Thalattosauriform Reptiles in Triassic Marine Ecosystems: Digital Cranial Retrodeformation, 3D Reconstruction and Functional Anatomy
Notice bibliographique
Résumé
Thalattosauriformes, are an exclusively Triassic clade of secondarily aquatic reptiles that are characterized by their bizarre and highly disparate cranial shapes, dentition types and body sizes. Its members have long been considered to be rare faunal components in Triassic ecosystems; thus, the evolutionary origins and biology of thalattosaurs have remained relatively poorly understood. This dissertation aims to provide a first detailed glimpse into the three-dimensional cranial anatomy and functional ecology of this group. Chapter I Focusses on the earliest representatives of the clade. Material from the Early and Middle Triassic of British Columbia was studied to compare to the putative weigeltisaurid Wapitisaurus problematicus. This taxon was shown to instead likely represent an early diverging thalattosauroid, and the close morphological similarities, including distinct aquatic adaptations, with later thalattosauroids. Their high abundance in the shallow marine settings of Canada may indicate an earlier invasion of the aquatic realm than previously assumed. Chapter II revolved around the cranial anatomy and functional ecology of the namesake species for the entire group, Thalattosaurus alexandrae. Multiple individuals were CT-scanned and digitally segmented providing unprecedented detail on aspects of their anatomy and biology, such as cranial kinesis, tooth composition, replacement and implantation. Although highly durophagous in appearance, thalattosauroids are incomparable to placodonts in terms of crunching capabilities. It is likely that niche differentiation occurred along a prey hardness scale and that durophagy developed in the presence of other tooth morphologies in thalattosaurs, as in some extant lepidosaurs, to widen the dietary range, thus crudely said: they specialize to be better generalist. Chapter III dealt with another historic specimen, one of the best known taxa, Askeptosaurus italicus. Despite their relatively good fossil record with several virtually complete skeletons, the high degree of compaction and fragmentation reduced the morphological information that could be extracted. By using innovative scanning methods, traditional problems with data extraction are overcome, allowing for a 3D cranial and muscle model to be produced. This in order to discuss the closure of the upper temporal fenestra in thalattosaurs and the consequences for muscle attachment and feeding ecology. Chapter IV Widened the scope to contemporaneous clades of secondarily aquatic marine reptiles, such as the placodonts. In this chapter, Placochelys placodonta is subjected to detailed radiological analyses to provide insight on tooth replacement, wear and tooth composition in highly specialized durophagous predators. This in order to contextualize the functional ecological data obtained from thalattosauroid thalattosaurifoms. It represents a preliminary study for a large ecosystem approach of the Monte San Giorgio fauna and their ecological niches.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,001 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».