Graeme T Lloyd

Graeme T Lloyd
Macquarie University · Department of Biological Sciences

About

70
Publications
33,109
Reads
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2,908
Citations
Additional affiliations
September 2013 - August 2014
University of Oxford
Position
  • Professor (Associate)
March 2009 - August 2011
Natural History Museum, London
Position
  • PDRA

Publications

Publications (70)
Article
A clade’s evolutionary history is shaped, in part, by geographical range expansion, sweepstakes dispersal and local extinction. A rigorous understanding of historical biogeography may therefore yield insights into macroevolutionary dynamics such as adaptive radiation. Modern historical biogeographic analyses typically fit statistical models to mole...
Article
The origin of birds from non-avian theropod dinosaurs is one of the greatest transitions in evolution. Shortly after diverging from other theropods in the Late Jurassic, Mesozoic birds diversified into two major clades—the Enantiornithes and Ornithuromorpha—acquiring many features previously considered unique to the crown group along the way. Here,...
Article
Phylogenetic trees provide a powerful framework for testing macroevolutionary hypotheses, but it is becoming increasingly apparent that inferences derived from extant species alone can be highly misleading. Trees incorporating living and extinct taxa are are needed to address fundamental questions about the origins of diversity and disparity but it...
Article
Full-text available
Analyses of morphological disparity have been used to characterize and investigate the evolution of variation in the anatomy, function and ecology of organisms since the 1980s. While a diversity of methods have been employed, it is unclear whether they provide equivalent insights. Here, we review the most commonly used approaches for characterizing...
Article
Establishing hypotheses of relationships is a critical prerequisite for any macroevolutionary analysis, but different approaches exist for achieving this goal. Amongst palaeontologists using morphological data the Bayesian approach is increasingly preferred over parsimony, but this shift also alters the way we think about samples of trees. Here we...
Preprint
Full-text available
A bstract Phylogenetic trees provide a powerful framework for testing macroevolutionary hypotheses, but it is becoming increasingly apparent that inferences derived from extant species alone can be highly misleading. Trees incorporating living and extinct taxa are are needed to address fundamental questions about the origins of diversity and dispar...
Preprint
We examine whether the proportion of women publishing in palaeontology is approaching parity, using data from the journal Palaeontology as a proxy for the discipline. This work was motivated by the sense that, despite increased representation of women, articles on palaeontological subjects almost never appear to have 50% female authorship, regardle...
Article
The Generalized Euclidean Distance (GED) measure has been extensively used to conduct morphological disparity analyses based on palaeontological matrices of discrete characters. This is in part because some implementations allow the use of morphological matrices with high percentages of missing data without needing to prune taxa for a subsequent or...
Article
Palaeontologists have long employed discrete categorical data to capture morphological variation in fossil species, using the resulting character–taxon matrices to measure evolutionary tempo, infer phylogenies and capture morphological disparity. However, to date these have been seen as separate approaches despite a common goal of understanding mor...
Article
Full-text available
microRNAs are conserved non-coding regulatory factors implicated in diverse physiological and developmental processes in multicellular organisms, as causal macroevolutionary agents and for phylogeny inference. However, the conservation and phylogenetic utility of microRNAs has been questioned on evidence of pervasive loss. Here we show that apparen...
Article
Full-text available
Mass extinctions have profoundly impacted the evolution of life through not only reducing taxonomic diversity but also reshaping ecosystems and biogeographic patterns. In particular, they are considered to have driven increased biogeographic cosmopolitanism, but quantitative tests of this hypothesis are rare and have not explicitly incorporated inf...
Article
Full-text available
Branch lengths—measured in character changes—are an essential requirement of clock-based divergence estimation, regardless of whether the fossil calibrations used represent nodes or tips. However, a separate set of divergence time approaches are typically used to date palaeontological trees, which may lack such branch lengths. Among these methods,...
Article
Branch lengths—measured in character changes—are an essential requirement of clock-based divergence estimation, regardless of whether the fossil calibrations used represent nodes or tips. However, a separate set of divergence time approaches are typically used to date palaeontological trees, which may lack such branch lengths. Among these methods,...
Article
Full-text available
Since Darwin, biologists have been struck by the extraordinary diversity of teleost fishes, particularly in contrast to their closest "living fossil" holostean relatives. Hypothesized drivers of teleost success include innovations in jaw mechanics, reproductive biology and, particularly at present, genomic architecture, yet all scenarios presuppose...
Article
Dated phylogenies of fossil taxa allow palaeobiologists to estimate the timing of major divergences and placement of extinct lineages, and to test macroevolutionary hypotheses. Recently developed Bayesian 'tip-dating' methods simultaneously infer and date the branching relationships among fossil taxa, and infer putative ancestral relationships. Usi...
Article
Discrete character-taxon matrices are increasingly being used in an attempt to understand the pattern and tempo of morphological evolution; however, methodological sophistication and bespoke software implementations have lagged behind. In the present study, an attempt is made to provide a state-of-the-art description of methodologies and introduce...
Article
Full-text available
The Early Cretaceous is a critical interval in the early history of birds. Exceptional fossils indicate that important evolutionary novelties such as a pygostyle and a keeled sternum had already arisen in Early Cretaceous taxa, bridging much of the morphological gap between Archaeopteryx and crown birds. However, detailed features of basal bird evo...
Article
Full-text available
How did evolution generate the extraordinary diversity of vertebrates on land? Zero species are known prior to ~380 million years ago, and more than 30,000 are present today. An expansionist model suggests this was achieved by large and unbounded increases, leading to substantially greater diversity in the present than at any time in the geological...
Data
Subsampled genus diversity within continental regions for a quorum of 0.4. (A) Results for all tetrapods; the dashed line is the general linear model predicting subsampled regional genus diversity from geological age for the entire Mesozoic, modelling taxon counts as a Gaussian distribution and using a ln() link function (slope = -0.003; standard e...
Data
Countries included in our contiguous continental regions. (DOCX)
Data
Histograms of global minimum spanning tree branch lengths (in km) for the ten intervals with the longest minimum spanning trees. Interval name abbreviations are given in S1 Table. Red dashed lines indicate 100 km and 1,000 km. The data displayed in this figure can be accessed at http://doi.org/10.5061/dryad.9fr76 [90]. (TIF)
Data
Additional methods and results. Justification of the continental regions used and subsampled genus diversity. (DOCX)
Data
Composite 9 Myr time bins used in the present study. Pg2 ends at 48.6 Ma. Occurrences were assigned to a time bin only if their stratigraphic age uncertainty was entirely contained within that bin. (DOCX)
Article
Full-text available
The Mk model was developed for estimating phylogenetic trees from discrete morphological data, whether for living or fossil taxa. Like any model, the Mk model makes a number of assumptions. One assumption is that transitions between character states are symmetric (i.e., the probability of changing from 0 to 1 is the same as 1 to 0). However, some c...
Article
A series of spectacular discoveries have transformed our understanding of Mesozoic mammals in recent years. These finds reveal hitherto-unsuspected ecomorphological diversity that suggests that mammals experienced a major adaptive radiation during the Middle to Late Jurassic [1]. Patterns of mammalian macroevolution must be reinterpreted in light o...
Article
Full-text available
Ornithuromorpha is the most inclusive clade containing extant birds but not the Mesozoic Enantiornithes. The early evolutionary history of this avian clade has been advanced with recent discoveries from Cretaceous deposits, indicating that Ornithuromorpha and Enantiornithes are the two major avian groups in Mesozoic. Here we report on a new ornithu...
Article
strap (Stratigraphic Tree Analysis for Palaeontology) is a new package for the freely available statistical programming language R designed to perform three main tasks: (1) to time-scale phylogenies of fossil taxa; (2) to plot those time-scaled trees against stratigraphy; and (3) to assess congruence between phylogenies and stratigraphy. Time-scali...
Article
Full-text available
The evolution of birds from theropod dinosaurs was one of the great evolutionary transitions in the history of life [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 and 22]. The macroevolutionary tempo and mode of this transition is poorly studied, which is surprising because it may offer key insight into major questions i...
Article
Non-avian dinosaurs went extinct 66 million years ago, geologically coincident with the impact of a large bolide (comet or asteroid) during an interval of massive volcanic eruptions and changes in temperature and sea level. There has long been fervent debate about how these events affected dinosaurs. We review a wealth of new data accumulated over...
Conference Paper
Background / Purpose: The Late Permian to Early Jurassic transition is the most important in tetrapod history, and incorporates two or three posited extinctions; at the end-Permian, end-Carnian (possibly) and end-Triassic. However, because of small sample sizes, these events are hard to establish when the data are inspected closely. Two datasets,...
Conference Paper
Full-text available
Background / Purpose: Our understanding of major evolutionary events – be they adaptive radiations or the origin of new clades – is underpinned by our knowledge of the rates involved. In a seminal study Westoll used a character-taxa matrix to show that during the Mid- to Late Devonian lungfish underwent rapid rates of change that tail off markedl...
Article
Fishes represent more than half of all living vertebrate species, but patterns of fish diversity remain little explored in the fossil record. A compendium of fossil occurrences from Great Britain was assembled in order to address a series of questions concerning the palaeontological record of fishes. There are broad similarities between British ric...
Article
Full-text available
Sampling bias created by a heterogeneous rock record can seriously distort estimates of marine diversity and makes a direct reading of the fossil record unreliable. Here we compare two independent estimates of Phanerozoic marine diversity that explicitly take account of variation in sampling-a subsampling approach that standardizes for differences...
Article
Large-scale trends in planktonic foraminiferal diversity have so far been based on utilization of synoptic biostratigraphic range charts. Although this approach ensures the taxonomic consistency and quality of the data being used, it takes no formal account of any sampling biases that might exist in the fossil record. We demonstrate that the occurr...
Article
Quantifying rates of morphological evolution is important in many macroevolutionary studies, and critical when assessing possible adaptive radiations and episodes of punctuated equilibrium in the fossil record. However, studies of morphological rates of change have lagged behind those on taxonomic diversification, and most authors have focused on c...
Article
Full-text available
Assessing the quality of the fossil record is notoriously hard, and many recent attempts have used sampling proxies that can be questioned. For example, counts of geological formations and estimated outcrop areas might not be defensible as reliable sampling proxies: geological formations are units of enormously variable dimensions that depend on ro...
Article
Full-text available
While many studies show a correlation between observed taxonomic richness and various measures of geological sampling, all have been based on the same record of terrestrial and marine sediments collected from the land. Here we present the first analyses of how rock and fossil records vary in the deep-sea. We have developed a novel database of speci...
Article
Full-text available
Understanding biases that affect how species are partitioned into higher taxa is critical for much of paleobiology, as higher taxa are commonly used to estimate species diversity through time. We test the validity of using higher taxa as a proxy for species diversity for the first time by examining one of the best fossil records we have, that of de...
Article
Full-text available
Modelling has been underdeveloped with respect to constructing palaeobiodiversity curves, but it offers an additional tool for removing sampling from their estimation. Here, an alternative to subsampling approaches, which often require large sample sizes, is explored by the extension and refinement of a pre-existing modelling technique that uses a...
Article
Variation in sampling intensity of the geological record has long been suspected to distort our view of the history of life. When the taxonomic diversity of the same widespread group of marine nannoplankton (coccolithophorids) is estimated conventionally and separately from published land and deep-sea fossil records, the two curves are very differe...
Article
Full-text available
The rise of archosaurs during the Triassic and Early Jurassic has been treated as a classic example of an evolutionary radiation in the fossil record. This paper reviews published studies and provides new data on archosaur lineage origination, diversity and lineage evolution, morphological disparity, rates of morphological character change, and fau...
Article
A key question in evolution is the degree to which morphofunctional complexes are constrained by phylogeny. We investigated the role of phylogeny in the evolution of biting performance, quantified as bite forces, using phylogenetic eigenvector regression. Results indicate that there are strong phylogenetic signals in both absolute and size-adjusted...
Article
Full-text available
The observed diversity of dinosaurs reached its highest peak during the mid- and Late Cretaceous, the 50 Myr that preceded their extinction, and yet this explosion of dinosaur diversity may be explained largely by sampling bias. It has long been debated whether dinosaurs were part of the Cretaceous Terrestrial Revolution (KTR), from 125-80 Myr ago,...
Article
Full-text available
The rise and diversification of the dinosaurs in the Late Triassic, from 230 to 200 million years ago, is a classic example of an evolutionary radiation with supposed competitive replacement. A comparison of evolutionary rates and morphological disparity of basal dinosaurs and their chief “competitors,” the crurotarsan archosaurs, shows that dinosa...
Article
Full-text available
The evolutionary radiation of dinosaurs in the Late Triassic and Early Jurassic was a pivotal event in the Earth's history but is poorly understood, as previous studies have focused on vague driving mechanisms and have not untangled different macroevolutionary components (origination, diversity, abundance and disparity). We calculate the morphologi...
Article
Full-text available
As the most diverse group of early tetrapods, temnospondyls provide a unique opportunity to investigate cladogenetic patterns among basal limbed vertebrates. We present five species-level supertrees for temnospondyls, built using a variety of methods. The standard MRP majority rule consensus including minority components shows slightly greater reso...

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