Publications in the Year: 2015

Journal Article

Strganac, C, Jacobs L, Polcyn M, Mateus O, Myers T, Araújo R, Fergunson KM, Gonçalves AO, Morais ML, Schulp AS, da Tavares TS, 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.

Hendrickx, C, Hartman SA, Mateus O.  2015.  An overview of non-avian theropod discoveries and classification. PalArch{'}s Journal of Vertebrate Palaeontology. 12:1-73., Number 1 Abstract
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Clemmensen, LB, Milàn J, Adolfssen JS, Estrup EJ, Frobøse N, Klein N, Mateus O, Wings O.  2015.  The vertebrate-bearing Late Triassic Fleming Fjord Formation of central East Greenland revisited: stratigraphy, palaeoclimate and new palaeontological data. Geological Society, London, Special Publications. 434 AbstractWebsite

In Late Triassic (Norian–Rhaetian) times, the Jameson Land Basin lay at 40° N on the northern part of the supercontinent Pangaea. This position placed the basin in a transition zone between the relatively dry interior of the supercontinent and its more humid periphery. Sedimentation in the Jameson Land Basin took place in a lake–mudflat system and was controlled by orbitally forced variations in precipitation. Vertebrate fossils have consistently been found in these lake deposits (Fleming Fjord Formation), and include fishes, dinosaurs, amphibians, turtles, aetosaurs and pterosaurs. Furthermore, the fauna includes mammaliaform teeth and skeletal material. New vertebrate fossils were found during a joint vertebrate palaeontological and sedimentological expedition to Jameson Land in 2012. These new finds include phytosaurs, a second stem testudinatan specimen and new material of sauropodomorph dinosaurs, including osteologically immature individuals. Phytosaurs are a group of predators common in the Late Triassic, but previously unreported from Greenland. The finding includes well-preserved partial skeletons that show the occurrence of four individuals of three size classes. The new finds support a late Norian–early Rhaetian age for the Fleming Fjord Formation, and add new information on the palaeogeographical and palaeolatitudinal distribution of Late Triassic faunal provinces.

Araújo, R, Polcyn MJ, Lindgren J, Jacobs LL, Schulp AS, Mateus O, Gonçalves OA, Morais M-L.  2015.  New aristonectine elasmosaurid plesiosaur specimens from the Early Maastrichtian of Angola and comments on paedomorphism in plesiosaurs, 2. Netherlands Journal of Geosciences. FirstView:1–16. Abstractaraujo_et_al_2015_paedomorphism-libre.pdfWebsite

ABSTRACT New elasmosaurid plesiosaur specimens are described from the Early Maastrichtian of Angola. Phylogenetic analyses reconstruct the Angolan taxon as an aristonectine elasmosaurid and the sister taxon of an unnamed form of similar age from New Zealand. Comparisons also indicate a close relationship with an unnamed form previously described from Patagonia. All of these specimens exhibit an ostensibly osteologically immature external morphology, but histological analysis of the Angolan material suggests an adult with paedomorphic traits. By extension, the similarity of the Angolan, New Zealand and Patagonian material indicates that these specimens represent a widespread paedomorphic yet unnamed taxon.

Xing, L, Lockley MG, Marty D, Zhang J, Wang Y, Klein H, McCrea RT, Buckley LG, Belvedere M, Mateus O, Gierliński GD, Piñuela L, Persons, IV SW, Wang F, Ran H, Dai H, Xie X.  2015.  An Ornithopod-Dominated Tracksite from the Lower Cretaceous Jiaguan Formation (Barremian–Albian) of Qijiang, South-Central China: New Discoveries, Ichnotaxonomy, Preservation and Palaeoecology, 10. PLoS ONE. 10:e0141059., Number 10: Public Library of Science Abstractlida_et_al_2015_an_ornithopod-dominated_tracksite_from_the.pdfWebsite

The historically-famous Lotus Fortress site, a deep 1.5–3.0-meter-high, 200-meter-long horizonal notch high up in near-vertical sandstone cliffs comprising the Cretaceous Jiaguan Formation, has been known since the 13th Century as an impregnable defensive position. The site is also extraordinary for having multiple tetrapod track-bearing levels, of which the lower two form the floor of part of the notch, and yield very well preserved asseamblages of ornithopod, bird (avian theropod) and pterosaur tracks. Trackway counts indicate that ornithopods dominate (69%) accounting for at least 165 trackmakers, followed by bird (18%), sauropod (10%), and pterosaur (3%). Previous studies designated Lotus Fortress as the type locality of Caririchnium lotus and Wupus agilis both of which are recognized here as valid ichnotaxa. On the basis of multiple parallel trackways both are interpreted as representing the trackways of gregarious species. C. lotus is redescribed here in detail and interpreted to indicate two age cohorts representing subadults that were sometimes bipedal and larger quadrupedal adults. Two other previously described dinosaurian ichnospecies, are here reinterpreted as underprints and considered nomina dubia. Like a growing number of significant tetrapod tracksites in China the Lotus Fortress site reveals new information about the composition of tetrapod faunas from formations in which the skeletal record is sparse. In particular, the site shows the relatively high abundance of Caririchium in a region where saurischian ichnofaunas are often dominant. It is also the only site known to have yielded Wupus agilis. In combination with information from other tracksites from the Jiaguan formation and other Cretaceous formations in the region, the track record is proving increasingly impotant as a major source of information on the vertebrate faunas of the region. The Lotus Fortress site has been developed as a spectacular, geologically-, paleontologically- and a culturally-significant destination within Qijiang National Geological Park.

Brusatte, SL, Butler RJ, Mateus O, Steyer JS.  2015.  A new species of Metoposaurus from the Late Triassic of Portugal and comments on the systematics and biogeography of metoposaurid temnospondyls. Journal of Vertebrate Paleontology. 35, Number 3 Abstract
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Marzola, M, Russo J, Mateus O.  2015.  Identification and comparison of modern and fossil crocodilian eggs and eggshell structures. Historical Biology. 27:115-133., Number 1 Abstract
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Hendrickx, C, Hartman SA, Mateus O.  2015.  An overview of non-avian theropod discoveries and classification. PalArch’s Journal of Vertebrate Palaeontology. 12:1-73. AbstractWebsite

Theropods form a taxonomically and morphologically diverse group of dinosaurs that include extant birds. Inferred relationships between theropod clades are complex and have changed dramatically over the past thirty years with the emergence of cladistic techniques. Here, we present a brief historical perspective of theropod discoveries and classification, as well as an overview on the current systematics of non-avian theropods. The first scientifically recorded theropod remains dating back to the 17th and 18th centuries come from the Middle Jurassic of Oxfordshire and most likely belong to the megalosaurid Megalosaurus. The latter was the first theropod genus to be named in 1824, and subsequent theropod material found before 1850 can all be referred to megalosauroids. In the fifty years from 1856 to 1906, theropod remains were reported from all continents but Antarctica. The clade Theropoda was erected by Othniel Charles Marsh in 1881, and in its current usage corresponds to an intricate ladder-like organization of ‘family’ to ‘superfamily’ level clades. The earliest definitive theropods come from the Carnian of Argentina, and coelophysoids form the first significant theropod radiation from the Late Triassic to their extinction in the Early Jurassic. Most subsequent theropod clades such as ceratosaurs, allosauroids, tyrannosauroids, ornithomimosaurs, therizinosaurs, oviraptorosaurs, dromaeosaurids, and troodontids persisted until the end of the Cretaceous, though the megalosauroid clade did not extend into the Maastrichtian. Current debates are focused on the monophyly of deinonychosaurs, the position of dilophosaurids within coelophysoids, and megaraptorans among neovenatorids. Some recent analyses have suggested a placement of dilophosaurids outside Coelophysoidea, Megaraptora within Tyrannosauroidea, and a paraphyletic Deinonychosauria with troodontids placed more closely to avialans than dromaeosaurids.

Pereira, BC, Benton MJ, Ruta M, Mateus O.  2015.  Mesozoic echinoid diversity in Portugal: Investigating fossil record quality and environmental constraints on a regional scale. Palaeogeography, Palaeoclimatology, Palaeoecology. 424:132-146. Abstractpereira_e_al_2015_mesozoic_echinoids_portugal.pdfWebsite

Abstract Several analyses of diversity through geological time use global, synoptic databases, and this practice often makes it difficult to distinguish true signals in changing diversity from regional-scale sampling and/or geological artefacts. Here we investigate how echinoid diversity changed through the Mesozoic of the Lusitanian basin in Portugal based on a comprehensive, revised database, and seek to distinguish biological signal from geological or environmental constraints. The observed diversity pattern is far from having a defined trend, showing many fluctuations that appear to be linked with gaps in the geological record. This study revealed that, independently of the method used, whether correlation tests or model fitting, the diversity signal is not completely explained by the studied sampling proxies. Among the different proxies, marine facies variation in combination with outcrop area best explains the palaeodiversity curve.

Foth, C, Evers SW, Pabst B, Mateus O, Flisch A, Patthey M, Rauhut OWM.  2015.  New insights into the lifestyle of \\textitAllosaurus (Dinosauria: Theropoda) based on another specimen with multiple pathologies, 5. PeerJ. 3:e940. AbstractWebsite

Adult large-bodied theropods are often found with numerous pathologies. A large, almost complete, probably adult \\textitAllosaurus specimen from the Howe Stephens Quarry, Morrison Formation (Late Kimmeridgian–Early Tithonian), Wyoming, exhibits multiple pathologies. Pathologic bones include the left dentary, two cervical vertebrae, one cervical and several dorsal ribs, the left scapula, the left humerus, the right ischium, and two left pedal phalanges. These pathologies can be classified as follows: the fifth cervical vertebra, the scapula, several ribs and the ischium are probably traumatic, and a callus on the shaft of the left pedal phalanx II-2 is probably traumatic-infectious. Traumatically fractured elements exposed to frequent movement (e.g., the scapula and the ribs) show a tendency to develop pseudarthroses instead of a callus. The pathologies in the lower jaw and a reduced extensor tubercle of the left pedal phalanx II-2 are most likely traumatic or developmental in origin. The pathologies on the fourth cervical are most likely developmental in origin or idiopathic, that on the left humerus could be traumatic, developmental, infectious or idiopathic, whereas the left pedal phalanx IV-1 is classified as idiopathic. With exception of the ischium, all as traumatic/traumatic-infectious classified pathologic elements show unambiguous evidences of healing, indicating that the respective pathologies did not cause the death of this individual. Alignment of the scapula and rib pathologies from the left side suggests that all may have been caused by a single traumatic event. The ischial fracture may have been fatal. The occurrence of multiple lesions interpreted as traumatic pathologies again underlines that large-bodied theropods experienced frequent injuries during life, indicating an active predatory lifestyle, and their survival perhaps supports a gregarious behavior for \\textitAllosaurus. Alternatively, the frequent survival of traumatic events could be also related to the presence of non-endothermic metabolic rates that allow survival based on sporadic food consumption or scavenging behavior. Signs of pathologies consistent with infections are scarce and locally restricted, indicating a successful prevention of the spread of pathogens, as it is the case in extant reptiles (including birds).

Hendrickx, C, Mateus O, Araújo R.  2015.  The dentition of megalosaurid theropods. Acta Palaeontologica Polonica. 60(3):627–642. Abstracthendrickx_et_al_2015_theropod_teeth_app.pdfWebsite

Theropod teeth are particularly abundant in the fossil record and frequently reported in the literature. Yet, the dentition of many theropods has not been described comprehensively, omitting details on the denticle shape, crown ornamentation and enamel texture. This paucity of information has been particularly striking in basal clades, thus making identification of isolated teeth difficult, and taxonomic assignments uncertain. We here provide a detailed description of the dentition of Megalosauridae, and a comparison to and distinction from superficially similar teeth of all major theropod clades. Megalosaurid dinosaurs are characterized by a mesial carina facing mesiolabially in most mesial teeth, centrally positioned carinae on both most mesial and lateral crowns, a mesial carina terminating above the cervix, and short to well-developed interdenticular sulci between distal denticles. A discriminant analysis performed on a dataset of numerical data collected on the teeth of 62 theropod taxa reveals that megalosaurid teeth are hardly distinguishable from other theropod clades with ziphodont dentition. This study highlights the importance of detailing anatomical descriptions and providing additional morphometric data on teeth with the purpose of helping to identify isolated theropod teeth in the future.

Xing, L, Lockley MG, Marty D, Zhang J, Wang Y, Klein H, McCrea RT, Buckley LG, Belvedere M, Mateus O, Gierli?ski GD, Piñuela L, Persons WS, Wang F, Ran H, Dai H, Xie X.  2015.  An ornithopod-dominated tracksite from the lower Cretaceous Jiaguan Formation (Barremian-Albian) of Qijiang, South-Central China: New discoveries, ichnotaxonomy, preservation and palaeoecology. PLoS ONE. 10, Number 10 Abstract
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Foth, C, Evers S, Pabst B, Mateus O, Flisch A, Patthey M, Rauhut OWM.  2015.  New insights into the lifestyle of Allosaurus (Dinosauria: Theropoda) based on another specimen with multiple pathologies, 2015. PeerJ PrePrints. 3:e824v1. Abstractfoth_et_al_2015_peerj-preprints-824.pdfWebsite

Adult large-bodied theropods are often found with numerous pathologies. A large, almost complete, probably adult Allosaurus specimen from the Howe Stephens Quarry, Morrison Formation (Late Kimmeridgian–Early Tithonian), Wyoming, shows multiple pathologies. Pathologic bones include the left dentary, two cervical vertebrae, one cervical and several dorsal ribs, the left scapula, the left humerus, right ischium, and two left pedal phalanges. These pathologies can be classified as follows: the fifth cervical vertebra, the scapula, several ribs and the ischium are traumatic, and a callus on the shaft of the left pedal phalanx II-2 is traumatic-infectious. Traumatically fractured elements exposed to frequent movement (e.g. the scapula and the ribs) show a tendency to develop pseudarthroses instead of callus healing. The pathologies in the lower jaw and a reduced flexor tubercle of the left pedal phalanx II-2 are most likely traumatic or developmental in origin. The pathologies on the fourth cervical are most likely developmental in origin or idiopathic, that on the left humerus is infectious or idiopathic, whereas left pedal phalanx IV-1 is classified as idiopathic. With exception of the ischium, all traumatic / traumatic-infectious pathologic elements show unambiguous evidences of healing, indicating that the respective pathologies did not cause the death of this individual. Alignment of the scapula and rib pathologies from the left side suggests that all may have been caused by a single traumatic event. The ischial fracture may have been fatal. The occurrence of multiple traumatic pathologies again underlines that large-bodied theropods experienced frequent injuries during life, indicating an active predatory lifestyle, and their survival perhaps supports a gregarious behavior for Allosaurus. Signs of infections are scarce and locally restricted, indicating a successful prevention of the spread of pathogens, as it is the case in extant reptiles (including birds).

Klein, H, Milàn J, Clemmensen LB, Frobøse N, Mateus O, Klein N, Adolfssen JS, Estrup EJ, Wings O.  2015.  Archosaur footprints (cf. Brachychirotherium) with unusual morphology from the Upper Triassic Fleming Fjord Formation (Norian–Rhaetian) of East Greenland. Geological Society, London, Special Publications. 434 AbstractWebsite

The Ørsted Dal Member of the Upper Triassic Fleming Fjord Formation in East Greenland is well known for its rich vertebrate fauna, represented by numerous specimens of both body and ichnofossils. In particular, the footprints of theropod dinosaurs have been described. Recently, an international expedition discovered several slabs with 100 small chirotheriid pes and manus imprints (pes length 4–4.5 cm) in siliciclastic deposits of this unit. They show strong similarities with Brachychirotherium, a characteristic Upper Triassic ichnogenus with a global distribution. A peculiar feature in the Fleming Fjord specimens is the lack of a fifth digit, even in more deeply impressed imprints. Therefore, the specimens are assigned here tentatively to cf. Brachychirotherium. Possibly, this characteristic is related to the extremely small size and early ontogenetic stage of the trackmaker. The record from Greenland is the first evidence of this morphotype from the Fleming Fjord Formation. Candidate trackmakers are crocodylian stem group archosaurs; however, a distinct correlation with known osteological taxa from this unit is not currently possible. While the occurrence of sauropodomorph plateosaurs in the bone record links the Greenland assemblage more closer to that from the Germanic Basin of central Europe, here the described footprints suggest a Pangaea-wide exchange.Supplementary material: Three-dimensional model of cf. Brachychirotherium pes–manus set (from MGUH 31233b) from the Upper Triassic Fleming Fjord Formation (Norian–Rhaetian) of East Greenland as pdf, ply and jpg files (3D model created by Oliver Wings; photographs taken by Jesper Milàn) is available at https://doi.org/10.6084/m9.figshare.c.2133546

Hendrickx, C, Mateus O, Araújo R.  2015.  A proposed terminology of theropod teeth (Dinosauria, Saurischia). Journal of Vertebrate Paleontology. :e982797. Abstracthendrickx_et_al_2015_theropod_teeth_svp.pdfWebsite

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