Dinosaurs

An extremely well-preserved dinosaur ( Cf. Edmontosaurus sp.) found in the Hell Creek Formation (Upper Cretaceous, North Dakota) retains soft-tissue replacement structures and associated organic compounds. Mineral cements precipitated in the skin apparently follow original cell boundaries, partially preserving epidermis microstructure. Infrared and electron microprobe images of ossified tendon clearly show preserved mineral zonation, with silica and trapped carbon dioxide forming thin linings on Haversian canals within apatite. Furthermore, Fourier transform infrared spectroscopy (FTIR) of materials recovered from the skin and terminal ungual phalanx suggests the presence of compounds containing amide groups. Amino acid composition analyses of the mineralized skin envelope clearly differ from the surrounding matrix; however, intact proteins could not be obtained using protein mass spectrometry. The presence of endogenously derived organics from the skin was further demonstrated by p...

Ticks are currently among the most prevalent blood-feeding ectoparasites, but their feeding habits and hosts in deep time have long remained speculative. Here, we report direct and indirect evidence in 99 million-year-old Cretaceous amber showing that hard ticks and ticks of the extinct new family Deinocrotonidae fed on blood from feathered dinosaurs, non-avialan or avialan excluding crown-group birds. A †Cornupalpatum burmanicum hard tick is entangled in a pennaceous feather. Two deinocrotonids described as †Deinocroton draculi gen. et sp. nov. have specialised setae from dermestid beetle larvae (hastisetae) attached to their bodies, likely indicating cohabitation in a feathered dinosaur nest. A third conspecific specimen is blood-engorged, its anatomical features suggesting that deinocrotonids fed rapidly to engorgement and had multiple gonotrophic cycles. These findings provide insight into early tick evolution and ecology, and shed light on poorly known arthropod-vertebrate inte...

Dracorex was a dinosaur of the family Pachycephalosauridae, that lived during the Late Cretaceous of North America. The type (and only) species is Dracorex hogwartsia, meaning "dragon king of Hogwarts".
It is known from one nearly complete skull (the holotype TCMI 2004.17.1), as well as four cervical vertebrae including the atlas, third, ninth and eighth. These were discovered in the Hell Creek Formation in South Dakota by three amateur paleontologists from Sioux City, Iowa. The skull was subsequently donated to the Children's Museum of Indianapolis for study in 2004, and was formally described by Bob Bakker and Robert Sullivan in 2006.

Dracorex, a herbivore, had a skull with spiky horns, bumps, and a long muzzle. The species also sports well-developed supratemporal fenestrae and a heavily-armored flat skull – lacking the characteristic pachycephalosaurid dome. Coupled with these two features is the excessive number of osteoderms in the form of irregular osteodermal crust: a number of nodes, larger hornlets, and spikes. Disregarding this, Dracorex is physically comparable to Stygimoloch. In the Pachycephalosauridae family, the Asian taxa includes a number of (somewhat) flat-headed pachycephalosaurs (Homalocephale calat'hocercos, Goyocephale lattimorei, and Wannanosaurus yansiensis). However, prior to the discovery of Dracorex, the only semi-flat-headed pachycephalosaur from North America was Stegoceras validum (inclusive of Ornatotholus' browni). Even then, the semi-flat-headed trait was only present in juveniles of the species.

Aside from having a flat, nodal skull, the most prominent feature of Dracorex is the pair of huge and unrestricted superior temporal openings. The supratemporal fenestrae are much larger front-to-back and side-to-side than in Homalocephale, and larger than in Goyocephale. Only a fragmentary Wannanosaurus skull shows fenestrae as large as those of Dracorex. This fenestral architecture has been seen in ancient archosaurs, but not in other pachycephalosaurs.

Consequently, if unreduced superior fenestrae are morphologically primitive, then Dracorex is more primitive in the temporal region than any other known pachycephalosaur. However, Sullivan (2003, 2006) demonstrated that the oldest known pachycephalosaurs were, in fact, fully-domed, and that the flat-headed morphology appeared later in the fossil record. This suggests that doming may be primitive for pachycephalosaurs and that a reversion to the non-domed, flat-headed state is a secondary (derived) character reversion, coupled with the re-opening of the supratemporal fenestrae. Indeed, while Stegoceras has been considered to be transitional between domed and flat-headed taxa, it may indicate the beginning of a character reversion to suppression of doming and opening of the supratemporal fenestrae in some taxa.

The excavated specimen was most likely a young adult. However, based on ossification of the mid-cervical arch with the centrum, it was near maturity. The animal was approximately 10 feet (3 m) long.

However, at the 2007 annual meeting of the Society of Vertebrate Paleontology, Jack Horner of Montana State University presented evidence, from analysis of the skull of holotype specimen TCMI 2004.17.1, that Dracorex may well be a juvenile form of Pachycephalosaurus.

Classification
In the original description, Bob Bakker included Dracorex in the family Pachycephalosauridae within the subfamily Pachycephalosaurinae. In the latter in the Pachycephalosaurini tribe together with Pachycephalosaurus forming a clearing next to Stygimoloch . To carry out the analysis of the relationships between the genders, he observed the differences in cranial ornamentation.

In a comprehensive study of numerous fossils of Pachycephalosaurus published in 2009, John R. Horner and Mark B. Goodwin , a strong variation warn ontogenetic of the skull : large morphological differences between juveniles and adults. For them, the flat Dracorex skull , the nodules at the front end, the small spines at the back, and the thick but non-dome-shaped frontoparietal, indicate that the only known specimen is a juvenile Pachycephalosaurus

Alternative interpretation
Dracorex may be a closely related individual of Stygimoloch and / or Pachycephalosaurus in which the cupola and horns are not well developed either because the animal was a juvenile or a female. This consideration was supported at the 2007 annual meeting of the Society of Vertebrate Paleontology.

Jack Horner from Montana State University presented evidence, from analysis of the skull of the only extant specimen of Dracorex , that this dinosaur could be a juvenile form of Stygimoloch . In addition, he presented data indicating that both Stygimoloch and Dracorex may be juvenile forms ofPachycephalosaurus . Horner and MB Goodwin published their findings in 2009, showing that the spine / nodule bones and cranial domes of all three species' exhibit extreme plasticity and that both Dracorex and Stygimoloch are known only from juvenile specimens, while Pachycephalosaurus is only known from specimens. Adults". These observations, plus the fact that all three forms lived at the same time and place, lead them to conclude that Dracorex and Stygimoloch may have simply been juvenile Pachycephalosaurs that had lost their spines and developed domes as they aged. The researchers were unable to break out Dracorex's skull to sample it,  and had to use a cast of the skull for descriptive purposes.
A 2010 study by Nick Longrich and colleagues also supported the hypothesis that all flat-headed pachycephalosaurus were juveniles, suggesting that flat-domed forms, such as Goyocephale and Homalocephale , represent the juveniles of domed adults. 
In 2016, Goodwin and Evans analyzed the youngest known ontogimorphs of Pachycephalosaurus , collected from the Hell Creek Formation. While this material would normally refer to DracorexSince it represented one or more individuals younger than the only known Dracorex individual and displayed similar characteristics, the items showed that the unique characters in Dracorex and Stygimoloch represent morphological characters consisting of a morphological continuum for Pachycephalosaurus . In other words, these younger individuals showed that Dracorex characteristics were probably transient and can be easily traced on a growth curve to Pachycephalosaurus , where Stygimoloch and Dracorex are incorporated into this genus. As such, DracorexIt is probably not a single species, but a more modern synonym for Pachycephalosaurus .
This study has not been challenging and represents the most recent analysis of this genre. In conclusion, an ontogenetic relationship is established, being infantile, juvenile and adult individuals of the same species, between Dracorex hogwartsia , Stygimoloch spinifer and Pachycephalosaurus wyomingensis , the latter being the bearer of the valid species name, as it is the first of the three to be described.

Name
The name Dracorex hogwartsia was inspired by young visitors to the Children's Museum of Indianapolis as a tribute to both dragons (Dracorex means "dragon king"), which the animal resembled, as well as the Harry Potter series of books by J.K. Rowling (hogwartsia for the Hogwarts School of Witchcraft and Wizardry, the fictional school from the popular series).

References
^ Bakker, R. T., Sullivan, R. M., Porter, V., Larson, P. and Saulsbury, S.J. (2006). "Dracorex hogwartsia, n. gen., n. sp., a spiked, flat-headed pachycephalosaurid dinosaur from the Upper Cretaceous Hell Creek Formation of South Dakota." in Lucas, S. G. and Sullivan, R. M., eds., Late Cretaceous vertebrates from the Western Interior. New Mexico Museum of Natural History and Science Bulletin 35, pp. 331–345. [1]
^ Erik Stokstad,"SOCIETY OF VERTEBRATE PALEONTOLOGY MEETING:Did Horny Young Dinosaurs Cause Illusion of Separate Species?", Science Vol. 18, 23 Nov. 2007, p. 1236; http://www.sciencemag.org/cgi/content/full/318/5854/1236.

This is the final chapter of my book tentatively entitled >Dinomania: Why We Love, Fear, and are Utterly Enchanted by Dinosaurs<, which is to be published by Reaktion Books in London. It discusses how dinosaurs mark a limit to our tendency to anthropocentrism, since we center the story of evolution around them, far more than about our biological ancestors. It also endeavors to sum up many themes of the book. I would be grateful for any perspective. Thank you very much for looking.

A comprehensive analysis of early dinosaur relationships raised the possibility that the group may have originated in Laurasia (Northern Hemisphere), rather than Gondwana (Southern Hemisphere) as often thought. However, that study focused solely on morphology and phylogenetic relationships and did not quantitatively evaluate this issue. Here, we investigate dinosaur origins using a novel Bayesian framework uniting tip-dated phylogenetics with dynamic, time-sliced biogeographic methods, which explicitly account for the age and locality of fossils and the changing interconnections of areas through time due to tectonic and eustatic change. Our analysis finds strong support for a Gondwanan origin of Dinosauria, with 99 % probability for South America (83 % for southern South America). Parsimony analysis gives concordant results. Inclusion of time-sliced biogeographic information affects ancestral state reconstructions (e.g., high connectivity between two regions increases uncertainty over which is the ancestral area) and influences tree topology (disfavouring uniting fossil taxa from localities that were widely separated during the relevant time slice). Our approach directly integrates plate tectonics with phylogenetics and divergence dating, and in doing so reaffirms southern South America as the most likely area for the geographic origin of Dinosauria. Dinosaurs are one of the most charismatic and heavily studied groups of vertebrates (e.g., Sereno 1999), but despite ongoing work and many recent discoveries, certain aspects of early dinosaurian evolution remain unclear. A recent study of early dinosaur relationships presented a new phylogeny that departs radically from existing models, but forms a broader framework for inferring dinosaur evolutionary history than those that were previously available (Baron et al. 2017a). While that study was focused primarily on early dinosaurian anatomy and relationships, a general observation was made: based upon the geographic locations of key taxa in their phylogeny, a Laurasian setting for dinosaur origin may have been plausible. This proposal ran contrary to an established consensus based on earlier phylogenies that favoured a Gondwanan and, more specifically, South American setting for this event (Nesbitt et al. 2009; Brusatte et al. 2010; Langer et al. 2010; Sues et al. 2011; Boyd 2015). In particular, the European presence of silesaurids, a close outgroup to dinosaurs, and some early dinosaur taxa (e.g., Saltopus) hinted that northern Pangaea may have played an important role in the earliest stages of dinosaur diversification. However, given the space limitations associated with the original article, no quantitative analyses were carried out to evaluate this alternative hypothesis rigorously. Here, we test the alternative hypothesis implicit in Baron et al. (2017a) by analysing their early dinosaur dataset using a novel integration of time-sliced Bayesian biogeographic models (Landis 2016) and tip-dated Bayesian phylogenetics (Drummond et al. 2012; Bielejec et al. 2014; Gavryushkina et al. 2017). The current method simultaneously estimates phylogenetic relationships, divergence dates, evolutionary rates and biogeographic patterns. Biogeographical changes are inferred using models that account for the changing relationships of continents (and thus dispersal abilities) over time-a 'chronobiogeographical' paradigm (Hunn & Upchurch 2001)-and this information provides potentially critical information for improving estimates of tree topology and divergence dates. For comparison, we also perform analogous analyses using traditional biogeographic parsimony-based methods. Previous studies have advocated a similar approach to integrating phylogeny, stratigraphy, morphology and bio-geography in a parsimony framework (reviewed in Rossie & Seiffert 2006). However, that implementation was problematic: as parsimony trees lack an explicit time element, only very simple time-sliced biogeographic models were possible (e.g., three areas and three time slices) and tree topology and divergence dates had to be assessed manually. The analyses attempted here tackle this complex multidimensional problem more efficiently , using explicit Bayesian computational approaches.

Abstract Sauropod dinosaurs were the largest terrestrial
herbivores and pushed at the limits of vertebrate biomechanics
and physiology. Sauropods exhibit high craniodental
diversity in ecosystems where numerous species coexisted,
leading to the hypothesis that this biodiversity is
linked to niche subdivision driven by ecological specialisation.
Here, we quantitatively investigate feeding behaviour
hypotheses for the iconic sauropod Diplodocus. Biomechanical
modelling, using finite element analysis, was used to
examine the performance of the Diplodocus skull. Three
feeding behaviours were modelled: muscle-driven static biting,
branch stripping and bark stripping. The skull was found to be
‘over engineered’ for static biting, overall experiencing low
stress with only the dentition enduring high stress. When
branch stripping, the skull, similarly, is under low stress, with
little appreciable difference between those models. When simulated for bark stripping, the skull experiences far greater
stresses, especially in the teeth and at the jaw joint. Therefore,
we refute the bark-stripping hypothesis, while the hypotheses
of branch stripping and/or precision biting are both
consistent with our findings, showing that branch stripping
is a biomechanically plausible feeding behaviour
for diplodocids. Interestingly, in all simulations, peak
stress is observed in the premaxillary–maxillary ‘lateral
plates’, supporting the hypothesis that these structures
evolved to dissipate stress induced while feeding. These
results lead us to conclude that the aberrant craniodental
form of Diplodocus was adapted for food procurement
rather than resisting high bite forces.

Iridescent feather colors involved in displays of many extant birds are produced by nanoscale arrays of melanin-containing organelles (melanosomes). Data relevant to the evolution of these colors and the properties of melanosomes involved in their generation have been limited. A data set sampling variables of extant avian melanosomes reveals that those forming most iridescent arrays are distinctly narrow. Quantitative comparison of these data with melanosome imprints densely sampled from a previously unknown specimen of the Early Cretaceous feathered Microraptor predicts that its plumage was predominantly iridescent. The capacity for simple iridescent arrays is thus minimally inferred in paravian dinosaurs. This finding and estimation of Microraptor feathering consistent with an ornamental function for the tail suggest a centrality for signaling in early evolution of plumage and feather color.

Ever wanted to travel around the world? Well, the Wildlife of Gondwana exhibition certainly has! After 20 years of captivating and educating people about the many millions of years of Australia’s unique fauna and flora, this exhibition will find its final home in the Australian Age of Dinosaurs (AAOD) Museum of Natural History in Winton, Queensland.

Non-avian dinosaurs went extinct 66 million years ago, geologically coincident with the impact of a large bolide (comet or asteroid) during an interval of massive volcanic eruptions and changes in temperature and sea level. There has long been fervent debate about how these events affected dinosaurs. We review a wealth of new data accumulated over the past two decades, provide updated and novel analyses of long-term dinosaur diversity trends during the latest Cretaceous, and discuss an emerging consensus on the extinction’s tempo and causes. Little support exists for a global, long-term decline across non-avian dinosaur diversity prior to their extinction at the end of the Cretaceous. However, restructuring of latest Cretaceous dinosaur faunas in North America led to reduced diversity of large-bodied herbivores, perhaps making communities more susceptible to cascading extinctions. The abruptness of the dinosaur extinction suggests a key role for the bolide

Tyrannosaurs, the group of dinosaurian carnivores that includes Tyrannosaurus rex and its closest relatives, are icons of prehistory. They are also the most intensively studied extinct dinosaurs, and thanks to large sample sizes and an influx of new discoveries, have become ancient exemplar organisms used to study many themes in vertebrate paleontology. A phylogeny that includes recently described species shows that tyrannosaurs originated by the Middle Jurassic but remained mostly small and ecologically marginal until the latest Cretaceous. Anatomical, biomechanical, and histological studies of T. rex and other derived tyrannosaurs show that large tyrannosaurs could not run rapidly, were capable of crushing bite forces, had accelerated growth rates and keen senses, and underwent pronounced changes during ontogeny. The biology and evolutionary history of tyrannosaurs provide a foundation for comparison with other dinosaurs and living organisms.

Feathers are stunning embellishments that stand out in avian history, a curious detail that has sparked great debate regarding origin and evolution, and as per Prum (1999, p. 291) a “complex
evolutionary novelty”. They are necessary for flight, warmth, camouflage, sexual selection (Prum, 1999) and even communication (Li et al., 2010). They are essential to overall survival of a species: one which has evolved over hundreds of millions of years, but how similar are these integumentary structures of modern birds (Neornithes) to those that covered ancestral relatives?
Protofeathers, or “dino-fuzz”, have been observed in several theropod fossils, such as Archaeopteryx lithographica (Longrich, Vinther, Meng, Li & Russell, 2012), Sinosauropteryx
(Sloan, 2010) and Anchiornis huxleyi (Longrich et al., 2012), but the specifics of their evolution is still a major point of contention for some researchers. Because research is constantly
suggesting new scenarios, hypotheses and discoveries about the evolution of feathers and flight, the range of thought varies widely. Amazingly, it’s only in the last three decades that so much new data has come to light, which means that theories are dynamic and researchers don’t always agree.

Earlymost Villafranchian fossil bones of an artiodactyl and a perissodactyl from the Milia excavation site in Grevena, Greece, were studied in order to evaluate diagenetic effects. Optical microscopy revealed the different bone types (fibro-lamellar and Haversian, respectively) of the two fragments and their good preservation state. The spatial distribution of bone apatite and soil-originating elements was studied using micro-X-ray fluorescence (µ-XRF) mapping and scanning electron microscopy. The approximate value of the Ca/P ratio was 2.2, as determined from scanning electron microscopy measurements. Bacterial boring was detected close to the periosteal region and Fe bearing oxides were found to fill bone cavities,e.g.Haversian canals and osteocyte lacunae. In the perissodactyl bone considerable amounts of Mn were detected close to cracks (the Mn/Fe weight ratio takes values up to 3.5). Goethite and pyrite were detected in both samples by means of metallographic microscopy. The lo...

Le thème des dinosaures, très attractif chez les jeunes enfants, est particulièrement intéressant à exploiter dès l'école maternelle. Ce projet interdisciplinaire, déjà expérimenté en classe de maternelle, s’appuie essentiellement sur le langage, la recherche documentaire, l’observation et la déduction.

The concept of ’natural heritage’ has become increasingly significant with the threat of dwindling resources, environmental degradation and climatic change. As humanity’s impact on the condition of life on earth has become more prominent, a discernible shift in the relationship between western society and the environment has taken place. This is reflective of wider historical processes which reveal a constantly changing association between humanity’s definition and perception of what ’nature’ constitutes or what can be defined as ’natural’. From the ornate collections of specimens which formed the basis of a distinct concept of ’nature’ emerging during the Enlightenment, this definition and the wider relationship between humanity and natural history have reflected issues of identity, place and politics in the modern era.

This book examines this process and focuses on the ideas, values and agendas that have defined the representation and reception of the history of the natural world, including geology and palaeontology, within contemporary society and addresses how the heritage of natural history, whether through museums, parks, tourist sites or popular culture is used to shape social, political, cultural and moral identities. It will be of interest to scholars and practitioners within heritage studies, public history, ecology, environmental studies and geography.

Desde Escitia a la Península Ibérica, de la Edad de Bronce -si no antes- a los primeros siglos de nuestra Era, diversos seres antropomorfos, humanos o mitológicos, han sido representados luchando contra el grifo -id est, la grifomaquia- a lo largo de milenios y kilómetros con distintos significados, muchos de los cuales aún suponen una incógnita para la arqueología...

At once reptilian and avian, dinosaurs enable us to imagine a world far beyond the usual boundaries of time, culture and physiology. We have envisioned them in diverse and contradictory ways, reflecting, in part, our changing conceptions of ourselves. Their discovery, around the start of the nineteenth century, was intimately tied to our awareness of geological time; their vast size and power called to mind railroads, battleships and factories, making dinosaurs, paradoxically, emblems of modernity. At the same time, their world was nature at its most pristine, and they simultaneously symbolized childhood innocence and wonder. Dinosaurs provided a sort of code that has enabled people to speak indirectly about the possibility of our own extinction. Not unlike humans today, dinosaurs seem both powerful – almost godly – and helpless in the face of cosmic forces even mightier than themselves.

Dinomania tells the story of our romance with the titanic saurians, from early stories that were inspired by their bones to the dinosaur theme parks of today. It concludes that, in our imaginations, dinosaurs are, and always have been, essentially dragons, and their contemporary representation is once again blending with the myth and legend from which it emerged at the start of the modern period.

La découverte de fossiles de dinosaures et d’animaux préhistoriques ne date pas de l’époque contemporaine. Répandue dans l’Antiquité, notamment en Grèce, elle a suscité de multiples interrogations, engendré des fantasmes et donné naissance à des créatures imaginaires ou extraordinaires. Parmi celles-ci, se trouvent entre autres les gryphons, les héros, caractérisés également par une taille démesurée, ou encore les Géants.