Amphicoelias and Euparkeria

Amphicoelias fragillimus
Africa

97,000,000-94,000,000

 Amphicoelias fragillimus (am-fi-see-lee-as fra-jil-i-mus) was the biggest dinosaur that has been discovered measuring about 30–60 meters in length. Amphicoelias as well as being the largest it might have had the longest life-span of any dinosaur, where as most sauropods could live up to 100 years Amphicoelias might have been able to live past 100 years do to its extreme body size.

 Amphicoelias was so large that it might have been the longest living animal to ever walked the earth, though the blue whale is bigger its life-span is around 80 years. Amphicoelias woes its incredibly long life-span to its large body size, since it was a herbivore (plant eater) it needed a large gut to digest the tough vegetation of the late Jurassic, their for the animal needed to get larger to support the large digestive system like the elephant has done today.

Euparkeria
Africa
248,000,000-245,000,000

Euparkeria (U-par-care-ee-a) may not look like a dinosaur never mind important but that is dead wrong cause this little insectivore (bug eater) is the ancestor of all dinosaurs known to man, yep giants like T. rex and brontosaurus can trace their family trees back the little Euparkeria.

 The reason that we know that Euparkeria is the ancestor of dinosaurs is not because of DNA but its special hip, for the first time in earth's history a animal was evolving the ability to stand upright. Much like the hadrosaurs (ducked-billed dinosaurs) Euparkeria walked on all four feet but when jumping after a dragonfly or running it would go on its two hind legs.