How To Build A Dinosaur
What image comes to mind when you see the word “Dinosaur”? Most likely Godzilla rampaging the streets of Tokyo; or maybe a pack of velociraptors prancing around Chris Pratt. Dinosaurs are so ingrained into popular culture that it's easy to forget that no one actually knows what they looked like. Our image of these creatures is based solely on fossil samples and paleontological inference. In the paper Dinosaur Biology (Farlow et. al.), a team of researchers take us through the process of determining the characteristics of these prehistoric phenomena.
Fossil Record
The first place paleontologists turn to for clues about dinosaurs is the fossil record. Fossils provide the most hard-backed primary evidence for certain dinosaur characteristics, so an inference is more likely to be accurate the more it is based on the fossil record. Unfortunately, it is not possible to reconstruct an entire skeletal model from just a single bone, and in most cases the complete fossilized bone structure is not available to scientists. Out of the 285 dinosaur types recognized in 1988, only 20% were based on complete skeletons and skulls.
Anatomy
Even without fossil evidence, scientists are able to infer that dinosaurs had hearts, lungs, arteries, and other organs. The presence and absence of these soft-tissue structures are based on the corresponding structures in crocodilians and birds. To determine likely body size, researchers look at muscle scars on bones: the more there are, the bigger the dinosaur probably was. Based on fossilized impressions, paleontologists have determined that non-feathered dinosaurs likely had scaly skin. Based on other impressions, it is assumed that crests and frills covered their bodies; and while it is reasonable to assume these decorative structures were colorful (based on similar structures seen on reptiles), the colors associated with any dinosaur depiction are all speculative.
Habitat
The best way to determine the habitat and migratory patterns of certain dinosaurs is to take samples of the same taxa over a widely distributed range of environments. For example, the remains of one large herbivore species were found distributed over a distance of 100 km across the Late Jurassic Morrison Formation of Western US: this particular dinosaur preferred to roam around, and it seems to follow drought patterns (preferring drier habitats than its surrounding taxa). But it is important to note that Earth’s climate patterns have shifted since the dinosaurs have been alive, so modern day fossil sites might not reflect the conditions that the creatures actually lived in. Using models of prehistoric continental positions as well as environmental reconstructions of different regions, scientists can “retrodict” the climate patterns of the Mesozoic Era (123) in order to accurately determine the climates of different dinosaur habitats. Overall, Earth was warmer during this era, but dinosaurs at higher latitudes had to deal with darker and colder conditions.
Behavior
To find behavioral patterns, paleontologists look at monotypic bonebeds: sedimentary deposits containing bones from one species of dinosaur. These bonebeds hugely suggest that prosauropod dinosaurs (those peaceful, long-necked herbivores) lived, traveled, and died in herds. Researchers can even determine the fossilized trails taken by these traveling herds, and most of these tracks show movement along ancient shorelines. Remains of dinosaur nesting sites also illustrate egg-laying patterns. Sometimes, the remains of an embryo can be found inside eggs; only then can scientists determine what species the egg belonged to.
Why does this matter?
Dinosaur remains are really small traces of really big creatures, which do not make for useful evolutionary models. So why do we even care to study dinosaurs? The answer is simple: dinosaurs defy logic. The very fact that these giants once roamed the Earth goes against what we know about how the body size of modern land animals correlates to movement, growth, and survival. Without dinosaurs, a whole line of ecological questioning would be closed. Paleontology poses theories that could enrich our understanding of modern ecology, and in return our modern understanding of the world could help us theorize about how these improbable creatures lived so long ago.
Reference:
Farlow, J. O., Dodson, P., & Chinsamy, A. (1995). Dinosaur Biology. Annual Review of Ecology and Systematics, 26, 445–471. http://www.jstor.org/stable/2097215
This is so sick! I loved reading about the logistics and ways that dinosaurs are brought back to life by paleontologists. In the back of my mind, I always had some doubts as to how we "know" what dinosaurs look like, but you did a really great job addressing this question and all of its points. After reading this, I wonder how these creatures really appeared and acted when they were alive, and if there is any other way for us to predict this more accurately.
ReplyDeleteIt's very true that I have these ideas of what a dinosaur looks like ingrained in my head but in reality, those images are all based off of popular media. I almost want to say that it was proven recently that there is a dinosaur that we completely made up, or just looks completely different than we predict. I believe it had to do with some mixing of the fossil record that occurred during excavation. This is definitely something that is easy to mess up if it's not done thoroughly. However it's really important that we come to understand the past archaeological records, and it's also mind boggling that such creatures once lived on the same planet that we live on.
ReplyDeleteAfter reading this article, I am curious to learn more about how dinosaurs defy the laws of ecology. I really like the way you structured this piece; the section headings make the information more digestible. You also did a good job of clarifying the importance of this topic. I also wonder how establishing a fuller picture of the climatic conditions in which the dinosaurs actually lived could help us understand more about how animals behave an adapt to various climates across spatial and temporal gradients. Maybe this could provide us with a greater understanding of how present-day species will be affected by global climate change.
ReplyDeleteThis article is very clearly written and does a great job of prioritizing and organizing certain facts in order to create a comprehensive and engaging piece of writing. I think it is very common for somebody to wonder how we seemingly know so much about dinosaur appearance and behavior from solely the fossil records, so this is a great concept to address. I think it is so interesting to interpret the migratory, social and reproductive behaviors of these prehistoric creatures, because it sheds light on the truth of their nature in a society where they are depicted similarly to supernatural monsters. I appreciate that you concluded the article with a statement about the current relevance of understanding dinosaur ecology, and I am inspired to learn more.
ReplyDeleteI never knew why paleontology was important! Reading this article helped me learn that as well as how much work goes into determining how dinosaurs lived! Learning that it is more than just the shape of the fossils, but the location and density of counts is really cool! Your pictures really added to the article and your intro got me really intrigued!
ReplyDeleteThis is a very interesting and well written post! It summarizes the different topics super well and posting the question in the end was a good way to have the reader curious and engaged. Really enjoyed reading it!
ReplyDeleteComment from Crystal:
ReplyDeleteI found this blog very interesting. I was particularly intrigued by the behavior section- I think it’s fascinating that scientists can determine certain behavioral patterns from millions of years ago using only sedimentary deposits. I also find it interesting that only 20% of the dinosaurs recognized were complete records; I would’ve assumed that the percentage was higher. Overall, this was a very engaging read, and I now have a greater appreciation for paleontologists.