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Intraspecific Variation in Early-Diverging Pseudosuchians: New Perspectives From the Aetosauria
Intraspecific Variation in Early-Diverging Pseudosuchians: New Perspectives From the Aetosauria
상세정보
- 자료유형
- 학위논문 서양
- 최종처리일시
- 20260311091531.5
- ISBN
- 9798270231392
- DDC
- 576.8
- 서명/저자
- Intraspecific Variation in Early-Diverging Pseudosuchians: New Perspectives From the Aetosauria / William Antonio Reyes
- 발행사항
- [Sl] : The University of Texas at Austin, 2025
- 형태사항
- 1 electronic resource (675 pages)
- 주기사항
- Source: Dissertations Abstracts International, Volume: 87-06, Section: B.
- 주기사항
- Advisors: Bell, Christopher J. Committee members: stocker, Michelle R.; Clarke, Julia A.; Stockli, Daniel F.
- 학위논문주기
- - Ph.D. : The University of Texas at Austin, 2025.
- 초록/해제
- 요약Intraspecific variation is a critical aspect of vertebrate paleontology because it impacts our conceptualization of the paleobiogeography, temporal longevity, paleobiology, evolutionary relationships, and taxonomy of species. Unfortunately, intraspecific variation remains poorly understood in extinct taxa because most are lacking an adequate sample size that allows us to explore patterns of variation. One such group affected by this are the early-diverging members of the Pseudosuchia from the Late Triassic. Most of our current understanding of intraspecific variation in those taxa is primarily based on osteohistological assessments, which provide insight into their growth rate and skeletal maturity. Although informative, our understanding of intraspecific variation with respect to their skeletal morphology is limited. In my dissertation, I used aetosaurs as a sample group to explore patterns of intraspecific variation in early-diverging pseudosuchians from the Late Triassic - a time when pseudosuchians experienced their largest diversity. In my first chapter, I describe two new specimens of Calyptosuchus wellesi as well as reassessed the type specimen and other material previously referred to the taxon. I used a systematic approach to support the referral of several specimens. Subsequently, I discovered two morphological characters associated with the vertebral column that are intraspecifically variable within that taxon. In my second chapter, I describe a cluster of small aetosaur individuals from the Otischalkian type assemblage in Texas. I use a combination of skeletal and osteohistological proxies to assess their skeletal maturity. Interestingly, those ontogenetic proxies yielded two conflicting taxonomic interpretations - one suggests that they individuals are juveniles and the other suggests that they represent a new paedomorphic species. I use a parsimonious approach in conjunction with our understanding of the growth dynamics in extant vertebrates to rationalize the incongruence between the proxies and deduce the taxonomic affinities of the individuals. For my third chapter, I established a growth series to assess how ontogeny and an increasing body size influence skeletal morphology in aetosaurs. I found that aetosaurs experience extensive plasticity in their skeleton and exhibit different growth and ossification patterns from their extant crocodylian relatives. Overall, my dissertation research provides new insight into the patterns of intraspecific variation in early-diverging pseudosuchians and how they vary from what we see in crocodylians today. Additionally, it highlights the complexity in how we conceptualize species in the fossil record as well as the limitations we face when incorporating intraspecific variation into our phylogenetic assessments.
- 언어주기
- English
- 일반주제명
- Morphology
- 일반주제명
- Paleontology
- 일반주제명
- Geology
- 기타저자
- The University of Texas at Austin Earth and Planetary Sciences
- 기본자료저록
- Dissertations Abstracts International. 87-06B.
- 전자적 위치 및 접속
- 로그인 후 원문을 볼 수 있습니다.
MARC
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■006m o d
■007cr|nu||||||||
■020 ▼a9798270231392
■040 ▼aMiAaPQD▼beng▼cMiAaPQD▼erda
■082 ▼a576.8
■1001 ▼aReyes, William Antonio▼eauthor.
■24510▼aIntraspecific Variation in Early-Diverging Pseudosuchians: New Perspectives From the Aetosauria ▼cWilliam Antonio Reyes
■260 ▼a[Sl]▼bThe University of Texas at Austin▼c2025
■264 1▼aAnn Arbor▼bProQuest Dissertations & Theses▼c2025
■300 ▼a1 electronic resource (675 pages)
■336 ▼atext▼btxt▼2rdacontent
■337 ▼acomputer▼bc▼2rdamedia
■338 ▼aonline resource▼bcr▼2rdacarrier
■500 ▼aSource: Dissertations Abstracts International, Volume: 87-06, Section: B.
■500 ▼aAdvisors: Bell, Christopher J. Committee members: stocker, Michelle R.; Clarke, Julia A.; Stockli, Daniel F.
■5021 ▼bPh.D.▼cThe University of Texas at Austin▼d2025.
■520 ▼aIntraspecific variation is a critical aspect of vertebrate paleontology because it impacts our conceptualization of the paleobiogeography, temporal longevity, paleobiology, evolutionary relationships, and taxonomy of species. Unfortunately, intraspecific variation remains poorly understood in extinct taxa because most are lacking an adequate sample size that allows us to explore patterns of variation. One such group affected by this are the early-diverging members of the Pseudosuchia from the Late Triassic. Most of our current understanding of intraspecific variation in those taxa is primarily based on osteohistological assessments, which provide insight into their growth rate and skeletal maturity. Although informative, our understanding of intraspecific variation with respect to their skeletal morphology is limited. In my dissertation, I used aetosaurs as a sample group to explore patterns of intraspecific variation in early-diverging pseudosuchians from the Late Triassic - a time when pseudosuchians experienced their largest diversity. In my first chapter, I describe two new specimens of Calyptosuchus wellesi as well as reassessed the type specimen and other material previously referred to the taxon. I used a systematic approach to support the referral of several specimens. Subsequently, I discovered two morphological characters associated with the vertebral column that are intraspecifically variable within that taxon. In my second chapter, I describe a cluster of small aetosaur individuals from the Otischalkian type assemblage in Texas. I use a combination of skeletal and osteohistological proxies to assess their skeletal maturity. Interestingly, those ontogenetic proxies yielded two conflicting taxonomic interpretations - one suggests that they individuals are juveniles and the other suggests that they represent a new paedomorphic species. I use a parsimonious approach in conjunction with our understanding of the growth dynamics in extant vertebrates to rationalize the incongruence between the proxies and deduce the taxonomic affinities of the individuals. For my third chapter, I established a growth series to assess how ontogeny and an increasing body size influence skeletal morphology in aetosaurs. I found that aetosaurs experience extensive plasticity in their skeleton and exhibit different growth and ossification patterns from their extant crocodylian relatives. Overall, my dissertation research provides new insight into the patterns of intraspecific variation in early-diverging pseudosuchians and how they vary from what we see in crocodylians today. Additionally, it highlights the complexity in how we conceptualize species in the fossil record as well as the limitations we face when incorporating intraspecific variation into our phylogenetic assessments.
■546 ▼aEnglish
■590 ▼aSchool code: 0227
■650 4▼aMorphology
■650 4▼aPaleontology
■650 4▼aGeology
■653 ▼aIntraspecific variation
■653 ▼aPaleobiogeography
■653 ▼aOsteohistological assessments
■653 ▼aPhylogenetic assessments
■7102 ▼aThe University of Texas at Austin▼bEarth and Planetary Sciences.▼edegree granting institution.
■7201 ▼aBell, Christopher J.▼edegree supervisor.
■7730 ▼tDissertations Abstracts International▼g87-06B.
■85640▼uhttp://www.riss.kr/pdu/ddodLink.do?id=T17361190▼nKERIS▼z이 자료의 원문은 한국교육학술정보원에서 제공합니다.
