Timothy Rowe- University of Texas at Austin
Timothy Rowe
- University of Texas at Austin
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Publications (105)
Although several well-preserved crania are known for the Mesozoic Eutriconodonta, three-dimensional reconstructions of the character-rich inner ear and basicranial region based on high-resolution computed tomography scans have previously only been published for the Late Jurassic Priacodon. Here we present a description of the petrosal and inner ear...
The evolutionary shift from a single-element ear, multi-element jaw to a multi-element ear, single-element jaw during the transition to crown mammals marks one of the most dramatic structural transformations in vertebrates. Research on this transformation has focused on mammalian middle-ear evolution, but a mandible comprising only the dentary is e...
The skeleton and inferred neurosensory system of the ancestral amniote provide a point of departure to trace neurosensory evolution in extinct stem-mammals that culminated in the origin of crown Mammalia. Early stem-mammal evolution mostly involved enhanced integration of skeletal elements for feeding and locomotion as they became apex predators. W...
The evolutionary shift from a single-element ear, multi-element jaw to a multi-element ear, single-element jaw during the transition to crown mammals marks one of the most dramatic structural transformations in vertebrates. Research on this transformation has focused on mammalian middle-ear evolution, but a mandible comprised of only the dentary is...
Odor stimuli consist of thousands of possible molecules, each molecule with many different properties, each property a dimension of the stimulus. Processing these high dimensional stimuli would appear to require many stages in the brain to reach odor perception, yet, in mammals, after the sensory receptors this is accomplished through only two regi...
As computed tomography and related technologies have become mainstream tools across a broad range of scientific applications, each new generation of instrumentation produces larger volumes of more-complex 3D data. Lagging behind are step-wise improvements in computational methods to rapidly analyze these new large, complex datasets. Here we describ...
Little is known about how the large brains of mammals are accommodated into the dazzling diversity of their skulls. It has been suggested that brain shape is influenced by relative brain size, that it evolves or develops according to extrinsic or intrinsic mechanical constraints, and that its shape can provide insights into its proportions and func...
Little is known about how the large brains of mammals are accommodated into the dazzling diversity of their skulls. It has been suggested that brain shape is influenced by relative brain size, that it evolves or develops according to extrinsic or intrinsic mechanical constraints, and that its shape can provide insights into its proportions and func...
We describe new specimens of the ornithischian dinosaur Scutellosaurus lawleri Colbert, 1981 Colbert, E. H. 1981. A primitive ornithischian dinosaur from the Kayenta Formation of Arizona. Museum of Northern Arizona Bulletin Series 53:1–60. [Google Scholar], from the Lower Jurassic Kayenta Formation of Arizona and discuss their systematic importance...
Paleontology affords a special signal on evolution of neurosensory systems because many parts of that system require rigid skeletal armatures to function properly. This relationship is traced from the ancestral amniote to the origin of Mammalia. Based on inferences about the skeleton and neurosensory system in the ancestral amniote, evolution of co...
We describe a new probainognathian cynodont, Pseudotherium argentinus, from the early Late Triassic Ischigualasto Formation of Argentina. Pseudotherium adds to a growing assemblage of small Triassic cynodonts that offers new insight into events leading up to the origin of crown Mammalia and the successively more inclusive Mammaliaformes and Mammali...
Sarahsaurus aurifontanalis, from the Kayenta Formation of Arizona, is one of only three sauropodomorph dinosaurs known from the Early Jurassic of North America. It joins Anchisaurus polyzelus, from the older Portland Formation of the Hartford Basin, and Seitaad reussi, from the younger Navajo Sandstone of Utah, in representing the oldest North Amer...
Appendix B.
Details of computed tomographic scans and lists of animations for TMM 43646–2 and MCZ 8893 in S1 to S21 Animations.
(DOCX)
Appendix D.
Character descriptions from modified Yates, Upchurch et al., and McPhee and Choiniere matrices, including a discussion on the changed character scores of Sarahsaurus aurifontanalis in this analysis.
(DOCX)
Appendix E.
TNT files for the phylogenetic and sensitivity analyses in this paper for the modified Yates, Upchurch et al. matrices, and McPhee and Choiniere matrices.
(ZIP)
Appendix C.
Linear measurements from undistorted holotype and paratype elements of Sarahsaurus aurifontanalis.
(DOCX)
Appendix F.
Bremer support and GC bootstrap scores for the phylogenetic analyses in this paper.
(ZIP)
Appendix A.
List of TMM specimen numbers figured in description.
(DOCX)
Transformations in morphology, physiology and behaviour along the mammalian stem lineage were accompanied by profound modifications to reproduction and growth, including the emergence of a reproductive strategy characterized by high maternal investment in a small number of offspring1,2 and heterochronic changes in early cranial development associat...
Computed tomography X-ray imaging of the internal face in well-preserved primate fossil crania permits reconstruction of the nature of their nasal anatomy, including some soft-tissue features. These features are diagnostic of the primate suborder Haplorhini, and allow reevaluation of the phylogenetic status of several purported early members of the...
The neocortex is characterized by lamination of its neuron cell bodies in six layers, but there are few clues as to how this comes about and what is its function. Recent studies provide evidence that evolution from simple three-layer cortex may give insight into this problem. Three-layer cortex arose in the olfactory, hippocampal and dorsal cortex...
Major transformations in brain size and proportions, such as the enlargement of the brain during the evolution of birds, are accompanied by profound modifications to the skull roof. However, the hypothesis of concerted evolution of shape between brain and skull roof over major phylogenetic transitions, and in particular of an ontogenetic relationsh...
Theropods have traditionally been portrayed as extinct bipedal predators built along the lines of such celebrated terrors as Tyrannosaurus, Deinonychus , and Allosaurus . The earliest theropods indeed fit that image, and all of them are decidedly extinct. However, it has become increasingly apparent that living birds trace their genealogy to those...
Over the past two decades, the development of methods for visualizing and analysing specimens digitally, in three and even four dimensions, has transformed the study of living and fossil organisms. However, the initial promise that the widespread application of such methods would facilitate access to the underlying digital data has not been fully a...
Paleontology affords a special signal on evolution of neurosensory systems because many parts of that system require rigid skeletal armatures to function properly. This relationship is traced from the ancestral amniote to the origin of Mammalia. Based on inferences about the skeleton and neurosensory system in the ancestral amniote, evolution of co...
The Pliocene fossil porpoise SDSNH 65276 has extremely elongate mandibular morphology, unlike that of any marine amniote, and is superficially most similar to the living bird species known as skimmers (Rynchops sp.). Endocasts of the pterygoid sinuses and endocranial cavity were digitally segmented from high-resolution X-ray CT scans of the specime...
The cranial osteology of the megachiropteran Pteropus Brisson, 1762, was the subject of recent study that covered all of the skull bones in significant detail, except for the anatomy of the nasal capsule. Here, we describe and illustrate the internal nasal skeleton of Pteropus lylei K. Andersen, 1908, using histological sections of a fetus and high...
The morphology of the labyrinth of zhelestids, a group of eutherian mammals from the Late Cretaceous, agrees with that of other extinct eutherians, including Kulbeckia kulbecke, Ukhaatherium gobiensis, and Zalambdalestes lechei. Features of the labyrinth of zhelestids include a cochlea with one and a half turns and a secondary common crus, which ar...
Three-dimensional computing is driving what many would call a revolution in scientific visualization. However, its power and
advancement are held back by the absence of sustainable archives for raw data and derivative visualizations. Funding agencies,
professional societies, and publishers each have unfulfilled roles in archive design and data mana...
![Figure][1]
Deccan plateau basalts.
Lava from Deccan volcanism formed distinct layering.
CREDIT: GSFC/NASA
In the Review “The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene boundary” (P. Schulte et al. , 5 March, p. [1214][2]), the terminal Cretaceous
IN THE REVIEW "THE CHICXULUB ASTEROID IMPACT AND MASS EXTINCTION AT THE CRETACEOUS-Paleogene boundary" (P. Schulte et al., 5 March, p. 1214), the terminal Cretaceous extinctions were confi dently attributed to a single event, the environmental consequences of the impact of an extraterrestrial body. The list of 41 authors, although suggesting a cons...
is rarely collected, probably because itis nocturnal, fossorial, and semiaquatic (Harrisson,1962; Manthey and Grossman, 1997). Few specimensexist in collections worldwide, and skeletons are ex-tremely rare. As a result of limited access to speci-mens, many phylogenetic analyses that include thisspecies relied upon the same specimen (REE 1445, col-l...
The troodontid Byronosaurus jaffei is known from two specimens from adjacent localities in the Nemegt basin, Omnogov Aimag, Mongolia. These specimens are composed of well- preserved cranial material and fragmentary postcrania. All of these elements are described here. Byronosaurus jaffei is included in a comprehensive phylogenetic analysis of Coelu...
We describe the skull of the holotype of Citipati osmolskae, one of the best preserved oviraptorid skulls known. The skull preserves stapes and epipterygoids, and the mandible preserves a slender coronoid bone, none of which has been reported before in oviraptorids. The braincase is similar to that of other basal coelurosaurs but possesses extensiv...
We review the morphology, taxonomy, and phylogenetic relationships of the upper Cretaceous Mongolian troodontid Saurornithoides. Saurornithoides mongoliensis is known only by the holotype from Bayan Zag, Djadokhta Formation. This specimen includes a nearly complete, but weathered, skull and mandibles, a series of dorsal, sacral, and caudal vertebra...
Ontogenetic sequences are a pervasive aspect of development and are used extensively by biologists for intra- and interspecific comparisons. A tacit assumption behind most such analyses is that sequence is largely invariant within a species. However, recent embryological and experimental work emphasizes that ontogenetic sequences can be variable an...
Monotremes have left a poor fossil record, and paleontology has been virtually mute during two decades of discussion about molecular clock estimates of the timing of divergence between the platypus and echidna clades. We describe evidence from high-resolution x-ray computed tomography indicating that Teinolophos, an Early Cretaceous fossil from Aus...
Cranial endocast, endosseous labyrinth, and some endocranial vascular structures in Nigersaurus taqueti (MNN GAD512) derived from surface renderings of µCT scan data. (A)-left lateral view. (B)-left anteroventrolateral view. (C, H)-ventral view. (D, I)-dorsal view. (E, J)-anterior view. (F, K)-posterior view. Color scheme: cyan blue, cranial endoca...
The prototype skull.
(0.08 MB PDF)
Partial skeleton of Nigersaurus taqueti (MNN GAD517) discovered during the 2000 Expedition to Niger. Expedition member G. Lyon is seated inside the curve of the proximal caudal vertebrae of a skeleton planed flat by wind-blown sand at a site in Gadoufaoua, Ténéré Desert, Niger (photo by M. Hettwer).
(0.34 MB TIF)
Endocast and labyrinth.
(0.15 MB PDF)
Microwear and incremental lines of von Ebner.
(0.13 MB PDF)
Phylogenetic analysis.
(0.16 MB PDF)
Endosseous labyrinths of the left inner ear of (A-C, stereopairs) the rebbachisaurid Nigersaurus taqueti (MNN GAD512), (D-E) the diplodocid Diplodocus longus (CM 11161), and (F-G) the basal neosauropod Camarasaurus lentus (CM 11338). (A, D, F)-left lateral view. (B, F, G)-dorsal view. (C)-posterior view. Abbreviations: c, cochlea; csc, caudal (post...
Geologic setting.
(0.07 MB PDF)
Location of outcrops of the Elrhaz Formation where fossils of Nigersaurus taqueti were found.
(0.13 MB TIF)
Assembled semi-translucent skull model of Nigersaurus taqueti built from prototyped skull bones (tooth batteries and reconstructed teeth in red) with unknown bones in green modeling clay (photo by T. Keillor).
(3.47 MB TIF)
Partitioned endocast with transparent osseous labyrinth from Nigersaurus taqueti. Colors highlight the partitions used for digital assessment of endocast volumes.
(1.27 MB TIF)
Intraspecific variation (e.g., ontogenetic, individual, sexual dimorphic) is rarely examined among cranial endocasts (infillings of the braincase cavity) because of the difficulty in obtaining multiple specimens of a species, particularly fossil taxa. We extracted digital cranial endocasts from CT scans of a growth series of skulls of Monodelphis d...
We generated a digital cranial endocast (infilling of the braincase) of Vincelestes neuquenianus, a Cretaceous theriiform mammal from Argentina, to achieve two goals. First, we described this endocast of Vincelestes to reconstruct the brain, associated soft-tissue structures, and internal osteological features. This report represents the first desc...
A digital cranial endocast of Pucadelphys andinus, a Paleocene metatherian from Bolivia, is described. This is the first cranial endocast described for the taxon and the only one (to date) from a stem marsupial (i.e., non-marsupial metatherian). The Pucadelphys endocast is compared with others generated from skulls from six taxa of extant marsupial...
A digital cranial endocast of Pucadelphys andinus, a Paleocene metatherian from Bolivia, is described. This is the first cranial endocast described for the taxon and the only one (to date) from a stem marsupial (i.e., non-marsupial metatherian). The Pucadelphys endocast is compared with others generated from skulls from six taxa of extant marsupial...
We describe a new dromaeosaurid theropod from the Upper Cretaceous Djadokhta Formation of Ukhaa Tolgod, Mongolia. The new taxon, Tsaagan mangas, consists of a well-preserved skull and cervical series. This specimen marks only the second dromaeosaurid taxon from a formation that has otherwise yielded numerous specimens of Velociraptor mongoliensis,...
A digital cranial endocast of the Miocene platypus Obdurodon dicksoni was extracted from high-resolution X-ray computed tomography scans. This endocast represents the oldest from an unequivocal member of either extant monotreme lineage and is therefore important for inferring character support for Monotremata, a clade that is not well diagnosed. We...
The skull of the trogonophid amphisbaenian Diplometopon zarudnyi is described from high-resolution X-ray computed tomographic (HRXCT) imagery of a whole museum specimen preserved in ETOH. The skull was digitally resliced and disarticulated into individual elements, producing novel visualizations that allow detailed morphological analysis of its thr...
Endocranial surfaces, volumes, and interconnectivities of extant and fossil odontocetes potentially offer information on the
general architecture of the brain and on the structure of the specialized cetacean circulatory system. Although conventional
methods for acquiring such data have generally involved invasive preparation of the specimen, partic...
The fossilized skull of a small extinct amphisbaenian referable to Rhineura hatcherii Baur is described from high-resolution X-ray computed tomographic (HRXCT) imagery of a well-preserved mature specimen from the Brule Formation of Badlands National Park, South Dakota. Marked density contrast between bones and surrounding matrix and at bone-to-bone...
CT imaging was undertaken on the skull of approximately 20-Myr-old Miocene Tremacebus harringtoni. Here we report our observations on the relative size of the olfactory fossa and its implications for the behavior of Tremacebus. The endocranial surface of Tremacebus is incomplete, making precise estimate of brain size and olfactory fossa size imprec...
This edited volume is provides an authoritative synthesis of knowledge about the history of life. All the major groups of organisms are treated, by the leading workers in their fields. With sections on: The Importance of Knowing the Tree of Life; The Origin and Radiation of Life on Earth; The Relationships of Green Plants; The Relationships of Fung...
