Papers by Stephen Brusatte
Acta Palaeontologica Polonica, 2013
Teleosauridae was a group of largely marine Mesozoic crocodylomorphs, typically considered as aki... more Teleosauridae was a group of largely marine Mesozoic crocodylomorphs, typically considered as akin to “marine gavials” due to their elongate, tubular, polydont rostra that are indicative of a piscivorous diet. We here show that these extinct crocodylomorphs were more anatomically, and perhaps ecologically, varied than previously thought. We report the first evidence of denticles in a teleosaurid tooth, revealed by scanning electron microscopic (SEM) analysis of a tooth from the holotype of "Steneosaurus" obtusidens. These denticles are cryptic, because they are microscopic, not contiguous along the carinae (instead forming short series), and are detectable only using SEM. This incipient denticle morphology is similar to that recently discovered in a closely related group of marine crocodylomorphs, the Metriorhynchidae. In particular, the denticulation morphology of "Steneosaurus" is similar to that of the geosaurin metriorhynchid Torvoneustes, indicating that these two taxa may have employed similar feeding styles and that "S."obtusidens may have been a nearshore ecological analogue to the more offshore, fast-swimming geosaurins. Previous authors have considered "S." obtusidens and Machimosaurus to be durophagous, but the discovery of denticulated teeth indicates that they had a more varied diet and feeding style, and included flesh slicing as part of their feeding toolkit. It is currently unknown how extensive denticulate carinae may be in Teleosauridae, and we hypothesise that cryptic denticles may also be present in other marine crocodylomorphs once they are subjected to SEM study.
Scottish Journal of Geology, 2015
Fossils of Mesozoic vertebrates are rare in Scotland, particularly specimens of marine reptiles s... more Fossils of Mesozoic vertebrates are rare in Scotland, particularly specimens of marine reptiles such as plesiosaurs and ichthyosaurs. We describe a suite of ichthyosaur fossils from the Early to Middle Jurassic of Skye, which to our knowledge are the first ichthyosaurs from Scotland to be described and figured in detail. These fossils span approximately 30 million years, from the Sinemurian to the Bathonian, and indicate that ichthyosaurs were a major component of Scottish marine faunas during this time. The specimens include isolated teeth that could represent the most northerly known occurrences of the widespread Sinemurian species Ichthyosaurus communis, a characteristic component of the famous Lyme Regis faunas of England, suggesting that such faunas were also present in Scotland during the Early Jurassic. An associated humerus and vertebrae from Toarcian-Bajocian-aged deposits are named as a new genus and species of basal neoichthyosaurian, Dearcmhara shawcrossi. The taxonomic affinities of this taxon, which comes from a critical but poorly sampled interval in the fossil record, suggest that non-ophthalmosaurid neoichthyosaurians dominated European assemblages around the Early-Middle Jurassic boundary, and were later replaced by ophthalmosaurids, whose radiation likely took place outside Europe. Many of these specimens were collected by amateurs and donated to museum collections, a co-operative relationship essential to the preservation of Scotland's fossil heritage.
Royal Society Open Science, 2014
Revista Brasileira de Paleontologia, 2014
ABSTRACT Phylogenetic Eigenvector Regression (PVR) is a flexible comparative method that allows t... more ABSTRACT Phylogenetic Eigenvector Regression (PVR) is a flexible comparative method that allows testing several hypotheses on phylogenetic signal and correlated evolution among traits. Selected phylogenetic eigenvectors extracted from a phylogenetic distance matrix among taxa allow representing their phylogenetic relatedness in a raw-data form (i.e. instead of a distance matrix) and can then be used as explanatory variables in statistical models aiming to estimate phylogenetic signal or phylogenetically corrected correlations. Because of the growing use of PVR by paleobiologists in recent times, here the main theoretical/statistical basis of the method and the developments made in the 15 years after its original proposition are reviewed, highlighting further potential applications in paleobiology. For the first time, a multivariate extension of the phylogenetic signal-representation curve for estimating phylogenetic signal is presented. Another innovation is to show how PVR can be used to assess morphological disparity in a phylogenetic context. A dataset of cranial morphology and function of 35 theropod dinosaur genera is used to illustrate the applications of PVR and how it can be used to answer four questions: (i) what are the phylogenetic patterns in theropod skull shape? (ii) is possible to tease apart the evolutionary models underlying variation in traits? (iii) how are evolutionary history, function, and diet related to variation in theropod skulls? (iv) what are the evolutionary components of morphological disparity in theropod skulls? Answering these questions provide a roadmap for using PVR to address a range of issues relevant to contemporary paleobiology research programs.
American Museum Novitates, 2015
ZooKeys, 2014
Metatherians, which comprise marsupials and their closest fossil relatives, were one of the most ... more Metatherians, which comprise marsupials and their closest fossil relatives, were one of the most dominant clades of mammals during the Cretaceous and are the most diverse clade of living mammals after Placentalia. Our understanding of this group has increased greatly over the past 20 years, with the discovery of new specimens and the application of new analytical tools. Here we provide a review of the phylogenetic relationships of metatherians with respect to other mammals, discuss the taxonomic definition and diagnosis of Metatheria, outline the Cretaceous history of major metatherian clades, describe the paleobiology, biogeography, and macroevolution of Cretaceous metatherians, and provide a physical and climatic background of Cretaceous metatherian faunas. Metatherians are a clade of boreosphendian mammals that must have originated by the Late Jurassic, but the first unequivocal metatherian fossil is from the Early Cretaceous of Asia. Metatherians have the distinctive tightly int...
Nature communications, 2014
The iconic tyrannosaurids were top predators in Asia and North America during the latest Cretaceo... more The iconic tyrannosaurids were top predators in Asia and North America during the latest Cretaceous, and most species had deep skulls that allowed them to generate extreme bite forces. Two unusual specimens of Alioramus from Mongolia seem to indicate a divergent long-snouted body plan among some derived tyrannosaurids, but the rarity and juvenile nature of these fossils leaves many questions unanswered. Here, we describe a remarkable new species of long-snouted tyrannosaurid from the Maastrichtian of southeastern China, Qianzhousaurus sinensis. Phylogenetic analysis places Qianzhousaurus with both species of Alioramus in a novel longirostrine clade, which was geographically widespread across latest Cretaceous Asia and formed an important component of terrestrial ecosystems during this time. The new specimen is approximately twice the size as both Alioramus individuals, showing that the long-snouted morphology was not a transient juvenile condition of deep-snouted species, but a char...
Current biology : CB, Jan 20, 2014
The evolution of birds from theropod dinosaurs was one of the great evolutionary transitions in t... more The evolution of birds from theropod dinosaurs was one of the great evolutionary transitions in the history of life. The macroevolutionary tempo and mode of this transition is poorly studied, which is surprising because it may offer key insight into major questions in evolutionary biology, particularly whether the origins of evolutionary novelties or new ecological opportunities are associated with unusually elevated "bursts" of evolution. We present a comprehensive phylogeny placing birds within the context of theropod evolution and quantify rates of morphological evolution and changes in overall morphological disparity across the dinosaur-bird transition. Birds evolved significantly faster than other theropods, but they are indistinguishable from their closest relatives in morphospace. Our results demonstrate that the rise of birds was a complex process: birds are a continuum of millions of years of theropod evolution, and there was no great jump between nonbirds and bir...
Page 1. ARTICLE A NEW SPECIES OF CARCHARODONTOSAURUS (DINOSAURIA: THEROPODA) FROM THE CENOMANIAN ... more Page 1. ARTICLE A NEW SPECIES OF CARCHARODONTOSAURUS (DINOSAURIA: THEROPODA) FROM THE CENOMANIAN OF NIGER AND A REVISION OF THE GENUS STEPHEN L. BRUSATTE*,1 and PAUL C. SERENO2 ...
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Papers by Stephen Brusatte