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Allosaurus lifestyle insights based on pathologies



Ben Creisler
bcreisler@gmail.com


A recent paper not yet mentioned:

Christian Foth, Serjoscha Evers, Ben Pabst, Octávio Mateus, Alexander
Flisch, Mike Patthey & Oliver W. M. Rauhut (2015)
New insights into the lifestyle of Allosaurus (Dinosauria: Theropoda)
based on another specimen with multiple pathologies.
PeerJ PrePrints 3:e824v1
doi: http://dx.doi.org/10.7287/peerj.preprints.824v1
https://peerj.com/preprints/824/

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).