Brachiosaurus was a very large herbivorous Sauropod Dinosaur that lived in North America with close relatives in the same family in Africa and Europe (an African species has been recently given its own scientific name Giraffatitan, once known as a type of Brachiosaurus) Brachiosaurus was a 13 metre tall, 70 tonne gargantuan reptile, that fed on the tops of Conifer trees in the Late Jurassic forests, sometimes felling them with their sheer bulk if they were taller than them or not.
Walking with Dinosaurs Brachiosaurus featured in Walking With Dinosaurs - Time of the Titans, as the archetypal giant Dinosaur of the Jurassic alongside the giant Diplodocidae genus Diplodocus. It was seen emerging behind the three juvenile Diplodocus 'creche' members, survivors of the forest fire driven out onto the dangerous open fern prairies. It is shown to dwarf the young Diplodocus (at least in sheer screen presence and definitely height) Adults are said to be 70 tonnes in weight, thanks to an exclusive diet, monopolising on the tallest tree tops which 'no other Dinosaurs can reach'. Though not strictly true, it is correct that at least the kinds of trees they fed on due to the teeth they had (chisel like) were not much sought after by anything else around; tough Conifer leaves and cones. Diplodocus for instance could only strip the soft ferns and cycads with their weak and simple peg like teeth.
Brachiosaurus is controversially referred to as 'the largest land animals that have ever existed'. Contextually one must be careful not to mistake this for having to mean that no other Dinosaur was or could be bigger than Brachiosaurus - or that 'Brachiosaurus was the largest'. From a sensible point of view, one should see that all that is meant by this admittedly dramatic statement, is that up to now it is the biggest, thus meaning so far life on Earth has never seen an animal of the sheer size of Brachiosaurus (in weight at least) As many now know, Brachiosaurus, though once the largest Dinosaur ever known for decades, has some many years ago now been relegated - far surpassed by the gigantic Argentinosaurus.
Nevertheless, Brachiosaurus is a mighty, majestic and awe-inspiring Dinosaur, as famous now as it has been for decades. Its name means, Arm Lizard, in reference to its and its whole families peculiar trait of having longer forelimbs - or 'arms' - than hindlimbs.(152-145)
In the show, an Allosaurus tried to attack a baby Brachiosaurus, but the mother arrives just in time to fend off the predator. After the attack they graze on leaves. It was also the main herbivore as not replacing Diplodocus.