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Majungasaurus had weird little arms (free pdf)
From: Ben Creisler
In the new issue of the Journal of Vertebrate Paleontology a study of
the forelimbs in Majungasaurus. The pdf is free!
S. H. Burch and M. T. Carrano (2012).
An articulated pectoral girdle and forelimb of the abelisaurid
theropod Majungasaurus crenatissimus from the Late Cretaceous of
Journal of Vertebrate Paleontology 32(1): 1-16.
Abelisaurid theropods are common members of Cretaceous Gondwanan
faunas and are characterized by a bizarre, highly reduced forelimb.
Unfortunately, forelimb elements are rarely preserved and thus the
basic structure of the abelisaurid forelimb remains poorly understood.
Until recently, the Upper Cretaceous Maevarano Formation of
northwestern Madagascar has produced numerous exceptional specimens of
the abelisaurid theropod Majungasaurus crenatissimus but comparatively
little forelimb material. A recently discovered articulated skeleton
of Majungasaurus preserves a virtually complete pectoral girdle and
forelimb, which, along with additional isolated forelimb elements,
affords important new insights into the structure of these elements.
New specimens of the scapulocoracoid and humerus allow more detailed
description of their morphology, and antebrachial and manual elements
are described for the first time. The radius and ulna are
approximately one-quarter the length of the humerus and both have
expanded proximal and distal articular surfaces relative to their
narrow diaphyses. The manus consists of four digits, each composed of
a short metacarpal and one (digits I and IV) or two (digits II and
III) phalanges. No ossified carpals are present. The proportions of
the brachium and antebrachium are stout, more similar to the condition
in Carnotaurus than in Aucasaurus. We reinterpret manual digit
identities in Aucasaurus and Carnotaurus based on new information
provided by the manus of Majungasaurus. Overall, the morphology of the
forelimb in Majungasaurus reveals that abelisaurids share an extremely
reduced, unique morphology that is dissimilar to the more typical
theropod condition seen in other ceratosaurs.