Creature of the Week #7: Giraffatitan

Galvasean

This week's creature's name does not sound familiar to most people, despite being one of the most famous dinosaurs in existence.
Giraffatitan, meaning 'giant giraffe', was one of the tallest dinosaurs ever, standing some 13 meters tall. It was up to 23 meters long and weighed somewhere between 20 and 50 tonnes (estimates vary). Truly a gigantic beast, a Tanzanian cousin of Brachiosaurus.

While Giraffatitan was for a long time believed to be the largest dinosaur of all time (until the discovery of gigantic titanosaurs such as Argentinosaurus, Puertasaurus and Paralititan, not to mention it's fellow brachiosaur Sauroposeidon). It also holds the record for being the largest near complete dinosaur skeleton on display in the world (at the Museum für Naturkunde in Berlin, Germany).


So, why has nobody heard of it?

As it turns out, Giraffatitan was originally classified as a new species of Brachiosaurus (B. brancai). Later studies suggested that the African Brachiosaurus was different enough from the North American brachiosaurs to warrant a new genus and name of it's own. By 1991 the African Brachiosaurus (brancai) was officially known by the title Giraffatitan brancai. In 1998 the skull of a North American Brachiosaurus was rediscovered (it was formerly mistakenly used as the head of 'Brontosaurus'). Interestingly, Brachiosaurus lacked the distinctive head crest usually associated with it. As it turns out this feature was exclusively a Giraffatitan one.

A further, more in depth study in 2009 showed that every single bone of Giraffatitan was actually different from that of Brachiosaurus, putting any niggling doubt of it's independance to rest.
So there you have it. If you think you have seen a Brachiosaurus, chances are you have actually seen a Giraffatitan!

Where have I seen you before?

The 'Brachiosaurus' in Jurassic Park actually looks a lot more like Giraffatitan than it does an actual Brachiosaurus. In fact, the same could be said for most popular restorations of Brachiosaurus.

Mind = Blown.

So, now that we know your name, tell us a bit more about yourself.

Giraffatitan lives up to it's name. It held it's neck upright like it's modern day namesake so that it could feed from tall trees. This trait is not particularly common among the long necked sauropods, many of whom had vertical forward pointing necks which were swung in an arc from side to side to gather low lying vegetation while using a minimal amount of energy.
Upright necked sauropods like Giraffatitan faced interesting problems due to their unusual physiology. For starters getting the blood up to their head would have required a very strong heart. It was once suggested that they may have had several hearts along the neck in order to help the blood flow upward, but this idea has not stood the test of time as nothing in the animal's physiology suggests it had extra hearts.
Interestingly, the key to the success of these long necks lied in their small brains. Having a small and mostly inactive brain means not much blood is required to circulate through it, allowing Giraffatitan to make the most out of what little brains it had. It probably spent it's days wandering about eating the leaves of trees and not worrying about a whole lot (once they reached maximum size they were virtually immune to predation).


Giraffatitan compared to a human.

Giraffatitan also had a 'thumb' spike on one of it's toes. It's use is unclear. It would have been fairly useless as a defensive weapon, so it has been suggested that it may have been used for digging. Perhaps it could have dug for water during times of drought.

It is also worth noting that a complete full grown Brachiosaurus skeleton has never been found. Adults labeled as Brachiosaurus all later turned out to be Giraffatitan. From the comparisons that have been made Brachiosaurus seems to have been the stockier of the two and was most likely longer than Giraffatitan when fully grown too.