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Rhamphosuchus crassidens

"Beak Crocodile"

Rhamphosuchus is an extinct genus of gavialoid crocodylian from the Indian subcontinent. Two species are currently recognized, the geologically older R. pachyrhynchus, represented by fossils recovered in Oligocene and Miocene deposits of Pakistan's Bugti and Laki Hills, and the younger R. crassidens, known from the Pliocene Siwalik Hills of Northern India. Additional remains are also known from the Pliocene of Nepal and a tentative third species was recovered in Pakistan. Both species are known for their great size, with rigorous estimates showing potential body lengths ranging from 8 to 11 m (26 to 36 ft) for R. crassidens while a 2025 estimate for R. pachyrhynchus recovers a length of approximately 6 to 8 m (20 to 26 ft).

Both Rhamphosuchus species were historically considered part of the genus Gavialis, though detailed study revealed that their morphology differs significantly from that genus, which is represented by the extant gharial. Compared to the gharial, species of Rhamphosuchus are noticeably more robust with snouts that gradually widen towards the back of the head, along with teeth that vary in size, are closely spaced, and form an "overbite" similar to that of modern alligators rather than the interlocking teeth of other gavialoids. Rhamphosuchus' skull bears prominent depressions around the bony naris that bears a close resemblance to the naris of male gharial skulls, which may indicate the presence of a knob-like soft tissue structure known as a ghara. The two named species are best differentiated by the shape of their snout tips, as that of R. crassidens is around the same height and width as the rest of the snout while that of R. pachyrhynchus is prominently expanded both to the sides and upwards.

The robust build and great size of Rhamphosuchus have been taken as indicators that, in life, the animal had a more generalist diet compared to the modern, mostly fish-eating gharial. Its prey may have included chalicotheres and rhinos, which may even have included juvenile Paraceratherium; these ungulates are known from the same geological formations as Rhamphosuchus and some of their fossils bear the bitemarks of a large-bodied species of crocodilian. However, Rhamphosuchus shared its environment with multiple large-bodied crocodilians, so the bitemarks are of ambiguous origin. Whatever the case, Rhamphosuchus inhabited the highly productive river systems that once spanned across the subcontinent, which persisted for millions of years through major shifts in climate that saw an ecological transition from forested biomes to more open grassland environments. The productivity of the ecosystem, warm temperatures, and geographically extensive wetlands of the time may have been key factors in allowing this animal to grow as large as it did.