Constraining Hydrodynamics on Plesiosaur Locomotion

• Author / Creator

  Pourfarzan, Ali

• Plesiosaurs were a diverse group of Mesozoic marine reptiles, notable among both extinct and extant animals for their unique body planform. Despite being known for more than 300 years, many aspects of their locomotion and behavior remain as mystery. Unlike any other flapping species, plesiosaurs exhibit two pairs of near-identical wing-like flippers, which have remained consistent throughout their evolution. Despite the similarity in geometry between fore and hind flippers, their morphologies have been identified to be slightly different. This has given rise to contradicting hypotheses on locomotion and their behavior. In particular, the role of the hind flipper and the relative motion of the flippers have been questioned. In this thesis, which consists of two research chapters, two different approach are considered
  to address these questions. First, by using universal scaling laws, it is shown that the group of plesiosaurs with short necks and large heads, known as pliosauroids, likely had a high agility level, possibly similar to penguins, while long-necked, small-headed plesiosaurs (plesiosauroids) likely had limited agility, possibly similar to that observed in sea turtles. Second, through a series of particle image velocimetry experiments on the effect of varying amplitude ratio on tandem oscillating foils, it is demonstrated that plesiosaurs utilizing rear-biased and equal amplitude propulsion, could have achieved higher thrust production and propulsive efficiency. However, the rear-biased model is found to be more efficient with slightly higher thrust production. This strategy may have been utilized by pliosauroids, known to be pursuit predators, as it is consistent with fossil records, with joints of the hind flipper accommodating greater flapping angles. It is possible that this strategy was also used by plesiosauroids for high thrust production such as during escape, however it is inconsistent
  with fossil measurements. The findings of this work suggest that amplitude ratio, along with other important parameters such as varying the phase differential of flipper oscillation and
  inter-foil spacing, was a critical optimizing parameter for the propulsive performance of a tandem-flipper propulsor.

• Subjects / Keywords

  • Plesiosaur Locomotion
  • Tandem Oscillating Foils
  • Vortex Interactions
  • Amplitude Ratio

• Graduation date

  Fall 2022

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-54z2-0921

• License

  This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.