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Mateus, O., Jacobs L. L., Polcyn {M. J. }, Myers T. S., & Schulp A. S. (2015).  The fossil record of testudines from Angola from the Turonian to Oligocene. : Journal of Vertebrate Paleontology Abstract
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Mateus, O., Callapez P. M., Polcyn M. J., Schulp A. S., Gonçalves A. O., & Jacobs L. L. (2019).  The Fossil Record of Biodiversity in Angola Through Time: A Paleontological Perspective. (Huntley, Brian J., Russo, Vladimir, Lages, Fernanda, Ferrand, Nuno, Ed.).Biodiversity of Angola: Science & Conservation: A Modern Synthesis. 53–76.: Springer International Publishing Abstractmateus2019_chapter_thefossilrecordofbiodiversityi.pdf

This chapter provides an overview of the alpha paleobiodiversity of Angola based on the available fossil record that is limited to the sedimentary rocks, ranging in age from Precambrian to the present. The geological period with the highest paleobiodiversity in the Angolan fossil record is the Cretaceous, with more than 80{%} of the total known fossil taxa, especially marine molluscs, including ammonites as a majority among them. The vertebrates represent about 15{%} of the known fauna and about one tenth of them are species firstly described based on specimens from Angola.

Mateus, O., Callapez P. M., Polcyn M. J., Schulp A. S., Gonçalves A. O., & Jacobs L. L. (2019).  The Fossil Record of Biodiversity in Angola Through Time: A Paleontological Perspective. (Huntley, Brian J., Russo, Vladimir, Lages, Fernanda, Ferrand, Nuno, Ed.).Biodiversity of Angola: Science {&} Conservation: A Modern Synthesis. 53–76., Cham: Springer International Publishing Abstract

This chapter provides an overview of the alpha paleobiodiversity of Angola based on the available fossil record that is limited to the sedimentary rocks, ranging in age from Precambrian to the present. The geological period with the highest paleobiodiversity in the Angolan fossil record is the Cretaceous, with more than 80{%} of the total known fossil taxa, especially marine molluscs, including ammonites as a majority among them. The vertebrates represent about 15{%} of the known fauna and about one tenth of them are species firstly described based on specimens from Angola.

Mallison, H., Schwarz-Wings D., Tsai H., Holliday C., & Mateus O. (2014).  Fossil longbone cartilage preserved in stegosaurs?. Journal of Vertebrate Paleontology. Program and Abstracts, 2014, 176.mallison_et_al._2014_fossil_longbone_cartilage_preserved_in_stegosaurs.pdf
Pereira, T., Mateus O., & Moreno-Azanza M. (2018).  Fossil amphibians from Portugal. 1st Palaeontological Virtual Congress. online. Abstractpereira_et_al_2018_amphibians_portugal.pdf

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Pereira, T., Mateus O., & Moreno-Azanza M. (2018).  Fossil amphibians from Portugal. 1st Palaeontological Virtual Congress. online. Abstract

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Mateus, O. (2008).  Fósseis de transição, elos perdidos, fósseis vivos e espécies estáveis. (Levy, et al, Ed.).Evolução: História e Argumentos. 77-96., Lisboa: Esfera do Caosmateus_2008_evolucao_fosseis_de_transicao.pdf
Ríos, M., Estraviz-López D., Martino R., Lohmann P., Mateus O., & Solounias N. (2022).  The first Sivatheriine (Artiodactyla, Giraffidae) from the Middle Miocene of Portugal. XIX Annual conference of the European Association of Vertebrate Palaeontologists (19th EAVP)At: Benevento, Italy. 167. Abstracteavp_2022_abstractvolume-176.pdf

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Mateus, O., & Milan J. (2010).  First records of crocodyle and pterosaur tracks in the Upper Jurassic of Portugal.. New Mexico Museum of Natural History and Science Bulletin. 51, 83-87., Jan Abstractmateus_and_milan_2010_portugal_first_records_of_crocodyle_and_pterosaur_tracks_in_the_upper_jurassic_of_portugal.pdfWebsite

The Upper Jurassic of Portugal has a rich vertebrate fauna well documented from both body and trace fossils. Although the occurrence of crocodyles and pterosaurs is well documented from body fossils, trace fossils from both groups were unknown until now. Here we describe an isolated crocodyle-like track from Praia da Peralta and pterosaur tracks from the Kimmeridgian of Pedreira do Avelino, Sesimbra (Azóia Fm.) and Porto das Barcas, Lourinhã (Lourinhã Fm.). An enigmatic track suggests the possible presence of a small, tail-dragging tetrapod.
Possible track-makers are suggested based on the known Late Jurassic vertebrate fauna of Portugal.

Mateus, O. (2010).  First records of crocodyle and pterosaur tracks in the Upper Jurassic of Portugal.. New Mexico Museum of Natural History and Science Bulletin. 51, 83–87., 1, Number NA Abstract

The Upper Jurassic of Portugal has a rich vertebrate fauna well documented from both body and trace fossils. Although the occurrence of crocodyles and pterosaurs is well documented from body fossils, trace fossils from both groups were unknown until now. Here we describe an isolated crocodyle-like track from Praia da Peralta and pterosaur tracks from the Kimmeridgian of Pedreira do Avelino, Sesimbra (Azóia Fm.) and Porto das Barcas, Lourinhã (Lourinhã Fm.). An enigmatic track suggests the possible presence of a small, tail-dragging tetrapod. Possible track-makers are suggested based on the known Late Jurassic vertebrate fauna of Portugal.

Campos, H., & Mateus O. (2018).  The first record of placodonts in Portugal and its chronological and paleoecological implications. XVI Annual Meeting of the European Association of Vertebrate Palaeontologists. 38.: Abstract book of the XVI Annual Meeting of the European Association of Vertebrate Palaeontologists, Caparica, Portugal June 26th-July 1st, 2018. Abstractcampos__mateus_2018_eavp_abstract.pdf

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Campos, H., & Mateus O. (2018).  The first record of placodonts in Portugal and its chronological and paleoecological implications. XVI Annual Meeting of the European Association of Vertebrate Palaeontologists. 38.: Abstract book of the XVI Annual Meeting of the European Association of Vertebrate Palaeontologists, Caparica, Portugal June 26th-July 1st, 2018. Abstract

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Pereira, A. M., Silva M. M., & Mateus O. (2022).  First record of Phymactis papillosa (Lesson, 1830), a Pacific south sea anemone in European shores. Journal of the Marine Biological Association of the United Kingdom. 1–4.: Cambridge University Press Abstractfirst-record-of-phymactis-papillosa-lesson-1830-a-pacific-south-sea-anemone-in-european-shores.pdfWebsite

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Mateus, O., Dyke G., Motchurova-Dekova N., Ivanov P., & Kamenov G. D. (2010).  The first record of a dinosaur from Bulgaria. Lethaia. 43, 88-94., Jan Abstractmateus_et_al__2010_the_first_record_of_a_dinosaur_in_bulgaria._lethaia.pdfWebsite

A portion of a left humerus from the Upper Maastrichtian of Vratsa district (NW Bulgaria)
is shown to be from a non-avian theropod dinosaur: this is the first record of a
dinosaur from Bulgaria. We describe this bone, suggest that it most likely pertains to an
ornithomimosaur, and discuss the fossil record of other similar taxa of Late Cretaceous
age that have been reported from Europe. To investigate the taphonomy of this fossil,
rare earth element (REE) analysis is combined with strontium (Sr) isotope data to confirm
that this Bulgarian dinosaur bone was initially fossilized in a terrestrial environment,
then later re-worked into late Maastrichtian marine sediments.

Mateus, O., Dyke G. A. J., Motchurova-Dekova N., Kamenov G. D., & Ivanov P. (2010).  The first record of a dinosaur from Bulgaria. Lethaia. 43, 88-94., Number 1 Abstract
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Mateus, O., Butler R. J., Brusatte S. L., Whiteside J. H., & Steyer S. J. (2014).  The first phytosaur (Diapsida, Archosauriformes) from the Late Triassic of the Iberian Peninsula. Journal of Vertebrate Paleontology. 34(4), 970-975.mateus_et_al_2014_first_phytosaur_algarve_portugal_jvp.pdfWebsite
Mateus, O., Butler R. J., Brusatte S. L., Whiteside J. H., & Steyer J. S. (2014).  The first phytosaur (Diapsida, Archosauriformes) from the Late Triassic of the Iberian Peninsula. Journal of Vertebrate Paleontology. 34, 970-975., Number 4 Abstract
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Mateus, O., Butler R. J., Brusatte S. L., Whiteside J. H., & Steyer J. S. (2014).  The first phytosaur (Diapsida, Archosauriformes) from the Late Triassic of the Iberian Peninsula. Journal of Vertebrate Paleontology. 34, 970–975., Number 4 Abstract
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Adams, T. L., Polcyn M. J., Mateus O., Winkler D. A., & Jacobs L. L. (2011).  First occurrence of the long-snouted crocodyliform Terminonaris (Pholidosauridae) from the Woodbine Formation (Cenomanian) of Texas. Journal of Vertebrate Paleontology. 31, 712-716., Jan: So Methodist Univ, Univ Nova Lisboa Abstractadams_polcyn_mateus_et_al_2011_terminonaris_crocodile_pholidosauridae.pdf

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Adams, T. L., Polcyn M. J., Mateus O., Winkler D. A., & Jacobs L. L. (2011).  First occurrence of the long-snouted crocodyliform Terminonaris (Pholidosauridae) from the Woodbine Formation (Cenomanian) of Texas. Journal of Vertebrate Paleontology. 31, 712-716., Number 3 Abstract
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Jésus, V. J. P., Mateus O., Milàn J., & Clemmensen L. B. (2022).  First occurrence of a frog-like batrachian (Amphibia) in the Late Triassic Fleming Fjord Group, central East Greenland. Bulletin of the Geological Society of Denmark. 70, 117–130. Abstractbull70-117-130.pdfWebsite

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Carrano, M., Mateus O., & Mitchell J. (2013).  First definitive association between embryonic Allosaurus bones and prismatoolithus eggs in the Morrison Formation (Upper Jurassic, Wyoming, USA). Annual Meeting of Vertebrate Paleontology. 101.: Journal of Vertebrate Paleontology, Program and Abstracts, 2013 Abstractcarrano_mateus_mitchell_2013_allosaurus_embryos_morrison_svp_abstract.pdf

Despite more than a century of collecting, resulting in one of the best-studied vertebrate fossil records anywhere in the world, the Upper Jurassic Morrison Formation has produced surprisingly few examples of dinosaur eggs associated with embryonic remains. Even more puzzling, none of these seem to pertain to the theropod Allosaurus, one of the most common and best-understood dinosaur taxa in the formation. Here we
report on a dinosaur nest site that has produced both abundant prismatoolithid eggshell and embryonic (or perinatal) bones of Allosaurus from Fox Mesa, Wyoming. This represents the first such discovery for any theropod in the Jurassic of North America. The nest is heavily weathered but contains a few ellipsoid eggshell clusters that suggest an egg size of about 8 x 6.5 cm. Study of the eggshell morphology and microstructure confirms that a single egg type is present throughout, which is indistinguishable from Prismatoolithus coloradensis. All of the identifiable embryonic materials pertain to theropods, and two premaxillae specimens show the five alveoli diagnostic for Allosaurus among Morrison theropods. This confirms the theropod origin of Prismatoolithus eggs and implicates Allosaurus as the specific Morrison parent taxon. As a result, it is now possible to assign several previous discoveries of dinosaur eggs and potential nests to Allosaurus, including the isolated egg from the Cleveland-Lloyd Quarry. This discovery
also calls into question prior assignments of Prismatoolithus eggs to ornithopods, and suggests that more detailed study of such sites is warranted. Prismatoolithus eggshells are also associated with the Upper Jurassic theropod Lourinhanosaurus from Portugal, along with larger embryos that exhibit four premaxillary alveoli.

Mateus, O. (2013).  First definitive association between embryonic Allosaurus bones and prismatoolithus eggs in the Morrison Formation (Upper Jurassic, Wyoming, USA). Journal of Vertebrate Paleontology. 101., 1 Abstract

Despite more than a century of collecting, resulting in one of the best-studied vertebrate fossil records anywhere in the world, the Upper Jurassic Morrison Formation has produced surprisingly few examples of dinosaur eggs associated with embryonic remains. Even more puzzling, none of these seem to pertain to the theropod Allosaurus, one of the most common and best-understood dinosaur taxa in the formation. Here we report on a dinosaur nest site that has produced both abundant prismatoolithid eggshell and embryonic (or perinatal) bones of Allosaurus from Fox Mesa, Wyoming. This represents the first such discovery for any theropod in the Jurassic of North America. The nest is heavily weathered but contains a few ellipsoid eggshell clusters that suggest an egg size of about 8 x 6.5 cm. Study of the eggshell morphology and microstructure confirms that a single egg type is present throughout, which is indistinguishable from Prismatoolithus coloradensis. All of the identifiable embryonic materials pertain to theropods, and two premaxillae specimens show the five alveoli diagnostic for Allosaurus among Morrison theropods. This confirms the theropod origin of Prismatoolithus eggs and implicates Allosaurus as the specific Morrison parent taxon. As a result, it is now possible to assign several previous discoveries of dinosaur eggs and potential nests to Allosaurus, including the isolated egg from the Cleveland-Lloyd Quarry. This discovery also calls into question prior assignments of Prismatoolithus eggs to ornithopods, and suggests that more detailed study of such sites is warranted. Prismatoolithus eggshells are also associated with the Upper Jurassic theropod Lourinhanosaurus from Portugal, along with larger embryos that exhibit four premaxillary alveoli.

Araújo, R., Castanhinha R., Martins R. M. S., Mateus O., Hendrickx C., Beckmann F., Schell N., & Alves L. C. (2013).  Filling the gaps of dinosaur eggshell phylogeny: Late Jurassic Theropod clutch with embryos from Portugal. Scientific Reports. 3(1924), , 2013/05/30/onlin: Macmillan Publishers Limited. All rights reserved Abstractaraujo_et_al_2013_filling_the_gaps_of_dinosaur_eggshell_phylogeny_late_jurassic_theropod_clutch_with_embryos_from_portugal.pdf

The non-avian saurischians that have associated eggshells and embryos are represented only by the sauropodomorph Massospondylus and Coelurosauria (derived theropods), thus missing the basal theropod representatives. We report a dinosaur clutch containing several crushed eggs and embryonic material ascribed to the megalosaurid theropod Torvosaurus. It represents the first associated eggshells and embryos of megalosauroids, thus filling an important phylogenetic gap between two distantly related groups of saurischians. These fossils represent the only unequivocal basal theropod embryos found to date. The assemblage was found in early Tithonian fluvial overbank deposits of the Lourinhã Formation in West Portugal. The morphological, microstructural and chemical characterization results of the eggshell fragments indicate very mild diagenesis. Furthermore, these fossils allow unambiguous association of basal theropod osteology with a specific and unique new eggshell morphology.

Araújo, R., Castanhinha R., Martins R. M. S., Mateus O., Hendrickx C., Beckmann F., Schell N., & Alves L. C. (2013).  Filling the gaps of dinosaur eggshell phylogeny: Late Jurassic Theropod clutch with embryos from Portugal. Scientific Reports. 3, , may: Nature Publishing Group AbstractWebsite
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Lategano, F., Conti S., Costa F., Mateus O., & Lozar F. (2022).  Fighter or bluffer: comparison of bending and compression in models of the caudal spines of dacentrurine and stegosaurine stegosaurs. XIX Annual Conference of the European Association of Vertebrate Paleontologists. 113. Abstract
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Polcyn, M. J., Bardet N., Amaghzaz M., Gonçalves O. A., Jourani E., Kaddumi H. F., Lindgren J., Mateus O., Meslouhf S., Morais M. L., Pereda-Suberbiola X., Schulp A. S., Vincent P., & Jacobs L. L. (2016).  An extremely derived plioplatecarpine mosasaur from the Maastrichtian of Africa and the Middle East. 5th Triennial Mosasaur Meeting- a global perspective on Mesozoic marine amniotes. 16-20(May 16-20, 2016), May 16-20, 2016., Uppsala, Sweden: Museum of Evolutiom, Uppsala University. Abstractpolcyn_et_al_2016_extremely_derived_mosasaur.pdf

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Polcyn, M. J., Bardet N., Amaghzaz M., Gon{\c c}alves O. A., Jourani E., Kaddumi H. F., Lindgren J., Mateus O., Meslouhf S., Morais M. L., Pereda-Suberbiola X., Schulp A. S., Vincent P., & Jacobs L. L. (2016).  An extremely derived plioplatecarpine mosasaur from the Maastrichtian of Africa and the Middle East. 5th Triennial Mosasaur Meeting- a global perspective on Mesozoic marine amniotes. 16-20, May 16-20, 2016., Uppsala, Sweden: Museum of Evolutiom, Uppsala University. Abstract

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Polcyn, M. J., Bardet N., Amaghzaz M., Gon\{\c c\}alves O. A., Jourani E., Kaddumi H. F., Lindgren J., Mateus O., Meslouhf S., Morais M. L., Pereda-Suberbiola X., Schulp A. S., Vincent P., & Jacobs L. L. (2016).  An extremely derived plioplatecarpine mosasaur from the Maastrichtian of Africa and the Middle East. 5th Triennial Mosasaur Meeting- a global perspective on Mesozoic marine amniotes. 16-20, May 16-20, 2016., Uppsala, Sweden Abstract
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Polcyn, {M. J. }, Bardet N., Amaghzaz M., Gonçalves {A. O. }, Jourani E., Kaddumi {H. F. }, Lindgren J., Mateus O., Meslouhf S., & Morais {M. L. } (2016).  An extremely derived plioplatecarpine mosasaur from the Maastrichtian of Africa and the Middle East. 32–33. Abstract
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Mateus, O. (2016).  Exemplos bizarros de evolução em dinossauros e alguns casos portugueses. Do Big Bang ao Homem. 81-95., Porto: U.Porto Ediçõesmateus_2016_capitulo_livro_dinosaurs.pdf
Mateus, O. (2016).  Exemplos bizarros de evolucão em dinossauros e alguns casos portugueses. Do Big Bang ao Homem. 81–95.: U.Porto Edicões Abstract
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Mateus, O. (2016).  Exemplos bizarros de evolução em dinossauros e alguns casos portugueses. Do Big Bang ao Homem. 81-95., Porto: U.Porto Edi{\c c}ões Abstract
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Mateus, O. (2016).  Exemplos bizarros de evolução em dinossauros e alguns casos portugueses. Do Big Bang ao Homem. 81-95., Porto Abstract
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Mateus, O. (2010).  Evolutionary major trends of ornithopod dinosaurs teeth.. (J Calvo, J Porfiri, Y, {D Dos Santos BGR}, Ed.).Dinosaurios y paleontología desde América Latina,. 25–31 pp.., 1: EDIUNC Abstract
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Araújo, R., Castanhinha R., & Mateus O. (2011).  Evolutionary major trends of ornithopod dinosaurs teeth. (J.Calvo, J. Porfiri, B. Gonzalez Riga y D. Dos Santos (scientific editors), Ed.).Dinosaurios y paleontología desde América Latina. 25-31., Jan: EDIUNC, Editorial de la Universidad Nacional de Cuyo Abstractaraujo_et_al_2011_evolutionary_major_trends_of_ornithopod_dinosaurs_teeth.pdf

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Mateus, O. (2011).  Evolutionary major trends of ornithopod dinosaurs teeth. (Unknown Unknown, Ed.).Dinosaurios y paleontología desde América Latina. 25–31., 1: EDIUNC, Editorial de la Universidad Nacional de Cuyo Abstract
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Moreno-Azanza, M., Gasca J. M., Canudo J. I., Lázaro B. B., & Mateus O. (2016).  The evolution of the ornithischian eggshell: State of the art and perspectives. Abstracts with Programs, the 2016 Annual Meeting, the Palaeontological Society of Japan. 6., Fukui, Japanmoreno_azanza_et_al_2016_the_evolution_of_the_ornithischian_eggshell.pdf
Moreno-Azanza, M., Gasca J. M., Canudo J. I., Lázaro B. B., & Mateus O. (2016).  The evolution of the ornithischian eggshell: State of the art and perspectives. Abstracts with Programs, the 2016 Annual Meeting, the Palaeontological Society of Japan. 6., Fukui, Japan Abstract
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Moreno-Azanza, M., Gasca J. M., Canudo J. I., L\áżaro B. B., & Mateus O. (2016).  The evolution of the ornithischian eggshell: State of the art and perspectives. Abstracts with Programs, the 2016 Annual Meeting, the Palaeontological Society of Japan. 6., Fukui, Japan Abstract
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Moreno-Azanza, M., Gasca J. M., Canudo J. I., Lázaro B. B., & Mateus O. (2016).  The evolution of the ornithischian eggshell: State of the art and perspectives. : Palaeontological Society of Japan Abstract
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Ezquerro, L., Balauz B., Coimbra R., Nuñez-Lahuerta C., Mateus O., Román T., & Moreno-Azanza M. (2021).  Evidence of sedimentary remodel of Jurassic theropod egg clutches (Lourinhã, Portugal). 18th Conference of the EAVP-Abstract book. 72-73. Abstractezquerro_et_al_2021_sedimentary_remodel.pdf

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Tschopp, E., & Mateus O. (2012).  Evidence for presence of clavicles and interclavicles in sauropod dinosaurs and its implications on the furcula-clavicle homology. Journal of Vertebrate Paleontology, Program and Abstracts, 2012, 184. ISSN 1937-2809 . 184. Abstracttschopp__mateus_2012_interclavicles_clavicles_svp_2012_abstract.pdf

Clavicles and interclavicles are plesiomorphically present in Reptilia. However, several groups show reduction or even loss of these elements. Crocodylimorpha, e.g., lost the clavicles, whereas dinosaurs are generally interpreted to only preserve the clavicles, the theropod furcula representing an unique case of fused clavicles. In sauropods, reports of clavicles are relatively frequent in non-titanosauriforms. These elements are elongated, curved, and rather stout bones with a spatulate and a bifurcate end. However, they were always found as single bones, and differ from the relatively short and unbifurcated clavicles found articulated with the scapulae of basal sauropodomorphs.
Elements from the Howe Quarry (Late Jurassic; Wyoming, USA) shed new light on these interpretations. Besides the elongated, curved bones (herein named morphotype A), also pairs of symmetric, L-shaped bones were recovered (morphotype B), associated with diplodocid dorsal and cervical vertebrae. Elements resembling morphotype B - articulated between the scapulae - have recently been reported from a diplodocid found near Tensleep, Wyoming. Taphonomic evidence, as well as the fact that they were preserved in symmetrical pairs, therefore implies that morphotype B represents the true sauropod clavicles.
Contrary to earlier reports, morphotype A elements from the Howe Quarry, as well as of previously reported specimens show a symmetry plane following the long axis of the elements. It is thus possible that the morphotype A elements were single bones from the body midline. The only such element present in the pectoral girdle of tetrapods are the interclavicle and the furcula. Comparison with crocodilian and lacertiform interclavicles indicates that the bifurcate end of the sauropod elements might represent the reduced transverse processes of the anterior end, and the spatulate end would have covered the coracoids or sternal plates ventrally.
The presence of both clavicles and interclavicles in the pectoral girdle stiffens the anterior trunk, and enhances considerably its stability. Such an enforcement might have been needed in diplodocids due to the strong lateral forces induced to the fore-limbs by the posteriorly placed center of mass (due to shorter fore- than hind-limbs), as well as lateral movements of the enormously elongated necks and tails. The absence of clavicles and interclavicles in titanosauriforms coincides with the development of wide-gauge locomotion style.
The presence of interclavicles in sauropods supports the recently proposed homology of the furcula with the interclavicle, instead of representing fused clavicles. Interclavicles were thus not lost, but may have remained cartilaginous or have yet to be found in basal dinosauriforms.

Mateus, O. (2012).  Evidence for presence of clavicles and interclavicles in sauropod dinosaurs and its implications on the furcula-clavicle homology. Journal of Vertebrate Paleontology. 184–185., 1 Abstract

Clavicles and interclavicles are plesiomorphically present in Reptilia. However, several groups show reduction or even loss of these elements. Crocodylimorpha, e.g., lost the clavicles, whereas dinosaurs are generally interpreted to only preserve the clavicles, the theropod furcula representing an unique case of fused clavicles. In sauropods, reports of clavicles are relatively frequent in non-titanosauriforms. These elements are elongated, curved, and rather stout bones with a spatulate and a bifurcate end. However, they were always found as single bones, and differ from the relatively short and unbifurcated clavicles found articulated with the scapulae of basal sauropodomorphs. Elements from the Howe Quarry (Late Jurassic; Wyoming, USA) shed new light on these interpretations. Besides the elongated, curved bones (herein named morphotype A), also pairs of symmetric, L-shaped bones were recovered (morphotype B), associated with diplodocid dorsal and cervical vertebrae. Elements resembling morphotype B - articulated between the scapulae - have recently been reported from a diplodocid found near Tensleep, Wyoming. Taphonomic evidence, as well as the fact that they were preserved in symmetrical pairs, therefore implies that morphotype B represents the true sauropod clavicles. Contrary to earlier reports, morphotype A elements from the Howe Quarry, as well as of previously reported specimens show a symmetry plane following the long axis of the elements. It is thus possible that the morphotype A elements were single bones from the body midline. The only such element present in the pectoral girdle of tetrapods are the interclavicle and the furcula. Comparison with crocodilian and lacertiform interclavicles indicates that the bifurcate end of the sauropod elements might represent the reduced transverse processes of the anterior end, and the spatulate end would have covered the coracoids or sternal plates ventrally. The presence of both clavicles and interclavicles in the pectoral girdle stiffens the anterior trunk, and enhances considerably its stability. Such an enforcement might have been needed in diplodocids due to the strong lateral forces induced to the fore-limbs by the posteriorly placed center of mass (due to shorter fore- than hind-limbs), as well as lateral movements of the enormously elongated necks and tails. The absence of clavicles and interclavicles in titanosauriforms coincides with the development of wide-gauge locomotion style. The presence of interclavicles in sauropods supports the recently proposed homology of the furcula with the interclavicle, instead of representing fused clavicles. Interclavicles were thus not lost, but may have remained cartilaginous or have yet to be found in basal dinosauriforms.

Coimbra, R., Moreno-Azanza M., Ezquerro L., Nuñez-Lahuerta C., Gasca J. M., Immenhauser A., Mateus O., & Rocha F. (2023).  Evaluating and comparing geochemical sampling protocols in dinosaur eggshells: refining Cretaceous ecosystem research. Cretaceous Research. 105632. Abstractsingle_file_coimbra_et_al._2023_cretresearch.pdfWebsite

The geochemical signatures of dinosaur eggshells represent well-established proxies in paleoenvironmental and paleobiological research. The variable sampling procedures reported in the literature, however, deserve attention. In order to evaluate the impact of different sampling methodologies on carbon and oxygen isotope and elemental concentrations, grinding was contrasted with drilling to extract powder samples from eggshell fragments collected at several locations. Eggshell data were further contrasted with surface materials, encasing matrix and compared with independent proxies using petrographic and elemental techniques. Iron and manganese elemental concentrations revealed an enrichment sequence depending on the sampling strategy for the same eggshell fragment. This pattern can be mistaken for a variable state of preservation. In contrast, carbon and oxygen isotope values exhibited only subtle differences and lacked clear trends. This suggests that isotope data are less susceptible to different methodological approaches. It is shown that drilling offers a wider range of possibilities compared to grinding (e.g., faster and less destructive). Additionally, drilled powder samples can confidently be used for elemental and isotope analysis, excluding contamination, thus providing a more accurate set of proxy data from eggshell archives.