OLD BONES - SVP'S BLOG

What to See - The Biggest of the Big

Few groups of animals epitomize large size more than dinosaurs. And among dinosaurs, the largest of them all were the small-headed, long-necked sauropods. A traveling exhibit by the American Museum of Natural History entitled “The World’s Largest Dinosaurs” focuses on this fascinating branch of the dinosaur evolutionary tree. It opened at the Cleveland Museum of Natural History in early June, which provided me a great opportunity to find out how knowledge of these amazing animals has changed since graduate school.


A fleshed-out head of Argentinosaurus greets visitors entering The World’s Largest Dinosaurs. Photo by D. Croft. Reuse permitted under CC BY-NC-SA 2.0.

The bottom line is that I really enjoyed this exhibit even though it seemed to include fewer actual specimens than some other traveling exhibits I have seen. The reason I liked it so much is because it mostly deals with paleobiology: how these extinct animals lived. This is clearly illustrated by the exhibit’s centerpiece: a life-sized (i.e., 60 feet or 18 m long), fleshed out reconstruction of Mamenchisaurus hochuanensis, a Late Jurassic sauropod that lived in what is now China. One side of this huge creature is covered with skin, as it may have appeared in life, whereas the other side exposes deeper tissues such as muscles and organs. A narrated audiovisual presentation explains how air would have moved through the lungs and air sacs of this animal to bring oxygen to its giant heart. The entire time, the breathing of Mamenchisaurus can be heard in the background. I have seen no other exhibit piece that does an equally good job of conveying what it may have been like to be in the presence of one of these gigantic beasts.


A narrated audiovisual display explains how a sauropod like Mamenchisaurus would have breathed. Photo by D. Croft. Reuse permitted under CC BY-NC-SA 2.0.

But how do paleontologists know how an extinct animal such as Mamenchisaurus might have breathed (or fed or reproduced), particularly considering that no sauropods are alive today? This question is answered over and over again throughout the exhibit, and this is another outstanding aspect of The World’s Largest Dinosaurs. Instead of just telling the visitor how these animals probably lived, the exhibit explains how paleontologists and other scientists have reached such conclusions. In some instances, scientists have reconstructed sauropod biology based on the anatomy and habits of their closest living relatives: birds and crocodilians. In other cases, they have relied on information from other large plant-eating animals, nearly all of which are mammals.


The skulls of a sauropod (Diplodocus) and a modern horse (Equus caballus) illustrate a mixture of similarities and differences in these plant-eaters. Photo by D. Croft. Reuse permitted under CC BY-NC-SA 2.0.

The question of how to weigh evidence from birds and crocodilians on the one hand and mammals on the other is something that makes studying the paleobiology of dinosaurs quite tricky (and interesting!). It is clear that sauropods sometimes arrived at solutions to biological problems very similar to those present in modern mammals. In other cases, their solutions were completely different. For example, instead of evolving complex grinding teeth to shred plants like hoofed mammals did, sauropods simplified their teeth and simply used them to strip leaves off of stems as quickly as possible. Virtually all of their food processing took place in their digestive tract. The unique combination of features present in sauropods was evidently very successful from an evolutionary standpoint; their branch of the dinosaur evolutionary tree existed for some 140 million years.


This display shows the sliced-open braincase of a sauropod (Diplodocus longus) and explains how the size of the opening of a particular nerve argues against this animal having an elephant-like trunk. Photo by D. Croft. Reuse permitted under CC BY-NC-SA 2.0.

Much of The World’s Largest Dinosaurs deals with body size, which is a fundamental aspect of any animal’s biology, be it large or small. Although size is an easy concept to appreciate, visitors leave this exhibit with a new appreciation for the many issues related to being so large. A recurring theme of the exhibit is dispelling myths and misconceptions about these creatures, and I found this to be a really nice way of solidifying the information that was being presented.

The layout of the exhibit is quite open, which fits with the non-linear nature of the content. You can go from area to area in pretty much any order, and it will still make sense. I found that the ongoing Mamenchisaurus narration periodically made it difficult to concentrate on reading exhibit text, but this may be because I toured the exhibit when few other visitors were present. This probably is not an issue when the exhibit is busy.

The World’s Largest Dinosaurs is child-friendly without being childish, and there are may opportunities to learn through play. An extremely popular part of the exhibit - in addition to the life-sized Mamenchisaurus - is a large “dig pit” where children can borrow tools to uncover casts of fossil bones. I am certain that my young niece and nephews will have a fantastic time in this exhibit when they visit Cleveland over Independence Day weekend.

The World’s Largest Dinosaurs will be at the Cleveland Museum of Natural History though January 2nd, 2016. After that, it will travel to the Fernbank Museum of Natural History in Fairbanks, Alaska. If you are unable to visit the exhibit in person, you can get a taste for it by visiting its page on the AMNH web site.

-Dr. Darin Croft is an Associate Professor at Case Western Reserve University
Posted: 7/1/2015 10:14:37 PM by croftdarinadmin | with 0 comments
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