Zak Holland, of Waikari School, asks :-

What is the biggest fossil ever found?

Dave MacKinnon, a geologist at the University of Canterbury, responded.

The skeleton of a dinosaur, Brachiosaurus.

The biggest land animals of all time were the huge plant-eating dinosaurs, or sauropods, which lived during the Jurassic Period, some 150 million years ago. One of the best known is Brachiosaurus which stood about 12 meters tall, was 22.5 meters long, and is estimated to have weighed nearly 80 tons. Skeletons of Brachiosaurus have been found in Tanzania, Africa, and partial skeletons have also been found in Colorado and Utah, in the United States. Brachiosaurus looked a bit like a giraffe, only much larger, with a very long neck and long forelimbs, and presumably fed on leaves at the tops of trees.

Others sauropods like Supersaurus and Ultrasaurus may have been even larger - up to 17 meters tall and weighing 100 tons or more - but their skeletons are incompletely known. Although the sauropods were the largest animals known to have walked on land, the largest animal ever to live on Earth is still around today. Blue whales can grow to more than 30 meters in length and weigh over 200 tons.