Research Interests:
Research Interests:
Weaponry, for the purpose of intraspecific combat or predator defence, is one of the most widespread animal adaptations, yet the selective pressures and constraints governing its phenotypic diversity and skeletal regionalization are not... more
Weaponry, for the purpose of intraspecific combat or predator defence, is one of the most widespread animal adaptations, yet the selective pressures and constraints governing its phenotypic diversity and skeletal regionalization are not well understood. Here, we investigate the evolution of tail weaponry in amniotes, a rare form of weaponry that nonetheless evolved independently among a broad spectrum of life including mammals, turtles and dinosaurs. Using comparative methods, we test for links between morphology, ecology and behaviour in extant amniotes known to use the tail as a weapon, and in extinct taxa bearing osseous tail armaments. We find robust ecological and morphological correlates of both tail lashing behaviour and bony tail weaponry, including large body size, body armour and herbivory, suggesting these life-history parameters factor into the evolution of antipredator behaviours and tail armaments. We suggest that the evolution of tail weaponry is rare because large, armoured herbivores are uncommon in extant terrestrial faunas, as they have been throughout evolutionary history.
Research Interests:
Research Interests:
Research Interests:
The diversity of mid-Cretaceous tyrannosauroids is poorly understood. We describe a partial tyrannosauroid femur from the Albian–Cenomanian Wayan Formation of eastern Idaho that helps to fill in an important spatiotemporal gap in the... more
The diversity of mid-Cretaceous tyrannosauroids is poorly understood. We describe a partial tyrannosauroid femur from the Albian–Cenomanian Wayan Formation of eastern Idaho that helps to fill in an important spatiotemporal gap in the North American record of tyrannosaurs. This specimen, consisting of the proximal half of the bone, is morphologically similar to the femur of Moros intrepidus, a small-bodied tyrannosauroid from the Cenomanian Mussentuchit Member of the Cedar Mountain Formation of Utah, but not referable to this taxon. The Wayan femur lacks an autapomorphy diagnostic for Moros intrepidus, indicating the presence of a previously unrecognized tyrannosauroid taxon in the early Late Cretaceous of Laramidia. Histological results indicate that, at the time of death, this individual was at least five years old, skeletally immature, and undergoing growth at a moderate rate. The addition of this tyrannosauroid to the Wayan-Vaughn Assemblage provides additional evidence for the w...
Research Interests: Evolutionary Biology, Geology, Paleontology, Ecology, Cretaceous, and 3 moreFemur, Cenomanian, and Taxon
Double tooth pathologies are important indicators of trauma, disease, diet, and feeding biomechanics, and are widely documented in mammals. However, diagnosis of double tooth pathologies in extinct non-mammalian vertebrates is complicated... more
Double tooth pathologies are important indicators of trauma, disease, diet, and feeding biomechanics, and are widely documented in mammals. However, diagnosis of double tooth pathologies in extinct non-mammalian vertebrates is complicated by several compounding factors including: a lack of shared terminology reflecting shared etiology, inconsistencies in definitions and key features within and outside of mammals (e.g., gemination, fusion, twinning, concrescence); differences in tooth morphology, heterodonty, regeneration, and implantation between mammals and non-mammalian vertebrates; and the unmet need for diagnostic criteria that can be applied to isolated teeth, which are common in the fossil record. Here we report on double tooth pathologies in the lamniform and carcharhiniform Cenozoic sharks Otodus megalodon (NCSM 33639) and Carcharhinus leucas (NCSM 33640, 33641). All three teeth bear a singular bifid crown with mirrored halves and abnormal internal microstructure—a single, b...
Research Interests: Biology and Vertebrate
Research Interests: Evolutionary Biology, Paleontology, Biology, Neurobiology, Medicine, and 14 moreBiological Sciences, Brain, Allometry, Birds, Animals, Biología, Aves, Biological evolution, Ciencias Biológicas, Encephalization, Enseñanza - Aprendizaje Ciencias Naturales Y Exactas, Psychology and Cognitive Sciences, brain size, and Medical and Health Sciences
Tyrannosaurus rexdominated its ecosystem by singularly exploiting the roles of mid- and large-sized carnivore as it grew up.
Research Interests:
The importance of adaptation [1-4] versus organizational constraints [5-7] in shaping common macroevolutionary trends remains unclear [8]. The fossil record is key to this problem, as it provides data on repetitive trait evolution between... more
The importance of adaptation [1-4] versus organizational constraints [5-7] in shaping common macroevolutionary trends remains unclear [8]. The fossil record is key to this problem, as it provides data on repetitive trait evolution between lineages [4, 8]. However, quantitative analyses investigating these dynamics with fossil data are rare [8]. Herbivory evolved multiple times within Mesozoic dinosaurs [9, 10], allowing analysis of common phenotypic responses to dietary evolution. Whereas repeated patterns of character acquisition [9] and functional changes [11-13] are observed between some herbivorous dinosaur clades, biomechanical studies resolve significant differences between morphologically similar taxa [12-14]. However, previous biomechanical analyses have not accounted for phylogenetic non-independence (e.g., [13-16]) or been restricted to individual clades (e.g., [11, 12, 16]). Here, we use multivariate analysis of biomechanical characters, within a robust phylogenetic context, to investigate functional pathways to herbivory in a large sample of non-avian dinosaurs. Results demonstrate multiple solutions to herbivory. Notably, two fundamentally different modes are observed to evolve independently multiple times, with morphofunctional changes in the skull co-varying with digestive strategy. These modes distinguish between gut-processing sauropodomorphs and theropods tending toward gracile crania and low bite forces and ornithischian taxa exhibiting character complexes associated with extensive oral processing. Although convergence within these subsets of taxa is common, it is not observed between them due to functional constraints imposed during the early evolution of each group. This highlights the hierarchical nature of evolution, with adaptation driving convergence within regions of morphospace delimited by phylogenetic contingency.
Research Interests:
Dietary habits in extinct species cannot be directly observed; thus, in the absence of extraordinary evidence, they must be reconstructed with a combination of morphological proxies. Such proxies often include information on dental... more
Dietary habits in extinct species cannot be directly observed; thus, in the absence of extraordinary evidence, they must be reconstructed with a combination of morphological proxies. Such proxies often include information on dental organization and function such as tooth formation time and tooth replacement rate. In extinct organisms, tooth formation times and tooth replacement rate are calculated, in part via extrapolation of the space between incremental lines in dental tissues representing daily growth (von Ebner Line Increment Width; VEIW). However, to date, little work has been conducted testing assumptions about the primary data underpinning these calculations, specifically, the potential impact of differential sampling and data extrapolation protocols. To address this, we tested a variety of intradental, intramandibular, and ontogentic sampling effects on calculations of mean VEIW, tooth formation times, and replacement rates using histological sections and CT reconstructions...
Research Interests:
Understanding the effects of climatic upheavals during the Early to Late Cretaceous transition is essential for characterizing the tempo of tectonically driven landscape modification and biological interchange; yet, current... more
Understanding the effects of climatic upheavals during the Early to Late Cretaceous transition is essential for characterizing the tempo of tectonically driven landscape modification and biological interchange; yet, current chronostratigraphic frameworks are too imprecise, even on regional scales, to address many outstanding questions. This includes the Mussentuchit Member of the uppermost Cedar Mountain Formation, central Utah (southwestern United States), which could provide crucial insights into these impacts within the Western Interior Basin of North America yet remains imprecisely constrained. Here, we present high-precision U-Pb zircon dates from four primary ash beds distributed across ∼50 km in central Utah that better constrain the timing of deposition of the Mussentuchit Member and the age of entombed fossils. Ages for ash beds are interpreted through a combination of Bayesian depositional age estimation and stratigraphic age modeling, resulting in posterior ages from 99.490 +0.057/−0.050 to 98.905 +0.158/−0.183 Ma. The age model predicts probabilistic ages for fossil localities between the ashes, including new ages for Moros intrepidus, Siats meekerorum, and several undescribed ornithischian dinosaur species of key interest for understanding the timing of faunal turnover in western North America. This new geochronology for the Mussentuchit Member offers unprecedented temporal insights into a volatile interval in Earth’s history.
Research Interests:
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... more
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.
Research Interests:
Ankylosaurid dinosaurs were heavily armoured herbivores with tails modified into club-like weapons. These tail clubs have widely been considered defensive adaptations wielded against predatory theropod dinosaurs. Here we argue instead... more
Ankylosaurid dinosaurs were heavily armoured herbivores with tails modified into club-like weapons. These tail clubs have widely been considered defensive adaptations wielded against predatory theropod dinosaurs. Here we argue instead that ankylosaurid tail clubs were sexually selected structures used primarily for intraspecific combat. We found pathological osteoderms (armour plates) in the holotype specimen of Zuul crurivastator , which are localized to the flanks in the hip region rather than distributed randomly across the body, consistent with injuries inflicted by lateral tail-swinging and ritualized combat. We failed to find convincing evidence for predation as a key selective pressure in the evolution of the tail club. High variation in tail club size through time, and delayed ontogenetic growth of the tail club further support the sexual selection hypothesis. There is little doubt that the tail club could have been used in defence when needed, but our results suggest that sexual selection drove the evolution of this impressive weapon. This changes the prevailing view of ankylosaurs, suggesting they were behaviorally complex animals that likely engaged in ritualized combat for social dominance as in other ornithischian dinosaurs and mammals.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests: Biology and Cretaceous
Research Interests:
Research Interests: Morphometrics and Biology
ABSTRACTAlthough intensified work on the volcaniclastic-rich sediments of the fossil-bearing Mussentuchit Member (uppermost Cedar Mountain Formation, Utah) has provided a refined chronostratigraphic framework, paleoenvironmental... more
ABSTRACTAlthough intensified work on the volcaniclastic-rich sediments of the fossil-bearing Mussentuchit Member (uppermost Cedar Mountain Formation, Utah) has provided a refined chronostratigraphic framework, paleoenvironmental interpretations remain cryptic. To resolve this, we performed facies analysis and architectural reconstruction on exposed Mussentuchit Member outcrops south of Emery, central Utah, USA. Contrary to previous interpretations (fluvial, lacustrine), we identified a broad suite of facies that indicate that deposition occurred on the landward part of a paralic depocenter, influenced by both distal alluvial and proximal coastal systems. We conclude that the Mussentuchit Member was a sink for suspension-settling fines with most undergoing pedogenic alteration, analogous to the modern coastal plain of French Guiana (Wang et al. 2002; Anthony et al. 2010, 2014). However, this landward paralic depocenter was not uniform through time. Sedimentological evidence indicates landscape modification was ongoing, influenced by an altered base-level (high groundwater table, long residency of water in sediments, shifts in paleosol types, heavier to lighter δ18O, and distinct shifts in relative humidity (ε); common in coastal settings). If the above data is coupled with recent age data, we interpret that the Mussentuchit Member correlates to the S.B. 4 Greenhorn Regression (Thatcher Limestone) of the adjacent Western Interior Seaway to the east. As a landward paralic depocenter, the Mussentuchit would have been sensitive to base-level conditions in response to ongoing tectonic processes pushing the foredeep east, and lower paleo-CO2 levels coupled with a minor global sea-level fall (brief glacial phase) just before to the Cenomanian–Turonian Thermal Maximum. Altogether, our results not only strengthen linkages in the central Western Interior Seaway, but simultaneously results in novel linkages to near-coeval paralic depocenters across mid-Cenomanian North America.
Research Interests:
Research Interests:
Paleopathological diagnoses provide key information on the macroevolutionary origin of disease as well as behavioral and physiological inferences that are inaccessible via direct observation of extinct organisms. Here we describe the... more
Paleopathological diagnoses provide key information on the macroevolutionary origin of disease as well as behavioral and physiological inferences that are inaccessible via direct observation of extinct organisms. Here we describe the external gross morphology and internal architecture of a pathologic right second metatarsal (MMNS VP‐6332) of a large‐bodied ornithomimid (~432 kg) from the Santonian (Upper Cretaceous) Eutaw Formation in Mississippi, using a combination of X‐ray computed microtomography (microCT) and petrographic histological analyses. X‐ray microCT imaging and histopathologic features are consistent with multiple complete, oblique to comminuted, minimally displaced mid‐diaphyseal cortical fractures that produce a “butterfly” fragment fracture pattern, and secondary osteomyelitis with a bone fistula formation. We interpret this as evidence of blunt force trauma to the foot that could have resulted from intra‐ or interspecific competition or predator–prey interaction, a...
Research Interests:
The geographic ranges in which species live is a function of many factors underlying ecological and evolutionary contingencies. Observing the geographic range of an individual species provides valuable information about these historical... more
The geographic ranges in which species live is a function of many factors underlying ecological and evolutionary contingencies. Observing the geographic range of an individual species provides valuable information about these historical contingencies for a lineage, determining the distribution of many distantly related species in tandem provides information about large‐scale constraints on evolutionary and ecological processes generally. We present a linear regression method that allows for the discrimination of various hypothetical biogeographical models for determining which landscape distributional pattern best matches data from the fossil record. The linear regression models used in the discrimination rely on geodesic distances between sampling sites (typically geologic formations) as the independent variable and three possible dependent variables: Dice/Sorensen similarity; Euclidean distance; and phylogenetic community dissimilarity. Both the similarity and distance measures ar...
Research Interests:
Research Interests:
Abstract. A new ichnospecies, Glossifungites gingrasi n. isp., is described from multiple locations in basal sand-filled coastal plain distributary channels of the Turonian (Upper Cretaceous) Ferron Sandstone (central Utah).... more
Abstract. A new ichnospecies, Glossifungites gingrasi n. isp., is described from multiple locations in basal sand-filled coastal plain distributary channels of the Turonian (Upper Cretaceous) Ferron Sandstone (central Utah). Glossifungites gingrasi n. isp. is attributed to the ichnogenus Glossifungites based on the presence of scratch imprints, passive fill, and a tongue-shaped structure, yet the new ichnospecies is distinct because it displays transverse bioglyphs that run perpendicular to the planiform structure, which contrasts to the axis parallel bioglyphs present in the ichnospecies G. saxicava. The transverse arrangement of ornamentation exhibited by G. gingrasi n. isp. is observed in modern subaqueous insect burrows produced by mayfly and chironomid larvae, and constitutes a way to differentiate insect-generated burrows from structures produced by crustaceans that are known to create other Glossifungites ichnospecies. Differentiating insect- from crustacean-generated burrows...
Research Interests: Geology, Paleontology, Ichnology, Cretaceous, Bioturbation, and 5 moreFauna, Ichnofacies, Trace Fossil, Burrow, and Mayfly
Research Interests:
Research Interests:
Terrestrial tetrapods use their claws to interact with their environments in a plethora of ways. Birds in particular have developed a diversity of claw shapes since they are often not bound to terrestrial locomotion and have heterogeneous... more
Terrestrial tetrapods use their claws to interact with their environments in a plethora of ways. Birds in particular have developed a diversity of claw shapes since they are often not bound to terrestrial locomotion and have heterogeneous body masses ranging several orders of magnitude. Numerous previous studies have hypothesized a connection between pedal claw shape and ecological mode in birds, yet have generated conflicting results, spanning from clear ecological groupings based on claw shape to a complete overlap of ecological modes. The majority of these studies have relied on traditional morphometric arc measurements of keratinous sheaths and have variably accounted for likely confounding factors such as body mass and phylogenetic relatedness. To better address the hypothesized relationship between ecology and claw shape in birds, we collected 580 radiographs allowing visualization of the bony core and keratinous sheath shape in 21 avian orders. Geometric morphometrics was use...
Research Interests:
Research Interests:
Reconstructing the evolution, diversity, and paleobiogeography of North America’s Late Cretaceous dinosaur assemblages requires spatiotemporally contiguous data; however, there remains a spatial and temporal disparity in dinosaur data on... more
Reconstructing the evolution, diversity, and paleobiogeography of North America’s Late Cretaceous dinosaur assemblages requires spatiotemporally contiguous data; however, there remains a spatial and temporal disparity in dinosaur data on the continent. The rarity of vertebrate-bearing sedimentary deposits representing Turonian–Santonian ecosystems, and the relatively sparse record of dinosaurs from the eastern portion of the continent, present persistent challenges for studies of North American dinosaur evolution. Here we describe an assemblage of ornithomimosaurian materials from the Santonian Eutaw Formation of Mississippi. Morphological data coupled with osteohistological growth markers suggest the presence of two taxa of different body sizes, including one of the largest ornithomimosaurians known worldwide. The regression predicts a femoral circumference and a body mass of the Eutaw individuals similar to or greater than that of large-bodied ornithomimosaurs,Beishanlong grandisa...
Research Interests: Geology, Paleontology, Biology, Multidisciplinary, Cretaceous, and 3 morePLoS one, Laurasia, and Taxon
Insufficient Evidence for Multiple Species of Tyrannosaurus in the Latest Cretaceous of North America: A Comment on “The Tyrant Lizard King, Queen and Emperor: Multiple Lines of Morphological and Stratigraphic Evidence Support Subtle Evolution and Probable Speciation Within the North American Gen...more
The Late Cretaceous dinosaur Tyrannosaurus rex was recently split into three species based on the premise that variation in the T. rex hypodigm is exceptional, indicating cryptic species and “robust” and “gracile” morphs. The morphs are... more
The Late Cretaceous dinosaur Tyrannosaurus rex was recently split into three species based on the premise that variation in the T. rex hypodigm is exceptional, indicating cryptic species and “robust” and “gracile” morphs. The morphs are based on proportional ratios throughout the skeleton. The species are claimed to be stratigraphically separate, with an early robust species followed by robust and gracile descendants. There are problems with the hypothesis: the taxon diagnoses are based on two features that overlap between the species; several skulls cannot be identified based on the diagnoses; proportional comparisons between Tyrannosaurus and other theropods are based on incomparable samples; the tooth data are problematic; the stratigraphic framework divides the Hell Creek Formation into thirds, without the stratigraphic position of each specimen, or independent age control showing the subdivisions are coeval over the entire geographic area; previous work found variation in T. re...
Research Interests:
Intensifying macrovertebrate reconnaissance together with refined age-dating of mid-Cretaceous assemblages in recent decades is producing a more nuanced understanding of the impact of the Cretaceous Thermal Maximum on terrestrial... more
Intensifying macrovertebrate reconnaissance together with refined age-dating of mid-Cretaceous assemblages in recent decades is producing a more nuanced understanding of the impact of the Cretaceous Thermal Maximum on terrestrial ecosystems. Here we report discovery of a new early-diverging ornithopod, Iani smithi gen. et sp. nov., from the Cenomanian-age lower Mussentuchit Member, Cedar Mountain Formation of Utah, USA. The single known specimen of this species (NCSM 29373) includes a well-preserved, disarticulated skull, partial axial column, and portions of the appendicular skeleton. Apomorphic traits are concentrated on the frontal, squamosal, braincase, and premaxilla, including the presence of three premaxillary teeth. Phylogenetic analyses using parsimony and Bayesian inference posit Iani as a North American rhabdodontomorph based on the presence of enlarged, spatulate teeth bearing up to 12 secondary ridges, maxillary teeth lacking a primary ridge, a laterally depressed maxil...
Research Interests:
Figure 4. High iron diamine (HID) staining of demineralized CB and MB. (A) Low, and (B) high magnification of chicken femur showing deposition of darkly staining MB on pre-existing CB. (C) low, and (D) high magnification of ostrich... more
Figure 4. High iron diamine (HID) staining of demineralized CB and MB. (A) Low, and (B) high magnification of chicken femur showing deposition of darkly staining MB on pre-existing CB. (C) low, and (D) high magnification of ostrich femoral MB. Similar to the pattern seen using Alcian blue (Fig. 3), the distribution of MB is less distinct but can be chemically differentiated from pre-existing CB in a more mixed fashion. CB from T. rex femur in low (E) and high (F) magnification shows slight staining, as seen in modern samples, but staining is much more pronounced in T. rex MB in low (G) and higher (H) magnifications. Scale bars as indicated.
Figure 5. Immunochemical staining of bone using monoclonal antibodies raised against the sulfated glycosaminoglycan keratan sulfate. (A,C,E,G,I,K,M,O) are overlay images showing tissue and localized binding; (B,D,F,H,},L,N,P) are... more
Figure 5. Immunochemical staining of bone using monoclonal antibodies raised against the sulfated glycosaminoglycan keratan sulfate. (A,C,E,G,I,K,M,O) are overlay images showing tissue and localized binding; (B,D,F,H,},L,N,P) are fluorescent images using FITC label. Chicken CB (A,B) shows no binding; chicken MB (C,D) shows positive staining, with green fluorescent signal representing antibody-antigen complexes, arranged in globular clusters. Similarly, ostrich femoral CB (E,F) does not bind antibodies, but ostrich MB (G,H) is positive for binding using the same data collection parameters. T. rex CB (I,}), does not show evidence of localized antibody binding, but sections of isolated MB (K,L) show localized specific binding to antibodies in a globular pattern, as seen in the chicken. (M,N) cortical region of tarsometatarsus and (O,P) internal (medullary) region of chicken genetically diagnosed with avian osteopetrosis (Materials and Methods) exposed to anti-keratan sulfate antibodies...
Figure 3. Alcian blue histochemical stain capitalizes on the differential presence of sulfated glycosaminoglycans found in MB vs CB. Low (A) and high (B) magnification of demineralized, sectioned bone from a laying hen femur show MB... more
Figure 3. Alcian blue histochemical stain capitalizes on the differential presence of sulfated glycosaminoglycans found in MB vs CB. Low (A) and high (B) magnification of demineralized, sectioned bone from a laying hen femur show MB (black arrows), forming along the borders of CB. Alcian blue stains MB intensely, but only lightly stains CB and TB, reflecting the differences in matrix composition. MB is shown to form around ovate vacancies that may represent vessels (red arrowheads). MB is sometimes found as islands within spicules of TB or CB (yellow arrows), possibly representing centripetal infilling of pre-existing vessel channels or erosion rooms with forming MB. Ostrich (C), shown at a lower magnification to encompass internal-most cortical bone and developing spicules of MB. The developmental pattern differs from that of chicken, reflecting macroscopic differences seen in hand sample, where MB and CB are not distinct, but more gradational in nature. Forming MB (black arrows) c...
Figure 1. Morphological differentiation between MB and CB. (A) Mid shaft section from reproductively active laying hen femur shows textural differences between CB and MB. (B) more proximal region of hen femur shows that trabecular bone... more
Figure 1. Morphological differentiation between MB and CB. (A) Mid shaft section from reproductively active laying hen femur shows textural differences between CB and MB. (B) more proximal region of hen femur shows that trabecular bone (T) can be differentiated from MB in hand sample, and that MB is deposited between trabeculae, infilling trabecular spaces. (C) MB in hand sample of ostrich femur appears to grade from CB, but can be differentiated by color and spiculation, as well as the presence of large erosion rooms (ER, arrows) at the boundary between layers. Infilling of erosion rooms with crystalline MB is also seen (*). (D) Ground section of ostrich at higher magnification shows clear separation of MB and CB. Bone fragment of MOR 1125 femur in (E) cross section and (F) medial, or medullary face orientation shows both textural and color differences between CB and MB, as well as the distinct separation between bone types. (G) Transverse section of MOR 1125 whole femur, showing a...
Table S3. Comparison of the distributions of MB and pneumaticity in the stylopod of all studied specimens. The presence (â ) or absence (X) of osteological pneumatic features on the proximal epiphyses of the humerus and femur was recorded... more
Table S3. Comparison of the distributions of MB and pneumaticity in the stylopod of all studied specimens. The presence (â ) or absence (X) of osteological pneumatic features on the proximal epiphyses of the humerus and femur was recorded for each sampled specimen and confronted to the dataset on the presence (â ) or absence (X) of MB in these elements. Conflicting results are highlighted in red. (XLS 52 kb)
Research Interests:
Figure S1. Virtual longitudinal section of the femur of Phaethon rubricauda (USNM-631988). MB fills up most of the medullary cavity, as well as inter-trabecular spaces in both epiphyses. (JPG 486 kb)
Research Interests:
Table S1. Dataset comprising information on 1) the 40 specimens sampled; 2) their skeletal distribution of MB. The presence (√) or absence (X) of MB was recorded in 19 skeletal elements / regions representing most of the bird skeleton... more
Table S1. Dataset comprising information on 1) the 40 specimens sampled; 2) their skeletal distribution of MB. The presence (√) or absence (X) of MB was recorded in 19 skeletal elements / regions representing most of the bird skeleton (manual phalanges nor included in the present study); 3) the history traits and ecology of the sampled species. See Material and Methods section for institutional abbreviations. (XLS 88 kb)
Research Interests:
Table S6. Subsample of specimens used for destructive analyses (petrographic and paraffin thin-sections, and chemical staining). (XLS 32 kb)
Research Interests:
Table S5. List of ÎźCT scans used in the present study. All ÎźCT scans are available in the MorphoSource repository, under the project # P640 at https://www.morphosource.org/Detail/ProjectDetail/Show/project_id/640 [89]. (XLS 60 kb)
Research Interests:
Figure S2. Virtual cross-sections of limb bones in four different bird species. A: Limnodromus griseus (TMM-M8889). MB is present in the medullary cavities of all figured skeletal elements, including the humeri; B: Ptilinopus melanospilus... more
Figure S2. Virtual cross-sections of limb bones in four different bird species. A: Limnodromus griseus (TMM-M8889). MB is present in the medullary cavities of all figured skeletal elements, including the humeri; B: Ptilinopus melanospilus (TMM-M11422). In this specimen, MB is not present in the humeri, carpometacarpi, and tarsometatarsi. As in all other specimens, MB has a granular aspect, while soft tissues appear smooth. Both femora show an unusual and very dense endosteal bone tissue (probably pathological) that fills up part of the medullary cavity, but is easily distinguishable from the neighboring MB; C: Colinus virginianus (TMM-M6536). In this specimen, MB is not present in the humeri, carpometacarpi, and tarsometatarsi. One ulna presents a pathology, with a periosteal pathological bone tissue and an endosteal pathological bone tissue that is clearly distinguishable from MB, based on mineralization rate and microstructure; D: Lonchura punctulata (TMM-M6977). MB is present in ...
Research Interests:
Major evolutionary transitions, in which animals develop new body plans and adapt to dramatically new habitats and lifestyles, have punctuated the history of life. The origin of cetaceans from land-living mammals is among the most famous... more
Major evolutionary transitions, in which animals develop new body plans and adapt to dramatically new habitats and lifestyles, have punctuated the history of life. The origin of cetaceans from land-living mammals is among the most famous of these events. Much earlier, during the Mesozoic Era, many reptile groups also moved from land to water, but these transitions are more poorly understood. We use computed tomography to study changes in the inner ear vestibular system, involved in sensing balance and equilibrium, as one of these groups, extinct crocodile relatives called thalattosuchians, transitioned from terrestrial ancestors into pelagic (open ocean) swimmers. We find that the morphology of the vestibular system corresponds to habitat, with pelagic thalattosuchians exhibiting a more compact labyrinth with wider semicircular canal diameters and an enlarged vestibule, reminiscent of modified and miniaturized labyrinths of other marine reptiles and cetaceans. Pelagic thalattosuchia...
Research Interests:
Research Interests:
Research Interests:
The Kaiparowits Basin Project was initiated in 2000 in order to explore Upper Cretaceous deposits preserved within Grand Staircase-Escalante National Monument. In particular, emphasis has been placed on excavation and study of... more
The Kaiparowits Basin Project was initiated in 2000 in order to explore Upper Cretaceous deposits preserved within Grand Staircase-Escalante National Monument. In particular, emphasis has been placed on excavation and study of macrovertebrates from two Campanian-aged units—the Kaiparowits and Wahweap formations. Results to date have been abundant and spectacular, with multiple new vertebrate taxa recovered. Significant finds include diagnostic remains of dinosaurs that more than double the known diversity of ...