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Re: Dilophosaurus Forelimb Bone Maladies
The authors propose that during the long healing period, the use of
the forelimbs by this smashed-up _Dilophosaurus_ was severely
compromised. But it wasn't fatal. This supports the interpretation
that theropod forelimbs were not all that useful for predation - even
when the forelimbs were healthy and undamaged. Although often quite
strong and/or robust, theropod forelimbs had limited reach and the
manus often had fairly mediocre grasping abilities (especially for
small theropods that were supposedly arboreal). So it's no surprise
(to me) that so many theropods reduced their forelimbs (carnotaurines
effectively lost them altogether), or turned them to other purposes,
such as display or locomotion (with display perhaps leading into
aerial locomotion in a couple of lineages).
On Thu, Feb 25, 2016 at 6:19 AM, Ben Creisler <email@example.com> wrote:
> Ben Creisler
> New in open-access PLoS ONE:
> Phil Senter & Sara L. Juengst (2016)
> Record-Breaking Pain: The Largest Number and Variety of Forelimb Bone
> Maladies in a Theropod Dinosaur.
> PLoS ONE 11(2): e0149140
> http: // journals.plos.org/plosone/article?id=10.1371/journal.pone.0149140
> Bone abnormalities are common in theropod dinosaur skeletons, but
> before now no specimen was known with more than four afflicted bones
> of the pectoral girdle and/or forelimb. Here we describe the pathology
> of a specimen of the theropod dinosaur Dilophosaurus wetherilli with
> eight afflicted bones of the pectoral girdle and forelimb. On its left
> side the animal has a fractured scapula and radius and large
> fibriscesses in the ulna and the proximal thumb phalanx. On its right
> side the animal has abnormal torsion of the humeral shaft, bony tumors
> on the radius, a truncated distal articular surface of metacarpal III,
> and angular deformities of the first phalanx of the third finger.
> Healing and remodeling indicates that the animal survived for months
> and possibly years after its ailments began, but its right third
> finger was permanently deformed and lacked the capability of flexion.
> The deformities of the humerus and the right third finger may be due
> to developmental osteodysplasia, a condition known in extant birds but
> unreported in non-avian dinosaurs before now.