Mazzetta and colleagues (1998, 1999) presumed that Carnotaurus was a swift runner, arguing that the thigh bone was adapted to withstand high bending moments while running.
The ability of an animal's leg to withstand those forces limits its top speed.
The running adaptations of Carnotaurus would have been better than those of a human, although not nearly as good as those of an ostrich.
Scientists calculate that Carnotaurus had a top speed of up to 48–56 km (30–35 mi) per hour.

In dinosaurs, the most important locomotor muscle was located in the tail.
This muscle, called the caudofemoralis, attaches to the fourth trochanter, a prominent ridge on the thigh bone, and pulls the thigh bone backwards when contracted.
Scott Persons and Phil Currie (2011) note that in the tail vertebrae of Carnotaurus, the caudal ribs did not protrude horizontally ("T-shaped"), but were angled against the vertical axis of the vertebrae, forming a "V".
This would have provided additional space for a caudofemoralis muscle larger than in any other theropod—the muscle mass was calculated at 111 to 137 kilograms (245 to 302 lb) per leg.
Therefore, Carnotaurus could have been one of the fastest large theropods.
While the caudofemoralis muscle was enlarged, the epaxial muscles situated above the caudal ribs would have been proportionally smaller.
These muscles, called the longissimus and spinalis muscle, were responsible for tail movement and stability.
To maintain tail stability in spite of reduction of these muscles, the caudal ribs bear forward projecting processes interlocking the vertebrae with each other and with the pelvis, stiffening the tail.
As a consequence, the ability to make tight turns would have been diminished, because the hip and tail had to be turned simultaneously, unlike in other theropods.
Mazzetta and colleagues (1998, 1999) presumed that Carnotaurus was a swift runner, arguing that the thigh bone was adapted to withstand high bending moments while running. The ability of an animal's leg to withstand those forces limits its top speed. The running adaptations of Carnotaurus would have been better than those of a human, although not nearly as good as those of an ostrich. Scientists calculate that Carnotaurus had a top speed of up to 48–56 km (30–35 mi) per hour.
In dinosaurs, the most important locomotor muscle was located in the tail. This muscle, called the caudofemoralis, attaches to the fourth trochanter, a prominent ridge on the thigh bone, and pulls the thigh bone backwards when contracted. Scott Persons and Phil Currie (2011) note that in the tail vertebrae of Carnotaurus, the caudal ribs did not protrude horizontally ("T-shaped"), but were angled against the vertical axis of the vertebrae, forming a "V". This would have provided additional space for a caudofemoralis muscle larger than in any other theropod—the muscle mass was calculated at 111 to 137 kilograms (245 to 302 lb) per leg. Therefore, Carnotaurus could have been one of the fastest large theropods. While the caudofemoralis muscle was enlarged, the epaxial muscles situated above the caudal ribs would have been proportionally smaller. These muscles, called the longissimus and spinalis muscle, were responsible for tail movement and stability. To maintain tail stability in spite of reduction of these muscles, the caudal ribs bear forward projecting processes interlocking the vertebrae with each other and with the pelvis, stiffening the tail. As a consequence, the ability to make tight turns would have been diminished, because the hip and tail had to be turned simultaneously, unlike in other theropods.
Carnotaurus