolk, within the water or onshore.
The animal was a mosasaur, an extinct, marine reptile associated to snakes and monitor lizards. Mosasaurs generally had piercing, conical tooth for gripping slippery prey or flat, crushing tooth for smashing hard-shelled animals. But this new selection had quick, serrated, squarish blades, packed tightly in collection to type a knife’s leading edge. This mouth of razors is exclusive amongst mosasaurs, and even throughout the entirety of the tetrapod lineage, principally landlubbing vertebrates that embrace amphibians, reptiles, birds and mammals.
The discovery, described January 16 in Cretaceous Research, means that mosasaurs have been evolving experimental physical traits and lifestyles right up until their abrupt extinction 66 million years in the past.
Phosphate miners in Morocco discovered the curious fossil: a chunk of higher jaw studded with tooth. The jaw got here from a mosasaur dwelling on the very finish of the Cretaceous Period. Many mosasaurs have been large predators, some stretching longer than a college bus. But this fossil belonged to an animal simply over a meter lengthy, Nick Longrich, a paleontologist on the University of Bath in England, and his colleagues decided.
Longrich says the animal’s small dimension is attention-grabbing, however that’s not what caught his eye. “Those teeth are just unlike anything I’ve seen in a lizard before,” Longrich says. The crew named the mosasaur Xenodens calminechari — Xenodens means “strange tooth;” calminechari is Arabic for “like a saw.”
Longrich says the closest match for X. calminechari’s tooth look like these of modern-day dogfish sharks, which might “cut large bolts of flesh out as they scavenge,” he says. “Probably these slicing teeth allowed it to process a huge range of foods,” says Longrich, noting that dogfish sharks use their tooth to cut up the whole lot from fish to sea anemones. Despite its small dimension, X. calminechari could have been in a position to prey upon fairly giant animals or scavenge their stays, because it shared its watery house with massive fish and cephalopods, in addition to orca-sized, long-necked plesiosaurs.
The fossil is “completely bizarre,” says Paulina Jiménez-Huidobro, a paleontologist on the University of Bonn in Germany not concerned with this analysis, noting the tooth could have been used to “slice and dice” crustaceans, shell and all.
She has doubts in regards to the comparability to shark feeding strategies and eating regimen based mostly solely on the tooth form, although, due to elementary variations between how sharks and mosasaurs bite prey. Shark tooth reduce into flesh on jaws that stretch outwards in direction of prey independently of the cranium.
“This mechanism does not occur in mosasaurs, even if Xenodens has a shark-like tooth shape,” Jiménez-Huidobro says. “No lizard can do that.”
For Longrich, X. calminechari’sdiscovery helps paint a image of the late Cretaceous’ tropical seas as teeming with biodiversity earlier than a dinosaur-era-ending asteroid hit Earth (SN: 6/17/20). The ocean ecosystem was thriving on the time, so there could have been dozens of mosasaur species in a single habitat, he says, and so they weren’t accomplished producing bizarre prototypes like Xenodens.
“The mosasaurs were still experimenting with new ways of feeding, new morphologies, new lifestyles just before that asteroid came down,” Longrich says.
Learning extra about this nimble, barracuda-like sea lizard will reveal extra of the evolutionary experimentation occurring on the time, however gaining that perceive requires the invention of extra fossil materials, which might take a whereas, Longrich says. In half a dozen years of looking out, he’s seen just one fossil of this species.
“Eventually something has to turn up, but it’s a waiting game.”