Notosuchus

Notosuchus terrestris was a small terrestrial crocodyliform from Late Cretaceous Patagonia. Unlike living crocodiles, it had a compact, high skull, several tooth types and complex contact between the upper and lower tooth rows. More than 60 complete or fragmentary specimens make it one of the better represented notosuchians, although its exact diet and the form of its nasal soft tissues remain debated. It is included in the catalogue of ancient crocodylomorphs.

Its anatomy is a reminder that crocodile-line reptiles were not all shoreline ambush hunters. Notosuchus had limbs suited to moving on land and a tooth row unlike the uniform conical teeth of most living crocodiles. These features support a distinct ecological role, but do not reveal a precise menu or measured running speed.

Quick facts

The first named notosuchian

Arthur Smith Woodward described Notosuchus terrestris in 1896 from material collected in Patagonia, Argentina. The generic name means “southern crocodile”; the species name reflects the early interpretation of a terrestrial animal. It was the first described member of the group later called Notosuchia.

More than 60 specimens have since entered Argentine collections. There is no single perfectly exposed skull: in many examples, the lower jaw remains closely joined to the skull and obscures the palate. Studying several individuals together has helped researchers reconstruct hidden areas of the braincase and respiratory passages without pretending that every detail comes from one complete fossil.

Three kinds of teeth

The front teeth were incisor-like, followed by enlarged caniniform teeth, while the rear crowns had a more complex shape. Broad wear surfaces are visible on the back teeth. Their regular position and matching wear indicate repeated contact between upper and lower crowns, rather than abrasion from accidental contact with food alone.

This arrangement differs from the row of similar conical teeth in a modern crocodile. It could first seize or hold an item and then process it farther back in the jaws. Comparisons with derived notosuchians support forward-and-back movement of the lower jaw during chewing, but the exact path in Notosuchus remains disputed because wear facets do not preserve every direction of movement equally well.

Differentiated teeth are often taken as evidence for omnivory. A mixed diet including invertebrates, small vertebrates and plant matter is plausible, yet tooth form does not tell us the proportion of each. No stomach contents or coprolites securely attributable to Notosuchus provide a direct list of meals.

Was the nose mobile?

The external nostrils faced forward, and an unusual depression surrounded them. Bony surfaces have been interpreted as possible attachment areas for muscles associated with soft tissue. One reconstruction therefore gives Notosuchus a flexible nose that could lift or help probe for food.

The familiar comparison with a pig's snout can be too literal. Bone may constrain the presence of unusual soft tissues, but it does not preserve the shape of the nose tip, cartilage thickness or its full range of motion. There are also no digging traces confidently linked to this genus. A small mobile snout is a scientific hypothesis, not a settled feature of its appearance.

A land-adapted body

Notosuchus was not a scaled-down river crocodile. Its limbs were positioned more beneath the trunk and suited to walking on land, and rows of bony armour protected its back. The relatively high, short skull and forward-facing nostrils also differ from the typical low-headed posture of a crocodile waiting in water.

Its speed is unknown because no trackway has been confidently assigned to the genus. It could move on land, but a claim that it sprinted rapidly would require biomechanical testing. Its relatives show how varied notosuchians were: the low, broad-snouted Simosuchus had its own specialisations, while the much larger Baurusuchus was more strongly predatory.

Late Cretaceous Patagonia

The Bajo de la Carpa Formation records continental environments including rivers, floodplains and drier areas. Notosuchus lived alongside dinosaurs, snakes, lizards and other crocodylomorphs. Their presence in the same ecosystem shows ecological proximity, not proof that Notosuchus hunted a particular dinosaur species.

Its modest size and versatile teeth may have allowed it to use food unavailable to larger predators. That is a reasonable ecological interpretation, not a direct fossil observation. In the ancient crocodylomorph catalogue, Notosuchus is a useful example of terrestrial diversity in a lineage that has almost entirely disappeared.