Brachiosaurus!

Brachiosaurus, meaning "arm lizard", from the Greek brachion/βραχιων meaning "arm" and sauros/σαυρος meaning "lizard", was a genus of sauropod dinosaur that lived during the Late Jurassic Period and possibly the Early Cretaceous Period. It was named thus because its forelimbs were longer than its hind limbs. One of the largest animals known to have walked the earth.

 

For many decades, Brachiosaurus was among the largest dinosaur known, especially when complete specimens (now classified as Giraffatitan) were attributed to it. However, a study comparing Brachiosaurus and Giraffatitan by Michael Taylor in 2009 found that the true Brachiosaurus specimens from North America actually represent a heavier, likely longer individual. In fact, the most complete and largest specimens of Brachiosaurus come from a sub-adult individual, so it likely would have grown larger than even current size estimates.

 

Based on measurements of comparable bones, Brachiosaurus was similar in overall size to the related Giraffatitan, which is estimated to have attained 25 metres (82 ft) in length and was probably able to raise its head about 13 metres (43 ft) above ground level. However, Brachiosaurus may have been longer, as it had a longer torso and possibly a longer tail than Giraffatitan. No neck material is known from the holotype specimen; however, there are some brachiosaur neck vertebra that have been assigned to Brachiosaurus by some authors. If the vertebrae do belong to Brachiosaurus then they suggest that it had a similarly proportioned neck to Giraffatitan. Additionally, the best known Brachiosaurus specimen was not fully grown when it died, meaning it may have had an adult length of over 25 m. Brachiosaurus was also stockier, and therefore likely heavier, than Giraffatitan. Brachiosaurus is estimated to have weighed 28.7 tonnes (28.2 LT; 31.6 ST), compared to 23.3 tonnes (22.9 LT; 25.7 ST) for Giraffatitan.