Head-biting behavior in theropod dinosaurs: paleopathological evidence /

Source: OAI

ABSTRACT Cranial material of Sinraptor dongi (Upper Jurassic, Xinjiang, China), Gorgosau- rus libratus, Daspletosaurus torosus (Upper Cretaceous, Alberta, Canada), and other large theropod dinosaurs exhibit similar paleopathological anomalies indicative of aggressive in- tra- or interspecific biting. Tooth strike trauma includes osseous lesions caused by solitary or multiple tooth punctures, or by dragging or gouging the tooth tips across the surfaces of cranial elements. Many of these lesions were undergoing active healing at the time of death. One isolated tyrannosaurid dentary bears a broken off and embedded tooth tip of another ty- rannosaur. Comparison with unhealed large theropod toothmarks on prey bone suggests that sublethal wounds of these types were caused by other large theropods, possibly rival conspecifics. This may indicate aggressive head or face-biting behavior in certain theropod families. Other associated traumatic osteopathy typified as localized rib and fibula fractures were observed but cannot be directly correlated with violent intra- or interspecific behavior. Healed and healing bite wounds of the head may be related to a number of factors. Establish- ment of dominance within a pack and territorial behavior are considered as two of the most likely causes. Study of paleopathologies is demonstrated to be a useful tool for understand- ing dinosaur behavior.

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    ABSTRACT: The type specimen of Stratiotosuchus maxhechti (DGM 1477-R), a baurusuchid mesoeucrocodylian from the Bauru Basin (Upper Cretaceous of Brazil) displays some abnormalities that are here described. The holotype was examined macroscopically and compared with other skeletal elements of S. maxhechti and Baurusuchus salgadoensis (UFRJ DG 288-R). After this analysis, the elements with signs of alterations were subjected to a computed tomography (CT) scan exam which gave more information about them. The medial and proximal thirds of the right metacarpal V show an extensive bone growth, which modified the normal form of this element. The left metatarsals I and II exhibit an abnormal bone callus covering part of the medial third of the distal end. Based on their morphology these features are regarded as the result of two injuries of distinct natures. In the right metacarpal V, the presence of a large bone callus and a fracture, with two possible causes: post-traumatic infection or tumour. In the metatarsal I and II a case of stress fracture with a marked bone callus. Additionally, insect boring marks in the left ulna and right and left tibia of the same specimen were observed, which could be confused with pathologies. These bone changes may provide additional clues about the palaeoenvironment, such as habitat conditions, in which the specimen studied here lived. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163, S140–S151.
    Zoological Journal of the Linnean Society 12/2011; 163(s1). · 2.66 Impact Factor
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    ABSTRACT: Monodominant bonebeds are a relatively common occurrence for non-avian dinosaurs, and have been used to infer associative, and potentially genuinely social, behavior. Previously known assemblages are characterized as either mixed size-classes (juvenile and adult-sized specimens together) or single size-classes of individuals (only juveniles or only adult-sized individuals within the assemblage). In the latter case, it is generally unknown if these kinds of size-segregated aggregations characterize only a particular size stage or represent aggregations that happened at all size stages. Ceratopsians ("horned dinosaurs") are known from both types of assemblages. Here we describe a new specimen of the ceratopsian dinosaur Protoceratops andrewsi, Granger and Gregory 1923 from Mongolia representing an aggregation of four mid-sized juvenile animals. In conjunction with existing specimens of groups of P. andrewsi that includes size-clustered aggregations of young juveniles and adult-sized specimens, this new material provides evidence for some degree of size-clustered aggregation behaviour in Protoceratops throughout ontogeny. This continuity of size-segregated (and presumably age-clustered) aggregation is previously undocumented in non-avian dinosaurs. The juvenile group fills a key gap in the available information on aggregations in younger ceratopsians. Although we support the general hypothesis that many non-avian dinosaurs were gregarious and even social animals, we caution that evidence for sociality has been overstated and advocate a more conservative interpretation of some data of 'sociality' in dinosaurs.
    PLoS ONE 11/2014; 9(11):e113306. · 3.53 Impact Factor
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    ABSTRACT: Bone pathology in the titanosaur dinosaur Uberabatitan ribeiroi from the Mar�ılia Formation (Bauru Group, Late Cretaceous) of Uberaba city (Minas Gerais State, Brazil) is analysed here. They include two fused procoelous mid-caudal vertebrae (CPPLIP-1020) and a haemal arch (CPPLIP-1006) of the middle section of the tail with a healing fracture callus. The analyses of the caudal vertebrae CPPLIP-1020 of Uberabatitan permit us to recognize the following signs, based on CT scan and external macroscopic observations: (1) ossified longitudinal tendons; (2) likely ossified intervertebral disc, producing fused vertebral bodies; (3) fused right zygapophyseal process with a laterally developed osteophyte affecting this joint; (4) osteophytes and exostoses at different portions of the vertebrae; (5) cloacae, bone erosion and likely internal infection. According to all the processes observed in these caudals, we could not discard at least two possibilities for the diagnosis of the fused vertebrae. It could be the result of a spondyloarthropathy process (considering most of the observed signs) or possibly have been associated with an infection (e.g. discospondylitis/infections spondylitis or septic arthritis). The bone lesion record in Uberabatitan ribeiroi from the Late Cretaceous of Brazil increases the range of study of titanosaur dinosaurs, which although have a large fossil record, have few pathological studies.
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