Description and Classification

Angaturama was a medium-sized carnivorous dinosaur, estimated to be around 6 to 8 meters (20 to 26 feet) in length, though these estimates are based on incomplete fossil material. Like other spinosaurids such as Spinosaurus and Baryonyx, Angaturama possessed an elongated, narrow snout, similar to that of a modern crocodile. Its jaws were filled with long, conical teeth that were not serrated, well-suited for grasping slippery prey like fish. The front part of its snout was notably tall and compressed from side to side. Some paleontologists suggest Angaturama may have had a small crest on its head, a feature seen in some related dinosaurs, but definitive evidence for a large sail like that of Spinosaurus is lacking for Angaturama itself.

Angaturama belongs to the family Spinosauridae, a group of theropod dinosaurs known for their specialized fish-eating adaptations. Within this family, its features place it among spinosaurids that were evolving increasingly crocodile-like skulls. The classification of Angaturama is complex due to its close similarity to Irritator challengeri, another spinosaurid from the same geological formation. Many scientists now consider Angaturama limai (the type species) to be a junior synonym of Irritator challengeri. If this is correct, the name Irritator has priority because it was named slightly earlier. However, some differences in the snouts have led other researchers to maintain them as separate, though closely related, genera.

Distinguishing Features

• A distinctive tall, thin (compressed from side to side) snout, particularly at the front.
• A low sagittal crest (a ridge running along the midline) on the upper surface of the premaxillae (the bones at the very tip of the snout).
• Conical, unserrated teeth, typical for spinosaurids but with specific placement and shape in the preserved fossil.
• Nostrils that were likely positioned further back on the skull than in many other theropods, an adaptation often seen in animals that spend time in or near water.

Paleoenvironment and Diet

Angaturama lived in what is now northeastern Brazil during the Early Cretaceous. The fossils were found in the Romualdo Member of the Santana Formation, which is famous for its exceptionally well-preserved fossils. During this time, the area was a warm, tropical coastal environment, likely a large lagoon or a series of estuaries with both saltwater and freshwater influences. This ancient ecosystem was rich with life, including many types of fish, pterosaurs (flying reptiles), turtles, crocodylomorphs, and other dinosaurs. The abundance of fish in this environment provided a perfect food source for specialized predators like Angaturama.

The primary diet of Angaturama is believed to have been fish. Its long snout and conical teeth were ideal for snapping up fish from the water, similar to modern-day crocodiles or gharials. While fish were likely its main food, like other spinosaurids, Angaturama may have been an opportunistic feeder. It might have also preyed on small terrestrial animals or scavenged carcasses if the opportunity arose. Evidence from the closely related (or possibly identical) Irritator suggests spinosaurids in this region also consumed pterosaurs.

Significance and Ongoing Research

The discovery of Angaturama has been important for understanding the diversity and distribution of spinosaurid dinosaurs, particularly in South America. It shows that these specialized theropods were present on multiple continents during the Cretaceous period. Alongside Irritator, it provides crucial evidence about the types of predators inhabiting the unique ecosystems of the ancient Santana Formation.

A major area of ongoing research is the taxonomic relationship between Angaturama and Irritator challengeri. Many paleontologists are working to compare the fossil material more closely to determine if they represent the same species or two distinct but closely related animals. Resolving this issue will help clarify the true diversity of spinosaurids in Early Cretaceous Brazil. Further fossil discoveries would be invaluable in providing more complete skeletal material for Angaturama, which could help solve this debate and give a clearer picture of its full anatomy, lifestyle, and how it differed from other spinosaurids like Suchomimus or Baryonyx. The study of Angaturama and its environment also contributes to our broader understanding of prehistoric ecosystems and the complex interactions between different species.