picured: diagram of watertight egg

At the museum, we were required to go on two tours led by professors Holtz and Merck, and one self-led tour. The guided tours were much more impactful, so I will be covering them on this page.

The fourth floor is heavily focused on evolutionary biology, specifically dedicated to the history of vertebrates, which first emerged as jawless fish about 500 million years ago. It is organized by placing certain large evolutionary traits along the “trunk” of the evolutionary tree. The tree wraps around the entire fourth floor, starting with the jawless fish, and ending with the mammals. The development of the floor started in the 90's so much of the evolutionary relationships have actually been amended or completely changed. Keep this in mind when I mention the inaccuracies pointed out by the Professors.

The first tour was led by Professor Merck, and took us through the first parts of the fourth floor of the museum. Merck skipped past the jawless fish rather quickly, but did explain how the development of a jaw emerged rather quickly with the first jawed fish being the placoderms. The internal skeleton was also a development that vertebrates didn't originally have. Following this, Merck pointed out one of the most important evolutionary splits: ray-finned fish that evolved into modern fish, and lobe-finned fish that evolved into most land vertebrates, but also strangely, lungfish. With the land animals, another important evolution occurred: a watertight egg for land-based birth. This is where Merck shifted his explanations to be more concise, as the creatures that were on display became more diverse, so he could afford less time for explanation. He made two important points though. The first is that turtles are only distantly related to pareiasaurs, though they are commonly (and falsely) thought to be sister species. In the museum, they are The second is that pterosaurs are not dinosaurs, thus being only distantly related to birds. Overall, Professor Merck did a good job explaining this section of the museum, but even without him, one can get a basic understanding of extinct vertebrate life. This is because of the models in the middle of the hall, as well as the cohesive design of the floor. The models can be touched, and have simple explanations of important evolutions. They help visitors put a mental timeline together, and even elementary school aged children would learn a few things from this hall.

The second tour was led by Professor Holtz, who covered the Dinosaur hall on the fourth floor. Dinosaurs are still part of the vertebrate tree, but branched off from the evolutionary path of mammals a long time ago. Holtz explained that all dinosaurs have one common ancestor: a small raptor-like creature that stood on two legs and had hollow hips. That distinction and ancestor is what makes a dinosaur a dinosaur. The dinosaur halls had much more to show, since the fossils on display were much larger. This is because of the development of very efficient lungs, making many species massive. From this common ancestor, a split occurred, those who kept standing on their hind legs and raptor-like features (theropods), those who became herbivores and developed armor(ornithischians), and long necked dinosaurs (Saurischians). An important correction that Holtz made is that the Allosaurus and Tyrannosaurus are not that closely related, despite the museum making them seem related. Once again, this was due to the installation being put in place with outdated knowledge. Unfortunately, the detailed descriptions of the dinosaurs and large fossils made it look very epic, but more difficult to understand. Without Holtz, I would have recognized many of the more popular dinosaur species, but not have understood the evolutionary distinctions. This hall is likely best suited for enthusiasts or students, not a general audience. I personally would add more models at major evolutionary points, much like the first hall, but the halls are already crowded with fossils as is.