Skip to Main Content
Frequently Asked Questions
Submit an ETD
Global Search Box
Need Help?
Keyword Search
Participating Institutions
Advanced Search
School Logo
Files
File List
Morhardt%2c Ashley Accepted Dissertation 8-9-16 Su16 (1).pdf (30.54 MB)
Supplemental Files
File List
Supp 2-1 - Generalized Archosaur Model.pdf
(235.3 MB)
Supp 2-10 - Hypacrosaurus.pdf
(113.31 MB)
Supp 2-11 - Plateosaurus.pdf
(57.11 MB)
Supp 2-12 - Nigersaurus.pdf
(225.31 MB)
Supp 2-13 - Diplodocus.pdf
(54.68 MB)
Supp 2-14 - Camarasaurus.pdf
(84.16 MB)
Supp 2-15 - Majungasaurus.pdf
(78.38 MB)
Supp 2-16 - Allosaurus.pdf
(53.37 MB)
Supp 2-17 - Tyrannosaurus.pdf
(45.77 MB)
Supp 2-18 - Troodon.pdf
(156.61 MB)
Supp 2-2 - Colorized endocast.pdf
(26.57 MB)
Supp 2-3 GABRA Shorthand.docx
(19.11 KB)
Supp 2-4 - Stegosaurus.pdf
(153.11 MB)
Supp 2-5 - Euoplocephalus.pdf
(116.46 MB)
Supp 2-6 - Stegoceras.pdf
(82.07 MB)
Supp 2-7 - Psittacosaurus.pdf
(54.82 MB)
Supp 2-8 - Pachyrhinosaurus.pdf
(237.68 MB)
Supp 2-9 - Triceratops.pdf
(191.41 MB)
Supp 3-1 - Sample_source_code.txt
(2.71 KB)
Supp 3-2 - Wiens et al. 2012_Nexus.nex
(5.81 MB)
Supp 3-3 - Wiens_pruned.tre
(2.12 KB)
Supp 3-4 - log_log_reptiles.csv
(1.23 KB)
Supp 3-5 - Jetz_pruned_tree.tre
(6.54 MB)
Supp 3-6 - log_log_birds.csv
(5.41 KB)
Supp 4-1.nex
(.85 KB)
Supp 4-2 log-transformed data.csv
(.89 KB)
Supp 4-3 - R code.txt
(2.15 KB)
ETD Abstract Container
Abstract Header
Gross Anatomical Brain Region Approximation (GABRA): Assessing Brain Size, Structure, and Evolution in Extinct Archosaurs
Author Info
Morhardt, Ashley C.
ORCID® Identifier
http://orcid.org/0000-0002-8351-3930
Permalink:
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1470743129
Abstract Details
Year and Degree
2016, Doctor of Philosophy (PhD), Ohio University, Biological Sciences (Arts and Sciences).
Abstract
Since its inception, paleoneurology has shown the value of studying brain evolution in extinct taxa, revealing the complex history of neurological change and associated cognitive and behavioral innovation. Brains almost never fossilize, and thus vertebrate paleoneurology relies on the fidelity between the brain and its surrounding endocranial cavity wall, which is reflected on an endocast for study. However, if the brain fails to fill the cavity in life, a resultant endocast may lack clear evidence of brain size and shape. Due to poor brain-filling in life, many non-avian dinosaur endocasts lack clear evidence of brain impressions. Previous quantitative studies of dinosaur brain size corrected for brain-filling discrepancies by reducing endocast volumes by some percentage. However, corrections were often subjective. Additionally, past whole-brain studies masked underlying regional changes that (1) contributed to overall relative brain size change and (2) provided functional information. A new approach, Gross Anatomical Brain Region Approximation (GABRA), permits study of archosaur brain and brain-region size and shape, even when endocasts lack details of the brain itself. GABRA uses anatomical landmarks on virtual endocasts as criteria for delimiting underlying brain regions. GABRA criteria are validated osteological correlates of endocranial soft tissues (e.g., cranial nerves, blood vessels) that provide consistent topological information for brain regions. Following GABRA assessment of the endocast, brain regions are modeled within it, providing volumetric estimates, which, when summed, offer a whole-brain estimate. Such data from several dinosaurs here permit analyses using modern comparative methods of relative brain-size evolution (e.g., encephalization quotient). Additionally, analyses of GABRA data show a mix of concerted and mosaic patterns of brain evolution, wherein the pituitary and olfactory bulbs emerge as evolving independently from the rest of the brain. In sum, GABRA provides insight into how brains evolved across dinosaur lineages. Future studies will examine rates of evolution and within-lineage changes, offering greater insight into how and why dinosaur brains evolved.
Committee
Lawrence Witmer, PhD (Advisor)
Mitchell Day, PhD (Committee Member)
Daniel Hembree, PhD (Committee Member)
Susan Williams, PhD (Committee Member)
Shawn Kuchta, PhD (Other)
Patrick O'Connor, PhD (Other)
Pages
276 p.
Subject Headings
Anatomy and Physiology
;
Evolution and Development
;
Neurobiology
;
Neurosciences
;
Paleontology
Keywords
archosaur
;
dinosaur
;
brain
;
GABRA
;
paleoneurology
;
brain region
;
brain model
;
brain volume
;
brain-region volume
;
encephalization quotient
;
EQ
;
PGLS
;
pRMA
;
pPCA
;
computed tomography
;
CT
;
diceCT
Recommended Citations
Refworks
EndNote
RIS
Mendeley
Citations
Morhardt, A. C. (2016).
Gross Anatomical Brain Region Approximation (GABRA): Assessing Brain Size, Structure, and Evolution in Extinct Archosaurs
[Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1470743129
APA Style (7th edition)
Morhardt, Ashley.
Gross Anatomical Brain Region Approximation (GABRA): Assessing Brain Size, Structure, and Evolution in Extinct Archosaurs.
2016. Ohio University, Doctoral dissertation.
OhioLINK Electronic Theses and Dissertations Center
, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1470743129.
MLA Style (8th edition)
Morhardt, Ashley. "Gross Anatomical Brain Region Approximation (GABRA): Assessing Brain Size, Structure, and Evolution in Extinct Archosaurs." Doctoral dissertation, Ohio University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1470743129
Chicago Manual of Style (17th edition)
Abstract Footer
Document number:
ohiou1470743129
Download Count:
442
Copyright Info
© 2016, some rights reserved.
Gross Anatomical Brain Region Approximation (GABRA): Assessing Brain Size, Structure, and Evolution in Extinct Archosaurs by Ashley C. Morhardt is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Ohio University and OhioLINK.