Michael I. Coates

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The Actinopterygii (ray-finned fishes) is the largest and most diverse vertebrate group, but little is agreed about the timing of its early evolution. Estimates using mitochondrial genomic data suggest that the major actinopterygian clades are much older than divergence dates implied by fossils. Here, the timing of the evolutionary origins of these clades(More)
Sequence heterochrony (changes in the order in which events occur) is a potentially important, but relatively poorly explored, mechanism for the evolution of development. In part, this is because of the inherent difficulties in inferring sequence heterochrony across species. The event-pairing method, developed independently by several workers in the(More)
Acanthodians, an exclusively Palaeozoic group of fish, are central to a renewed debate on the origin of modern gnathostomes: jawed vertebrates comprising Chondrichthyes (sharks, rays and ratfish) and Osteichthyes (bony fishes and tetrapods). Acanthodian internal anatomy is primarily understood from Acanthodes bronni because it remains the only example(More)
In an attempt to investigate differences between the most widely discussed hypotheses of early tetrapod relationships, we assembled a new data matrix including 90 taxa coded for 319 cranial and postcranial characters. We have incorporated, where possible, original observations of numerous taxa spread throughout the major tetrapod clades. A stem-based(More)
Development involves a series of developmental events, separated by transformations, that follow a particular order or developmental sequence. The sequence may in turn be arbitrarily subdivided into contiguous segments (developmental stages). We discuss the properties of developmental sequences. We also examine the differing analytical approaches that have(More)
Lampreys are the most scientifically accessible of the remaining jawless vertebrates, but their evolutionary history is obscure. In contrast to the rich fossil record of armoured jawless fishes, all of which date from the Devonian period and earlier, only two Palaeozoic lampreys have been recorded, both from the Carboniferous period. In addition to these,(More)
CONTENTS PAGE 1. Introduction 435 2. Material 437 3. Methods 437 4. Systematic palaeontology 437 5. Taxonomic note 439 6. Description 439 (a) External morphology 439 (b) Internal morphology: general features 440 (c) Thèbrain cast' and otic capsule 442 7. Discussion 445 (a) Characters used in analysis 445 (b) Results of phylogenetic analysis 452 (c)(More)
Current phylogenies show that paired fins and limbs are unique to jawed vertebrates and their immediate ancestry. Such fins evolved first as a single pair extending from an anterior location, and later stabilized as two pairs at pectoral and pelvic levels. Fin number, identity, and position are therefore key issues in vertebrate developmental evolution.(More)
Heterochrony is important as a potential mechanism of evolutionary change. However, the analysis of developmental timing data within a phylogenetic framework to identify important shifts has proven difficult. In particular, analytical problems with sequence (event) heterochrony revolve around the lack of an absolute time frame in development to allow(More)
Exceptionally complete material of a new stethacanthid chondrichthyan, Akmonistion zangerli, gen. et sp. nov., formerly attributed to the ill-defined genera Cladodus and Stethacanthus, is described from the Manse Burn Formation (Serpukhovian, Lower Carboniferous) of Bearsden, Scotland. Distinctive features of A. zangerli include a neurocranium with broad(More)