aggressive allosaurus animal animal themes animals hunting artwork assault attack beast biped carnivore concept conflict confrontation creation creature dinosaur enemy existence extinct fear fierce five animals geology herbivore herd illustration imagination jurassic long megafauna mesozoic era monster neck no people origin outdoors past predator prehistoric era prey primeval primitive reptile saurischia sauropod scavenger science species stalking survival tail theropod threat toughness trees vertebrate wilderness wildlife young