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Celebration of Scholarship and Creative Activity 2021

Comparison and Analysis of Ichthyosaurus Breviceps and Ichthyosaurus Communis to New Three-Dimensional Jurassic-Aged Ichthyosaurus Skull Fossil, Found on the Dorset Coast, UK

Meghan H. Krueger

Junior, Geology

Abstract

In this study, a three-dimensional Ichthyosaur skull fossil was analyzed to determine whether it belonged to the relatively common Ichthyosaurus communis species or the rare Ichthyosaurus breviceps species. The three-dimensional preservation of the fossil is unique because deformation occurred in the dorsal-ventral direction, preserving the detailed anatomy of the skull roof. Measurements of the skull were taken for species comparison. The Ichthyosaur specimen matches closely to I. breviceps because it has a shorter snout and larger eyes, which are diagnostic traits of the species. The length of the snout to length of the jaw has a ratio of 0.449 on the study specimen. The diameter of the orbit to the length of the jaw has a ratio of 0.327 for the study. Both of those ratios match the breviceps diagnostic criteria. Crushing of the skull during fossilization has restricted the accuracy of certain measurements, limiting the ability to determine the precise identification of the species. Bone texture was used to determine the maturity level of the specimen. The nasal and frontal bones contain long-grained texture indicative of a juvenile. However, a comprehensive study of Ichthyosaur bone texture is needed to determine the significance of these data.

Project Background 

I decided to do this research because I am fascinated by the history of the earth. Fossils tell us so much about what life was like during different time periods, and studying them gives you a unique window to the past. Ichthyosaurs were powerful animals that were important to the diversification of reptiles. It is exciting to study an animal that had a profound impact. The fossil I’m studying offers a unique perspective of how Ichthyosaurs looked like when they were alive. It’s exciting to see something in a new light. That is why I decided to research this topic. The process of my research depended on the collaboration of different institutions. The Weis Earth Science Museum facilitated the study of the Ichthyosaur skull fossil. I was able to work with faculty from the Oshkosh campus, namely Joseph Peterson from the Geology Department. He helped create the 3-D print of the Ichthyosaur fossil, which was a valuable research tool.

What Do You Think? 

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10 Comments

  1. Meg Olson

    Fascinating! Great job!

    Reply
  2. Katrina E Hornung

    You did a wonderful job! For the poster, I especially appreciate how the background is a faded photo of the specimen that was used. It looks and sounds great!

    Reply
  3. Eric Hiatt

    Interesting study! Well done!

    Reply
  4. Timothy Paulsen

    Nice presentation and poster Meghan!

    Reply
  5. Ben Hallett

    Great Job Meghan! I’m interested in how you study the bone texture. Do you use a microscope to see internal textures (would that even be preserved?) or can it be recognized on the surface? What is the “long-grained” texture of juvenile bones and what is different in adult bones?

    Reply
    • Meghan Krueger

      Hi Ben,
      You can study the bone texture with a hand lens or even with the naked eye. I used a hand lens for greater accuracy. Long grained texture features long parallel marks on the bone surface. It resembles tree bark. Adult texture is smoother and doesn’t have a pattern. There is also a third texture called mottled texture. This is characterized by a fine pitting on the bone surface. Mottled texture is a transition texture from a juvenile Ichthyosaur to an adult Ichthyosaur. Because almost all of the skull featured long grained texture, the Ichthyosaur fossil is most likely a juvenile.

      Thank you for your question.

      Reply
  6. Meghan Krueger

    Hi Ben,
    You can study the bone texture with a hand lens or even with the naked eye. I used a hand lens for greater accuracy. Long grained texture features long parallel marks on the bone surface. It resembles tree bark. Adult texture is smoother and doesn’t have a pattern. There is also a third texture called mottled texture. This is characterized by a fine pitting on the bone surface. Mottled texture is a transition texture from a juvenile Ichthyosaur to an adult Ichthyosaur. Because almost all of the skull featured long grained texture, the Ichthyosaur fossil is most likely a juvenile.

    Thank you for your question.

    Reply
    • Meghan Krueger

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      Reply
  7. Jacob M McCloskey

    Hi Meghan. Very fascinating how the the two species are characterized based on skull features. I apologize for such a late comment but I found your study to be extremely fascinating. I am interested to know exactly when this particular specimen was uncovered.

    Reply
    • Meghan Krueger

      Hello Jacob,
      Thank you for taking an interest in my research.
      The specimen was found in the early 1990’s in a hard limestone nodule from the Charmouth beach by Tony Gill, a noted collector of many Charmouth fossils. This fossil was found specifically in the Black Ven Marle, Obtusum Zone formation. It was preserved with the ventral side (bottom of the skull) up which contributed to the excellent preservation.

      Reply

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