Tyrannosaurus Research Articles

Mandibular force profiles and tooth morphology in growth series of Albertosaurus sarcophagus and Gorgosaurus libratus (Tyrannosauridae: Albertosaurinae) provide evidence for an ontogenetic dietary shift in tyrannosaurids1

The albertosaurines Albertosaurus sarcophagus and Gorgosaurus libratus are among the best represented tyrannosaurids, known from nearly complete growth series. These specimens provide an opportunity to study mandibular biomechanical properties and tooth morphology to infer changes in feeding behaviour and bite force through ontogeny in tyrannosaurids. Mandibular force profiles reveal that the symphyseal region of albertosaurines is consistently stronger in bending than the mid-dentary region, indicating that the anterior extremity of the jaws played an important role in prey capture and handling through ontogeny. The symphyseal region was better adapted to withstand torsional stresses than in most non-avian theropods, but not to the extent seen in Tyrannosaurus rex, suggesting that albertosaurine feeding behaviour may have involved less bone crushing or perhaps relatively smaller prey than in Tyrannosaurus rex. The constancy of these biomechanical properties at all known growth stages indicates that although albertosaurines maintained a similar feeding strategy through ontogeny, prey size/type had to change between juvenile and mature individuals. This ontogenetic dietary shift likely happened when individuals reached a mandibular length of ∼58 cm, a size at which teeth shift from ziphodont to incrassate in shape and bite force begins to increase exponentially. The fact that large albertosaurines were capable of generating bite forces equivalent to similar-sized tyrannosaurines suggests that no significant differences in jaw-closing musculature existed between the two clades and that the powerful bite of Tyrannosaurus rex is the result of its large body size rather than of unique adaptations related to a specialized ecology.

Keratan sulfate as a marker for medullary bone in fossil vertebrates.

The ability to determine the sex of extinct dinosaurs by examining the bones they leave behind would revolutionize our understanding of their paleobiology; however, to date, definitive sex-specific skeletal traits remain elusive or controversial. Although living dinosaurs (i.e., extant birds) exhibit a sex-specific tissue called medullary bone that is unique to females, the confident identification of this tissue in non-avian archosaurs has proven a challenge. Tracing the evolution of medullary bone is complicated by existing variation of medullary bone tissues in living species; hypotheses that medullary bone structure or chemistry varied during its evolution; and a lack of studies aimed at distinguishing medullary bone from other types of endosteal tissues with which it shares microstructural and developmental characteristics, such as pathological tissues. A recent study attempted to capitalize on the molecular signature of medullary bone, which, in living birds, contains specific markers such as the sulfated glycosaminoglycan keratan sulfate, to support the proposed identification of medullary bone of a non-avian dinosaur specimen (Tyrannosaurus rex MOR 1125). Purported medullary bone samples of MOR 1125 reacted positively to histochemical analyses and the single pathological control tested (avian osteopetrosis) did not, suggesting the presence of keratan sulfate might serve to definitively discriminate these tissues for future studies. To further test these results, we sampled 20 avian bone pathologies of various etiologies (18 species), and several MB samples. Our new data universally support keratan sulfate as a reliable marker of medullary bone in birds. However, we also find that reactivity varies among pathological bone tissues, with reactivity in some pathologies indistinguishable from MB. In the current sample, some pathologies comprised of chondroid bone (often a major constituent of skeletal pathologies and developing fracture calluses in vertebrates) contain keratan sulfate. We note that beyond chemistry, chondroid bone shares many characteristics with medullary bone (fibrous matrix, numerous and large cell lacunae, potential endosteal origin, trabecular architecture) and medullary bone has even been considered by some to be a type of chondroid bone. Our results suggest that the presence of keratan sulfate is not exclusive evidence for MB, but rather must be used as one in a suite of criteria available for identifying medullary bone (and thus gravid females) in non-avian dinosaur specimens. Future studies should investigate whether there are definite chemical or microstructural differences between medullary bone and reactive chondroid bone that can discriminate these tissues.

Sculpture: Only Connect

Sculpture: Only Connect LINCOLN PERRY My mother would take us to New York’s Museum of Natural History when I was a child. Tyrannosaurus Rex, his skeletal tail firmly on the ground, and the gargantuan blue whale, airborne as if leaping from the sea, were of course magical to a young boy. The snowbound diorama of wolves running and leaping beneath the Northern Lights terrified me, and in my bad dreams no glass intervened to protect me from their gleaming fangs. Two groups of figures in bronze loomed in the entry hall’s semi-darkness, one of growling lions, faced diagonally across the huge hall by natives preparing to throw spears. I was enchanted, less by the artistry of the sculptor (I was only a kid) than by this wonderful tension, a drama unfolding right there on the Upper West Side. The reasoning now operating behind the move to take down the statue of Teddy Roosevelt on Central Park West may have been responsible for the removal of this vivid confrontation of hunters and hunted (it was unclear which would be which). On re-visiting the museum decades later, I also missed the busts by Malvina Hoffman that had graced the upper halls, including one of Mangbetu Woman. She was glorious, even more magnetic to a very young boy than the Tyrannosaurus or the whale. She may have been removed as we re-thought the premise of Hoffman’s series, “The Races of Mankind,” or because her spectacular breasts had been polished to a golden glow by young hands reaching up to touch them. While Hoffman herself might have been troubled that her piece’s dark matte patina contrasted so dramatically and distractingly with the woman’s shiny breasts, she may also have felt amused or even honored. For Mangbetu Woman arion 29.1 spring/summer 2021 2 sculpture: only connect had very young admirers, one might almost say worshippers, paying homage or seeking comfort from an inanimate chunk of metal. This might be a tribute to mammary glands, but also to the power of sculpture. Toes of marble saints across Europe have been worn down to stubs by a similar need to bond with objects that transcend objecthood . Jules Dalou’s bronze of the recumbent/tumescent Victor Noir in Paris’ Pere Lachaise Cemetery was briefly fenced to prevent women from rubbing his member, made to glow with an almost supernatural radiance. As an adult, I can’t imagine I’m alone in the desire to touch, to identify or merge with tangible forms in space, be they bronze, stone, wood or flesh. Atavistic needs and memories surely come into play even with abstract sculpture, taking Jean Arp as but one example. His work recognizes these urges and perhaps even teases the viewer, or I might say the fondler. For while our eye may try to comprehend Arp’s biomorphic bulbs, we respond more viscerally, somewhere between touch and a bodily identification, deep in our own sense of being. His piece lacks our symmetry, resembling a squeezed balloon bulging in unpredictable ways, but this quirky swelling might remind us intuitively of our own proclivity to move and grow. Whether we hold such a form in our hands the way cave Lincoln Perry 3 dwellers held the Willendorf Venus 25 millennia ago, or stand humbly before it, some mysterious fusion or projection can take place. Surely some of this power depends on actuality, on being able to circumnavigate, say, this African sculpture in the Art Gallery of Ontario’s collection. It’s our loss if we stride past and dismiss her as foreign or unfamiliar, for the more time we spend in her presence the more we subtly assume her semi-squat, as if we all belong to the same gym. She being about our height, we feel as much as see her, sensing her kindred nature, with weight shifts we’ve experienced ourselves. Scientists call this proprioception, our awareness of location in space as a kind of sixth sense, making this figure’s pinched waist, protruding belly and bent knees evoke an unconscious echo in our limbs, as if mass precedes sight or surface. For me, some of the devotional...

A comprehensive diagnostic approach combining phylogenetic disease bracketing and CT imaging reveals osteomyelitis in a Tyrannosaurus rex

Traditional palaeontological techniques of disease characterisation are limited to the analysis of osseous fossils, requiring several lines of evidence to support diagnoses. This study presents a novel stepwise concept for comprehensive diagnosis of pathologies in fossils by computed tomography imaging for morphological assessment combined with likelihood estimation based on systematic phylogenetic disease bracketing. This approach was applied to characterise pathologies of the left fibula and fused caudal vertebrae of the non-avian dinosaur Tyrannosaurus rex. Initial morphological assessment narrowed the differential diagnosis to neoplasia or infection. Subsequent data review from phylogenetically closely related species at the clade level revealed neoplasia rates as low as 3.1% and 1.8%, while infectious-disease rates were 32.0% and 53.9% in extant dinosaurs (birds) and non-avian reptiles, respectively. Furthermore, the survey of literature revealed that within the phylogenetic disease bracket the oldest case of bone infection (osteomyelitis) was identified in the mandible of a 275-million-year-old captorhinid eureptile Labidosaurus. These findings demonstrate low probability of a neoplastic aetiology of the examined pathologies in the Tyrannosaurus rex and in turn, suggest that they correspond to multiple foci of osteomyelitis.

Testing Utility

Tyrannosaurus rex is infamous for its large body size and seemingly mismatched forelimbs, which are extremely small relative to body size. Since its first description by Osborn in 1905, the diminutive size of this attribute has fueled an arms race of sorts wherein specialists have advanced numerous theories seeking to prove a seemingly single-track use or non-use for the arms. While the overall debate on the evolutionary processes behind the small limb size are not addressed here, previous functional theories are reviewed within a functionalist perspective. This paper contends that Tyrannosaurus rex would have used its limbs for whatever purposes possible and that selecting one function to the exclusion of others is not a realistic approach to understanding the lifeways of the Tyrant King. Rather, a functionality assessment is suggested and tested using existing theories with the aim of providing a tool to assess future use case theories.

Sociolinguistics, Indexicality and “Global English”

This paper presents a critique of the paper “Global English: From ‘Tyrannosaurus Rex’ to ‘Red Herring’” from a sociolinguistic perspective. The paper takes the position that it is undeniable that the English language’s presence on the world stage, alongside the various political, cultural and economic hegemonies that continue to support it, reverberates down to many varied local linguistic contexts of different time depths. Taking these seriously, sociolinguistically, means paying attention to the subtle indexical, sociolinguistic and linguistic anthropological groundings of contexts as a precursor to any type of ‘applied linguistic’ approach. The paper therefore argues for a dissolution of the term Global English and increased awareness of sociolinguistic and semiotic values in many and varied situations. The paper also discusses one online media example of linguistic ideologizing on the role of English and Danish in Denmark. We take the stance that inter-disciplinarity on this issue, as Anna Kristina Hultgren envisages it, is best built upon strong disciplinary foundations. Keywords: ; ; ; ; ;

Response to Anna Kristina Hultgren’s Global English: From “Tyrannosaurus Rex” to “Red Herring”

In this response to Anna Kristina Hultgren’s paper, ‘Global English: From “Tyrannosaurus Rex” to “Red Herring”’, I begin by aligning myself with the general thrust of Hultgren’s argument, namely that if Applied Linguists really want to help combat social injustice in the world, they will have to abandon the notion that language must be at the centre of all social analysis, realising that this focus is never going to be enough to ensure the achievement of their goal. In addition, they will need to engage with Marxist political economy in greater depth than they perhaps have done in the past. I then devote some space to clarifications of key terminology such as political economy, materialism and class, before moving back to the key idea I mean to convey, namely that a focus on language is not going to make much of a contribution to making world a better place when the real problem is the ongoing march of capitalism and the increasing inequality and the damage to the environment that it engenders.

Global English: From “Tyrannosaurus Rex” to “Red Herring”

The rise of English as the world’s main international language has prompted a social justice agenda underpinned by an assumption that English causes or exacerbates inequality and injustice in the world. In this position statement, I set out to problematise and complexify this assumption, suggesting that English is neither a “Tyrannosaurus Rex”, a “Cuckoo” nor a “Lingua Frankensteinia”, but a “Red Herring”, distracting attention away from the underlying causes of inequality. Within the theoretical framework of “verbal hygiene” (Cameron 1995, 2012a), and drawing on my own empirical work and that of others, I argue for widening the scope of global English and more broadly applied linguistics. I suggest that as socially committed applied linguists, we stand a better chance of solving “real-world problems” (Brumfit 1995: 27) if greater attention is accorded to systems of inequality that are not obviously language-based. I will suggest that a too narrow focus on linguistic injustice risks losing sight of the underlying non-linguistic conditions that produce this injustice. I conclude by suggesting some ways forward that centre on co-thinking language with political, social, economic, cultural and material conditions.

Was Tyrannosaurus rex a Ferocious Predator or a Wimp?

Tyrannosaurus rex is the most famous dinosaur in the world: beloved by paleontologists and the public alike (especially kids). How T. rex lived is one of the most hotly debated topics in dinosaur research. T. rex was the largest predator in its ecosystem with a powerful and (possibly) poisonous bite. It has been suggested, however, that T. rex was a scavenger, like the dinosaurian equivalent of a vulture, rather than an active predator. The aim of this article is therefore to examine the behavior and lifestyles of these incredible animals and to provide you with clues on whether T. rex was a predator.

A high-resolution growth series ofTyrannosaurus rexobtained from multiple lines of evidence

BackgroundDuring the growth of complex multicellular organisms, chronological age, size and morphology change together in a hierarchical and coordinated pattern. Among extinct species, the growth ofTyrannosaurus rexhas received repeated attention through quantitative analyses of relative maturity and chronological age. Its growth series shows an extreme transformation from shallow skulls in juveniles to deep skulls in adults along with a reduction in tooth count, and its growth curve shows thatT. rexhad a high growth rate in contrast to its closest relatives. However, separately, these sets of data provide an incomplete picture of the congruence between age, size, and relative maturity in this exemplar species. The goal of this work is to analyze these data sets together using cladistic analysis to produce a single hypothesis of growth that includes all of the relevant data.MethodsThe three axes of growth were analyzed together using cladistic analysis, based on a data set of 1,850 morphological characters and 44 specimens. The analysis was run in TNT v.1.5 under a New Technology search followed by a Traditional search. Correlation tests were run in IBM SPSS Statistics v. 24.0.0.0.ResultsAn initial analysis that included all of the specimens recovered 50 multiple most parsimonious ontograms a series of analyses identified 13 wildcard specimens. An analysis run without the wildcard specimens recovered a single most parsimonious tree (i.e., ontogram) of 3,053 steps. The ontogram is composed of 21 growth stages, and all but the first and third are supported by unambiguously optimized synontomorphies.T. rexontogeny can be divided into five discrete growth categories that are diagnosed by chronological age, morphology, and, in part, size (uninformative among adults). The topology shows that the transition from shallow to deep skull shape occurred between 13 and 15 years of age, and the size of the immediate relatives ofT. rexwas exceeded between its 15th and 18th years. Although size and maturity are congruent among juveniles and subadults, congruence is not seen among adults; for example, one of the least mature adults (RSM 2523.8) is also the largest and most massive example of the species. The extreme number of changes at the transition between juveniles and subadults shows that the ontogeny ofT. rexexhibits secondary metamorphosis, analogous to the abrupt ontogenetic changes that are seen at sexual maturity among teleosts. These results provide a point of comparison for testing the congruence between maturity and chronological age, size, and mass, as well as integrating previous work on functional morphology into a rigorous ontogenetic framework. Comparison of the growth series ofT. rexwith those of outgroup taxa clarifies the ontogenetic trends that were inherited from the common ancestor of Archosauriformes.

Anatomy of a dinosaur-Clarification of vertebrae in vertebrate anatomy.

The flat-end surfaces of dinosaur vertebral centra led to the presumption that intervertebral discs occupied the space between their vertebrae. A set of fused hadrosaur vertebrae allowed that hypothesis to be tested. The Tyrannosaurus rex responsible for this pathology did not escape unscathed. It left behind a tooth crown that had fractured. Fragments of that tooth were scattered through the intervertebral space, evidencing that there was no solid structure to impede its movement. That eliminates the possibility of an intervertebral disc and instead proves the presence of an articular space, similar to that in modern reptiles, but at variance to what is noted in birds. While avian cervical vertebral centra appear to be separated by diarthrodial joints, the preponderance of their thoracic vertebral centra is not separated by synovial joints.

New Dromaeosaurid Dinosaur (Theropoda, Dromaeosauridae) from New Mexico and Biodiversity of Dromaeosaurids at the end of the Cretaceous

Dromaeosaurids (Theropoda: Dromaeosauridae), a group of dynamic, swift predators, have a sparse fossil record, particularly at the time of their extinction near the Cretaceous-Paleogene boundary. Here we report on a new dromaeosaurid, Dineobellator notohesperus, gen. and sp. nov., consisting of a partial skeleton from the Upper Cretaceous (Maastrichtian) of New Mexico, the first diagnostic dromaeosaurid to be recovered from the latest Cretaceous of the southern United States (southern Laramidia). The holotype includes elements of the skull, axial, and appendicular skeleton. The specimen reveals a host of morphologies that shed light on new behavioral attributes for these feathered dinosaurs. Unique features on its forelimbs suggest greater strength capabilities in flexion than the normal dromaeosaurid condition, in conjunction with a relatively tighter grip strength in the manual claws. Aspects of the caudal vertebrae suggest greater movement near the tail base, aiding in agility and predation. Phylogenetic analysis places Dineobellator within Velociraptorinae. Its phylogenetic position, along with that of other Maastrichtian taxa (Acheroraptor and Dakotaraptor), suggests dromaeosaurids were still diversifying at the end of the Cretaceous. Furthermore, its recovery as a second North American Maastrichtian velociraptorine suggests vicariance of North American velociraptorines after a dispersal event during the Campanian-Maastrichtian from Asia. Features of Dineobellator also imply that dromaeosaurids were active predators that occupied discrete ecological niches while living in the shadow of Tyrannosaurus rex, until the end of the dinosaurs’ reign.

Dinosaur art evolves with new discoveries in paleontology

Under soft museum lights, the massive skeleton of a Tyrannosaurus rex is easy to imagine fleshed out and alive, scimitar teeth glimmering. What did it look like in life? How did its face contort under the Montana sun some 66 million years ago? What color and texture was its body? Was it gauntly wrapped in scales, fluffy with feathers, or a mix of both? Among the earliest examples of paleoart, this 1830 watercolor painting, called Duria Antiquior or “A more ancient Dorset,” imagines England's South Coast populated by ichthyosaurs, plesiosaurs, and pterosaurs. Image credit: Wikimedia Commons/Sir Henry Thomas De la Beche. Increasingly, paleontologists can offer answers to these questions, thanks to evidence of dinosaur soft tissues discovered in the last 30 years. Translating those discoveries into works that satisfy the public’s imagination is the purview of paleoartists, the scientific illustrators who reconstruct prehistory in paintings, drawings, and sculptures in exhibit halls, books, magazines, and films. Those creations necessarily require some artistic license, says freelancer Gabriel Ugueto, who’s based in Miami, FL. As new discoveries offer artists a better sense of what their subjects looked like, the findings also constrain their creativity, he says, by leaving fewer details to the imagination. Even so, he and other artists welcome new discoveries, as the field strives for accuracy. The challenge now is sifting through all this new information, including characteristics that are still up for debate, such as the extent of T. rex’s feathers, to conjure new visions of the prehistoric world. Paleoartists often have a general science background or formal artistic training, although career paths vary. “There is no one way that people get into paleoart,” says Mark Witton, a paleoartist and paleontologist at the University of Portsmouth in the United Kingdom, who recently wrote a paleoart handbook (1). Regardless of their …

Neurosensory and Sinus Evolution as Tyrannosauroid Dinosaurs Developed Giant Size: Insight from the Endocranial Anatomy of Bistahieversor sealeyi.

Tyrannosaurus rex and other tyrannosaurid dinosaurs were apex predators during the latest Cretaceous, which combined giant size and advanced neurosensory systems. Computed tomography (CT) data have shown that tyrannosaurids had a trademark system of a large brain, large olfactory bulbs, elongate cochlear ducts, and expansive endocranial sinuses surrounding the brain and sense organs. Older, smaller tyrannosauroid relatives of tyrannosaurids developed some, but not all, of these features, raising the hypothesis that tyrannosaurid-style brains evolved before the enlarged tyrannosaurid-style sinuses, which might have developed only with large body size. This has been difficult to test, however, because little is known about the brains and sinuses of the first large-bodied tyrannosauroids, which evolved prior to Tyrannosauridae. We here present the first CT data for one of these species, Bistahieversor sealeyi from New Mexico. Bistahieversor had a nearly identical brain and sinus system as tyrannosaurids like Tyrannosaurus, including a large brain, large olfactory bulbs, reduced cerebral hemispheres, and optic lobes, a small tab-like flocculus, long and straight cochlear ducts, and voluminous sinuses that include a supraocciptal recess, subcondyar sinus, and an anterior tympanic recess that exits the braincase via a prootic fossa. When characters are plotted onto tyrannosauroid phylogeny, there is a two-stage sequence in which features of the tyrannosaurid-style brain evolved first (in smaller, nontyrannosaurid species like Timurlengia), followed by features of the tyrannosaurid-style sinuses (in the first large-bodied nontyrannosaurid tyrannosauroids like Bistahieversor). This suggests that the signature tyrannosaurid sinus system evolved in concert with large size, whereas the brain did not. Anat Rec, 303:1043-1059, 2020. © 2020 American Association for Anatomy.

Morphology of the endocranial cavities of Campinasuchus dinizi (Crocodyliformes: Baurusuchidae) from the Upper Cretaceous of Brazil

Two specimens of Campinasuchus dinizi (CPPLIP 1319 and CPPLIP 1360) belonging to Baurusuchidae (Crocodyliformes, Notosuchia) from the Upper Cretaceous Bauru Group of Minas Gerais state (Brazil) were scanned in a Toshiba Aquilion 64 CT machine. Based on these data, it was possible to identify and reconstruct the paranasal sinuses, the nasal cavity proper, the nasopharyngeal duct, the encephalon, the paratympanic sinuses, and the semicircular canals of the inner ear. The paranasal sinuses present similar morphology to those of other mesoeucrocodylians, especially eusuchians. The nasal cavity proper occupies the entire rostral region, with an expansion in the olfactory region. The expansion in the nasal cavity is present in other notosuchians and theropod dinosaurs (e.g., Tyrannosaurus rex Osborn, 1905), but less developed in aquatic crocodilians, which may indicate an olfactory acuity related to terrestrial habits. The encephalon is similar in shape to that of other mesoeucrocodylians. The rostral semicircular canal is smaller than the caudal one, differing from most mesoeucrocodylians. The paratympanic sinuses are more developed in C. dinizi than in eusuchians, being more similar to Tyrannosaurus rex. Campinasuchus dinizi presents few variations in the internal structures of the skull in relation to taxa with different ecological niches, probably indicating that ecological factors do not strongly influence the morphology of these structures.

Growing up Tyrannosaurus rex: Osteohistology refutes the pygmy "Nanotyrannus" and supports ontogenetic niche partitioning in juvenile Tyrannosaurus.

Despite its iconic status as the king of dinosaurs, Tyrannosaurus rex biology is incompletely understood. Here, we examine femur and tibia bone microstructure from two half-grown T. rex specimens, permitting the assessments of age, growth rate, and maturity necessary for investigating the early life history of this giant theropod. Osteohistology reveals these were immature individuals 13 to 15 years of age, exhibiting growth rates similar to extant birds and mammals, and that annual growth was dependent on resource abundance. Together, our results support the synonomization of "Nanotyrannus" into Tyrannosaurus and fail to support the hypothesized presence of a sympatric tyrannosaurid species of markedly smaller adult body size. Our independent data contribute to mounting evidence for a rapid shift in body size associated with ontogenetic niche partitioning late in T. rex ontogeny and suggest that this species singularly exploited mid- to large-sized theropod niches at the end of the Cretaceous.

Mechanisms of soft tissue and protein preservation in Tyrannosaurus rex

The idea that original soft tissue structures and the native structural proteins comprising them can persist across geological time is controversial, in part because rigorous and testable mechanisms that can occur under natural conditions, resulting in such preservation, have not been well defined. Here, we evaluate two non-enzymatic structural protein crosslinking mechanisms, Fenton chemistry and glycation, for their possible contribution to the preservation of blood vessel structures recovered from the cortical bone of a Tyrannosaurus rex (USNM 555000 [formerly, MOR 555]). We demonstrate the endogeneity of the fossil vessel tissues, as well as the presence of type I collagen in the outermost vessel layers, using imaging, diffraction, spectroscopy, and immunohistochemistry. Then, we use data derived from synchrotron FTIR studies of the T. rex vessels to analyse their crosslink character, with comparison against two non-enzymatic Fenton chemistry- and glycation-treated extant chicken samples. We also provide supporting X-ray microprobe analyses of the chemical state of these fossil tissues to support our conclusion that non-enzymatic crosslinking pathways likely contributed to stabilizing, and thus preserving, these T. rex vessels. Finally, we propose that these stabilizing crosslinks could play a crucial role in the preservation of other microvascular tissues in skeletal elements from the Mesozoic.

Tooth replacement in a specimen of Tyrannosaurus rex (Dinosauria, Theropoda) from the Hell Creek Formation (Maastrichtian), Montana

ABSTRACT A well-preserved skull of Tyrannosaurus rex from the Late Cretaceous (Maastrichtian) Hell Creek Formation of Montana is used to document its tooth replacement with the help of high-resolution medical CT scanning. A pattern of retaining only one single replacement tooth before replacing the functional tooth is reconstructed for most alveoli of the jaws, with exception of the second alveolus of the left maxilla, and the fourth alveolus of the right dentary, where another, second replacement tooth can be seen. The youngest replacement teeth have only a thin layer of enamel around the tooth crown, the larger replacement teeth have thicker enamel, fortified at the apex as in the functional teeth. The Zahnreihen approach allows to reconstruct a z-spacing of 2 in the upper jaws, whereas the right dentary displays a z-spacing of 1 in the rostral and distal third of the tooth row and a z-spacing of 2 in its medial part. In MB.R.91216, teeth of the upper jaws and the medial part of the dentary were probably replaced in a regular alternating pattern between odd and even teeth, whereas the mesial and distal teeth of the dentary were replaced simultaneously.

Reproducibility and Transparency by Design

The reproducibility of bioinformatics analyses can be elevated to equal status with biological discovery. To achieve this, reproducibility must become part of the process, not an afterthought. Graphical Abstract Highlights • Repositories are enabling sharing of data. • Sharing analyses remains a major stumbling block for reproducibility. • Three simple steps can enable sharing analyses, with nominal effort.

Palatal Biomechanics and Its Significance for Cranial Kinesis in Tyrannosaurus rex.

The extinct nonavian dinosaur Tyrannosaurus rex, considered one of the hardest biting animals ever, is often hypothesized to have exhibited cranial kinesis, or, mobility of cranial joints relative to the braincase. Cranial kinesis in T. rex is a biomechanical paradox in that forcefully biting tetrapods usually possess rigid skulls instead of skulls with movable joints. We tested the biomechanical performance of a tyrannosaur skull using a series of static positions mimicking possible excursions of the palate to evaluate Postural Kinetic Competency in Tyrannosaurus. A functional extant phylogenetic bracket was employed using taxa, which exhibit measurable palatal excursions: Psittacus erithacus (fore-aft movement) and Gekko gecko (mediolateral movement). Static finite element models of Psittacus, Gekko, and Tyrannosaurus were constructed and tested with different palatal postures using anatomically informed material properties, loaded with muscle forces derived from dissection, phylogenetic bracketing, and a sensitivity analysis of muscle architecture and tested in orthal biting simulations using element strain as a proxy for model performance. Extant species models showed lower strains in naturally occurring postures compared to alternatives. We found that fore-aft and neutral models of Tyrannosaurus experienced lower overall strains than mediolaterally shifted models. Protractor muscles dampened palatal strains, while occipital constraints increased strains about palatocranial joints compared to jaw joint constraints. These loading behaviors suggest that even small excursions can strain elements beyond structural failure. Thus, these postural tests of kinesis, along with the robusticity of other cranial features, suggest that the skull of Tyrannosaurus was functionally akinetic. Anat Rec, 303:999-1017, 2020. © 2019 Wiley Periodicals, Inc.