Researchers at the University of Portsmouth and Hassan II University of Casablanca have identified a 170-million-year-old crocodile relative, Ctenosuchus tenuidens, featuring a long, narrow snout lined with exceptionally thin, comb-like teeth. Published on October 8, 2026, in the Journal of Vertebrate Paleontology, the discovery reveals how ancient reptiles independently evolved filter-feeding mechanisms for consuming tiny aquatic prey in the rivers and lakes of Jurassic Gondwana, SciTechDaily reported.
Fossil Teeth Reveal a Specialized Diet
Unearthed from rocks in the Atlas Mountains of southeastern Morocco, the fossil specimen possesses dental structures unlike any known close relative. Under powerful microscopes, the research team observed specialized ridges and a tightly packed arrangement of needle-like teeth flanking the central jaw bone.
The delicacy of these structures dictates what the animal could safely ingest. Large, wriggling prey would shatter the fragile teeth.
“The teeth are so fine that we don’t think it was catching normal prey. If it caught a big fish, and the fish wriggled, those delicate teeth would get smashed. We think the animal was probably eating soft prey like shrimp, worms and tiny fish, so nothing that would break its teeth,” said lead author Hamzah Imran from the University of Portsmouth’s School of the Environment and Life Sciences.
Detecting the anatomy required meticulous laboratory work. Researchers initially noticed small black circles on either side of the jaw bone. Using a scalpel under magnification, they uncovered the exceptionally thin, comb-like morphology that ultimately inspired the genus and species name Ctenosuchus tenuidens.
Convergent Evolution in Jurassic Ecosystems
While unusual among thalattosuchians—a group of marine and freshwater reptiles thriving during the age of the dinosaurs—the dentition parallels that of entirely separate prehistoric lineages. Similar filter-feeding adaptations appear in ancient aquatic reptiles known as mesosaurs, as well as Jurassic pterosaurs such as Gnathosaurus and Ctenochasma.
These distant animal groups independently developed comparable anatomical tools to strain small food items out of water. The Moroccan finds expand current paleontological models regarding the ecological niches filled by Middle Jurassic fauna across Gondwana, highlighting the complex and varied aquatic environments preserved in North African strata.
“It just shows there is much more out there that needs to be explored,” Imran noted regarding the region’s fossil history.
