Spinosaurus, a distinctive dinosaur, captivates with its unusual physical characteristics. Its long, crocodile-like snout had straight, conical teeth, unlike the serrated teeth of many other large meat-eaters. Its most striking feature was the prominent sail-like structure on its back, formed by elongated neural spines up to 1.65 meters (5.4 feet) long. These adaptations, including a paddle-shaped tail and dense bones, suggest a life closely tied to water.
Spinosaurus’s Environment
Spinosaurus lived during the Cenomanian stage of the Late Cretaceous period, approximately 100 to 94 million years ago. Its habitat was primarily in North Africa, with significant fossil discoveries in the Kem Kem Beds of Morocco, Egypt, Algeria, and Tunisia. This ancient landscape was a vast system of braided rivers, estuaries, and coastal plains, with tidal flats and mangrove forests. This wet delta environment supported abundant aquatic life, influencing the creatures that thrived alongside Spinosaurus.
The Kem Kem Group, also known as the Kem Kem Beds, provides a rich fossil record of this ancient ecosystem. German paleontologist Ernst Stromer first described Spinosaurus remains from Egypt in 1915, though these original fossils were destroyed during World War II. Subsequent discoveries, especially in the Kem Kem Beds since the early 2000s, have advanced understanding of Spinosaurus and its contemporaries. The region’s geological processes and fossilization biases can sometimes create an appearance of greater predator diversity than may have existed at any single moment.
Large Carnivorous Dinosaurs
The Kem Kem ecosystem was rich in large predatory dinosaurs, with Spinosaurus sharing its territory with other meat-eaters. One such contemporary was Carcharodontosaurus saharicus, a massive terrestrial carnivore that could reach lengths of 40 feet (13 meters). While Spinosaurus was adapted for a semi-aquatic lifestyle, Carcharodontosaurus was built for hunting on land, likely preying on large herbivorous dinosaurs. This difference in hunting grounds and prey indicates niche partitioning, allowing multiple large predators to coexist without direct competition.
Another theropod in the Kem Kem Beds was Deltadromeus agilis, a fast-running abelisaurid 25 to 30 feet long. Its slender, lightweight build and long hind limbs suggest it was an agile predator, likely pursuing smaller, swifter prey across the ancient landscape. The classification of Deltadromeus has been debated, with some studies suggesting it might be synonymous with Bahariasaurus, another large theropod from the region. The presence of these diverse carnivores highlights the predatory pressures within this ancient North African environment.
Herbivorous and Other Dinosaurs
Beyond the carnivores, the Kem Kem Beds reveal a range of herbivorous and smaller dinosaur species that formed the base of the food web. Among the large plant-eaters was Rebbachisaurus garasbae, a long-necked sauropod. This dinosaur, a relative of Diplodocus, was adapted for a terrestrial existence, foraging on vegetation. Rebbachisaurus was a food source for the predators of the region.
Another herbivore was Ouranosaurus nigeriensis, an iguanodontian known for its large dorsal sail, similar to Spinosaurus’s but serving a different role. While the exact function of Ouranosaurus’s sail is debated, hypotheses include thermoregulation, display, or even supporting a fatty hump for energy storage. Its robust hind limbs allowed for bipedal movement, and its teeth suggest a diet of plants. The fossil record indicates the presence of other titanosaurian sauropods in the Kem Kem Group, diversifying the herbivorous inhabitants.
Aquatic and Aerial Neighbors
Given Spinosaurus’s semi-aquatic nature, its ecosystem included a rich array of non-dinosaurian life in water and air. Large crocodilians, such as Sarcosuchus imperator, inhabited the same river systems, representing another predator. Other crocodylomorphs, like Elosuchus with its gharial-like snout and the flat-snouted Laganosuchus, also shared these waterways. These diverse crocodilians occupied various niches, from fish-eaters to ambush predators, sometimes even scavenging on land.
The aquatic environment teemed with diverse fish, forming a significant part of Spinosaurus’s diet. This included giant coelacanths, sawfish like Onchopristis, and large lungfish, some of which were considerably larger than their modern counterparts. Soaring overhead were various pterosaurs, winged reptiles that dominated the skies, as no birds are known from this fossil group. Pterosaurs such as Alanqa and Coloborhynchus were present, with their jaw shapes suggesting different feeding strategies, including fish-eating.