The Tyrannosaurus rex, also known as T. rex, is one of the most iconic dinosaurs in history. Standing over 12 meters tall and weighing around 9 tons, the T. rex was a formidable predator during the late Cretaceous period. However, despite being at the top of the food chain, the T. rex still had animals that posed a threat to it.
Smaller Faster Dinosaurs
One of the main threats to the T. rex were smaller, faster carnivorous dinosaurs. Raptors such as the Velociraptor and Deinonychus were agile predators that hunted in packs. Their speed and numbers meant that they could surround and overwhelm even a giant T. rex. While a single raptor would not stand a chance, a pack could injure or even kill a T. rex if given the opportunity.
Evidence for raptor attacks on T. rex comes from bite marks and wounds found on T. rex fossils. Most famous is a T. rex specimen nicknamed Sue that has V-shaped marks from raptor teeth on its tail bones. This indicates Sue survived an encounter with raptors during its life.
Velociraptor
The Velociraptor was a genus of dromaeosaurid theropod dinosaur that lived approximately 75 to 71 million years ago during the later part of the Cretaceous Period. Velociraptor was a mid-sized dromaeosaurid, with adults measuring up to 2.07 m (6.8 ft) long, 0.5 m (1.6 ft) high at the hip, and weighing up to 15 kg (33 lb), though there is a higher estimate of 19.7 kg (43 lb). The skull, which grew up to 25 cm (10 in) long, was uniquely up-curved, concave on the upper surface and convex on the lower. The jaws were lined with 26–28 widely spaced teeth on each side, each more strongly serrated on the back edge than the front.
Velociraptor was a bipedal feathered carnivore with a long tail and an enlarged sickle-shaped claw on each hindfoot, which is thought to have been used to tackle prey. Velociraptor can be distinguished from other dromaeosaurids by its long and low skull, with an upturned snout. It likely hunted small animals and possibly scavenged or hunted in packs. Like other dromaeosaurids, Velociraptor may have had feathers covering its entire body, including the legs and arms. Multiple fossil specimens have been found with quill nobs on the ulna bone, confirming the presence of wing feathers. Though Velociraptor is closely related to birds, evidence suggests that pro-avian traits like fully developed wings and a wishbone evolved only in more derived maniraptorans closer to birds on the evolutionary family tree.
| Velociraptor Facts | |
|---|---|
| Time period | Late Cretaceous |
| Length | 1.8 m (6 ft) |
| Diet | Carnivore |
Deinonychus
Deinonychus was a genus of carnivorous dromaeosaurid dinosaur that lived during the early Cretaceous period, about 115–108 million years ago (Albian-Aptian stages). It could grow up to 3.4 m (11 ft) long, though the average length was closer to 2.4 m (8 ft). It had a skull length of 410 mm (16 in), a hip height of 0.87 m (2 ft 10 in) and an estimated weight of 73 kg (161 lb). Its hands bore large sickle-shaped claws. Deinonychus had extremely long arms for its body. This feature, along with its light build and stiffened tail, indicates that it was an agile predator.
Deinonychus teeth found in association with fossils of the ornithopod dinosaur Tenontosaurus are indicative of Deinonychus having fed on this dinosaur. Teeth discovered in the area where this interaction is thought to have occurred match the dentition of Deinonychus almost exactly. While Tenontosaurus was initially thought to have been Deinonychus’ primary food source, a later study found little evidence for predation and concluded that Deinonychus probably did not prey on Tenontosaurus frequently.
| Deinonychus Facts | |
|---|---|
| Time period | Early Cretaceous |
| Length | 3.4 m (11 ft) |
| Diet | Carnivore |
Pterosaurs
Giant flying reptiles known as pterosaurs were also a threat to T. rex, especially juveniles. Pterosaurs like Quetzalcoatlus had wingspans over 10 meters wide and could swoop down and use their sharp beaks to attack dinosaurs from the air. They could easily grab infant T. rexes to feed themselves or their young.
Adult T. rexes were less vulnerable but still at risk to groups of Quetzalcoatlus working together. Fossil evidence shows T. rex specimens with healed pterosaur bite marks and punctures, indicating non-lethal conflict between the giant creatures.
Quetzalcoatlus
Quetzalcoatlus was a pterosaur known from the Late Cretaceous of North America (Maastrichtian stage) and one of the biggest known flying animals of all time. It was a member of the Azhdarchidae, a family of advanced toothless pterosaurs with unusually long, stiffened necks, which may or may not have been covered in an insulating layer of fuzz. Its wingspan was about 10.7 m (35 ft), more in some estimates.
Quetzalcoatlus stood roughly as tall as a giraffe when feeding with its neck extended, and may have weighed around 200 kg (440 lb). It was one of the largest known flying animals yet was still capable of flight. It fed on carrion and small vertebrates, probably by using its standing or walking abilities on the ground to avoid competition from other pterosaurs and terrestrial carnivorous dinosaurs. Quetzalcoatlus may have used its long sharp beak to feed on dinosaurs and pterosaurs, similar to storks.
| Quetzalcoatlus Facts | |
|---|---|
| Wingspan | 10.7 m (35 ft) |
| Height | 5.5 m (18 ft) |
| Weight | 200 kg (440 lb) |
Large Sauropods
Giant long-necked sauropod dinosaurs like Argentinosaurus also posed a threat to T. rex due to their massive size and deadly tail weapons. Weighing up to 80-100 tons, sauropods were far larger than the 9 ton Tyrannosaurus. Although not predators, they could lethally strike back using their whip-like tails if attacked.
Evidence suggests T. rex did prey on large sauropods, but only juveniles and sick or weak adults. Healthy adult sauropods were extremely dangerous prey that could easily kill a T. rex with a blow from its tail. This restricted T. rex to hunting juvenile and weaker sauropods to avoid serious injury.
Argentinosaurus
Argentinosaurus is a genus of giant titanosaur sauropod dinosaur first discovered in Argentina. It is known from only fragmentary remains, but estimations based on these place Argentinosaurus as one of the largest known land animals of all time. Argentinosaurus was estimated to measure around 30–39.7 meters (98–130 ft) long and weigh between 60–90 tonnes (66–99 short tons). It lived during the Cenomanian to Turonian stages of the Late Cretaceous Period, between 99 and 95 million years ago. The holotype is currently part of the paleontological collection of the Carmen Funes Municipal Museum in Plaza Huincul, Neuquén Province, Argentina.
Like all sauropod dinosaurs, Argentinosaurus had a small head sitting atop a long neck and a massive, pillar-like body carried by four robust legs. Certain unusual features suggest that it was adapted for feeding higher off the ground than other sauropods. Based on the relative sizes of other bones, Argentinosaurus may have reached lengths of 30–39.7 meters (98–130 ft) and weights of 60–90 tonnes (66–99 short tons). Some weight estimates exceed 100 tonnes.
| Argentinosaurus Facts | |
|---|---|
| Time period | Late Cretaceous |
| Length | 30 – 40 m (98 – 131 ft) |
| Weight | 60 – 100 tonnes (66 – 110 tons) |
Cannibalistic Tyrannosaurids
One of the most dangerous threats to T. rex were other tyrannosaurids. Large tyrannosaurid species like Tarbosaurus and Gorgosaurus likely competed with T. rex when ranges overlapped. If food was scarce, they may have turned to cannibalism and hunted each other.
Bite marks matching T. rex teeth have been found on Tarbosaurus fossils. And T. rex specimens have been discovered with partially healed tyrannosaur bite wounds, evidence that they survived encounters with other giant carnivores. Fighting between giant tyrannosaurids would have been a path to injury or death for either participant.
Tarbosaurus
Tarbosaurus was a genus of tyrannosaurid theropod dinosaur that lived in Asia during the Late Cretaceous period, between 70 and 65 million years ago. It was a member of the family Tyrannosauridae and was most closely related to Tyrannosaurus rex. Like Tyrannosaurus, Tarbosaurus was a bipedal predator with tiny two-fingered arms. It was one of the largest known tyrannosaurids; adults measured between 10–12 m (33–39 ft) in length and weighed 4–6 tonnes (3.9–5.9 long tons; 4.4–6.6 short tons).
Specimens of Tarbosaurus have been recovered from Mongolia, with more fragmentary remains from parts of China. Although many species have been named, modern paleontologists recognize only one, T. bataar, as valid. Some experts see the contemporary North American tyrannosaurid Tyrannosaurus as an Asian migrant and derived from Tarbosaurus stock. It is known from relatively complete remains, allowing scientists to study its anatomy and behavior in detail.
| Tarbosaurus Facts | |
|---|---|
| Time period | Late Cretaceous |
| Length | 10 – 12 m (33 – 39 ft) |
| Weight | 4 – 6 tonnes (4.4 – 6.6 tons) |
Gorgosaurus
Gorgosaurus is a genus of tyrannosaurid theropod dinosaur that lived in North America during the Late Cretaceous Period, between 76.5 and 74 million years ago. Fossil remains have been found in the Canadian province of Alberta and possibly Montana and Wyoming. Paleontologists recognize only the type species, G. libratus; other species that were once referred to Gorgosaurus are now classified in other genera. Like most known tyrannosaurids, Gorgosaurus was a bipedal predator weighing more than 2 metric tons (2.2 short tons) as an adult. It stood about 3 meters (10 ft) tall at the hips and was 8–9 meters (26–30 ft) long, with an estimated maximum weight of 2.5 metric tons (2.8 short tons).
The size and shape of the head, torso, and hind limbs of G. libratus are proportionally similar to those of Albertosaurus and Daspletosaurus, more than in the larger, more massive Tyrannosaurus. As in other tyrannosaurids, the largest individuals had proportionately larger skulls and longer legs than smaller individuals. Adult Gorgosaurus were apex predators, possibly preying upon abundant ceratopsids and hadrosaurs. Gorgosaurus spent at least part of its life in associations of several individuals or mixed-species groups. These groups may have congregated at carcasses, similar to groups of modern Komodo dragons.
| Gorgosaurus Facts | |
|---|---|
| Time period | Late Cretaceous |
| Length | 8 – 9 m (26 – 30 ft) |
| Weight | 2 – 2.5 tonnes (2.2 – 2.8 tons) |
Disease
Infectious diseases and parasites may have also posed a constant danger to T. rex throughout its life. Bacteria, viruses, and fungi could have infected wounds and injuries sustained during hunting or intraspecies combat. Parasites like giant fleas, ticks, and worms would have lived on T. rex skin, spreading diseases between individuals and packs.
Evidence for ancient diseases in dinosaurs comes from lesions and abnormal bone growth found on many fossil specimens. Pathologies like osteomyelitis, gout, and bone fractures showing signs of infection indicate dinosaurs suffered from illness just like modern animals.
Conclusion
Although one of the apex predators of its time, the Tyrannosaurus rex faced many lethal threats from adversaries like raptors, pterosaurs, sauropods, other tyrannosaurids, and disease. Its enormous size and deadly arsenal of teeth and jaws helped T. rex overcome most predators. But life in the Cretaceous period was a constant struggle for survival even for giant tyrant kings of the dinosaurs.