Texas holds an extensive record of the Mesozoic Era, particularly the Cretaceous Period, where the vast majority of the state’s dinosaur fossils originated. During this time, the landscape was dominated by a broad, shallow marine environment. An ancient inland sea regularly covered large portions of the state, leaving behind vast limestone and shale deposits. These deposits preserved the remains of both marine life and the dinosaurs that roamed the coastal plains, providing a detailed picture of a rich and diverse prehistoric ecosystem.
The Massive Long-Necked Dinosaurs
The colossal sauropods, characterized by their immense size and elongated necks, represent some of the most impressive dinosaurs to walk the Texas landscape. The official state dinosaur of Texas is Paluxysaurus jonesi, an Early Cretaceous sauropod. This giant is estimated to have reached lengths of up to 70 feet and weighed over 30 tons, browsing on high-growing foliage.
Later in the Cretaceous Period, the massive titanosaur Alamosaurus sanjuanensis dominated the western regions of the state, particularly the Big Bend area. Alamosaurus was one of the last surviving sauropods in North America and ranks among the largest land animals to ever live. Individuals potentially reached lengths of 100 feet and weights exceeding 50 tons, surviving until the very end of the dinosaur age.
The Predatory Dinosaurs
The apex predators of ancient Texas were the theropods, a group of bipedal, mostly carnivorous dinosaurs. The most formidable was Acrocanthosaurus atokensis, a massive Carcharodontosaurid whose fossils and tracks are widespread. Known as the “high-spined lizard,” this hunter was recognizable by the tall neural spines along its backbone, likely supporting a low hump or sail. Acrocanthosaurus reached lengths of 38 feet and weighed between four and seven tons.
This large predator occupied the top of the food chain during the Early Cretaceous, targeting large, slow-moving prey like the enormous sauropods. Evidence of its hunting behavior is preserved in fossilized trackways, showing a possible pursuit of a herd of long-necked dinosaurs. Smaller, swifter theropods also inhabited the region, including the ostrich-like Ornithomimus and the fearsome dromaeosaur Deinonychus, known for its deadly, sickle-shaped claw.
Plant-Eaters and Armored Species
A diverse community of other plant-eating dinosaurs thrived in Texas, including hadrosauroids, ceratopsians, and armored species. The ornithopod Protohadros byrdi is a notable Late Cretaceous discovery from the Dallas-Fort Worth area. This “almost-duck-billed” dinosaur was an important evolutionary link to the later, more famous duck-billed dinosaurs. Estimated to be around 22 feet long, Protohadros likely fed on low-growing vegetation.
In the Big Bend region, horned dinosaurs were represented by species like Agujaceratops, a ceratopsian with a prominent neck frill. Dome-headed pachycephalosaurs, such as Texacephale, were also present, likely using their thickened skull dome in head-butting contests.
The defensive lineup was anchored by the ankylosaurs, the armored “walking tanks” of the period. Pawpawsaurus campbelli, an Early Cretaceous nodosaurid, was covered in bony armor plates but lacked the famous tail club of later ankylosaurs. A recent discovery of a new, yet-unnamed spike-armored ankylosaur in West Texas suggests a greater diversity of these defensive herbivores, featuring a heavily armored body and a clubbed tail.
Famous Texas Dinosaur Discoveries
The most famous physical evidence of Texas dinosaurs is the Glen Rose Formation, specifically the extensive trackways found at Dinosaur Valley State Park near the Paluxy River. These fossilized footprints, preserved in Lower Cretaceous limestone, offer rare insights into dinosaur behavior that bones alone cannot provide. Paleontologists have documented numerous parallel trackways left by massive sauropods, suggesting these herbivores traveled in herds.
A dramatic sequence of tracks at Glen Rose includes a large three-toed theropod trackway running alongside a sauropod path. This evidence is interpreted as a “chase sequence,” a snapshot of a predatory event likely involving Acrocanthosaurus. Another significant discovery was the 2001 airlift of a giant Alamosaurus fossil from Big Bend National Park. The sheer size of the neck vertebrae required a helicopter to remove the plaster-encased bones.