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Paromomyidae are one of several families of plesiadapiforms that flourished during the Paleocene in North America soon after the extinction of non-avian dinosaurs some 66 million years ago. Although they are often among the best-represented plesiadapiforms in mammalian faunas in both North America and Europe, the early history of paromomyids is poorly understood, and their fossil record at higher latitudes is comparatively depauperate. We report here on the discovery of two new species of paromomyids from Paleocene deposits in southwestern Alberta: Edworthia greggi new species is the second known species of the basal paromomyid Edworthia Fox, Scott, and Rankin, 2010 whereas Ignacius glenbowensis new species is among the most abundantly represented species of Ignacius Matthew and Granger, 1921. These new discoveries document, for the first time, parts of the upper dentition of Edworthia, and the new species of Ignacius represents the first new, pre-Clarkforkian species of the genus to be described in nearly 100 years. A comprehensive phylogenetic analysis of nearly all known paromomyid taxa (including the new species described herein) recovered both species of Edworthia near the base of the paromomyid tree in a polytomy with Paromomys depressidens Gidley, 1923 and a paraphyletic Ignacius. The new paromomyids from Alberta not only increase the known taxonomic diversity of Edworthia and Ignacius but also add significantly to knowledge of the dental anatomy of these poorly known genera and further add to a uniquely Canadian complement of Paleocene plesiadapiforms.UUID: http://zoobank.org/a2f31cfe-09b9-4168-b09f-9d0c3d0af342

A large collection of dentigerous jaws quarried from the Gao Mine locality, late Paleocene, Paskapoo Formation, central Alberta, Canada, documents a new species of the early Paleogene phenacodontid “condylarth” Ectocion Cope, 1882. The new species, Ectocion stockeyae, the smallest of the genus, occurs well before the abrupt global warming at the Paleocene–Eocene Thermal Maximum, an event purportedly causing the rapid evolution of “dwarfed” mammals, including a species of Ectocion; however, there is no evidence of increased temperatures at Gao Mine to account for the small size of Ectocion stockeyae, raising questions of the relationship between temperature and body size in Ectocion. Ectocion stockeyae also exhibits sexual dimorphism of the canines, a pattern in mammals often associated with a population structure in which the males are relatively few and polygynous, resulting in intense male rivalry for mating success. The sample of Ectocion stockeyae from Gao Mine includes a substantial majority of “juvenile” individuals retaining deciduous posterior premolars, many even after eruption of the molars had been completed, suggesting short life spans, accelerated growth, and rapid dental development in this species as expressed in Schultz’s Rule.

As the incidence of traumatic spinal cord injury (tSCI) in the elderly rises, clinicians are increasingly faced with difficult discussions regarding aggressiveness of management, likelihood of recovery, and survival. Our objective was to outline risk factors associated with in-hospital mortality in elderly surgical and non-surgical patients following tSCI and to determine those unlikely to have a favorable outcome. Data from elderly patients (≥ 65 years of age) in the Canadian Rick Hansen SCI Registry from 2004 to 2017 were analyzed using descriptive analysis. Survival and mortality groups in each of the surgical and non-surgical group were compared to explore factors associated with in-hospital mortality and their impact, using logistical regression. Of 1340 elderly patients, 1018 had surgical data with 826 having had surgery. In the surgical group, the median time to death post-injury was 30 days with 75% dying within 50 days compared with 7 days and 20 days, respectively, in the non-surgical group. Significant predictors for in-hospital mortality following surgery are age, comorbidities, neurological injury severity (American Spinal Injury Association [ASIA] Impairment Scale [AIS]), and ventilation status. The odds of dying 50 days post-surgery are six times higher for patients ≥77 years of age versus those 65-76 years of age, five times higher for those with AIS A versus those with AIS B/C/D, and seven times higher for those who are ventilator dependent. An expected probability of dying within 50 days post-surgery was determined using these results. In-hospital mortality in the elderly after tSCI is high. The trend with age and time to death and the significant predictors of mortality identified in this study can be used to inform clinical decision making and discussions with patients and their families.

Background: The skull diploic venous space (DVS) represents a potential route for cerebrospinal fluid (CSF) diversion and absorption in the treatment of hydrocephalus. The goal of this study was to carry out a detailed characterization of the drainage pattern of the DVS of the skull using high-resolution MRI, especially the diploic veins draining to the lacunae laterales (LLs) since the LLs constitute an important channel for the CSF to access the superior sagittal sinus and subsequently the systemic circulation. The objective was to identify those skull regions optimally suited for an intraosseous CSF diversion system. Methods: High-resolution, T1-weighted MRI scans from 20 adult and 16 pediatric subjects were selected for analysis. Skulls were divided into four regions, that is, frontal, parietal, temporal, and occipital. On each scan, a trained observer counted all diploic veins in every skull region. Each diploic vein was also followed to determine its final drainage pathway (i.e., dural venous sinus, dural vein, LL, or indeterminate). Results: In the adult age group, the frontal and occipital skull regions showed the highest number of diploic veins. However, the highest number of draining diploic veins connecting to the lacunae lateralis was found in the frontal and parietal skull region, just anterior and just posterior to the coronal suture. In the pediatric age group, the parietal skull region, just posterior to the coronal suture, showed the highest overall number of diploic veins and also the highest number of draining diploic veins connecting to the LL. Conclusion: This study suggested that diploic venous density across the skull varies with age, with more parietal diploic veins in the pediatric age range, and more occipital and frontal diploic veins in adults. If the DVS is ultimately used for CSF diversion, our anatomical data point to optimal sites for the insertion of specially designed intraosseous infusion devices for the treatment of hydrocephalus. Likely the optimal sites for CSF diversion would be the parietal region just posterior to the coronal suture in children, and in adults, frontal and/or parietal just anterior or just posterior to the coronal suture.

The fossil record of the earliest primates, purgatoriid plesiadapiforms, has become increasingly well documented during the past two decades, but their dietary preferences remain poorly understood. While the available evidence, which consists mostly of isolated teeth and incomplete jaws with teeth, suggests that purgatoriids were insectivorous to omnivorous, we describe here a new species of Purgatorius, Purgatorius pinecreeensis sp. nov., that extends the range of purgatoriid dental disparity toward greater omnivory than had been known before. Purgatorius pinecreeensis sp. nov., from the early Paleocene (Puercan) Ravenscrag Formation of southwestern Saskatchewan, differs from other species of Purgatorius in having slightly lower crowned teeth with a lower trigonid relative to talonid, blunter and more swollen major cusps, more transverse lower molar paracristids, and m3 with a more robustly developed posterior lobe. Taken together, these specializations enhanced the capacity for crushing and grinding at the expense of orthal shear, and represent the first instance of a modest degree of bunodonty in the family. The discovery of P. pinecreeensis sp. nov., along with other recently reported basal plesiadapiforms from the Puercan and Torrejonian of the northern Western Interior, lends additional support to the notion of a significant primate radiation soon after the Cretaceous–Paleogene extinction event.

Cimolestes Marsh is a North American eutherian mammal primarily known from latest Cretaceous deposits in Alberta, Wyoming, Saskatchewan, and Montana. At present, five species of Cimolestes are considered valid, all Lancian in age; they include one of the largest North American Late Cretaceous therian mammals as well as one of the smallest, a size range far exceeding that within other genera of tribosphenic therians contemporary with Cimolestes, such as the leptictoid eutherian Gypsonictops Simpson or genera of alphadontid or pediomyid marsupials. Moreover, the species of Cimolestes display a disparity of dental morphology in addition to size well in excess of interspecific differences within these genera. Given these considerations, Cimolestes is clearly a grade-taxon, uniting species sharing an adaptively subzalambdodont dentition, but showing divergent specializations within this pattern that are inconsistent with monophyly of its presently included species. To correct these imbalances, this paper limits Cimolestes to Cimolestes incisus Marsh and Cimolestes stirtoni Clemens; Cimolestes magnus Clemens and Russell, Cimolestes cerberoides Lillegraven, and Cimolestes propalaeoryctes Lillegraven are reclassified in the new genera Altacreodus, Ambilestes, and Scollardius, respectively. Altacreodus magnus, having a massive shearing dentition, is reconfirmed as showing a relationship to some Tertiary ‘creodonts’ not shared by other species of Lancian cimolestids; Ambilestes cerberoides exhibits a distinctive molar wear pattern that emphasized horizontal grinding, not orthal shear; Scollardius propalaeoryctes, the smallest species in this revision and having hyper-faunivorous molars, was not ancestral to Paleogene Palaeoryctidae, as indicated in part by contradictions in premolar number and morphology.

Ultrafast ultrasound imaging is used to capture driven spinal vibrations as a new method for non-invasive spinal testing in living subjects. Previously, it has been shown that accelerometer-based vibration testing in cadaveric models can reveal the presence, location and magnitude of spinal pathology. However, this process remains an invasive procedure as current non-invasive sensors are inadequate. In this paper, the ability of non-invasive ultrafast ultrasound to quantify in vivo vertebral vibration response across a broad range of frequencies (10–100Hz) in anesthetized pig models is investigated. Close agreement with invasive accelerometer measurements is achieved using the non-invasive ultrasound method, opening up unique opportunities to investigate spinal pathologies.

Although stagodontid marsupials are among the most distinctive mammals of Late Cretaceous age in North America, there remain significant gaps in knowledge of their dental anatomy, particularly that of the stratigraphically oldest genus, Eodelphis Matthew, 1916. We report here on stagodontid specimens from the Judithian Belly River Group of southeastern Alberta, Canada, that document what was until now previously unknown parts of the upper and lower premolar dentition of Eodelphis browni Matthew, 1916 and Eodelphis cutleri (Smith Woodward, 1916). The new information further confirms the distinctiveness of both nominal species of Eodelphis, and bolsters previous hypotheses suggesting a close phylogenetic relationship between E. cutleri and the advanced stagodontid Didelphodon Marsh, 1889. Although the new specimens from Alberta suggest that the problematic holotype of “Boreodon matutinus” Lambe, 1902 is an upper third premolar, a referral to Eodelphis cannot be made with confidence and the name should continue to be treated as a nomen dubium. Lastly, we report the first occurrence of Didelphodon in strata of the Belly River Group, extending the geological age of the genus into the Judithian, co-eval with species of Eodelphis, and suggesting a significant prior and as yet undiscovered evolutionary history.

A new tribotherian mammal, Tirotherium aptum gen. et sp. nov., is described from the late Santonian to early Campanian upper Milk River Formation of Verdigris Coulee, southern Alberta, Canada. The new mammal is known only from isolated teeth, five upper and three lower molars. The upper molars represent two or possibly three pre-ultimate loci and are marked by reduction and loss of the stylar shelf anteriorly, loss of the stylocone, a paracone that is larger than the metacone, weakly developed conules, a low, small protocone, and specialized postvallum single-rank shear. The lower molars probably represent two pre-ultimate loci and are characterized by an anteriorly positioned paraconid, trenchant paracristid, small, posterolingual metaconid, a distal metacristid, broadly open trigonid angle, and a short, basined talonid in which the hypoconulid is closer to the entoconid than to the hypoconid. The molars of Tirotherium most closely resemble those of Picopsis Fox, 1980, a tribotherian that also occurs in the upper Milk River Formation, but the molars of Tirotherium are significantly larger than those of Picopsis. Nonetheless, Tirotherium aptum is best classified in the Picopsidae, a boreosphenidan family of tiny mammalian faunivores of uncertain relationships to other tribotherians, and displaying a unique mosaic of primitive and derived characters.

Ursolestes perpetior gen. et sp. nov. is a large purgatoriid plesiadapiform primate from the middle/late Puercan (earliest Paleocene) Simpson Quarry, Montana, USA. It differs from Purgatorius Van Valen and Sloan, 1965, the only other known purgatoriid and the oldest discovered primate, in its substantially larger body size as inferred from the dimensions of the known parts of its dentition, while resembling Purgatorius in possessing a large lower canine, unreduced p1, and in the upper molars, a protocone twist and weakly developed postprotocone fold; moreover, the m3 of U. perpetior possesses an expanded, plesiadapiform-like posterior lobe of the talonid that supports the hypoconulid. The large lower canine and the greater development of trenchant molar crests suggest that U. perpetior was more insectivorous, differing appreciably from the omnivorous niche long hypothesized for Purgatorius and purportedly marking the insectivore–primate transition. Hence, U. perpetior adds significant new knowledge regarding the breadth of the adaptive zone occupied by purgatoriids in their position at the very beginnings of primate evolution.

Choristoderes are a group of extinct diapsid reptiles that once occupied the freshwater systems in the Northern Hemisphere from the Middle Jurassic through the Miocene. The Early Cretaceous monjurosuchid Philydrosaurus from western Liaoning, China, represents a transitional morphotype between a broad-snouted (crocodile-like) and a narrow-snouted (gavial-like) skull during the evolution of Choristodera. New specimens of the taxon from the Early Cretaceous Jiufotang Formation include an incomplete braincase and a nearly complete juvenile skeleton; the study of these specimens provides new information on the braincase and ontogenetic change of the skeleton of this transitional monjurosuchid. In the braincase floor, the foramen internus canalis caroticus externus opens in a groove lateral to the constricted lateral aspect of the parasphenoid, and ventral exposure of this foramen differs from Champsosaurus, in which parasphenoid/pterygoid fusion completely encloses the canal. On the occiput, the vagus nerve foramen penetrates the basioccipital, while the two foramina for the hypoglossal nerve open at the exoccipital/basioccipital suture. Comparative study of the new juvenile specimen with adult Philydrosaurus reveals previously unknown developmental changes of the cranial and postcranial skeleton of this monjurosuchid. Ontogenetically, Philydrosaurus underwent a dramatic change of skull proportions, including elongation of the antorbital and postorbital regions, and elongation of the jaws, with a great increase of the number of marginal teeth. The lower temporal fenestra is entirely closed in early ontogeny, as in large, fully-grown adults.

Although the known record of Mesozoic eutherian mammals has been significantly enriched in recent years, early eutherian evolution is still not well understood. Among the more controversial of Mesozoic eutherians is Paranyctoides Fox, which was described in 1979 from the Judithian Dinosaur Park Formation, Alberta, Canada. It is a rare taxon and therefore has been identified in only a few other North American Late Cretaceous local faunas since. Within the past decade, dental and gnathic remains discovered in Central Asia have also been referred to Paranyctoides, thereby expanding the geographic range of the genus substantially and making it the only Late Cretaceous eutherian ostensibly occurring in both continents. As a result of our detailed study of Paranyctoides, however, we find that the Central Asian species lack the diagnostic characters of Paranyctoides and must be referred to other taxa. We conclude that this genus was limited to North America, ranging from Aquilan to Lancian time, and accordingly we recognize as valid only the following species: Paranyctoides sternbergi (Judithian, Alberta), P. maleficus (Aquilan, Alberta), Paranyctoides Wahweap sp. A and sp. B (Judithian, Utah), Paranyctoides Kaiparowits sp. A and sp. B (Judithian, Utah). Another purported species of Paranyctoides, P. megakeros, from the Lancian of Wyoming, is a junior synonym of Alostera saskatchewanensis.

Pterosaurs were a unique clade of flying reptiles that were contemporaries of dinosaurs in Mesozoic ecosystems. The Pterodactyloidea as the most species-diverse group of pterosaurs dominated the sky during Cretaceous time, but earlier phases of their evolution remain poorly known. Here, we describe a 160 Ma filter-feeding pterosaur from western Liaoning, China, representing the geologically oldest record of the Ctenochasmatidae, a group of exclusive filter feeders characterized by an elongated snout and numerous fine teeth. The new pterosaur took the lead of a major ecological transition in pterosaur evolution from fish-catching to filter-feeding adaptation, prior to the Tithonian (145–152 Ma) diversification of the Ctenochasmatidae. Our research shows that the rise of ctenochasmatid pterosaurs was followed by the burst of eco-morphological divergence of other pterodactyloid clades, which involved a wide range of feeding adaptations that considerably altered the terrestrial ecosystems of the Cretaceous world.

STUDY DESIGN Modified-Delphi expert consensus method. OBJECTIVE The aim of this study was to develop competence-based spine fellowship curricula as a set of learning goals through expert consensus methodology in order to provide an educational tool for surgical educators and trainees. Secondarily, we aimed to determine potential differences among specialties in their rating of learning objectives to defined curriculum documents. SUMMARY OF BACKGROUND DATA There has been recent interest in competence-based education in the training of future surgeons. Current spine fellowships often work on a preceptor-based model, and recent studies have demonstrated that graduating spine fellows may not necessarily be exposed to key cognitive and procedural competencies throughout their training that are expected of a practicing spine surgeon. METHODS A consensus group of 32 spine surgeons from across Canada was assembled. A modified-Delphi approach refined an initial fellowship-level curriculum set of learning objectives (108 cognitive and 84 procedural competencies obtained from open sources). A consensus threshold of 70% was chosen with up to 5 rounds of blinded voting performed. Members were asked to ratify objectives into either a general comprehensive or focused/advanced curriculum. RESULTS Twenty-eight of 32 consultants (88%) responded and participated in voting rounds. Seventy-eight (72%) cognitive and 63 (75%) procedural competency objectives reached 70% consensus in the first round. This increased to 82 cognitive and 73 procedural objectives by round 4. The final curriculum document evolved to include a general comprehensive curriculum (91 cognitive and 53 procedural objectives), a focused/advanced curriculum (22 procedural objectives), and a pediatrics curriculum (22 cognitive and 9 procedural objectives). CONCLUSION Through a consensus-building approach, the study authors have developed a competence-based curriculum set of learning objectives anticipated to be of educational value to spine surgery fellowship educators and trainees. To our knowledge, this is one of the first nationally based efforts of its kind that is also anticipated to be of interest by international colleagues.

Plesiadapidae are a family of Paleogene mammals thought to have phylogenetic affinities with modern Primates. We describe previously unpublished dentitions and the first skull and isolated petrosals of the plesiadapid Pronothodectes gaoi, collected from middle Tiffanian localities of the Paskapoo Formation in Alberta. Other species of Pronothodectes, traditionally considered the most basal members of the Plesiadapidae, occur at earlier, Torrejonian horizons in Montana, Wyoming, and Alberta. Classification of P. gaoi as a species of Pronothodectes has proved controversial; accordingly, we use the newly available samples and the more extensively preserved specimens to re-evaluate the generic affinities of this species. Included in our study are comparisons with craniodental material known for other plesiadapids and plesiadapiforms. Cladistic analysis of craniodental characters is used to assess the hypothesis that P. gaoi and other species in this genus are basal members of the Plesiadapidae. The new dental evidence confirms that P. gaoi lacks derived character states of other plesiadapids except for a variably present fissuring of the m3 hypoconulid. Moreover, several aspects of the cranium seem to be more primitive in P. gaoi (i.e., more like nonplesiadapid plesiadapiforms) than in later occurring plesiadapids, such as Plesiadapis tricuspidens and Plesiadapis cookei. Cladistic analysis of craniodental morphology supports a basal position of P. gaoi among species of Plesiadapidae, with the exception of other species of Pronothodectes. The basicranium of P. gaoi preserves a laterally placed bony canal for the internal carotid neurovascular system, suggesting that this was the ancestral condition for the family. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc.

A new plesiadapiform primate, Phoxomylus puncticuspis gen. et sp. nov., is described based on an isolated but well-preserved upper molar from the early Tiffanian (late Paleocene) Cochrane 2 locality, southwestern Alberta, Canada. Although possessing a robust postprotoconal fold, an unambiguous synapomorphy of primates, Phoxomylus differs from other plesiadapiforms in its retention of primitive molar features, including acutely pointed major cusps and sharp crests, deep trigon basin, and lack of the bunodont coronal specializations that purportedly marked the transition from insectivorous non-primate ancestors to omnivorous/frugivorous basal primates. Coronal features of the holotype of P. puncticuspis imply that during mastication the mandible was adducted in a near-vertical plane, with little capacity for the transverse movement that is already seen in molar morphology of the earliest and most basal plesiadapiform, Purgatorius. Instead, molar morphology in P. puncticuspis implies emphasis on vertical pie...

New specimens of an as yet unidentified carnivoran from the earliest Paleocene of Saskatchewan are described. The new specimens augment the evidence on which the contentious earliest (middle Puercan) occurrence of Carnivora is based, provide novel information of the lower dentition of the earliest carnivorans, and provides evidence for the earliest taxonomic diversity in Carnivora.

A primitive paromomyid plesiadapiform primate,Edworthia lerbekmoinew genus and species, is described from a recently discovered locality in the Paskapoo Formation, exposed at a road cut in Edworthy Municipal Park, Bow River Valley, Calgary, Alberta, Canada. The new taxon, probably middle Torrejonian (To2) in age, is based on two dentary fragments containing well-preserved dentitions that bracket p2-4, m1-3. With the exception of the basalParomomys, E. lerbekmoidiffers from all other paromomyids in retaining p2, but p2 in the new paromomyid is single-rooted, not two-rooted as inParomomys. E. lerbekmoidiffers further fromParomomysin having an enlarged anterior alveolus for a tooth immediately anterior to p2, hypothesized to be il. Unlike other paromomyids with an enlarged il, however, this tooth inE. lerbekmoiwas obliquely, not horizontally, oriented and its alveolus opens dorsally, in the alveolar row, not anteriorly, as in other paromomyids in which il is greatly enlarged. This suggests thatE. lerbekmoirepresents a previously unknown paromomyid lineage that evolved from an ancestor having obliquely oriented lower incisors as in the basal primatePurgatorius, not from an ancestor in which il was already subhorizontal in orientation, as inParomomys.If this working hypothesis is correct or whether in the future some other evolutionary scenario will better account for the unique anterior dentition inE. lerbekmoi, the new paromomyid nonetheless demonstrates that crucial aspects of the earliest history of the important plesiadapiform family Paromomyidae remain to be discovered.

Epaxial tendons play an important role in the study of the musculoskeletal system and locomotory style of dinosaurs. Although the ossified epaxial tendon lattice is fairly well known in Iguanodontoidea, only recently has knowledge of this complex been extended to ceratopsians. This study concerns the gross morphology and microstructure of the tendon lattice in Psittacosaurus, a basal ceratopsian. As in the neoceratopsian Chasmosaurus, the ossified tendons of Psittacosaurus form a three-layered, lattice-like structure. The microstructure of the tendons in large psittacosaur individuals retains an early stage of ossification, as in juvenile birds and nestling hadrosaurs, suggesting a slow developmental rate of ossification of the tendons in psittacosaur ontogeny. Comparative study indicates that a lattice-like arrangement of three-layered epaxial tendons is widely distributed in Cerapoda. This pattern also extends to Ankylosauria, implying a similar pattern of the epaxial muscles through the ornithischian clade. In addition, comparison with crocodiles implies that the different morphology of ossified tendons in dinosaurs may be associated with adaptive aspects of their paleobiology, not simply a side effect of skeletal ossification. In contrast to the short tendons in quadrupedal Chasmosaurus and Protoceratops, the elongated tendons in Psittacosaurus may be related to the bipedal locomotion characteristic of this taxon.

Psittacosaurs, small basal ceratopsians with a parrot-like beak, are among the most abundant dinosaurs, but occur only in the Early Cretaceous of East Asia. Although the general morphology of psittacosaurs is fairly well understood, the endocranial anatomy of the group has never been described. New discoveries of well-preserved skulls from the celebrated Liaoning beds in northeastern China provide the material for conducting research on psittacosaur endocranial morphology. Using computed tomography scans of three-dimensionally preserved skulls, this study reveals basic endocranial anatomy of psittacosaurs and provides the first palaeoneurological evidence of psittacosaurs in relation to their behaviour. Although commonly believed to have had a small brain and small eyes, psittacosaurs had relatively high brain/body size ratios that are comparable to those in the large theropod Tyrannosaurus , and probably had a keen sense of smell and acute vision, as evidenced by their enlarged olfactory lobes and bulbous optic lobes. The configuration of the semicircular canals agrees with limb proportions to suggest that psittacosaurs were agile animals, perhaps better able to escape predation by carnivorous dinosaurs on that account. The behavioural adaptations implied by this study may have been crucial for the successful radiation of psittacosaurs during the Early Cretaceous of East Asia.

An incomplete lower jaw with teeth documents the presence of a new genus and species of placental mammal from the Upper Cretaceous (Lancian; late Maastrichtian) Frenchman Formation, Saskatchewan, Canada. This new mammal is characterized by highly compressed lower molars that decrease in size from m1 to m3 and superficially resemble the molars of Tertiary Mesonychia. These resemblances, however, are interpreted as convergent, and the new mammal is classified in its own family and incertae sedis at the ordinal level. This new mammal thus joins other recent discoveries in western Canada of mammals of Tertiary aspect (Condylarthra; Taeniodonta) occurring in the Late Cretaceous.

Spinal epidural hematoma is a rare clinical entity and has a varied etiology. Urgent surgical evacuation to prevent serious permanent neurologic deficits is generally indicated. We describe a case of a 52-year-old man, on oral anticoagulant therapy, who presented with Brown-Sequard syndrome due to spontaneous spinal epidural hematoma at the cervicothoracic junction. This diagnosis was initially overlooked, given the asymmetric pattern of deficit. He later underwent cervical laminectomy and had complete restoration of neurologic function.

OBJECT This study was undertaken to evaluate the impact of postoperative MRI artifact on the assessment of ongoing spinal cord or nerve root compression after anterior cervical discectomy and fusion (ACDF) using a trabecular tantalum cage or bone autograft or allograft. METHODS The authors conducted a retrospective review of postoperative MRI studies of patients treated surgically for cervical disc degenerative disease or cervical instability secondary to trauma. Standard ACDF with either a trabecular tantalum cage or interbody bone graft had been performed. Postoperative MR images were shown twice in random order to each of 3 assessors (2 spine surgeons, 1 neuroradiologist) to determine whether the presence of a tantalum interbody cage and/or anterior cervical fixation plate or screws imparted MRI artifact significant enough to prevent reliable postoperative assessment of ongoing spinal cord or nerve root compression. RESULTS A total of 63 patients were identified. One group of 29 patients received a tantalum interbody cage, with 13 patients (45%) undergoing anterior plate fixation. A second group of 34 patients received bone auto- or allograft, with 23 (68%) undergoing anterior plate fixation. The paramagnetic implant construct artifact had minimal impact on visualization of postoperative surgical level spinal cord compression. In the cage group, 98% (171/174) of the cases were rated as assessable versus 99% in the bone graft group (201/204), with high intraobserver reliability. In contrast, for the assessment of ongoing surgical level nerve root compression, the presence of a tantalum cage significantly decreased visualization of nerve roots to 70% (121/174) in comparison with 85% (173/204) in the bone graft group (p < 0.001). When sequences using turbo spin echo (TSE), a T2-weighted axial sequence, were acquired, nerve roots were rated as assessable in 88% (69/78) of cases; when only axial T2-weighted sequences were available, the nerve roots were rated as assessable in 54% (52/96) of cases (p < 0.01). The presence of anterior plate fixation had minimal impact on visualization of the spinal cord (99% [213/216] for plated cases vs 98% [159/162] for nonplated cases; p = 1.0) or nerve roots (79% [170/216] for plated cases vs 77% [124/162] for nonplated cases; p = 0.62). CONCLUSIONS Interbody fusion with tantalum cage following anterior cervical discectomy imparts significant paramagnetic artifact, which significantly decreases visualization and assessment of ongoing surgical level nerve root, but not spinal cord, compression. Anterior plate constructs do not affect visualization of these structures. TSE T2-weighted sequences significantly improve nerve root visualization and should be performed as part of a standard postoperative protocol when imaging the cervical spine following interbody implantation of materials with potential for paramagnetic artifact.

A new eutherian mammal of uncertain taxonomic position is described on the basis of well-preserved dental and gnathic specimens collected from localities in the Paleocene Paskapoo Formation of Alberta, Canada. Horolodectes sunae new genus and species is represented by seven incomplete maxillae, eleven incomplete dentaries, and numerous isolated teeth, together preserving nearly all of the postcanine dentition. The unusual dentition of Horolodectes n. gen. consists of trenchant, posteriorly leaning premolars in combination with comparatively primitive molars, suggestive of a masticatory cycle that consisted primarily of shearing and, to a lesser degree, horizontal grinding. Included among the specimens of Horolodectes is an incomplete dentary of an immature individual, with the teeth having been in various stages of eruption at the time of death. Although the dentition of Horolodectes broadly resembles that of apheliscine hyopsodontids, pentacodontine pantolestids, and “ungulatomorphs” among eutherian mammals, significant differences in the coronal structure of the teeth prevent unequivocal referral of Horolodectes to any of these groups, or to any known eutherian order.

Newly discovered, well-preserved skulls and mandibles from the lowest part of the Early Cretaceous Yixian Formation, western Liaoning Province, China, document the earliest known record of psittacosaurs and provide the basis for recognition of a new species, Psittacosaurus lujiatunensis . This discovery increases the taxonomic diversity of psittacosaurs to eight valid species and extends the stratigraphic range of the family Psittacosauridae from late Barremian-Albian to Hauterivian. Comparative study of the new species with other well-known psittacosaurs indicates that the new taxon is probably the most basal member of the psittacosaur clade now known. This interpretation is in agreement with the temporal distribution of the clade and supports the hypothesis that the Psittacosauridae originated from the basal ceratopsian stem no later than the earliest part of the Cretaceous.

The publication of the scientific name Monjurosuchus splendens in 1940 documented the first tetrapod fossil of the later world-renowned Jehol Biota. For more than half a century since this discovery, however, Monjurosuchus has remained as a monotypic genus of the family Monjurosuchidae, and the relationships of the family with choristoderes have not been correctly recognized until quite recently. In this paper, a new monjurosuchid is named and described based on a nearly complete skull and postcranial skeleton from the Early Cretaceous Chiufotang Formation exposed near Chaoyang, western Liaoning Province, China. This new material documents the first occurrence of monjurosuchid choristoderes outside the type Lingyuan area, and extends the geological range of the family from the Yixian Formation to the younger Chiufotang Formation. Cladistic analyses were conducted with inclusion of monjurosuchids, and the results support the placement of the family Monjurosuchidae as a primitive clade outside the Neochoristodera. A new classification scheme is proposed for choristoderes on the basis of the recovered phylogenetic framework of the group. © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society, 2005, 145, 427–444.

Since 1908, the peculiar North American primate Picrodus Douglass, 1908 (Picrodontidae; Plesiadapiformes) has been thought to contain only a single species, P. silberlingi Douglass, 1908, of late Paleocene age. However, new collections from the Paskapoo Formation, Alberta, Canada, reveal that instead a rich complex of Picrodus species lived during the Paleocene. Three of these, Picrodus calgariensis, P. canpacius, and P. lepidus, are described herein as new. Others, represented by more fragmentary specimens from Canada and the United States, are included in this paper, but are not named. P. calgariensis, from Who Nose? (late Torrejonian), Calgary, is the most primitive known species of Picrodus, having molars with little crenulation of the enamel. P. canpacius, from Cochrane 2 (earliest Tiffanian), northwest of Calgary, most resembles P. silberlingi sensu stricto, but differs in P4 structure, denser enamel crenulation, and weaker molar cusps. P. lepidus, from DW-2 (middle Tiffanian), near Red Dee...

As recognized by McKenna and Bell (1997), the family Palaeoryctidae (Mammalia: Eutheria) includes three genera, Palaeoryctes Matthew, 1913 (Paleocene and Eocene), Aaptoryctes Gingerich, 1982 (late Paleocene), and Eoryctes Thewissen and Gingerich, 1989 (early Eocene). Each is North American, although Palaeoryctes is said to occur in North Africa as well (Gheerbrant, 1992; however, the classification of the North African species as a palaeoryctid is almost certainly erroneous [personal observation]), and there are additional, ostensible records of palaeoryctids from Asia, Africa, and Europe that have yet to be described (McKenna and Bell, 1997). In spite of this broad distribution, palaeoryctids are poorly known and documented primarily by isolated teeth, although occasionally better-preserved specimens are found. Palaeoryctids are classified together on the basis of dental resemblances, mostly those of the molars: palaeoryctid upper molars are anteroposteriorly short but transversely wide (especially lingual to the paracone+metacone), the major cusps are tall and pointed, and the paracone and metacone are connate, i.e., they arise from a common base and are joined through much of their height. The lower molar trigonid of palaeoryctids is anteroposteriorly short and the trigonid cusps tall, the talonid tends to be labiolingually narrow and skewed labially relative to the trigonid, and shearing crests are strongly developed on upper and lower teeth. The dental evidence suggests that although palaeoryctids were small in body size, they were predaceous. They probably subsisted on insects and other small terrestrial invertebrates and perhaps even on small vertebrates. The relationships of palaeoryctids to other eutherian mammals are uncertain. For example, they have often been thought to have affinities with Creodonta and Carnivora (see McKenna and Bell, 1997) as one alternative, or with zalambdodont lipotyphlans, including the extant West Indian Solenodon Brandt, 1833 and Afro- Malagasy tenrecs (see Matthew, 1913; Asher et al., 2002), as …

Re-examination of the dentitions of carpolestid plesiadapiform mammals from the late Paleocene Swan Hills locality, northern Alberta, and correlative localities in the vicinity of Roche Percée, southeastern Saskatchewan, Canada, indicates that Carpodaptes cygneus (Russell) as known from these sites is polyphyletic: the name C. cygneus is here restricted to the Swan Hills carpolestid, while the Roche Percée form represents a new, more derived species, Carpodaptes stonleyi. Other purported records of C. cygneus are reconsidered as well: C. cygneus from DW-1, central Alberta, is more appropriately dubbed C. cf. cygneus; C. cygneus at Canyon Ski Quarry, central Alberta, is best identified as C. cf. stonleyi, while C. cf. cygneus from Police Point, southeastern Alberta, has closest affinities to C. hazelae Simpson. Carpolestids from the Tongue River Formation, North Dakota, are referred to Carpodaptes cf. hobackensis Dorr and C. cf. hazelae. After a review of the available evidence, the recent hypothesis that C. cygneus and other North American carpolestids are congeneric with Carpocristes oriens Beard and Wang from the Paleocene or Eocene of China, is rejected.

Borealosuchus griffithi, sp. nov., is described on the basis of an incomplete skeleton from the basal Paleocene, southern Alberta. This new species records one of a few basal Cenozoic occurrences of Crocodylia so far known. B. griffithi is most distinctive in having a markedly laterally concavo-convex snout; a deep, elongate recess or fossa on the anteroventral surface of the jugal; and a large, nearly rectangular incisive foramen. Within Borealosuchus, B. griffithi probably takes a "more crownward" position than does B. sternbergii of the late Late Cretaceous. With additional information from the new species, the diagnosis of Borealosuchus is revised.

Significant new material of the plesiadapiform Elphidotarsius russelli is described from Montana and Alberta. Previously the most poorly documented carpolestid, this species is now known from numerous isolated teeth and many jaw fragments. New material from the Crazy Mountains Basin, Montana substantially extends its known geographic range and shows that E. russelli is the most derived species of Elphidotarsius, with many features that foreshadow characteristics of Carpodaptes; consequently, emending the diagnosis of Elphidotarsius has been necessary. A phylogenetic analysis based on 73 characters scored for all species of Elphidotarsius, Pronothodectes, and Saxonella, as well as Purgatorius unio, Purgatorius janisae, Pandemonium dis, Chronolestes simul, and Carpodaptes hazelae, indicates that Elphidotarsius is a paraphyletic stem taxon at the base of Carpolestidae. Numerous crossing synapomorphies among these taxa show that a single anagenetic lineage can no longer represent the evolution of ear...

A recent paper by Fanti and Miyashita (2009. A high latitude vertebrate fossil assemblage from the Late Cretaceous of west-central Alberta, Canada: Evidence for dinosaur nesting and vertebrate latitudinal gradient. Palaeogeography, Palaeoclimatology, Palaeoecology 275, 37–53) reports on a new assemblage of terrestrial vertebrate fossils from the Campanian (Late Cretaceous) of northern Alberta. In addition to the several dinosaur and microvertebrate specimens reported by Fanti and Miyashita (2009), the new assemblage also contains two mammalian teeth, identified by the authors as pertaining to “Cimolodon sp.” and “Didelphodon sp.” The taxonomic identifications of these teeth are either highly questionable or simply incorrect, and the accompanying descriptions are replete with errors; as a result of these lapses, at least part of the biogeographic conclusions drawn by the authors about the Kleskun Hills Park area is also rendered incorrect. While the discovery of a Late Cretaceous high-latitude vertebrate fauna in Alberta is unquestionably important, the significance of the Kleskun Hills mammalian taxa, both taxonomically and biogeographically, should be reconsidered.

New choristoderan fossils from the Late Cretaceous and Palaeocene of Alberta and Saskatchewan, Canada, are described: incomplete maxillae and dentaries from the Upper Cretaceous Oldman Formation, Alberta, extend the range of the primitive Cteniogenys from the Jurassic in the North American Western Interior; an incomplete dentary from the Palaeocene Ravenscrag Formation, Saskatchewan, comprises the first occurrence of the crocodile-like Simoedosaurus in Canada and the earliest record of the genus; well-preserved skulls and mandibles from the Oldman and Horseshoe Canyon formations, Alberta, document a new species of Champsosaurus and clarify the status of previously known species of the genus. New information about Asian choristoderes supports a Tchoiria –( Ikechosaurus + Simoedosaurus ) relationship, contrary to previous work. Choristoderes share no convincing synapomorphies with either Lepidosauromorpha or Archosauromorpha, but occupy a more basal position within Diapsida, possibly as a sister-taxon with Neodiapsida (Younginiformes+Sauria).

Multituberculate petrosals with well-preserved, three-dimensional internal anatomy from the Late Cretaceous/early Paleocene Bug Creek Anthills, Montana, U.S.A., are described from X-radiographic and SEM images, as well as from conventional visual observations, and are compared with the anatomy of the osseous inner ear in monotremes and in primitive non-therian and therian mammals. Results of this study indicate that: (1) the cochlea of at least some multituberculates retained a lagena, previously known only in monotremes among mammals; (2) an enlarged vestibule evolved in several lineages of multituberculates independently, and hence is not a synapomorphy of the order; (3) the cochlear canal lacks osseous laminae in support of the short, wide basilar membrane, which was probably inefficient in responding to high-frequency airborne vibrations; and (4) consequently, bone-conducted hearing in some multituberculate species may have been important in interpretation of their surroundings. Comparisons with the inner ear of monotremes and primitive therians indicate that curvature of the cochlea and cribriform plates for passage of vestibulocochlear nerve branches through the petrosal are unlikely homologues between monotremes and therians. From non-therian to therian mammals, there is a distinct morphological gap in the inner ear transition, characterized by acquisition of a number of neomorphs in the therian inner ear; an intermediate stage has yet to be discovered.

Based on the internal anatomy of petrosal bones as shown in radiographs and scanning electron microscopy, the inner ear structures of Late Cretaceous marsupials and placentals (about 65 Myr ago) from the Bug Creek Anthills locality of Montana, USA, are described. The inner ears of Late Cretaceous marsupials and placentals are similar to each other in having the following tribosphenic therian synapomorphies: a fully coiled cochlea, primary and secondary osseous spiral laminae, the perilymphatic recess merging with the scala tympani of the cochlea, an aqueductus cochleae, a true fenestra cochleae, a radial pattern of the cochlear nerve and an elongate basilar membrane extending to the region between the fenestra vestibuli and fenestra cochleae. The inner ear structures of living therians differ from those of their Late Cretaceous relatives mainly in having a greater number of spiral turns of the cochlea and a longer basilar membrane. Functionally, a coiled cochlea not only permits the development of an elongate basilar membrane within a restricted space in the skull but also allows a centralized nerve system to innervate the elongate basilar membrane. Qualitative and quantitative analyses show that, with a typical therian inner ear, Late Cretaceous marsupials and placentals were probably capable of high-frequency hearing.

Schowalteria clemensi Fox and Naylor, from the latest Cretaceous lower Scollard Formation, Red Deer Valley, Alberta, is the only known Mesozoic member of the extinct mammalian order Taeniodonta. Schowalteria clemensi was originally classified in the derived family Stylinodontidae, but more recent studies employing computer-assisted phylogenetic and stratocladistic analyses of taeniodont interrelationships contend that S. clemensi is the basal taeniodont, whereas Onychodectes, long considered the basal taeniodont, is instead the sister group of stylinodontids alone. These studies, however, are deeply flawed, marred by selection of problematic outgroups, incorrect scoring of numerous character states and of the stratigraphic age of S. clemensi, omission of all stylinodontid-like characters of S. clemensi, and reliance on major, implausible reversals during early taeniodont history. The more recent of these analyses also examined the relationship of taeniodonts within Eutheria, but this data set incl...

Therian petrosals from the Milk River and Oldman formations of Alberta are described. The Milk River specimen is the earliest known ear structure of a therian from North America and has a cochlea w...

The earliest Carnivora are known from two families, the Miacidae, which retain M3/m3 and occur first in latest Paleocene (Clarkforkian) rocks, and the Viverravidae, which have lost M3/m3, but are known first in the middle Paleocene (Torrejonian). This paper describes two new genera and species of carnivorans, one (Pristinictis connata) a viverravid and the other (Ravenictis krausei) of uncertain familial affinities, from the early Tiffanian of Alberta and early Puercan of Saskatchewan, respectively; both have a molar structure more primitive than previously known for the order. The new carnivorans allow a reassessment of character state polarities in the early evolution of the Carnivora, thereby providing the opportunity for reexamination of the relationships of carnivorans to other eutherian orders. As a consequence of this study, it appears that carnivorans and creodonts share no uniquely derived character states of the dentition that might indicate they are sister-groups, and that carnivorans ...

New evidence from Elphidotarsius and Carpodaptes indicates that the primitive dental formula for Carpolestidae is I3/3, Cl/1, P4/3, M3/3, not I2/2, Cl/1, P3/3, M3/3, the formula long thought to be primitive for carpolestids and all other plesiadapiforms except Purgatorius; the revised formula differs from that of primitive Tertiary eutherians generally only in the loss of p1. Hence, if Carpolestidae and Plesiadapidae are sister groups, as has traditionally been believed, primitive carpolestids are more primitive than known plesiadapids in the number of incisors and retention of two upper teeth (C and P1) between I3 and P2. Nothing of the dentition or other known parts of the anatomy supports the recent suggestion that carpolestids are dermopterans.

The discovery of a skull and partial postcranial skeleton of Dicamptodon from northern Alberta is the earliest certain record of the subfamily Dicamptodontinae. The specimen comes from Late Paleocene lake sediments, which also contain the remains of fish and plants. The close resemblance of the specimen to larvae or neotenes of extant Dicamptodon shows that this family exhibits the common trend of extreme conservatism known from other salamanders. The specimen is found in association with floral assemblages, confirming Nussbaum's hypothesis of the origin of the genus in northwestern North America.

Study Design. Multicenter ambispective cohort analysis. Objective. The purpose of this study is to determine whether applying Enneking's principles to surgical management of primary bone tumors of the spine significanti decreases local recurrence and/or mortality. Summary of Background Data. Oncologic management of primary tumors of spine has historically been inconsistent, controversial, and open to individual interpretation. Methods. A multicenter ambispective cohort analysis from 4 tertiary care spine referral centers was done. Patients were analyzed in 2 cohorts, "Enneking Appropriate" (EA), surgical margin as recommended by Enneking, and "Enneking Inappropriate" (EI), surgical margin not recommended by Enneking. Benign tumors were not included in mortality analysis. Results. Two cohorts represented an analytic dataset with 147 patients, 86 male, average age 46 years (range: 10-83). Median follow-up was 4 (2-7) years in the EA and 6 (5.5-15.5) years in the EI. Seventy-one patients suffered at least 1 local recurrence during the study, 57 of 77 in the EI group and 14 of 70 in the EA group. EI surgical approach caused higher risk of first local recurrence (P < 0.0001). There were 48 deaths in total; 29 in the EI group and 19 in the EA. There was a strong correlation between the first local recurrence and mortality with an odds ratio of 4.69, (P < 0.0001). EI surgical approach resulted in a higher risk of mortality with a hazard ratio of 3.10, (P = 0.0485) compared to EA approach. Conclusion. Surgery results in a significant reduction in local recurrence when primary bone tumors of the spine are resected with EA margins. Local recurrence has a high concordance with mortality in resection of these tumors. A significant decrease in mortality occurs when EA surgery is used.

A new trirachodontid eucynodont, Beishanodon youngi, is named and described based on a well-preserved skull from Triassic lacustrine deposits exposed in the Beishan Hills, northern Gansu Province, China. The new discovery documents the second record of trirachodontid eucynodonts known from China, along with Sinognathus gracilis from the Middle Triassic Ermaying Formation exposed in Shanxi Province. Cladistic analysis supports the placement of the new taxon as the sister group of Sinognathus, and the two together can be classified in Sinognathinae, a new subfamily differentiated from other trirachodontids by possession of several derived character states, including extremely short snout and strongly expanded temporal region. In addition, the stratigraphic and biogeographic significance of the new discovery are discussed. Because trirachodontids have a restricted stratigraphic range in the Triassic, as best documented by the Cynognathus Assemblage Zone of South Africa, discovery of the new fossil o...

Saxonella Russell is a small plesiadapiform described in 1964 from incomplete dental and jaw remains occurring in Paleocene fissure fills at Walbeck, Germany. The first North American discovery of Saxonella was reported in 1984, based on an incomplete dentary with teeth from the late Paleocene Paskapoo Formation, Alberta, nearly 10,000 km from the Walbeck site; since then, several additional Paskapoo specimens have been collected. The Canadian fossils represent a new species evidently more primitive than the Walbeck S. crepaturae. In the new species, both p3 and p4 are bladelike teeth (p3 is the larger), in contrast with S. crepaturae, in which p4 is smaller relative to p3 and its crown rounded. The new fossils include three incomplete maxillaries that together preserve P2–4, M1–3; these are the only articulated upper dentitions of Saxonella now known. A long diastema separates P2, which is small and peg-like, from the next more anterior tooth, which is undiscovered. P3 is the largest cheek-tooth...