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Title: The taxonomy, taphonomy and palaeoecology of Late Jurassic testudines from Europe
Author: Fielding, Sarah Elizabeth
ISNI:       0000 0001 3464 3766
Awarding Body: Portsmouth
Current Institution: University of Portsmouth
Date of Award: 2006
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Testudine remains are exceptionally scarce in the Middle Jurassic in Western Europe. However, in the Upper Jurassic testudines are represented by two pleurodiran families, the Notoemydidae and the Platychelidae, and cryptodires: the paracryptodiran Pleurosternidae (known only from fragmentary remains from the continent and a single taxon from the Portland Limestone Formation), and the eucryptodiran families Eurysternidae and the Plesiochelyidae. The sudden appearance of these families in marine deposits of the European Upper Jurassic suggests that they constitute one of the earliest marine radiations of testudines. The work described herein is the first study of European Late Jurassic testudines that combines multiple aspects of osteology, palaeopathologies, taphonomy and functional morphology. The most significant testudine remains in terms of these aspects are from the Kimmeridgian Reuchenette Formation, Switzerland, and the Tithonian Solnhofen Limestone Formation, Germany. The synonymy of Tholemys Andrews, 1921, with Plesiochelys Rütimeyer, 1873, is refuted. Thalassemys chelonia, previously a nomen nudum, is described and figured here for the first time. A new genus and species of eurysternid unique to the British Isles is described and figured. The first record of the range and extent of palaeopathologies in Late Jurassic testudines, and a new classification scheme is provided. An experimental method using a moderately controlled and monitored outdoor environment illustrates differences between natural disarticulation and predation or scavenger attack, preferential scavenging activity and the effects of resistant integuments within a carcass. Upper Jurassic testudines are preserved in a variety of styles, reflecting different taphonomic pathways. The Kimmeridge Clay represents an attritional accumulation of testudines, whilst the accumulation of the Solnhofen Limestone Formation is a combination of attritional and catastrophic. The process which resulted in the accumulation of the Reuchenette Formation remains enigmatic. For the first time, the relationship between the length of the mantis relative to the length of the arm has been applied to Late Jurassic testudines as a method of determining habitat preference. No Late Jurassic testudines included in the analysis had forelimbs with ratios equivalent to fully terrestrial or fully marine turtles, but most appear to have been moderately adapted for the neritic (shallow to coastal marine) environment, with increased mobility and terrestrial ability when compared to extant marine turtles. These factors would probably be a selective advantage in a coastal island environment, where widespread migrations were not required, but large marine predators (e. g. Machimosaurus) were present.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available