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Sousa, J., & Mateus O. (2018).  A review of Ichthyosauria from Portugal. XVI Annual Meeting of the European Association of Vertebrate Palaeontologists. 179., Caparica, Portugal June 26th-July 1st, 2018 Abstractsousa_e_mateus_2018_eavp_abstract.pdf

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Smith, A., Araújo R., & Mateus O. (2010).  A plesiosauroid skull from the Toarcian (Lower Jurassic) of Alhadas, Portugal. 70th Annual Meeting of the Society of Vertebrate Paleontology. 166A., October 10 - 13t, Pittsburgh, Pennsylvania, USA Abstractsmith_araujo__mateus_2010_plesiosauroid_skull_toarcian_jurassic_alhadas_portugal_svp10abstracts.pdf

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Smith, A. S., Araújo R., & Mateus O. (2012).  A new plesiosauroid from the Toarcian (Lower Jurassic) of Alhadas, Portugal. Acta Palaeontologica Polonica. 57(2), 257–266., Jan Abstractsmith__araujo__mateus_2012_a_new_plesiosauroid_from_the_toarcian_lower_jurassic_of_alhadas_portugal.pdf

A partial plesiosauroid skull from the São Gião Formation (Toarcian, Lower Jurassic) of Alhadas, Portugal is re−evaluated and described as a new taxon, Lusonectes sauvagei gen. et sp. nov. It has a single autapomorphy, a broad triangular parasphenoid cultriform process that is as long as the posterior interpterygoid vacuities, and also a unique character combination, including a jugal that contacts the orbital margin, a distinct parasphenoid–basisphenoid suture exposed between the posterior interpterygoid vacuities, lack of an anterior interpterygoid vacuity, and striations on the ventral surface of
the pterygoids. Phylogenetic analysis of Jurassic plesiosauroids places Lusonectes as outgroup to “microcleidid elasmosaurs”, equivalent to the clade Plesiosauridae. Lusonectes sauvagei is the only diagnostic plesiosaur from Portugal, and the westernmost occurrence of any plesiosaurian in Europe.

Smith, A. S., Araújo R., & Mateus O. (2012).  A new plesiosauroid from the Toarcian (Lower Jurassic) of Alhadas, Portugal. Acta Palaeontologica Polonica. 57, 257-266., Number 2 Abstract
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Silva, T., Costa F., Fernandes J., Calvo R., & Mateus O. (2016).  The use of a portable X-ray fluorescence analyzer in the reconstitution of dinosaur fossils. European Conference on X-Ray Spectrometry. , June 19 – 24, 2016, Gothenburg, Sweden Abstract
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Silva, T., Costa F., Fernandes J., Calvo R., & Mateus O. (2016).  The use of a portable X-ray fluorescence analyzer in the reconstitution of dinosaur fossils. , 7: European Conference on X-Ray Spectrometry (EXRS) Abstract

Portable X-ray fluorescence spectrometers (p-XRF) have been used in many fields of application/studies like art, archaeology, heavy metals in soil, rocks and ores characterization, and have been a powerful tool for a rapid non-destructive in-situ analysis, without any sample preparation required. This approach was applied in the present case, to distinguish the origin of the fossil bones of two dinosaur specimens from different localities that were accidentally put together in the museum a few years ago. Fossil bones with sedimentary matrix associated were stored together until today in the collection of Geological Museum (Lisbon) and regarded as one single specimen. One set of bones is part of the holotype MG 5787 of the ankylosaur Dracopelta zbyszweskii, which was discovered at Praia do Sul, and described in 1980, while the other, is an undescribed half skeleton of dacentrurine stegosaur, unearthed in the 1960’s at Atouguia da Baleia, near Peniche (both in the coast of central Portugal, distanced about 100 km from each other). Since both specimens are highly valuable for paleontology, a study was developed with the aim of separating and reconstituting the two specimens. The handheld p-XRF (Genius 9000+7000 from Skyray Instrument) was directly used in the sedimentary matrix when it was separated from the bone, and the measure of the chemical content was performed in the intermediate layer between the surface and the bone, to avoid contaminations. Although the light elements could not be attained, because the analyzer is not equipped with the option of gas charging system, the spectra obtained showed differences mainly in the ratio K/Ca, allowing distinguishing the provenance of the bones (Atouguia or Praia do Sul). These results were compared with chemical analysis obtained with XRF laboratorial equipment and complemented by the mineralogical study through X-ray diffraction (XRD) of the sediments where the bones fossilized. The difference observed in the mineralogical constitution of the sedimentary matrix from the two localities (mainly quartz, calcite, feldspars and micas with variable content) explains the variation in the values found for the ratio K/Ca (<0.5 for Atouguia and >>1 for Praia do Sul). The data obtained will be presented and discussed focusing on the importance of using a portable X-ray fluorescence analyzer applied to the reconstitution of dinosaur fossils that proved to be very useful in the present case.

Silva, T., Costa F., Fernandes J., Calvo R. \é\}rio, & Mateus O. \á\}vio (2016).  The use of a portable X-ray fluorescence analyzer in the reconstitution of dinosaur fossils. European Conference on X-Ray Spectrometry. , June 19 \–\} 24, 2016, Gothenburg, Sweden Abstract
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Schulp, A. S., Polcyn M. J., Mateus O., Jacobs L. L., Morais L. M., & Tavares T. S. (2006).  New mosasaur material from the Maastrichtian of Angola, with notes on the phylogeny, distribution and palaeoecology of the genus Prognathodon. Publicaties van het Natuurhistorisch Genootschap in Limburg Reeks XLV aflevering 1. Stichting Natuurpublicaties Limburg, Maastricht . 57-67 .schulp_polcyn_mateus_jacobs_et_al_2006_new_mosasaur_material_from_the_maastrichtian_of_angola_with_notes_on_the_phylogeny_distribution_and_palaeoecology_of_the_genus_prognathodon.pdf
Schulp, A. S., Polcyn M. J., Mateus O., & Jacobs L. L. (2013).  Two rare mosasaurs from the Maastrichtian of Angola and the Netherlands. Netherlands Journal of Geosciences — Geologie en Mijnbouw. 92(1), 3-10. Abstractschulp_et_al_2013_two_rare_mosasaurs_from_the_maastrichtian_of_angola__njg-92-1-schulp.pdf

We report here the addition of two rare mosasaur taxa to the Maastrichtian marine amniote fauna of Angola. The new specimens include a dentary fragment referable to the large carnivore Prognathodon saturator and an isolated tooth of the small durophage Carinodens belgicus. Both were recovered from Maastrichtian outcrops in southern Angola in 2011. Additionally, a complete posterior mandibular unit of a large mosasaur from the type Maastrichtian of The Netherlands, collected some time prior to 1879 and previously identified as ‘Mosasaurus giganteus’, is described and reassigned here to Prognathodon saturator; historical issues surrounding the taxonomic attribution of this specimen are clarified. The new material extends the known geographic distribution of Prognathodon saturator and Carinodens belgicus.

Schulp, A. S., Polcyn M. J., Mateus O., Jacobs L. L., & Morais M. L. (2008).  A new species of Prognathodon (Squamata, Mosasauridae) from the Maastrichtian of Angola, and the affinities of the mosasaur genus Liodon. Proceedings of the Second Mosasaur Meeting, Fort Hays Studies Special Issue 3, Fort Hays State University, Hays, Kansas. 1-12. Abstract
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Schulp, A. S., Mateus O., Polcyn M., c}alves G. {\cA., & Jacobs L. L. (2019).  Angola and its role in the paleobiogeography of Gondwana. Journal of Vertebrate Paleontology, Program and Abstracts. 188. Abstract
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Schulp, A. S., Polcyn M. J., Mateus O., Jacobs L. L., Morais M. L., & Tavares T. S. (2006).  New mosasaur material from the Maastrichtian of Angola, with notes on the phylogeny, distribution and palaeoecology of the genus Prognathodon. Publicaties van het Natuurhistorisch Genootschap in Limburg Reeks XLV aflevering 1. Stichting Natuurpublicaties Limburg, Maastricht. 57-67. Abstract
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Schulp, A. S., Polcyn M. J., Mateus O., & Jacobs L. L. (2013).  Two rare mosasaurs from the Maastrichtian of Angola and the Netherlands. Geologie en Mijnbouw/Netherlands Journal of Geosciences. 92, 3-10., Number 1 Abstract
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Schulp, A. S., Mateus O., Polcyn M., Gonçalves A., & Jacobs L. L. (2019).  Angola and its role in the paleobiogeography of Gondwana. Journal of Vertebrate Paleontology, Program and Abstracts. 188.schulp_et_al_2019_angola_svp_abstract.pdf
Schulp, A., Mateus O., Polcyn M., & Jacobs L. (2006).  A new Prognathodon (Squamata : Mosasauridae) from the Cretaceous of Angola. JOURNAL OF VERTEBRATE PALEONTOLOGY. 26, 122A-122A., Jan Abstractschulp_et_al_2006.pdf

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Schulp, A. S., Polcyn M. J., Mateus O., Jacobs L. L., & Morais M. L. (2008).  A new species of Prognathodon (Squamata, Mosasauridae) from the Maastrichtian of Angola, and the affinities of the mosasaur genus Liodon. Proceedings of the Second Mosasaur Meeting, Fort Hays Studies Special Issue 3, Fort Hays State University, Hays, Kansas. 1-12. Abstractschulp_et_al_2008_prognathodon_kianda.pdf

Here we describe a new species of the mosasaurine genus Prognathodon from the Maastrichtian of Namibe, Angola, on the basis of five specimens which represent most of the cranial skeleton including the diagnostic quadrate. Phylogenetic analysis shows this new taxon, P. kianda nov. sp., to be the sister taxon to all other species of Prognathodon. It is unique amongst Prognathodon in possessing a high marginal tooth count and relatively small pterygoid teeth. The tooth morphology in the new taxon is reminiscent of some species of the genus Liodon, allowing association of Liodon-like dentition with otherwise Prognathodon-like crania, and thus resolves the long-standing question of the phylogenetic affinities of Liodon.

Sander, P. M., Mateus O., Laven T., & Knötschke N. (2006).  Bone histology indicates insular dwarfism in a new Late Jurassic sauropod dinosaur. Nature. 441, 739-741. Abstract
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Sander, M., Laven T., Mateus O., & Knotschke N. (2004).  Insular dwarfism in a brachiosaurid sauropod from the Upper Jurassic of Germany. Journal of Vertebrate Paleontology. 23, 108., Number Suppl. to 3 Abstract
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Sander, P. M., Mateus O., Laven T., & Knotschke N. (2006).  Bone histology indicates insular dwarfism in a new Late Jurassic sauropod dinosaur. Nature. 441, 739-741., Jan Abstractsander_mateus_et_al_2006_europasaurus_sauropod_histology_drwarfism_nature.pdf

Sauropod dinosaurs were the largest animals ever to inhabit the land, with truly gigantic forms in at least three lineages1, 2, 3. Small species with an adult body mass less than five tonnes are very rare4, 5, and small sauropod bones generally represent juveniles. Here we describe a new diminutive species of basal macronarian sauropod, Europasaurus holgeri gen. et sp. nov., and on the basis of bone histology we show it to have been a dwarf species. The fossils, including excellent skull material, come from Kimmeridgian marine beds of northern Germany6, 7, and record more than 11 individuals of sauropods 1.7 to 6.2 m in total body length. Morphological overlap between partial skeletons and isolated bones links all material to the same new taxon. Cortical histology of femora and tibiae indicates that size differences within the specimens are due to different ontogenetic stages, from juveniles to fully grown individuals. The little dinosaurs must have lived on one of the large islands around the Lower Saxony basin8. Comparison with the long-bone histology of large-bodied sauropods suggests that the island dwarf species evolved through a decrease in growth rate from its larger ancestor.

Sander, M., Laven T., Mateus O., & Knotschke N. (2004).  Insular dwarfism in a brachiosaurid sauropod from the Upper Jurassic of Germany. Journal of Vertebrate Paleontology. 23, 108–108., Number Suppl. to Abstract
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Salminen, J., Dinis J., & Mateus O. (2014).  Preliminary Magnetostratigraphy for the Jurassic–Cretaceous Transition in Porto da Calada, Portugal. {STRATI} 2013. 873–877.: Springer Science $\mathplus$ Business Media Abstract
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Salminen, J., Dinis J., & Mateus O. (2014).  Preliminary Magnetostratigraphy for the Jurassic–Cretaceous Transition in Porto da Calada, Portugal. (Rogério Rocha, João Pais, José Carlos Kullberg, Stanley Finney, Ed.).STRATI 2013 First International Congress on Stratigraphy At the Cutting Edge of Stratigraphy. 873-877., Heidelberg New York Dordrecht London: Springer Abstractsalminen_et_al_2014_porto_da_calada_stratigraphy_jk_boundary_in_rocha_et_al_strati_.pdf

We present a stratigraphic log supporting a preliminary magnetostratigraphy of a Tithonian–Berriasian section in Porto da Calada (Portugal). Based on biostratigraphy and reversed and normal magnetostratigraphy, the location of the Tithonian–Berriasian boundary is tentatively located at ca. 52 m, not in disagreement
with former proposals. Due to the occurrence of later remagnetization (diagenesis), the magnetostratigraphic definition of the Tithonian–Berriasian section at the Cabo Espichel (Portugal) location was not able to be established.

Salminen, J., Dinis J., & Mateus O. (2013).  Preliminary magnetostratigraphy for Jurassic/Cretaceous transition in Porto da Calada, Portugal. In: Veikkolainen, T., Suhonen, K., Näränen, J., Kauristie, K., and Kaasalainen, S. (eds.). XXVI Geofysiikan päivät,. 119-122., May 21-22 2013 in Helsinkisalminen.johanna_gfp2013_portugal_preliminary_magnetostratigraphy_for_jurassic_cretaceous_transition_in.pdf
Saleiro, A., Guillaume A. R. D., Rotatori F. M., Ríos-Ibañez M., López E. D., Conti S., Martino R., Puértolas-Pascual E., Mateus O., & Moreno-Azanza M. (2022).  A beta taxonomy approach to Late Jurassic and Early Cretaceous dinosaur assemblages. Abstract book of the XIX Annual Conference of the European Association of Vertebrate Palaeontologists, Benevento/Pietraroja, Italy, 27th June-2 nd July 2022.. 176-177.: PalaeoVertebrata, Special Volume 1- 2022, 224. Doi: 10.18563/pv.eavp2022 Abstractsaleiroetal_2022-eavp.pdf

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Saleiro, A., & Mateus O. (2017).  Upper Jurassic bonebeds around Ten Sleep, Wyoming, USA: overview and stratigraphy. Abstract book of the XV Encuentro de Jóvenes Investigadores en Paleontología/XV Encontro de Jovens Investigadores em Paleontologia, Lisboa, 428 pp.. 357-361. Abstractsaleiro__mateus_2017._upper_jurassic_bonebeds_around_ten_sleep_wyoming_usa-overview_and_stratigraphy..pdf

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Saleiro, A., & Mateus O. (2017).  Upper Jurassic bonebeds around Ten Sleep, Wyoming, USA: overview and stratigraphy. Abstract book of the XV Encuentro de Jóvenes Investigadores en Paleontolog{\'ıa/XV Encontro de Jovens Investigadores em Paleontologia, Lisboa, 428 pp.. 357–361. Abstract
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Russo, J., Mateus O., Balbino A., & Marzola M. (2014).  Crocodylomorph eggs and eggshells from the Lourinhã Fm. (Upper Jurassic), Portugal. Comunica\\c cões Geológicas. 101, Especial I, 563-566. Abstract

We here present fossil Crocodylomorpha eggshells from the Upper Jurassic Lourinhã Formation of Portugal, recovered from five sites: one nest from Cambelas with 13 eggs, and three partial eggs and various fragments from, Paimogo N (I), Paimogo S (II), Casal da Rola, and Peralta. All specimens but the nest were found in association with dinosaur egg material. Our research reveals that on a micro- and ultrastructural analysis, all samples present the typical characters consistent with crocodiloid eggshell morphotype, such as the shell unit shape, the organization of the eggshell layers, and the triangular blocky extinction observed with crossed nicols. We assign the material from the Lourinhã Formation to the oofamily Krokolithidae, making it the oldest crocodylomorph eggs known so far, as well as the best record for eggs of non- crocodylian crocodylomorphs. Furthermore, our study indicates that the basic structure of crocodiloid eggshells has remained stable since at least the Upper Jurassic.

Russo, J., Mateus O., Marzola M., & Balbino A. (2017).  Two new ootaxa from the late Jurassic: The oldest record of crocodylomorph eggs, from the Lourinhã Formation, Portugal. PLOS ONE. 12, 1-23., 03, Number 3: Public Library of Science Abstractrusso_et_al_2017_two_new_ootaxa.pdfWebsite

The Late Jurassic Lourinhã Formation is known for its abundant remains of dinosaurs, crocodylomorphs and other vertebrates. Among this record are nine localities that have produced either dinosaur embryos, eggs or eggshell fragments. Herein, we describe and identify the first crocodiloid morphotype eggs and eggshells from the Lourinhã Formation, from five occurrences. One clutch from Cambelas, composed of 13 eggs, eggshell fragments from Casal da Rola and Peralta, one crushed egg and eggshells from Paimogo North, and four crushed eggs as well as eggshell fragments from Paimogo South. We observed and confirmed diagnostic morphological characters for crocodiloid eggshells and which are consistent with a crocodylomorph affinity, such as the ellipsoidal shape, wedge-shaped shell units, triangular extinction under cross-polarized light, and tabular ultrastructure. This material is distinctive enough to propose two new ootaxa within the oofamily Krokolithidae, Suchoolithus portucalensis, oogen. and oosp. nov., for the material from Cambelas, the most complete clutch known for crocodiloid eggs, and Krokolithes dinophilus, oosp. nov., for the remaining material. These are the oldest crocodylomorph eggs known, extending the fossil record for this group to the Late Jurassic. Furthermore, except for the clutch from Cambelas, the material was found with theropod eggs and nests, in the other four occurrences, which seem to suggest some form of biological relationship, still unclear at this point.

Russo, J., Mateus O., Marzola M., & Balbino A. (2017).  Two new ootaxa from the late Jurassic: The oldest record of crocodylomorph eggs, from the Lourinhã Formation, Portugal. PLoS ONE. 12, , Number 3 Abstract
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Russo, J., Mateus O., Balbino A., & Marzola M. (2014).  Crocodylomorph eggs and eggshells from the Lourinhã Fm. (Upper Jurassic), Portugal. Comunica\\c cões Geológicas. 101, Especial I, 563-566. Abstract
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Russo, J., Mateus O., Marzola M., & Balbino A. (2014).  Eggs and eggshells of crocodylomorpha from the Late Jurassic of Portugal. Journal of Vertebrate Paleontology. Program and Abstracts, 2014, 218.russo_et_al_2014eggs_crocodylomorpha_portugal.pdf
Russo, J., Mateus O., Balbino A., & Marzola M. (2014).  Crocodylomorph eggs and eggshells from the Lourinhã Fm. (Upper Jurassic), Portugal. Comunicações Geológicas. 101, Especial I, 563-566. Abstractrusso_et_al_2014_crocodylomorph_eggs_and_eggshells_from_the_lourinha_fm_upper_jurassic_portugal.pdf

We here present fossil Crocodylomorpha eggshells from the Upper Jurassic Lourinhã Formation of Portugal, recovered from five sites: one nest from Cambelas with 13 eggs, and three partial eggs and various fragments from, Paimogo N (I), Paimogo S (II), Casal da Rola, and Peralta. All specimens but the nest were found in association with dinosaur egg material. Our research reveals that on a micro- and ultrastructural analysis, all samples present the typical characters consistent with crocodiloid eggshell morphotype, such as the shell unit shape, the organization of the eggshell layers, and the triangular blocky extinction observed with crossed nicols. We assign the material from the Lourinhã Formation to the oofamily Krokolithidae, making it the oldest crocodylomorph eggs known so far, as well as the best record for eggs of non- crocodylian crocodylomorphs. Furthermore, our study indicates that the basic structure of crocodiloid eggshells has remained stable since at least the Upper Jurassic.

Russo, J., & Mateus O. (2019).  A new Ankylosaur Dinosaur Skeleton from the Upper Jurassic of Portugal. Journal of Vertebrate Paleontology, Program and Abstracts. 184.russo__mateus_2019_svp_abstract.pdf
Russo, J., & Mateus O. (2019).  A new Ankylosaur Dinosaur Skeleton from the Upper Jurassic of Portugal. Journal of Vertebrate Paleontology, Program and Abstracts. 184. Abstract
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Russo, J., Mateus O., Balbino A., & Marzola M. (2014).  Crocodylomorph eggs and eggshells from the Lourinhã Fm. (Upper Jurassic), Portugal. Comunica\\c cões Geológicas. 101, Especial I, 563-566. Abstract
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Rotatori, F. M., Moreno-Azanza M., & Mateus O. (2018).  Isolated dryosaurid (Dinosauria: Ornithopoda) cranial remains from the Late Jurassic of Portugal. EJIP Life finds a way. 95-98., Gasteiz, Spainrotatori_et_al_2018_ejip.pdf
Rotatori, F. M., Silva B. C., Moreno-Azanza M., & Mateus O. (2021).  A systematic overview of medium and large-sized iguanodontians (Dinosauria, Ornithopoda) from the Upper Jurassic Lourinhã Formation, Portugal. XIX Encontro de Jovens Investigadores em Paleontologia. 62-63. Abstractrotatoriet_l_2021_ejip.pdf

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Rotatori, F. M., Moreno-Azanza M., & Mateus O. (2021).  Re-evaluation of the Holotype of Draconyx loureiroi (Dinosauria, Ornithopoda) with report of new holotype material. PALEODAYS 2021 – XXI Convegno della Società Paleontologica Italiana. 73. Abstractrotatoriet_l_2021_paleodays.pdf

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Rotatori, F. M., Moreno-Azanza M., & Mateus O. (2018).  Dryosaurid ornithopods from the Late Jurassic of Portugal: an overview. XVI Annual Meeting of the European Association of Vertebrate Palaeontologists. 166., Caparica, Portugal June 26th-July 1st, 2018: Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa Abstractrotatori_et_al_2018_eavp_abstract.pdf

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Rotatori, F. M., Camilo B., Bertozzo F., Mateus O., & Moreno-Azanza M. (2022).  A basal ankylopollexian dinosaur from the Late Jurassic of Portugal and its implications for iguanodontian diversity. Abstract book of the XIX Annual Conference of the European Association of Vertebrate Palaeontologists, Benevento/Pietraroja, Italy, 27th June-2nd July 2022. 170-171.: PalaeoVertebrata, Special Volume 1- 2022, 224. Doi: 10.18563/pv.eavp Abstractrotatorietal_2022.pdf

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Rotatori, F. M., Moreno-Azanza M., & Mateus O. (2018).  Dryosaurid ornithopods from the Late Jurassic of Portugal: an overview. XVI Annual Meeting of the European Association of Vertebrate Palaeontologists. 166., Caparica, Portugal June 26th-July 1st, 2018: Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa Abstract

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Rotatori, F., Moreno-Azanza M., & Mateus O. (2019).  New ornithopod dinosaur remains from the Late Jurassic Lourinhã Formation. 17th Conference of the EAVP. 100., Bruxelles: European Association of Vertebrate Paleontologistsrotatori_et_al_2019_ornithopod_portugal_eavp_2019_abstract.pdf
Rotatori, F. M., Moreno-Azanza M., & Mateus O. (2022).  Reappraisal and new material of the holotype of Draconyx loureiroi (Ornithischia: Iguanodontia) provide insights on the tempo and modo of evolution of thumb-spiked dinosaurs. Zoological Journal of the Linnean Society. , 02 Abstractrotatori_etal2022.pdfWebsite

{The Upper Jurassic Lourinhã Formation is well known for its rich assemblage of fossil vertebrates. In this formation, ornithopod dinosaurs are represented by two iguanodontian species, Eousdryosaurus nanohallucis and Draconyx loureiroi. We recently became aware of unreported material belonging to the holotype of Draconyx loureiroi, consisting of partially articulated manual elements. We here re-describe the holotype specimen ML 357, including the newly discovered material. The specimen was subjected to CT-scanning and its surface data used to assess anatomical characters. Linear measurements of metatarsal III were used to estimate the body length of the specimen. The Draconyx loureiroi holotype was included in two datasets and analysed with maximum parsimony and Bayesian inference approaches to estimate evolutionary rates among Iguanodontia. We present evidence that Draconyx loureiroi is a valid taxon nested in Styracosterna and is clearly diagnosable by a unique combination of characters. Both maximum parsimony and Bayesian inference indicate high evolutionary rates across the Jurassic/Cretaceous transition for the base of Iguanodontia. Length estimation suggests that Draconyx loureiroi was a relatively small, bipedal and possibly cursorial animal. Given its basal phyletic position, we interpret this bauplan was the ancestral condition for Styracosterna, that only later in the Cretaceous evolved into giant quadrupedal forms.}