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ABSTRACTVirtual palaeontology is a growing field, leading palaeontologists to better understand the microanatomy of many extinct species. The application of techniques such as CT and μCT-scanning allows the researchers to study micro-anatomical features in a non-invasive way and make inferences on the palaeobiology of animals. Dinosaurs have been extensively studied using these techniques, with particular focus on the microanatomy of the cranium, whereas relatively little is known of other cranial elements, such as the lower jaw. Here, we aim to fill this gap, describing the microanatomy of the specimen ML 768, an isolated dentary belonging to a dryosaurid iguanodontian dinosaur from the Upper Jurassic of Lourinhã Fm. The dentary ML 768 was subjected to μCT-scanning, and subsequently the data were segmented in Avizo and rendered in Blender. We identified functional and replacement teeth, recognising remnants of old replacement cycles. Furthermore, we mapped a rich neurovascular network present in the dentary and compared it with reference literature. We found that the high vascularisation is shared with other cerapodan dinosaurs with high tooth replacement rates, although homoeostasis may have also played a role in the development of this condition. Further evidence is needed to appreciate the macroevolutionary significance of these findings.

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The material in analysis is the skull of an Ornitiquous Psittacosaurus of the China Cretaceous suspicious of being a fraud. The fossil described here appeared to be in very good condition and conservation. The skull is almost complete but because it is filled by sediment, this prevents an analyse of the intra-skull anatomy.
With the intuition of confirming or not the existence of fossiled bone elements in the interior of the sedimented mass that filled the Psittacossaurus skull, it was submitted to a Computorized Tomography.
The Psittacosaurus skull showed an unexpected absorption of the x-rays, because of the outstanding differences of density between the bone and the matrix due to the fact that the interior of the skull was composed by an amalgam of materials, where a less compact and relatively homogeneous material (soil and wax) was found and that material united and mounted the whole skull and the normal bone structures were non-existing.
The capacity of the Computorized Axial Tomography of differentiating materials with different densities of absorption of x-rays, permitted an easy and reliable investigation and explained beyond doubt the quality of the fossil specimen studied, concluding with no doubt that in spite of the realistic aspect, we had come before a fraud.

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Remains of dinosaurian embryos, hatchlings and early juveniles are currently the subject of increasing interest, as new discoveries and techniques now allow to analyse palaeobiological subjects such as growth and life history strategies of dinosaurs. So far, available ‘embryonic’ material mainly involved Ornithopods and some Theropods of Upper Cretaceous age. We describe here the histology of several bones (vertebrae, limb bones) from the tiny but exceptionally well preserved in ovo remains of Upper Jurassic Theropod dinosaurs from the Paimogo locality near Lourinhã (Portugal). This Jurassic material allows to extend in time and to considerably supplement in great details our knowledge of early phases of growth in diameter and in length of endoskeletal bones of various shape, as well as shape modelling among carnivorous dinosaurs. Endochondral ossification in both short and long bones involves extensive pads of calcified cartilages permeated by marrow buds. We discuss the likely occurrence of genuine cartilage canals in dinosaurs and of an avian-like ‘medullary cartilaginous cone’ in Theropods. Patterns of periosteal ossification suggest high initial growth rates (20 μ m·day−1 or more), at once modulated by precise and locally specific changes in rates of new bone deposition. The resulting very precise shape modelling appears to start early and to involve at once some biomechanical components.

Two new Late Jurassic (uppermost Late Kimmeridgian) dinosaur eggshell sites are described, Casal da Rola and Porto das Barcas, both near Lourinha˜, central-west Portugal. Casal da Rola yields eggshells with an obliquiprismatic morphotype comparable to those from a nest with the associated fossil embryos from Paimogo, tentatively assigned to the theropod Lourinhanosaurus antunesi. The Porto das Barcas eggshells have a dendrospherulitic morphotype with a prolatocanaliculate pore system. This morphotype was also recognised in eggshells from a clutch with associated Torvosaurus embryos at the Porto das Barcas locality. A preliminary cladistic analysis of eggshell morphology suggests theropod affinities for the Casal da Rola eggs, but is unable to resolve the phylogenetic position of the Porto das Barcas eggs. The eggshells at both sites are preserved in distal flood plain mudstones and siltstones. Carbonate concretions within the deposits indicate paleosol development.

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{We here describe an articulated partial skeleton of a small neosuchian crocodylomorph from the Lourinhã Formation (Late Jurassic, Portugal). The skeleton corresponds to the posterior region of the trunk and consists of dorsal, ventral and limb osteoderms, dorsal vertebrae, thoracic ribs and part of the left hindlimb. The paravertebral armour is composed of two rows of paired osteoderms with the lateral margins ventrally deflected and an anterior process for a ‘peg and groove’ articulation. We also compare its dermal armour with that of several Jurassic and Cretaceous neosuchian crocodylomorphs, establishing a detailed description of this type of osteoderms.These features are present in crocodylomorphs with a closed paravertebral armour bracing system. The exceptional 3D conservation of the specimen, and the performance of a micro-CT scan, allowed us to interpret the bracing system of this organism to assess if previous models were accurate. The characters observed in this specimen are congruent with Goniopholididae, a clade of large neosuchians abundant in most semi-aquatic ecosystems from the Jurassic and Early Cretaceous of Laurasia. However, its small size, contrasted with the sizes observed in goniopholidids, left indeterminate whether it could have been a dwarf or juvenile individual. Future histological analyses could shed light on this.}

A new plesiosaur partial skeleton, comprising most of the trunk and including axial, limb, and girdle bones, was collected in the lower Sinemurian (Coimbra Formation) of Praia da Concha, near São Pedro de Moel in central west Portugal. The specimen represents a new genus and species, Plesiopharos moelensis gen. et sp. nov. Phylogenetic analysis places this taxon at the base of Plesiosauroidea. Its position is based on this exclusive combination of characters: presence of a straight preaxial margin of the radius; transverse processes of mid-dorsal vertebrae horizontally oriented; ilium with sub-circular cross section of the shaft and subequal anteroposterior expansion of the dorsal blade; straight proximal end of the humerus; and ventral surface of the humerus with an anteroposteriorly long shallow groove between the epipodial facets. In addition, the new taxon has the following autapomorphies: iliac blade with less expanded, rounded and convex anterior flank; highly developed ischial facet of the ilium; apex of the neural spine of the first pectoral vertebra inclined posterodorsally with a small rounded tip. This taxon represents the most complete and the oldest plesiosaur species in the Iberian Peninsula. It is also the most complete, best preserved, and oldest marine vertebrate in the region and testifies to the incursion of marine reptiles in the newly formed proto-Atlantic sea, prior to the Atlantic Ocean floor spreading in the Early Cretaceous.

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Abstract We present the first detailed braincase anatomical description and neuroanatomical study of Portugalosuchus azenhae, from the Cenomanian (Late Cretaceous) of Portugal. This eusuchian crocodylomorph was originally described as a putative Crocodylia and one of the oldest representatives of this clade; however, its phylogenetic position remains controversial. Based on new data obtained from high resolution Computed Tomography images (by micro-CT scan), this study aims to improve the original description of this taxon and also update the scarce neuroanatomical knowledge of Eusuchia and Crocodylia from this time interval, a key period to understand the origin and evolution of these clades. The resulting three-dimensional models from the CT data allowed a detailed description of its well-preserved neurocranium and internal cavities. Therefore, it was possible to reconstruct the cavities of the olfactory region, nasopharyngeal ducts, brain, nerves, carotid arteries, blood vessels, paratympanic sinus system and inner ear, which allowed to estimate some neurosensorial capabilities. By comparison with other crocodylomorphs, these analyses showed that Portugalosuchus, back in the Cenomanian, already displayed an olfactive acuity, sight, hearing and cognitive skills within the range of that observed in other basal eusuchians and crocodylians, including extant species. In addition, and in order to test its disputed phylogenetic position, these new anatomical data, which helped to correct and complete some of the original observations, were included in one of the most recent morphology-based phylogenies. The position of Portugalosuchus differs slightly from the original publication since it is now located as a “thoracosaurid” within Gavialoidea, but still as a crocodylian. Despite all this, to better contrast these results, additional phylogenetic analyses including this new morphological character coding together with DNA data should be performed.

In this session we review the Upper Cretaceous marine amniote records from the west coasts of North America and Africa. Recent work by our group in Angola, on the west coast of Africa, has opened up new fossiliferous localities, producing well-preserved turtles, plesiosaurs, and mosasaurs, ranging in age from Late Turonian to Late Maastrichtian. These African localities were deposited in arid latitudes and highly productive upwelling zones along the passive margin of a growing South Atlantic Ocean. The fossil record of Cretaceous marine amniotes from the West Coast of North America is relatively meager when compared to the African record and the prolific fossil beds laid down in the epicontinental seas of the Western Interior Seaway and northern Europe. Nonetheless, these localities provide an important glimpse of a marine ecosystem that developed on the active margins of a deep ocean basin. Historically considered to be depauperate and endemic, the west coast fauna was characterized by unusual forms such as Plotosaurus, arguably one of the most derived mosasaurs; however, in recent years, additional taxa have been described, revealing species diversity and ecological partitioning within these communities and in some cases, faunal interchange with other regions. The large quantity of well-preserved fossils from the west coast of Africa is influenced in part by its paleogeographic position, deposited within highly productive areas of Hadley Cell controlled upwelling zones. By contrast, the North American west coast localities have been deposited in temperate and higher latitudes since the Late Cretaceous. Nonetheless, the North American and African faunas share some common characteristics in a possessing a mix of endemic and more cosmopolitan forms. Habitat partitioning reflected in tooth form and body size is comparable between the Angolan and the North American west coast, and there is remarkable convergence in taxa which appear to exploit certain like-niches.

Recent fieldwork in the Namibe province in southern Angola yielded cranial and postcranial elements of at least two individuals of the rare and enigmatic mosasaur Halisaurus from a single small excavation. The genus Halisaurus is unique in retaining a primitive configuration of the temporal arcade, specifically a broad, vertically oriented contact between the parietal and the supratemporal. The supratemporal is broadly sutured to the opisthotic and prootic, unlike the condition in varanoids in which the simple lunate element lies between the parietal ramus and the squamosal and does not form a sutural contact with the opisthotic or prootic, but as in other halisaurines retains a plesiomorphic, vertically oriented contact with the parietal rami. The squamosal is lightly built and broadly arched as in Varanus. Comparison with known halisaurines indicates the new material is referable to the species Halisaurus arambourgi.
The locality that yielded the new specimens has also yielded a large number of isolated teeth, bones, articulated, and associated skeletons of Mosasaurus, Prognathodon, Globidens, and Plioplatecarpus, which with Halisaurus comprise a mosasaur assemblage most similar to that reported from the Maastrichtian of Morocco.

Mosasaurs are marine squamates with a 32.5 million-year history from their appearance at 98 Ma to their extinction at the K-Pg boundary (65.5 Ma). Using a database of 43 generic and 94 species-level taxa, we compare the taxonomic diversity and patterns of morphological disparity in mosasaurs with sea level, sea surface temperature, and stable carbon isotope curves for the Upper Cretaceous to explore factors that may have influenced their evolution. No single factor unambiguously accounts for all radiations, diversification, and extinctions; however, the broader patterns of taxonomic diversification and
morphological disparity point to niche differentiation in a “fishing up” scenario under the influence of “bottom-up” selective pressures. The most likely driving force in mosasaur evolution was high productivity in the Late Cretaceous, driven by tectonically controlled sea levels and climatically controlled ocean stratification and nutrient delivery. When productivity collapsed at the end of the Cretaceous, coincident with bolide impact, mosasaurs became extinct.

Although occurrences of marine reptiles have been previously reported from Angola, with the exception of two Turonian taxa, these reports were based largely on isolated teeth. Fieldwork in 2005 and 2006 yielded well-preserved remains of marine reptiles including plesiosaurs, turtles, and mosasaurs. The mosasaurs discussed here were recovered from two field areas: Turonian sediments at Iembe along the north coast and Maastrichtian sediments at Bentiaba on the south coast. The Turonian section near Iembe produced at least two new specimens of Angolasaurus bocagei and one fragmentary specimen of Tylosaurus iembeensis. One of the Angolasaurus specimens is represented by a well preserved, complete and articulated skull and partial postcrania, including portions of the forelimbs and pectoral girdle. The preservation of material from the Bentiaba locality is remarkable due to the grain support of the entombing sandstone, which preserves fine anatomical details with little apparent crushing, and in the number of articulated, semi-articulated, and associated skeletons. Identifications from the field and preliminary preparation show the Bentiaba mosasaur fauna is represented by at least five genera including Mosasaurus, Prognathodon, Globidens, Plioplatecarpus and Halisaurus. Collectively, these new specimens greatly expand our knowledge of the anatomy and systematics of Angolan mosasaurs.

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In this session we review the Upper Cretaceous marine amniote records from the west coasts of North America and Africa. Recent work by our group in Angola, on the west coast of Africa, has opened up new fossiliferous localities, producing well-preserved turtles, plesiosaurs, and mosasaurs, ranging in age from Late Turonian to Late Maastrichtian. These African localities were deposited in arid latitudes and highly productive upwelling zones along the passive margin of a growing South Atlantic Ocean. The fossil record of Cretaceous marine amniotes from the West Coast of North America is relatively meager when compared to the African record and the prolific fossil beds laid down in the epicontinental seas of the Western Interior Seaway and northern Europe. Nonetheless, these localities provide an important glimpse of a marine ecosystem that developed on the active margins of a deep ocean basin. Historically considered to be depauperate and endemic, the west coast fauna was characterized by unusual forms such as Plotosaurus, arguably one of the most derived mosasaurs; however, in recent years, additional taxa have been described, revealing species diversity and ecological partitioning within these communities and in some cases, faunal interchange with other regions. The large quantity of well-preserved fossils from the west coast of Africa is influenced in part by its paleogeographic position, deposited within highly productive areas of Hadley Cell controlled upwelling zones. By contrast, the North American west coast localities have been deposited in temperate and higher latitudes since the Late Cretaceous. Nonetheless, the North American and African faunas share some common characteristics in a possessing a mix of endemic and more cosmopolitan forms. Habitat partitioning reflected in tooth form and body size is comparable between the Angolan and the North American west coast, and there is remarkable convergence in taxa which appear to exploit certain like-niches.