Q: Which dinosaur is the largest?
A: The biggest dinosaur is probably ultrasauros. We only have a few bones of this late Jurassic (140 million years ago) plant-eater from Colorado, but the bones show an animal who was six-stories high and may have weighed more than 50 tons. A four-legged plant-eating dinosaur found recently in Argentina, argentinasaurus, may have been even heavier than ultrasauros. If it was a brachiosaur like ultrauros then it probably was the biggest, but if it was a titanosaur, another kind of big plant-eater common in South America, it wouldn't have been so bulky.

Q: Which dinosaurs were bigger  — plant-eaters or meat-eaters?
A: Plant-eaters by far. T. rex and giganotosaurus, the biggest meat-eaters, were 7 or 8 tons and 45 feet long. The biggest plant-eaters were100 tons and 110 feet long!

Q: What was the smallest dinosaur?
A: The smallest dinosaur that we know of was a meat-eater 200 million years old from Nova Scotia which was the size of a little robin. But we know it only from footprints, and maybe that was only a baby. As for full-grown fossil dinosaurs, the smallest are the little bird-hipped plant-eaters like lesothosaurus, which were only the size of big chickens. Compsognathus, a meat-eater the size of a turkey, is often called the smallest, but that was information based on a skeleton that belonged to a young, not yet full -grown animal.

Q: Which dinosaur was the strongest?
A: The strongest was probably the biggest, ultrasauros, who was six-stories high. Or, among meat-eaters, T. rex.

Q: In the book The Biggest Dinosaurs by Michael Berenstain, it says that the seismosaurus, found in Mexico, might be larger than the ultrasaurus. Do you know if it is?
A: Ultrasauros was the biggest we know, but we only know it from a few bones. It appears to be a brachiosaur, which was giraffe-like and heavily built. Seismosaurus was indeed longer, the longest we know, and we know it from a whole back end. It was a diplodocus relative, a longer-bodied animal with a whip tail but not so heavily built. It comes from New Mexico.

Q: How heavy and how tall was gigantosaurus?
A: I figure you are asking about giganotosaurus, the newly named biggest of all meat-eaters. The name means giant of the south. From most of the skeleton it is estimated to be about 46 feet long and 8 tons in weight. We don't measure dinosaurs by height since they didn't stand tall like people. Meat-eaters leaned forward with their tails held high, so they were nearly horizontal over their hips. There is also a gigantosaurus. It is a big plant-eater with four legs, like brachiosaurus. It is known from just a few bones from England found more than a century ago.

Q: What is the largest dinosaur bone ever found?
A: The biggest single dinosaur bone, by weight, is one of the backbones of argentinosaurus. One backbone was five feet by five feet and more than one ton in fossil weight. Of course it was lighter when the animal was alive before minerals entered into it to preserve it. The largest bone group ever found was the hip area of the supersaurus, another four-legged plant-eater. Brigham Young University researchers dug it up in Colorado about five years ago. It is about six feet wide and up to eight feet tall. The biggest skull ever found was the eight foot long skull of torosaurus, a horned dinosaur which ate plants near the end of dinosaur time in the American West. It was discovered by the Milwaukee Public Museum crews about eight years ago.

Q: What is the smartest dinosaur? What dinosaur had the largest brain? The smallest brain?
A: The smartest dinosaur, if you compare body size to brain size (a rough measurement of intelligence) is troodon. Troodon was a meat-eater the size of a man, with a brain as big as an avocado pit. It was not only the smartest dinosaur, but the smartest animal of dinosaur times, including our ancestors — the mammals of the Mesozoic Era. The biggest brained dinosaur of all was probably T. rex, since it was such a huge animal. Its brain was about as big as ours but it was many times bigger than us. Stegosaurus was a tiny-brained dinosaur compared to its size. Its brain wasn't much bigger than a ping pong ball and its body was the size of a truck.

Q: How old is the oldest dinosaur?
A: The oldest dinosaurs known are 228 million years old, such as eoraptor, a dog sized meat-eater found in Argentina. Eoraptor means "dawn thief."

Q: What was the most ferocious dinosaur?
A: The scariest dinosaur was probably T. rex, since it was the most powerful meat-eater. Or perhaps Utahraptor, a giant raptor 20 feet long, with a huge killer toe and hand claws and sharp teeth.

Q: What was the speed of the fastest dinosaur?
A: The fastest dinosaurs were probably the ostrich mimic ornithomimids, toothless meat-eaters with long limbs like ostriches. They ran at least 25 miles per hour from our estimates based on footprints in mud. But that's just a guess and you don't run your fastest in mud.

Q: What were the smallest and biggest eggs ever found?
A: The biggest dinosaur eggs we know are shaped like giant footballs and are about 19 inches long. They belong to a meat-eater from Asia called segnosaurus. The smallest dinosaur eggs are just a few inches across and more tennis ball-shaped, and we don't know what dinosaur made them.

Q: Which dinosaur has the longest neck?
A: The longest necked dinosaur was the 90-foot mamenchisaurus, a four-legged plant-eater from China. Its neck alone was 32 feet long — nearly as long as a school bus.

Q: Which dinosaur was nicknamed "long neck"? And which one really had the longest neck?
A: "Long neck" is a term used in the movie The Land Before Time to refer to what they loosely drew as apatosaurus, also known as brontosaurus, by the looks of it. The longest necked dinosaurs were the giant plant-eaters, the sauropods which included apatosaurus and particularly mamenchisaurus. That dinosaur, from China, had the longest neck of any animal ever, more than 33 feet long on a body about 85 feet long. This giant's neck was held up by 19 neck vertebrae and neck ribs the size of poster tubes.

Q: Which dinosaur had the biggest head?
A: The biggest-headed dinosaur was torosaurus, "bull lizard," a horned dinosaur related to triceratops which lived in the American West 65 million years ago. It had a skull eight feet long, longer than any animal on land ever.

Q: Which Mesozoic period had the smallest dinosaur?
A: The smallest dinosaurs were probably from the late Triassic and early Jurassic. That's where we find the smallest ornithischian dinosaurs so far. Dinosaurs got biggest in the late Jurassic and Cretaceous.

Q: Did the ankylosaurus have the hardest shell?
A: Ankylosaurs sure had hard shells, even on their eyelids! Hard to say which was hardest of any dinosaur though. Same for sharpest teeth.

Q: What is the ugliest dinosaur?
A: I don't know about the ugliest dinosaur — they probably all were good looking to their own kind. I think the eankylosaurs were really ugly — squat and covered with armor.

Q: How do we know that the Tyrannosaurus rex was the meanest dinosaur?
A: T. rex may not have been the meanest, he might just have been a garbage eater, a scavenger. We don't know. But we do know he had the strongest jaws and the biggest teeth of any meat-eater and that he was the biggest, so we guess that he might have been the meanest. One scientist says Utahraptor was meaner, even though it was just 20 feet long. But it had huge claws on its toes and fingers, weapons T. rex didn't have.