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Allosaurus pathologies (free pdf)

Ben Creisler

A new paper in open-access PeerJ:

Christian Foth, Serjoscha W. 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 3:e940
doi:  https://dx.doi.org/10.7717/peerj.940

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, 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 Allosaurus. 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).