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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., 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., 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. 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.

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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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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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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e Sousa, J. R. P. (2018).  A review of Ichthyosauria from Portugal. Abstract
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Steyer, J. S., Mateus O., Butler R. J., Brusatte S. L., & Whiteside J. H. (2011).  A new metoposaurid (temnospondyl) bonebed from the Late Triassic of Portugal. 71st Annual Meeting of the Society of Vertebrate Paleontology. 200., Jan: Abstracts of the 71st Annual Meeting of the Society of Vertebrate Paleontology Abstractsteyer_mateus_et_al_2011_._a_new_metoposaurid_temnospondyl_bonebed_from_the_late_triassic_of_portugal_svp11abstracts.pdf

The end-Triassic extinction event (ETE), considered one of the ‘Big Five’ mass extinctions, marks a dividing line between early Mesozoic vertebrate assemblages, typically including abundant temnospondyls, basal synapsids and basal archosaurs, and ‘typical’ Mesozoic faunas dominated by dinosaurs, pterosaurs, crocodylomorphs, turtles and mammaliaforms.
Recent geochemical work has provided strong evidence that the ETE is synchronous with, and likely caused by, the emplacement of the Central Atlantic magmatic province (CAMP).
However, stratigraphic sections containing both terrestrial vertebrates and CAMP basalts are scarce, complicating attempts to examine terrestrial faunal changes during this extinction event. The Triassic–Jurassic Algarve Basin, southern Portugal, is an extensional rift basin

to-marginal marine red beds (the ‘Grés de Silves’ Group) interbedded with CAMP basalts.

bonebed from the interval ‘AB1’ of the Grés de Silves. Preliminary excavations yielded at least nine well-preserved temnospondyl individuals represented by partial to nearly complete skulls and disarticulated postcranial elements of juvenile to adult ages. Nearly all material appears to represent a single species of metoposaurid referable to the genus Metoposaurus, well known from the late Carnian–early Norian of Germany and Poland. A number of characters of the occiput and mandible suggest that the Algarve material may represent a new species. This new material provides new data on the diversity and paleogeographical distribution of the metoposaurids, a highly autapomorphic and peculiar group composed of large aquatic carnivores with a unique elongated but brevirostral skull. This taxon also provides

Horizon may be within or close to the late Carnian–early Norian. Additional bone-bearing horizons within the ‘Grés de Silves’ provide a rare opportunity to examine terrestrial faunal change in the lead-up to the ETE.

Stockdale, M., Benton M., & Mateus O. (2014).  Cracking dinosaur endothermy: paleophysiology unscrambled. Journal of Vertebrate Paleontology. Program and Abstracts, 2014, 235-236.stockdale_et_al_2014_eggshells_abstract_svp.pdf
Strganac, C., Salminen J., Jacobs L. L., Polcyn M. J., Ferguson K. M., Mateus O., Schulp A. S., Morais M. L., Tavares T. S., & Gon?alves A. O. (2014).  Carbon isotope stratigraphy, magnetostratigraphy, and 40Ar/39Ar age of the cretaceous South Atlantic coast, Namibe Basin, Angola. Journal of African Earth Sciences. 99, 452-462., Number PA2 Abstract
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Strganac, C., Ferguson, K.M, Jacobs J. L., Polcyn M. J., & Mateus O. (2012).  Age and paleoecology of mosasaurs and plesiosaurs from the Late Cretaceous South Atlantic margin at Bentiaba, Angola. Journal of Vertebrate Paleontology, Program and Abstracts, 2012. 180.strganac_et_al_mateus_2012_age_bentiaba_angola_2012_svp_abstract.pdf
Strganac, C., Jacobs L. L., Ferguson K. M., Polcyn M. J., Mateus O., Schulp A. S., & Morais M. L. (2013).  Late Cretaceous marine reptiles and cooling at the South Atlantic coast inferred through stable oxygen isotopes of Inoceramus from the Namibe Basin, Angola. Geological Society of America Abstracts with Programs. Vol. 45, No. 7, p.0.
Strganac, C., Salminen J., Jacobs L. L., Ferguson K. M., Polcyn M. J., Mateus O., Schulp A. S., Morais M. L., Tavares T. S., & Gonçalves A. O. (2014).  Carbon isotope stratigraphy and 40Ar/39Ar age of the Cretaceous South Atlantic coast, Namibe Basin, Angola. Journal of African Earth Sciences. onine, 1-11. Abstractstrganac_et_al_2014_carbon_isotope_stratigraphy_magnetostratigraphy_and_40ar_39ar_age_of.pdfWebsite

We present the δ13C and paleomagnetic stratigraphy for marine strata at the coast of southern Angola, anchored by an intercalated basalt with a whole rock 40Ar/39Ar radiometric age of 84.6 ± 1.5 Ma, being consistent with both invertebrate and vertebrate biostratigraphy. This is the first African stable carbon isotope record correlated to significant events in the global carbon cycle spanning the Late Cenomanian to Early Maastrichtian. A positive ∼ 3‰ excursion seen in bivalve shells below the basalt indicates the Cenomanian-Turonian Boundary Event at 93.9 Ma, during Oceanic Anoxic Event 2. Additional excursions above the basalt are correlated to patterns globally, including a negative ∼ 3‰ excursion near the top of the section interpreted as part of the Campanian-Maastrichtian Boundary Events. The age of the basalt ties the studied Bentiaba section to a pulse of Late Cretaceous magmatic activity around the South Atlantic and significant tectonic activity, including rotation, of the African continent.

Strganac, C., Jacobs L. L., Polcyn M. J., Ferguson K. M., Mateus O., Gon?alves A. O., Morais M. - L., & da Silva Tavares T. (2014).  Stable oxygen isotope chemostratigraphy and paleotemperature regime of mosasaurs at Bentiaba, Angola. Geologie en Mijnbouw/Netherlands Journal of Geosciences. 94, 137-143., Number 1 Abstract
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Strganac, C., Jacobs L., Polcyn M., Mateus O., Myers T., Araújo R., Fergunson K. M., Gonçalves A. O., Morais M. L., Schulp A. S., da Tavares T. S., & Salminen J. (2015).  Geological Setting and Paleoecology of the Upper Cretaceous Bench 19 Marine Vertebrate Bonebed at Bentiaba, Angola. Netherlands Journal of Geosciences. 94(1), 121-136. Abstractstrganac_et_al_2014_geological_setting_bentiaba_angola.pdfWebsite

The Bench 19 Bonebed at Bentiaba, Angola, is a unique concentration of marine vertebrates preserving six species of mosasaurs in sediments best correlated by magnetostratigraphy to chron C32n.1n between 71.4 and 71.64 Ma. The bonebed formed at a paleolatitude near 24°S, with an Atlantic width at that latitude approximating 2700 km, roughly half that of the current width. The locality lies on an uncharacteristically narrow continental shelf near transform faults that controlled the coastal outline of Africa in the formation of the South Atlantic Ocean. Biostratigraphic change through the Bentiaba section indicates that the accumulation occurred in an ecological time dimension within the 240 ky bin delimited by chron 32n.1n. The fauna occurs in a 10 m sand unit in the Mocuio Formation with bones and partial skeletons concentrated in, but not limited to, the basal 1–2 m. The sediment entombing the fossils is an immature feldspathic sand shown by detrital zircon ages to be derived from nearby granitic shield rocks. Specimens do not appear to have a strong preferred orientation and they are not concentrated in a strand line. Stable oxygen isotope analysis of associated bivalve shells indicates a water temperature of 18.5°C. The bonebed is clearly mixed with scattered dinosaur and pterosaur elements in a marine assemblage. Gut contents, scavenging marks and associated shed shark teeth in the Bench 19 Fauna indicate biological association and attrition due to feeding activities. The ecological diversity of mosasaur species is shown by tooth and body-size disparity and by δ13C analysis of tooth enamel, which indicate a variety of foraging areas and dietary niches. The Bench 19 Fauna was formed in arid latitudes along a coastal desert similar to that of modern Namibia on a narrow, tectonically controlled continental shelf, in shallow waters below wave base. The area was used as a foraging ground for diverse species, including molluscivorus Globidens phosphaticus, small species expected near the coast, abundant Prognathodon kianda, which fed on other mosasaurs at Bench 19, and species that may have been transient and opportunistic feeders in the area.

Strganac, C., Jacobs L. L., Polcyn M. J., Ferguson K. M., Mateus O., Gonçalves O. A., Morais M. - L., & da Silva Tavares T. (2015).  Stable oxygen isotope chemostratigraphy and paleotemperature regime of mosasaurs at Bentiaba, Angola. Netherlands Journal of Geosciences. FirstView, 1–7., 2 Abstractstrganac_etal2015_stable_oxigen_isotopes.pdfWebsite

ABSTRACT Stable oxygen isotope values of inoceramid marine bivalve shells recovered from Bentiaba, Angola, are utilised as a proxy for paleotemperatures during the Late Cretaceous development of the African margin of the South Atlantic Ocean. The δ18O values derived from inoceramids show a long-term increase from –3.2‰ in the Late Turonian to values between –0.8 and –1.8‰ in the Late Campanian. Assuming a constant oceanic δ18O value, an ∼2‰ increase may reflect cooling of the shallow marine environment at Bentiaba by approximately 10°. Bentiaba values are offset by about +1‰ from published records for bathyal Inoceramus at Walvis Ridge. This offset in δ18O values suggests a temperature difference of ∼5° between coastal and deeper water offshore Angola. Cooler temperatures implied by the δ18O curve at Bentiaba coincide with the stratigraphic distribution of diverse marine amniotes, including mosasaurs, at Bentiaba.

Strganac, C., Jacobs L. L., Polcyn M. J., Mateus O., Myers T. S., Salminen J., May S. R., Araújo R., Ferguson K. M., Gon?alves A. O., Morais M. L., Schulp A. S., & da Silva Tavares T. (2014).  Geological setting and paleoecology of the Upper Cretaceous Bench 19 Marine Vertebrate Bonebed at Bentiaba, Angola. Geologie en Mijnbouw/Netherlands Journal of Geosciences. 94, 121-136., Number 1 Abstract
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Tomas, C., Mateus O., & Abreu C. (2009).  Dinolourinhã; a integração dos jovens na paleontologia: o caso-estudo do Museu da Lourinhã. Journal of Paleontological Techniques 5: 28-29.. 28-29., Jan Abstracttomas_et_al_2009_dinolourinha_abstracts_jpt.pdf

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Tomas, C., Mateus O., & Abreu C. (2009).  Dinolourinhã – a integração dos jovens na paleontologia: o caso-estudo do Museu da Lourinhã.. Journal of Paleontological Techniques 5: 28-29.. Abstract
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Tschopp, E., Tschopp F. A., & Mateus O. (2017).  The Overlap Index, a tool to quantify the amount of anatomical overlap among groups of incomplete terminal taxa in phylogenetic analyses. Journal of Vertebrate Paleontology, Program and Abstracts. 2017, 205-206. Abstract
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Tschopp, E., & Mateus O. (2016).  Diplodocus Marsh, 1878 (Dinosauria, Sauropoda): proposed designation of D. carnegii Hatcher, 1901 as the type species. Bulletin of Zoological Nomenclature. 73, 17-24. Abstract
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Tschopp, E., Mateus O., Kosma R., Sander M., Joger U., & Wings O. (2014).  A specimen-level cladistic analysis of Camarasaurus (Dinosauria, Sauropoda) and a revision of camarasaurid taxonomy. Journal of Vertebrate Paleontology. Program and Abstracts, 2014, 241-242.tschopp_et_al._2014_a_specimen-level_cladistic_analysis_of_camarasaurus.pdf
Tschopp, E., Brinkman D., Henderson J., Turner M. A., & Mateus O. (2018).  Considerations on the replacement of a type species in the case of the sauropod dinosaur Diplodocus Marsh, 1878. Geology of the Intermountain West. 5, 245-262.tschoppetal2018.pdf
Tschopp, E., & Mateus O. (2012).  A sternal plate of a large-sized sauropod dinosaur from the Late Jurassic of Portugal. 10th Annual Meeting of the European Association of Vertebrate Paleontologists ¡Fundamental! . 20, 263-266.: European Association of Vertebrate Paleontologist tschopp__mateus_2012_sternal_plate_sauropod_portugal.pdf
Tschopp, E., & Mateus O. (2013).  Clavicles, interclavicles, gastralia, and sternal ribs in sauropod dinosaurs: new reports from Diplodocidae and their morphological, functional and evolutionary implications. Journal of Anatomy. 222, 321-340. Abstracttschopp__mateus_2013_clavicles_interclavicles_gastralia_and_sternal_ribs_in_diplodocid.pdfWebsite

Ossified gastralia, clavicles and sternal ribs are known in a variety of reptilians, including dinosaurs. In sauropods, however, the identity of these bones is controversial. The peculiar shapes of these bones complicate their identification, which led to various differing interpretations in the past. Here we describe different elements from the chest region of diplodocids, found near Shell, Wyoming, USA. Five morphotypes are easily distinguishable: (A) elongated, relatively stout, curved elements with a spatulate and a bifurcate end resemble much the previously reported sauropod clavicles, but might actually represent interclavicles; (B) short, L-shaped elements, mostly preserved as a symmetrical pair, probably are the real clavicles, as indicated by new findings in diplodocids; (C) slender, rod-like bones with rugose ends are highly similar to elements identified as sauropod sternal ribs; (D) curved bones with wide, probably medial ends constitute the fourth morphotype, herein interpreted as gastralia; and (E) irregularly shaped elements, often with extended rugosities, are included into the fifth morphotype, tentatively identified as sternal ribs and/or intercostal elements. To our knowledge, the bones previously interpreted as sauropod clavicles were always found as single bones, which sheds doubt on the validity of their identification. Various lines of evidence presented herein suggest they might actually be interclavicles – which are single elements. This would be the first definitive evidence of interclavicles in dinosauromorphs. Previously supposed interclavicles in the early sauropodomorph Massospondylus or the theropods Oviraptor and Velociraptor were later reinterpreted as clavicles or furculae. Independent from their identification, the existence of the reported bones has both phylogenetic and functional significance. Their presence in non-neosauropod Eusauropoda and Flagellicaudata and probable absence in rebbachisaurs and Titanosauriformes shows a clear character polarity. This implicates that the ossification of these bones can be considered plesiomorphic for Sauropoda. The proposed presence of interclavicles in sauropods may give further support to a recent study, which finds a homology of the avian furcula with the interclavicle to be equally parsimonious to the traditional theory that furcula were formed by the fusion of the clavicles. Functional implications are the stabilizing of the chest region, which coincides with the development of elongated cervical and caudal vertebral columns or the use of the tail as defensive weapon. The loss of ossified chest bones coincides with more widely spaced limbs, and the evolution of a wide-gauge locomotor style.

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.

Tschopp, {E. D. }, Tschopp {F. A. }, & Mateus O. (2017).  Overlap Indices: Tools to quantify the amount of anatomical overlap among groups of incomplete terminal taxa in phylogenetic analyses. Acta Zoologica. 99, 169–176., 6, Number 2: Wiley-Blackwell Abstract

Phylogenetic analyses of morphological data are often characterized by missing data due to incomplete operational taxonomic units, as in fossils. This incomplete knowledge derives from various reasons, including—in the case of fossils—the numerous filters an organism has to pass through during taphonomy, fossilization, weathering and collecting. Whereas several methods have been proposed to address issues raised by the inclusion of incomplete terminal taxa, until recently no tool existed to easily quantify the amount of anatomical overlap within a particular clade. The Overlap Indices provide such values and might prove useful for comparative cladistics. We herein describe these new indices and their applications in detail and provide an example file for their calculation. A case study of diplodocid sauropod dinosaurs shows how the Overlap Indices will help to explore and quantify, which one of a number of conflicting tree topologies is supported by more anatomical traits, which skeletal regions are underrepresented in a particular phylogenetic matrix, and which taxon would improve character state score completeness.

Tschopp, E., & Mateus O. (2016).  Diplodocus Marsh, 1878 (Dinosauria, Sauropoda): proposed designation of D. carnegii Hatcher, 1901 as the type species. Bulletin of Zoological Nomenclature. 73(1), 17-24. Abstracttschopp_mateus_2016_-_case_3700_-_diplodocus_type.pdf

The purpose of this application, under Articles 78.1 and 81.1 of the Code, is to replace Diplodocus longus Marsh, 1878 as the type species of the sauropod dinosaur genus Diplodocus by the much better represented D. carnegii Hatcher, 1901, due to the undiagnosable state of the holotype of D. longus (YPM 1920, a partial tail and a chevron). The holotype of D. carnegii, CM 84, is a well-preserved and mostly articulated specimen. Casts of it are on display in various museums around the world, and the species has generally been used as the main reference for studies of comparative anatomy or phylogeny of the genus. Both species are known from the Upper Jurassic Morrison Formation of the western United States. The genus Diplodocus is the basis for the family-level taxa diplodocinae Marsh, 1884, diplodocidae Marsh, 1884, diplodocimorpha Marsh, 1884 (Calvo & Salgado, 1995) and diplodocoidea Marsh, 1884 (Upchurch, 1995). It is also a specifier of at least 10 phylogenetic clades. With the replacement of D. longus by D. carnegii as type species, Diplodocus could be preserved as a taxonomic name with generally accepted content. Taxonomic stability of the entire clade diplodocoidea, and the proposed definitions of several clades within Sauropoda, could be maintained.

Tschopp, E., & Mateus O. (2013).  The skull and neck of a new flagellicaudatan sauropod from the Morrison Formation and its implication for the evolution and ontogeny of diplodocid dinosaurs. Journal of Systematic Palaeontology. 11(7), 853–888. Abstracttschopp__mateus_2013_the_skull_and_neck_of_a_new_flagellicaudatan_sauropod_from_the_morrison.pdfWebsite

A new taxon of diplodocid sauropod, Kaatedocus siberi gen. et sp. nov., is recognized based on well-preserved cervical vertebrae and skull from the Morrison Formation (Kimmeridgian, Late Jurassic) of northern Wyoming, USA. A phylogenetic analysis places it inside Diplodocinae (Sauropoda: Flagellicaudata: Diplodocidae), as a sister taxon to a clade uniting Tornieria africana and the classical diplodocines Barosaurus lentus and Diplodocus. The taxon is diagnosed by a unique combination of plesiomorphic and derived traits, as well as the following unambiguous autapomorphies within Diplodocidae: frontals separated anteriorly by a U-shaped notch; squamosals restricted to the post-orbital region; presence of a postparietal foramen; a narrow, sharp and distinct sagittal nuchal crest; the paired basal tuber with a straight anterior edge in ventral view; anterior end of the prezygapophyses of mid- and posterior cervical vertebrae is often an anterior extension of the pre-epipophysis, which projects considerably anterior to the articular facet; anterodorsal corner of the lateral side of the posterior cervical vertebrae marked by a rugose tuberosity; posterior margin of the prezygapophyseal articular facet of posterior cervical vertebrae bordered posteriorly by conspicuous transverse sulcus; posterior cervical neural spines parallel to converging. The inclusion of K. siberi and several newly described characters into a previously published phylogenetic analysis recovers the new taxon as basal diplodocine, which concurs well with the low stratigraphical position of the holotype specimen. Dinheirosaurus and Supersaurus now represent the sister clade to Apatosaurus and Diplodocinae and therefore the most basal diplodocid genera. The geographical location in the less known northern parts of the Morrison Fm., where K. siberi was found, corroborates previous hypotheses on faunal provinces within the formation. The probable subadult ontogenetic stage of the holotype specimen allows analysis of ontogenetic changes and their influence on diplodocid phylogeny.

Tschopp, E., Tschopp F. A., & Mateus O. (2017).  Overlap Indices: Tools to quantify the amount of anatomical overlap among groups of incomplete terminal taxa in phylogenetic analyses. Acta Zoologica. 99(2), 169-176. Abstracttschopp_et_al-2017-acta_zoologica_overlap_indices_tools_to_quantify_the_amount.pdfWebsite

Phylogenetic analyses of morphological data are often characterized by missing data due to incomplete operational taxonomic units, as in fossils. This incomplete knowledge derives from various reasons, including—in the case of fossils—the numerous filters an organism has to pass through during taphonomy, fossilization, weathering and collecting. Whereas several methods have been proposed to address issues raised by the inclusion of incomplete terminal taxa, until recently no tool existed to easily quantify the amount of anatomical overlap within a particular clade. The Overlap Indices provide such values and might prove useful for comparative cladistics. We herein describe these new indices and their applications in detail and provide an example file for their calculation. A case study of diplodocid sauropod dinosaurs shows how the Overlap Indices will help to explore and quantify, which one of a number of conflicting tree topologies is supported by more anatomical traits, which skeletal regions are underrepresented in a particular phylogenetic matrix, and which taxon would improve character state score completeness.

Tschopp, E., & Mateus O. (2017).  Osteology of Galeamopus pabsti sp. nov. (Sauropoda: Diplodocidae), with implications for neurocentral closure timing, and the cervico-dorsal transition in diplodocids. PeerJ. 5, e3179. Abstracttschopp__mateus_2017_osteology_of_galeamopus_pabsti_sp.__nov._sauropoda__diplodocidae_.pdfWebsite

Diplodocids are among the best known sauropod dinosaurs. Numerous specimens of currently 15 accepted species belonging to ten genera have been reported from the Late Jurassic to Early Cretaceous of North and South America, Europe, and Africa. The highest diversity is known from the Upper Jurassic Morrison Formation of the western United States: a recent review recognized 12 valid, named species, and possibly three additional, yet unnamed ones. One of these is herein described in detail and referred to the genus \textit{Galeamopus}. The holotype specimen of \textit{Galeamopus pabsti} sp. nov., SMA 0011, is represented by material from all body parts but the tail, and was found at the Howe-Scott Quarry in the northern Bighorn Basin in Wyoming, USA. Autapomorphic features of the new species include a horizontal canal on the maxilla that connects the posterior margin of the preantorbital and the ventral margin of the antorbital fenestrae, a vertical midline groove marking the sagittal nuchal crest, the presence of a large foramen connecting the postzygapophyseal centrodiapophyseal fossa and the spinopostzygapophyseal fossa of mid- and posterior cervical vertebrae, a very robust humerus, a laterally placed, rugose tubercle on the concave proximal portion of the anterior surface of the humerus, a relatively stout radius, the absence of a distinct ambiens process on the pubis, and a distinctly concave posteroventral margin of the ascending process of the astragalus. In addition to the holotype specimen SMA 0011, the skull USNM 2673 can also be referred to \textit{Galeamopus pabsti}. Histology shows that the type specimen SMA 0011 is sexually mature, although neurocentral closure was not completed at the time of death. Because SMA 0011 has highly pneumatized cervical vertebrae, the development of the lamination appears a more important indicator for individual age than neurocentral fusion patterns. SMA 0011 is one of very few sauropod specimens that preserves the cervico-dorsal transition in both vertebrae and ribs. The association of ribs with their respective vertebrae shows that the transition between cervical and dorsal vertebrae is significantly different in \textit{Galeamopus pabsti} than in \textit{Diplodocus carnegii} or \textit{Apatosaurus louisae}, being represented by a considerable shortening of the centra from the last cervical to the first dorsal vertebra. Diplodocids show a surprisingly high diversity in the Morrison Formation. This can possibly be explained by a combination of geographical and temporal segregation, and niche partitioning.

Tschopp, E., Brinkman D., Henderson J., Turner M. A., & Mateus O. (2018).  Considerations on the replacement of a type species in the case of the sauropod dinosaur Diplodocus Marsh, 1878. Geology of the Intermountain West. 5, 245-262. Abstract
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Tschopp, E., Mateus O., & Benson R. B. J. (2015).  A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda). {PeerJ}. 3, e857.: {PeerJ} AbstractWebsite
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Tschopp, E., & Mateus O. (2016).  Case 3700 Diplodocus Marsh, 1878 (Dinosauria, Sauropoda): Proposed designation of D. carnegii Hatcher, 1901 as the type species. Bulletin of Zoological Nomenclature. 73, 17–24., Number 1: International Commission on Zoological Nomenclature Abstract

The purpose of this application, under Articles 78.1 and 81.1 of the Code, is to replace Diplodocus longus Marsh, 1878 as the type species of the sauropod dinosaur genus Diplodocus by the much better represented D. carnegii Hatcher, 1901, due to the undiagnosable state of the holotype of D. longus (YPM 1920, a partial tail and a chevron). The holotype of D. carnegii, CM 84, is a well-preserved and mostly articulated specimen. Casts of it are on display in various museums around the world, and the species has generally been used as the main reference for studies of comparative anatomy or phylogeny of the genus. Both species are known from the Upper Jurassic Morrison Formation of the western United States. The genus Diplodocus is the basis for the family-level taxa diplodocinae Marsh, 1884, diplodocidae Marsh, 1884, diplodocimorpha Marsh, 1884 (Calvo & Salgado, 1995) and diplodocoidea Marsh, 1884 (Upchurch, 1995). It is also a specifier of at least 10 phylogenetic clades. With the replacement of D. longus by D. carnegii as type species, Diplodocus could be preserved as a taxonomic name with generally accepted content. Taxonomic stability of the entire clade diplodocoidea, and the proposed definitions of several clades within Sauropoda, could be maintained.

Tschopp, E., Mateus O., Marzola M., & Norell M. (2018).  Indications for a horny beak and extensive supraorbital connective tissue in diplodocid sauropods. Annual Meeting of the Society of Vertebrate Paleontology. 229.: Society of Vertebrate Paleontologytschopp_et_al_2018_svp_abstract.pdf
Tschopp, E., Mateus O., & Norell M. (2018).  Complex Overlapping Joints between Facial Bones Allowing Limited Anterior Sliding Movements of the Snout in Diplodocid Sauropods. American Museum NovitatesAmerican Museum Novitates. 1 - 16., 2018: American Museum of Natural History Abstracttschopp_et_al_2018.pdfWebsite

ABSTRACT Diplodocid sauropods had a unique skull morphology, with posteriorly retracted nares, an elongated snout, and anteriorly restricted, peglike teeth. Because of the lack of extant analogs in skull structure and tooth morphology, understanding their feeding strategy and diet has been difficult. Furthermore, the general rarity of sauropod skulls and the fragility of their facial elements resulted in a restricted knowledge of cranial anatomy, in particular regarding the internal surface of the facial skull. Here, we describe in detail a well-preserved diplodocid skull visible in medial view. Diagnostic features recognized in other skulls observable in lateral view, such as the extended contribution of the jugal to the antorbital fenestra, are obliterated in medial view due to extensive overlapping joints between the maxilla, jugal, quadratojugal, and the lacrimal. These overlapping joints permitted limited anterior sliding movement of the snout, which likely served as a kind of ?shock-absorbing? mechanism during feeding. Diplodocid skulls therefore seem to have evolved to alleviate stresses inflicted on the snout during backward movements of the head, as would be expected during branch-stripping or raking.ABSTRACT Diplodocid sauropods had a unique skull morphology, with posteriorly retracted nares, an elongated snout, and anteriorly restricted, peglike teeth. Because of the lack of extant analogs in skull structure and tooth morphology, understanding their feeding strategy and diet has been difficult. Furthermore, the general rarity of sauropod skulls and the fragility of their facial elements resulted in a restricted knowledge of cranial anatomy, in particular regarding the internal surface of the facial skull. Here, we describe in detail a well-preserved diplodocid skull visible in medial view. Diagnostic features recognized in other skulls observable in lateral view, such as the extended contribution of the jugal to the antorbital fenestra, are obliterated in medial view due to extensive overlapping joints between the maxilla, jugal, quadratojugal, and the lacrimal. These overlapping joints permitted limited anterior sliding movement of the snout, which likely served as a kind of ?shock-absorbing? mechanism during feeding. Diplodocid skulls therefore seem to have evolved to alleviate stresses inflicted on the snout during backward movements of the head, as would be expected during branch-stripping or raking.

Tschopp, E., Mateus O., & Benson R. B. J. (2015).  A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda). PeerJ. 3, e857., 4 Abstracttschopp_et_al_2015_brontosaurus_peerj-857.pdfWebsite

Diplodocidae are among the best known sauropod dinosaurs. Several species were described in the late 1800s or early 1900s from the Morrison Formation of North America. Since then, numerous additional specimens were recovered in the USA, Tanzania, Portugal, and Argentina, as well as possibly Spain, England, Georgia, Zimbabwe, and Asia. To date, the clade includes about 12 to 15 nominal species, some of them with questionable taxonomic status (e.g., ‘\textit{Diplodocus}’ \textit{hayi} or \textit{Dyslocosaurus polyonychius}), and ranging in age from Late Jurassic to Early Cretaceous. However, intrageneric relationships of the iconic, multi-species genera \textit{Apatosaurus} and \textit{Diplodocus} are still poorly known. The way to resolve this issue is a specimen-based phylogenetic analysis, which has been previously implemented for \textit{Apatosaurus}, but is here performed for the first time for the entire clade of Diplodocidae.The analysis includes 81 operational taxonomic units, 49 of which belong to Diplodocidae. The set of OTUs includes all name-bearing type specimens previously proposed to belong to Diplodocidae, alongside a set of relatively complete referred specimens, which increase the amount of anatomically overlapping material. Non-diplodocid outgroups were selected to test the affinities of potential diplodocid specimens that have subsequently been suggested to belong outside the clade. The specimens were scored for 477 morphological characters, representing one of the most extensive phylogenetic analyses of sauropod dinosaurs. Character states were figured and tables given in the case of numerical characters.The resulting cladogram recovers the classical arrangement of diplodocid relationships. Two numerical approaches were used to increase reproducibility in our taxonomic delimitation of species and genera. This resulted in the proposal that some species previously included in well-known genera like \textit{Apatosaurus} and \textit{Diplodocus} are generically distinct. Of particular note is that the famous genus \textit{Brontosaurus} is considered valid by our quantitative approach. Furthermore, “\textit{Diplodocus}” hayi represents a unique genus, which will herein be called \textit{Galeamopus} gen. nov. On the other hand, these numerical approaches imply synonymization of “\textit{Dinheirosaurus}” from the Late Jurassic of Portugal with the Morrison Formation genus \textit{Supersaurus}. Our use of a specimen-, rather than species-based approach increases knowledge of intraspecific and intrageneric variation in diplodocids, and the study demonstrates how specimen-based phylogenetic analysis is a valuable tool in sauropod taxonomy, and potentially in paleontology and taxonomy as a whole.

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Vineyard, D. P., Jacobs L. L., Polcyn M. J., Mateus O., Schulp A. S., & Strganac C. (2009).  Euclastes from the Maastrichtian of Angola and the distribution of the Angolachelonia. Eugene Gaffney Turtle Symposium. , Royal Tyrrell Museum
Vineyard, D., Mateus O., Jacobs L. L., Polcyn M. J., & Schulp A. (2012).  A new marine turtle from the Maastrichtian of Angola. Journal of Vertebrate Paleontology, Program and Abstracts, 2012, 189. ISSN 1937-2809 . 189.vineyard_mateus_et_al_2012_euclastes_chelonia_turtle_angola_svp_2012_abstract.pdf