Geology 103 Slide Set 1-Intro to Dinosaurs (1)
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College of the Canyons**We aren't endorsed by this school
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GEOLOGY 103
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Geology
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Jan 14, 2025
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Intro to Dinosaurs, Paleontology & PaleobiologyCarly Gott- College of the CanyonsGeology 103
XEtymology of DinosaurIn 1842, paleontologist Sir Richard Owen proposed the word ‘Dinosauria’ to refer to the newly described massive relatives of reptiles.The word dinosaur comes from the Greek ‘deinos’ meaning terrible, powerful or wonderous and ‘sauros’ which means lizard.Image Source: Sir Richard Owen (1845) by Henry William Pickersgill.Accessed Dec 19 2023, Public Domain
XKeep in Mind- Slide Set 1, 1The word dinosaur means “terrible lizard”
XDiscovery of DinosaursHumans almost certainly found dinosaur fossils before the 19thcentury but here we discuss the first discoveries after being recognized by modern paleontologyBones found in a quarry in 1815 were officially declared as belonging to a Megalosaurus. This formal name was given by William Buckland in 1824 making this the first officially named dinosaur specimen. The name Megalosaurus means great lizard. Image source: Sketch of Megalosaurus jaw fragment drawn by Mary Buckland (1824), public domain
XKeep in Mind- Slide Set 1, 2The first dinosaur fossil discovered was the Megalosaurus
Dinosaur, DefinedWhile the definition of dinosaur varies slightly between sources, there are key traits that are possessed by all members of dinosauria. Such traits are partly why animals such as pterosaurs and marine reptiles (ichthyosaurs, mosasaurs, plesiosaurs etc.) are not classed as dinosaurs.
0000000000What is a dinosaur?Archosaur reptile subgroupWarm blooded (endothermic)Stance with legs under bodyBird-like neck (ornithodiran)Diapsid Skulls
Distinguishing TraitsAmong the most distinctive traits are the stance and skull. The limbs of dinosaurs are positioned under them as can be seen in birds and land mammals. Conversely, the limbs of a plesiosaur extend outward from the sides of their bodies such as those in platypuses and reptiles.The skulls of dinosaurs are described as diapsid. The prefix ‘di’ refers to the fact that dinosaurs have two holes in the temple region of their skulls. These openings are termed ‘temporal fenestrae'Image source: https://commons.wikimedia.org/wiki/File:Skull_diapsida_1.pngAccessed Dec 19 2023, GNU Free Documentation Licensing
XEctothermic vs EndothermicEctothermic is also called ‘cold blooded’. Such animals rely on external heat sources to control body temperature and support metabolism.Ectothermic animals include most reptiles, amphibians and invertebrates.Endothermic or ‘warm blooded’ animals regulate temperature and with internally produced heat. They can maintain body temperature in a range of conditions.Examples include birds birds and mammals.
XKeep in Mind- Slide Set 1, 3Dinosaurs were endothermic (warm blooded)
XWhy are dinosaurs interesting?DiverseAccording to the USGS, over 700 species have been described and named*AbundantNew species are frequently discovered, check out ScienceDaily.com for articles on new researchMysteriousPaleontologists have estimated that within the next 100 years we will still not have found all discoverable speciesVersatileKnown species span a massive range of sizes, morphologies (form/shape), and ecological nichesWidespreadFossilized remains and traces of dinosaurs have been found on every continent.*https://pubs.usgs.gov/gip/dinosaurs/types.html** https://www.pnas.org/doi/abs/10.1073/pnas.0606028103
XKeep in Mind- Slide Set 1, 4No dinosaurs ever lived in oceans. Although many lived along coastlines and may have hunted in water, none appear to have been obligate ocean dwellers.
Early FindingsIn addition to the Megalosaurus jaw described by William Buckland, early findings include an Iguanodon tooth discovered by Gideon and Mary Ann Mantell. This name was decided upon due to the resemblance the large teeth bear to those of an Iguana. Gideon Mantell is also credited for finding a hylaeosaurus specimen in 1932.These three first specimen of Megalosaurus, Iguanodon and Hyleaosaurus each belong to a different group of dinosaurs thereby signaling to paleontologists that the newly described group of Dinosauria was interesting and diverse.All three images created and uploaded to Wikimedia Commons by UnexpectedDinoLesson, CC BY-SA 4.0
XFeuds for Fossil SupremacyFollowing the discovery and naming of the first described dinosaur specimen, paleontologists began to hunt for more dinosaurs. Akin to the gold rush, the Great Dinosaur Rush began. This period is also referred to as the Bone Wars and the two key players in North America were sworn enemies; Othniel Charles Marsh and Edward Drinker Cope.Photo of O.C. Marsh, Public DomainPhoto of E.D. Cope, Public Domain
XKeep in Mind- Slide Set 1, 5Marsh and Cope were the two paleontologists who led the Great North American Dinosaur Rush.
XHow are dinosaurs studied?Paleontology“a science dealing with the life of past geologic periods as known from fossil remains”-Merriam-WebsterPaleobiology“a branch of paleontologyconcerned with the biology of fossil organisms”-Merriam-WebsterBoth rely on evidence from the fossil record to draw inferences about how life in the pastlooked and functioned. Application of these sciences have provided an understanding of the distribution, diet, physiology, and evolution of extinct species including dinosaurs. Paleontology is a science which encompasses both geologic and biologic principles. Like any field of scientific research, paleontologists apply the scientific method.
MMMMMMMMMMMMMMMXThe Scientific MethodClick to add TextClick to add TextClick to add TextClick to add Text1Make initial observations2Develop a working hypothesis based on observations3Design and run an experiment to test hypothesis4Collect data and identify if trends or correlations exist5Accept, modify or reject hypothesis based on dataOnly after a hypothesis has been widely accepted and undisputed by scientific findings does it get elevated to the status of a scientific theory.Paleontologists can predict where they may find dinosaur specimen based fundamentals of geology such as principles of stratigraphy and the theory of plate tectonics.
XKeep in Mind- Slide Set 1, 6A theory is a scientific concept that has been tested and is strongly supported by experimental and/or observational evidence.
XThe world is always changing in terms of climate, atmospheric composition, topography, and continental position. To understand Earth’s life in the past, must first understand what the Earth was like at any given point of interest.To do this, we need to know some basics of Geology.Paleontologists must know the ages of sediments and what types of environment the sediments represent in order to predict the type of fossils that can be found in a given region.Paleontologists Use Geology
XUniformitarianismThe crossbedding in found in the fossilized sand dune shown here indicates that this feature was once a sand dune like those that exist in our deserts today.image source: Photo by John Fowler. (CC BY 2.0)Uniformitarianism is the concept the geologic processes are the same in any region at anytime.If we know the characteristics of sediments in a modern environment, we can look for those same features in the rock record to find ancient lake beds, river beds, mud flats, etc.
Older Layers Lay Beneath•A useful stratigraphic principle for predicting the age of a layer of sedimentary rock is called the Principle of Superposition.•In an undeformed (not folded or faulted) sequence of sedimentary rock, the younger layers are on top of older layers.•Even in the case of erosions, magmatic intrusions and displacement that you can still infer relative ages of layers although it can sometimes become complicated.image shows the Law of Superposition, Law of Original Horizontality, Law of Lateral Continuity, Cross-Cutting Relationship. Source: Wikimedia Commons, Created by User Tenzinsonam995 (CC BY-SA 4.0)
XMissing Geologic TimeNot every spot on our planet contains geologic layers from the time of the Dinosaurs.Sediments are not continually deposited because depositional conditions change. Furthermore, deposited layers can be eroded.We call these gaps in the geologic record unconformities.Image Source: Drawing by Pearson Scott Foresman, Public Domain
XKeep in Mind- Slide Set 1, 7An unconformity occurs when a layer has either been eroded or was never lain down to begin with (nondeposition)
X24Fossils used a guides for agesPaleontologists can infer the age of a geologic layer from the fossils they find. If an animal is known only to have existed in a short time span of time, it is useful as an ‘index fossil’.The principle of fossil succession cannot provide exact ages but can guide to to the determination of a general time from the geologic timescale.Image Source: Wikimedia Commons, Created and Uploaded by User: יקד (CC BY-SA 3.0)
XKeep in Mind- Slide Set 1, 8An index fossil can help a geologist determine the age of the sediments being studied.
XThe Changing Face of EarthDigging through sediments you can find fossils not only from another era but from another environment.When looking at sediments in much of Southern California, you can stand in the desert and see fossils from a time when the area was covered by ocean.In fact, much of the United States was covered by sea during the time of the Dinosaurs. This shift of environment is due in part to climatic variations as well as a shift in what latitude a mass of land occupies. As the continents move, they transit through climatic belts.image source: This Dynamic Earth: The Story of Plate Tectonics. (Online ed.). Reston, Virginia, US: USGS. ISBN 0-160482208. http://pubs.usgs.gov/gip/dynamic/historical.html.
Alfred Wegener and the evidence for shifting continentsAlfred Wegener, a German meteorologist, hypothesized that the continents used to fit together as a single supercontinent he named Pangaea (“Pan”= all, “Gaea”= Earth)Because he had no formal background in geology, the scientific community was slow to accept his idea that the continents have not always been in the same formation nor have they always been in the same place on our planet.He noted that not only did the continental edges fit together like a puzzle but when this arrangement was created one could see cohesive bands of fossils, rock types, mountain chains and glacial evidence that are otherwise separated by vast oceans.Photo of Alfred Wegener, public domain
XKeep in Mind- Slide Set 1, 9Evidence in support of continental drift includes: glacial striation patterns, fossil distribution, fit of continental margins and much more!
X29Plate Boundary TypesWith the acceptance of the Plate Tectonics Theory, Geologists Developed a new vocabulary to describe how plates interact.Divergentplates move away from each other.Convergentplates move toward each other.Transformplates move past each other.Source: Wikimedia Commons. All three images created by domdomegg, CC BY 4.0
XKeep in Mind- Slide Set 1, 10The three plate boundary types are: divergent, convergent and transform.