Overview

The basic construction, ‘bauplan’, of pterosaurs, Mesozoic flying reptiles, has been hotly debated for more than two centuries and remains highly controversial. The fundamental question is this: what was the extent of the flight membranes and how did they connect the limbs? Were pterosaurs bat-like with flight surfaces that linked the hind limbs to each other, and to the fore limbs, forming in effect a single anatomical and functional module? Or, were they more bird-like, with flight surfaces confined to individual limbs, resulting in a bauplan composed of multiple independent modules? These questions, which have yet to be resolved despite more than two centuries of study, are of critical importance to understanding pterosaurs because, as birds and bats show, anatomical and functional linkage, or independence, of the limbs has profound implications for flight and terrestrial locomotion. Locomotory abilities, in turn, are primary determinants of ecological diversity and, it is widely assumed, played a key role in shaping the macroevolutionary history of flying vertebrates.

The aim of this project is to show that combining different types of taphonomic data can provide a robust approach to reconstructing the bauplan of pterosaurs. Quantitative analyses of skeletal completeness, degree of articulation and the geometry of limb bones will generate data sets that capture key constructional attributes of pterosaurs such as correlations of integrity between and within limbs.

Analyses of the preservation of flight membranes will help underpin rigorous new evaluations of the extent of these integumentary structures and their relationship to the fore and hind limbs. Combined, the skeletal and soft tissue data sets will permit the development of robust, accurate, testable models of the basal pterosaur and pterodactyloid bauplan. Understanding of the relationship between flight membranes and the skeleton will be used to generate models for multiple species that span the morphological, systematic and temporal range of  pterosaurs. Alongside reconstructions that can be used for more refined analyses of the flight, terrestrial abilities and palaeoecology of pterosaurs these models, set within a phylogenetic framework, will provide new insights into the evolutionary history of pterosaurs and vertebrate flight more generally.

Exceptionally well preserved skeleton and soft tissues in Rhamphorhynchus. Upper Jurassic, Bavaria, Germany (UV light).

Methodology

This project will take advantage of recent dramatic improvements in the pterosaur fossil record most notably from deposits in Europe (Figure 1) China and South America. 50+ species, recovered from 16 lagerstäten ranging from the Upper Triassic to Upper Cretaceous, are known from skeletons that are sufficiently complete for this project and evidence of wing membranes is preserved in at least 15 of these. Using protocols originally developed by Kemp and Unwin (1997) and adapted by Beardmore et al (2017) direct measurement of key specimens combined with photogrammetric analysis of a digital data set of 200+ specimens (compiled by Unwin and to be further developed in this study), will be used to generate quantitative data on completeness, articulation and bone geometry. Determination of the topography of flight membranes will take advantage of advances in digital imaging, including UV photography (Tischlinger and Arratia 2013). The evolution of the pterosaur bauplan wil be investigated using a well established phylogenetic framework developed by Unwin and others.

Training and Skills

Students will benefit from 45 days training throughout their PhD including a 10 day placement. Initially, students will be trained as a single cohort on research methods and core skills. Training will progress to master classes, specific to projects and themes. Specialist training will include identification and interpretation of pterosaur skeletal anatomy and soft tissues, supervised by Unwin and Gabbott, development and application of quantitative approaches to skeletal taphonomy supervised by Unwin and Purnell and the use of phylogenetic techniques, supervised by Purnell. The student will also receive training, supervised by Purnell and Unwin, in data base construction with a particular emphasis on the statistical analysis of palaeontological data.

Timeline

Year 1: Familiarisation with literature and approaches to taphonomic analyses of skeletal and soft tissue preservation. Development and testing of collection protocols for skeletal data using UK collections (principally NHM). Fieldwork in Germany to collect taphonomic data for pterosaurs from the Posidonienschiefer and Solnhofen Limestone sequences. Analysis of these data sets.

Year 2: Fieldwork to collect taphonomic data from China (Tiaojishan Formation, Jehol Biota), South America (Crato and Santana Formations) and North America (Niobrara Chalk, Javelina Formation). Development of general models for basal pterosaurs and pterodactyloids.

Year 3: Development of models for selected species. Analysis of bauplan modularity within a phylogenetic context. Generation of hypotheses of bauplan evolution in Pterosauria. Write up and submit thesis.

Partners and collaboration (including CASE)

Dr Unwin has 35+ years experience of research on pterosaurs, holds extended datasets on pterosaur skeletal and soft tissue anatomy and taphonomy and has arranged access to key specimens that will be studied during this project. Professors Purnell and Gabbott have an extended track record of innovative research in the field of taphonomy, in particular the preservation of soft tissues, and its application to the palaeobiology of extinct organisms.

Further Details

Ideally, applicants should have a first degree in the geological or biological sciences and an aptitude for quantitative analysis. At Leicester you will join a dynamic group of researchers, PhD and Masters students developing novel approaches to understanding the palaeobiology and evolution of fossil vertebrates.

M. Unwin

School of Museum Studies,

University of Leicester,

19 University Road, Leicester LE1 7RF

Tel: +44 116 252 3947.