Taphonomic comparison of Hypacrosaurus stebingeri (Hadrosauridae: Lambeosaurinae) bonebeds from the upper Campanian Oldman and Two Medicine formations of Alberta and Montana

Joubarne, Tristan

Taphonomic comparison of Hypacrosaurus stebingeri (Hadrosauridae: Lambeosaurinae) bonebeds from the upper Campanian Oldman and Two Medicine formations of Alberta and Montana

dc.contributor.advisor	Zelenitsky, Darla
dc.contributor.author	Joubarne, Tristan
dc.contributor.committeemember	Sullivan, Corwin
dc.contributor.committeemember	Dolphin, Glenn
dc.date	2024-11
dc.date.accessioned	2024-06-20T18:26:39Z
dc.date.available	2024-06-20T18:26:39Z
dc.date.issued	2024-06-19
dc.description.abstract	Hadrosaurid social structure is still poorly understood. Evidence from bonebeds suggests that juvenile individuals lived apart from herds composed of older individuals, a phenomenon called age segregation. However, the timing at which juvenile individuals became segregated and later rejoined a multigenerational herd is still unknown. Three monodominant bonebeds that preserve the remains of multiple individuals of the lambeosaurine hadrosaurid Hypacrosaurus stebingeri at different ontogenetic stages offer an opportunity to better understand the timing of the age structuring in this species’ social structure. One of the three bonebeds, known as the Devil’s Coulee juvenile hadrosaur bonebed (JBB) from the Oldman Formation of Alberta (Canada), studied here for the first time, preserves a minimum of four similar-sized late juvenile individuals. The two other bonebeds, Blacktail Creek North (BCN) and Lambeosite (LS) from the Two Medicine Formation of Montana (U.S.A.), preserve a minimum of 23 nestling individuals, and four similar-sized late juvenile individuals with one adult, respectively. These bonebeds show uniform taphonomic signatures throughout the assemblage, characterized by little to no weathering and abrasion, uniform style of fracturing, and rare tooth marks in the assemblages. All three bonebeds are interpreted as mass-mortality assemblages. Histological data indicates that the late juvenile individuals from the JBB were three years old at the time of death, similar to the slightly larger late juvenile individuals from the LS, whereas the individuals from the BCN were less than one year old. A taphonomic comparison with osteological considerations of the three bonebeds reveal that Hypacrosaurus stebingeri individuals became segregated when they were less than one year old, and rejoined a multigenerational herd when they were three years old, as evidenced by the presence of an adult with four three-year-old individuals in the LS. Furthermore, the smaller number of individuals associated with later ontogenetic stages reveals that group size appears to decrease as Hypacrosaurus stebingeri individuals grew older.
dc.identifier.citation	Joubarne, T. (2024). Taphonomic comparison of Hypacrosaurus stebingeri (Hadrosauridae: Lambeosaurinae) bonebeds from the upper Campanian Oldman and Two Medicine formations of Alberta and Montana (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.
dc.identifier.uri	https://hdl.handle.net/1880/119002
dc.identifier.uri	https://doi.org/10.11575/PRISM/46598
dc.language.iso	en
dc.publisher.faculty	Graduate Studies
dc.publisher.institution	University of Calgary
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subject	Taphonomy
dc.subject	Bonebed
dc.subject	Hadrosaurs
dc.subject	Age segregation
dc.subject	Life history
dc.subject	Histology
dc.subject.classification	Paleontology
dc.subject.classification	Geology
dc.subject.classification	Paleoecology
dc.title	Taphonomic comparison of Hypacrosaurus stebingeri (Hadrosauridae: Lambeosaurinae) bonebeds from the upper Campanian Oldman and Two Medicine formations of Alberta and Montana
dc.type	master thesis
thesis.degree.discipline	Geoscience
thesis.degree.grantor	University of Calgary
thesis.degree.name	Master of Science (MSc)
ucalgary.thesis.accesssetbystudent	I do not require a thesis withhold – my thesis will have open access and can be viewed and downloaded publicly as soon as possible.