Richard J. Butler

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Mutations in the SPAST (SPG4) gene, which encodes the microtubule-severing protein spastin, are the most common cause of autosomal dominant hereditary spastic paraplegia (HSP). Following on from previous work in our laboratory showing that spastin is required for axon outgrowth, we report here that the related microtubule-severing protein katanin is also(More)
Ceratopsians (horned dinosaurs) represent a highly diverse and abundant radiation of non-avian dinosaurs known primarily from the Cretaceous period (65-145 million years ago). This radiation has been considered to be geographically limited to Asia and western North America, with only controversial remains reported from other continents. Here we describe new(More)
BACKGROUND Heterodontosaurids are an important but enigmatic and poorly understood early radiation of ornithischian dinosaurs. The late-surviving heterodontosaurid Fruitadens haagarorum from the Late Jurassic (early Tithonian) Morrison Formation of the western USA is represented by remains of several small (<1 metre total body length, <1 kg body mass)(More)
Pneumatic (air-filled) postcranial bones are unique to birds among extant tetrapods. Unambiguous skeletal correlates of postcranial pneumaticity first appeared in the Late Triassic (approximately 210 million years ago), when they evolved independently in several groups of bird-line archosaurs (ornithodirans). These include the theropod dinosaurs (of which(More)
BACKGROUND Archosaurs (birds, crocodilians and their extinct relatives including dinosaurs) dominated Mesozoic continental ecosystems from the Late Triassic onwards, and still form a major component of modern ecosystems (>10,000 species). The earliest diverse archosaur faunal assemblages are known from the Middle Triassic (c. 244 Ma), implying that the(More)
The fossil record is our primary window onto the diversification of ancient life, but there are widespread concerns that sampling biases may distort observed palaeodiversity counts. Such concerns have been reinforced by numerous studies that found correlations between measures of sampling intensity and observed diversity. However, correlation does not(More)
Uniquely among extant vertebrates, birds possess complex respiratory systems characterised by the combination of small, rigid lungs, extensive pulmonary air sacs that possess diverticula that invade (pneumatise) the postcranial skeleton, unidirectional ventilation of the lungs, and efficient crosscurrent gas exchange. Crocodilians, the only other living(More)
Cope's rule, the tendency towards evolutionary increases in body size, is a long-standing macroevolutionary generalization that has the potential to provide insights into directionality in evolution; however, both the definition and identification of Cope's rule are controversial and problematic. A recent study [J. Evol. Biol. 21 (2008) 618] examined body(More)
The significance of co-evolution over ecological timescales is well established, yet it remains unclear to what extent co-evolutionary processes contribute to driving large-scale evolutionary and ecological changes over geological timescales. Some of the most intriguing and pervasive long-term co-evolutionary hypotheses relate to proposed interactions(More)