Brachiosaurus: A morphology review

Brachiosaurus: A morphology review

Sauropods were the largest animals to ever walk the earth, with estimated weights up to eighty tons (Barras, 2020). Sauropods were widely distributed across the globe, with tracks and or fossils found on every continent except Antarctica so far, which date through the mid-Jurassic, and to the end of the Cretaceous (Falkingham, Bates, Mannion, 2020). They dominated the planet for about one-hundred million years. Members of the Sauropod family were voracious herbivores, and some reports indicate that they had to eat about one ton of food every day to maintain the growth rates and body mass that they did (Sander, Clauss, 2008). The reason they were able to eat this much seems to come down to the fact that they did not chew their food, or chewed very little, as indicated by studies on their teeth morphology (Barras, 2020). However, this is only one of the major traits that sauropods evolved that allowed them to grow to be the biggest creatures that ever walked the land on earth. 

Sauropods owe their massive scale to 3 factors, at least. They ate a ton of food a day at maturity and did not have to chew their food, allowing for more to be ingested, plus they had no gastrointestinal mill, thus saving even more energy, their long necks allowed them to access food that was not available to shorter dinosaurs, giving them the opportunity to consume more nutrient-dense food sources like new growth, and finally, their avian-like lung system, in which an air sac allows breath flow to travel one way instead of in and out as is common in mammals, made their respiratory systems much more effective (Barras, 2020). There is much debate still about whether the brachiosaurus was endothermic or ectothermic, with some sides saying that the daily caloric intake was not enough to support endothermy at their scale, mostly due to the problem of dissipating heat quickly enough as an endotherm, and other sides claiming that it is not possible that they grow to the size that they did without a high resting metabolic rate, as is found in endotherms (Weaver, 2016)(Curry, 2011). There is also a quite large discrepancy in how quickly sauropods were said to grow to full size, with some research teams claiming they went from five kilogram hatchling to thirty-eight thousand kilograms (in the case of brachiosaurus, specifically) in twenty years, and some claiming it was closer to forty years to achieve maximum weight (Weaver, 2016).

Brachiosaurus was amongst the largest of the Sauropods, the most famous specimen, in the Natural History Museum of Berlin is hypothesized to have weighed thirty-eight thousand kilograms or more, about 42 tons (Gunga et. al, 2008). They are found commonly in the central United States, around the rocky mountains (Carpenter, Tidwell, 2001). Finding brachiosaur bodies intact is a mighty challenge. Brachiosaurus was so large that it was very uncommon for them to be buried whole and intact. Tar pits and swamps were often too shallow, so most of our fossilized skeletons, if not all, are incomplete (Barras, 2020). 

Brachiosaurus, like all sauropods, laid eggs, about 10 at a time, and were seemingly careful parents, watching over their very small young until they were old enough to fend for themselves (Sander, Clauss, 2008). The main concern of the brachiosaurus, at least for a long time, was the allosaurus. Allosaurus didn’t pose a risk to adult brachiosaurus but were able to eat juveniles quite easily, if they could get through the parents to get to them. The long tail of the brachiosaurus likely allowed for a very powerful tail-whip to help defend their young against allosaurus. Brachiosaurus likely laid hard-shelled eggs with a porous membrane (Apaldetti et. al, 2018). This indicates that they, like most sauropods, buried their eggs, similar to turtles and crocodilians, a mechanism that would help protect their young even further, allowing more to grow into adulthood. 

The massive size of the brachiosaurus has prompted some equally large questions from scientists. The long neck of the brachiosaur is responsible for a large part of the success obtained by brachiosaurus, as it allowed for ample feeding from high quality food sources while allowing most of the body to be immobile (Sander et. al, 2011). This feeding style seems to have raised a lot of questions in the scientific community about how flexible their necks really were. Recent studies have found that some of the bone we see in brachiosaurus vertebral fossils is actually ossified cartilage, which would have allowed for a more extreme level of flexibility than all-bone vertebrae (Weaver 2016). This supports theories that brachiosaurus mostly commonly stood with a vertical neck posture, at least while stationary, and likely could not often lower their heads for very long periods (Andreas, Wolf-Deter, 1998).(Sander et. al, 2011)

Works Cited

Andreas Christian; Wolf-Dieter Heinrich (1998). The Neck Posture of Brachiosaurus brancai. , 1(1), 73–80. doi:10.1002/mmng.19980010105

Apaldetti, C., Martínez, R.N., Cerda, I.A. et al. An early trend towards gigantism in Triassic sauropodomorph dinosaurs. Nat Ecol Evol 2, 1227–1232 (2018).

Barras, C. (2020). Here be giants. New Scientist, 246(3286), 40–43.

Currie, A. (2017). Hot-Blooded Gluttons: Dependency, Coherence, and Method in the Historical Sciences. The British Journal for the Philosophy of Science, 68(4), 929–952.

Falkingham, P. L., Bates, K. T., & Mannion, P. D. (2012). Temporal and palaeoenvironmental distribution of manus- and pes-dominated sauropod trackways . Current links for DOI: 10.1144/0016-76492011-019. Retrieved February 1, 2022,

Gill, F.L., Hummel, J., Sharifi, A.R., Lee, A.P. and Lomax, B.H. (2018), Diets of giants: the nutritional value of sauropod diet during the Mesozoic. Palaeontology, 61: 647-658.

​​Gunga, H.-C., Suthau, T., Bellmann, A., Stoinski, S., Friedrich, A., Trippel, T., Kirsch, K., and Hellwich, O.: A new body mass estimation of Brachiosaurus brancai Janensch, 1914 mounted and exhibited at the Museum of Natural History (Berlin, Germany), Foss. Rec., 11, 33–38,, 2008.

Sander, M., & Clauss, M. (2008, October 10). Sauropod Gigantism. Science. Retrieved February 1, 2022, from 

Sander, P.M., Christian, A., Clauss, M., Fechner, R., Gee, C.T., Griebeler, E.-M., Gunga, H.-C., Hummel, J., Mallison, H., Perry, S.F., Preuschoft, H., Rauhut, O.W.M., Remes, K., Tütken, T., Wings, O. and Witzel, U. (2011), Biology of the sauropod dinosaurs: the evolution of gigantism. Biological Reviews, 86: 117-155.

Weaver, J. (2016). The improbable endotherm: The energetics of the sauropod dinosaur Brachiosaurus. Paleobiology, 9(2), 173-182. doi:10.1017/S0094837300007557

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