Interspecies Conflict/lion pack
1) 7,5t african elephant vs lion pack (2x250kg lion + 8x 150kg lioness), they have a good organization
2) 18t indricotherium vs lion pack (6x250kg lion + 20x 150kg lioness), they have a good organization
3) 7t acrocanthosaurus vs (4x250kg lion + 10x 150kg lioness), they have a good organization
African elephant (7.5t) vs 2 lions (250kg) and 8 lionesses (150kg): Groups of lions have killed elephants before, but these are usually subadults, females, or unhealthy ones. Lions will attack an elephant from behind (to avoid the weapons in the front), and will use their weight to eventually drag the huge mammal to the ground. In the case of a healthy 7 1/2 ton elephant, this technique won't be as successful. The lions will likely be challenged at every turn, and may get trampled or gored in their attack attempt. A throat bite won't be a plausible option for the lions here, and wearing this huge pachyderm down (by fatigue or blood loss) will be a very difficult task that will take a long time to accomplish. An African elephant this size will be over 3 times taller at the shoulder than a male lion (and over 3 1/2 times taller than a lioness), and will be almost impossible to hang on to. Even an enormous lion pride wouldn't likely attempt this due to the risk of injury & death, but if they were determined to do so anyway, it would require a much larger number of them. African elephant wins.
Indricotherium (18t) vs 6 lions (250kg) and 20 lionesses (150kg): Indricotherium was quite possibly the largest land mammal to ever walk the earth. Its massive size was enough of a defense against the predators of its day. Indricotherium may have kicked or used a bite in self-defense (like the modern-day Indian rhino does on occasion), but no one knows for sure. Lion prides are definitely a force to be reckoned with on the African plains, but they never encounter anything close to the size of an Indricotherium. Even the huge, well-organized pride in this scenario will have trouble finding a way to bring this enormous mammal down. To illustrate the size difference, imagine 26 housecats trying to bring down an okapi! For the lions to overpower any large animal they must apply a suffocating throat bite, bite hard enough to sever the spinal cord, cause enough bleeding to affect the prey's normal functions, or use their collective body weight to collapse the quarry (where a bite can be readily applied). None of these techniques will be a reasonable option against an animal as large as an Indricotherium. This lion pride will leave this beast alone. Indricotherium wins.
Acrocanthosaurus (7t) vs 4 lions (250kg) and 10 lionesses (150kg): Acrocanthosaurus was a huge theropod that was likely an allosaurid, but possibly a carcharodontosaurid. Its huge jaws were armed with approximately 70 long teeth, which were serrated & sharp. Acrocanthosaurus preyed on large animals like Sauroposeidon (a 40-ton sauropod), and may have actually been able to use its small forelimbs (armed with sharp claws) to grab/slash prey while attacking. Lion prides dominate the African savannah, but never encounter a predator as large as Acrocanthosaurus. A single bite from the jaws of Acrocanthosaurus can easily dispatch a lion, and the lions won't risk a confrontation with a foe that offers that level of danger. This Acrocanthosaurus weighs 25 times as much as one of the male lions, and 2 1/2 times as much as the entire lion pride combined. The techniques lions use to overpower large animals will be lost on a theropod weighing 7 tons, and the pride in this scenario will give this dinosaur a wide berth. Even if the lions attack without regard to their own safety, their numbers will likely be reduced before they make adequate headway. Acrocanthosaurus wins.