The massive predator known as Acrocanthosaurus, meaning “high-spined lizard,” was one of the largest meat-eating dinosaurs of its time. Its most recognizable feature was the row of tall neural spines that ran along its back, likely supporting a thick, muscular ridge. As the dominant carnivore in its environment, Acrocanthosaurus sat at the top of a complex food web. This ecosystem was home to a diverse community of dinosaurs and other prehistoric animals that interacted with the gigantic theropod.
The Early Cretaceous Environment
This immense carcharodontosaurid lived during the Aptian to Albian stages of the Early Cretaceous period, approximately 125 to 100 million years ago. Its geographic range covered a large portion of North America, with fossils found in Oklahoma, Texas, and Wyoming. The landscape was characterized by a warm and humid climate.
The environment consisted primarily of vast, low-lying floodplains and sprawling river deltas, which drained into a shallow inland sea. Coastal swamps and extensive river systems provided a lush, resource-rich habitat capable of sustaining a large population of herbivores. The abundance of vegetation, including early flowering plants, ferns, and conifers, supported this wide array of large animals.
Major Herbivores of the Ecosystem
The survival of this large predator relied on the enormous herbivorous dinosaurs that formed the base of the food chain. Among the most impressive was Sauroposeidon, a gigantic sauropod that ranks as one of the tallest dinosaurs known. It could raise its head over 50 feet above the ground, making it an immense potential target for Acrocanthosaurus.
A full-grown Sauroposeidon would have been an intimidating challenge, suggesting Acrocanthosaurus may have targeted juveniles or injured adults. Another prevalent herbivore was the large ornithopod Tenontosaurus. The remains of Tenontosaurus are frequently found in the same rock layers as its predators, indicating it was a common food source.
Other herbivores included the smaller sauropod Astrodon and the armored nodosaurid Sauropelta. Sauropelta possessed a thick, bony shield and defensive spikes, which would have made it a difficult meal. This variety of prey ensured a stable food supply, with different species occupying various niches.
Coexisting Predators and Smaller Vertebrates
While Acrocanthosaurus was the apex predator, it was not the only carnivore roaming the Early Cretaceous plains. The smaller theropod Deinonychus lived alongside the giant. Deinonychus was a dromaeosaur known for the large, sickle-shaped claw on its foot, and it likely hunted in small packs to take down prey like Tenontosaurus.
The two carnivores occupied different ecological roles; the smaller Deinonychus posed minimal competition to the massive Acrocanthosaurus. The giant theropod may have viewed Deinonychus as a scavenger to be chased away or even as an occasional meal.
Non-Dinosaurian Fauna
The ecosystem also included a variety of large non-dinosaurian reptiles that shared the waterways and swamps. Giant crocodylomorphs, such as the large neosuchians, inhabited the rivers and coastal areas. These formidable ambush predators, alongside turtles and various species of flying pterosaurs, completed the fauna. Small, early mammals, such as Gobiconodon, scurried in the underbrush, representing a modest food source for smaller predators.
Interpreting the Fossil Record
Scientists confirm the coexistence of these diverse species by studying the fossil record. The Antlers Formation (Oklahoma and Texas) and the Twin Mountains Formation (Texas) both contain the remains of Acrocanthosaurus, Sauroposeidon, Tenontosaurus, and Deinonychus in the same rock layers.
The Paluxy River trackways in the Glen Rose Formation of Texas provide further evidence. These preserved footprints include the tracks of a large theropod, attributed to Acrocanthosaurus, following the tracks of a sauropod, likely Sauroposeidon. This remarkable trackway sequence offers a snapshot in time, suggesting a predator-prey interaction. Such trace fossils provide behavioral insight that bone discoveries alone cannot offer.