[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
New Palaeontology refs - including Ornitholestes forelimbs
PHIL SENTER (2006). FORELIMB FUNCTION IN ORNITHOLESTES HERMANNI OSBORN
(DINOSAURIA, THEROPODA) . Palaeontology 49: 1029-1034.
Abstract: Ornitholestes hermanni is a Late Jurassic theropod dinosaur from
North America. This kinematic study of Ornitholestes uses manual
manipulations of forelimb casts to determine range of motion. The manual
phalanges of the O. hermanni holotype, previously unidentified, are here
identified as phalanges I-1, I-2 (ungual), II-2 and II-3 (ungual). At all
represented manual joints, hyperextensibility is small or absent, whereas
flexion is strong, as in most other theropods. The elbow can be strongly
flexed beyond a right angle. When data on range of forelimb motion in
Ornitholestes are added to such data from other theropods, high elbow
flexion is present in maniraptoriform coelurosaurs but not in basal
theropods. Forelimb functions requiring strong elbow flexion (such as
holding objects to the chest, or tucking the forearms in for their
protection or to reduce wind resistance or heat loss) were therefore
available to maniraptoriform coelurosaurs but not to basal theropods.
NADIA B. FRÖBISCH and JÖRG FRÖBISCH (2006) A NEW BASAL PTEROSAUR GENUS FROM
THE UPPER TRIASSIC OF THE NORTHERN CALCAREOUS ALPS OF SWITZERLAND.
Palaeontology 49: 1081-1090
Abstract: A lower jaw with multicusped teeth and a number of unique
characteristics was discovered in an extensive exposure of the Upper
Triassic Kössen Formation in the Northern Calcareous Alps. The ramus of the
jaw is high and dominated by a row of large, oval foramina that lies
parallel to the tooth row. In addition, the anterior portion of the dentary
exhibits a large number of nutritive foramina and small pits, which might
indicate an association with a soft tissue structure and/or the presence of
a keratinous cover of that area during life. All elements of the jaw are
thin-walled and hollow, possibly pneumatic. Two teeth are preserved within
the dentary. One is tricuspid and the other bears four cuSPS. The teeth are
noticeably small in comparison with the overall size of the ramus, being
only one-third of the height of the ramus. The teeth show a strong
similarity to those of the well-known basal pterosaur genus Eudimorphodon,
whose jaw morphology, however, clearly differs from the specimen described
in this study. The dentition and the pneumatic bone structure make an
assignment to the Pterosauria plausible. Based on the great number of
distinct morphological characters the specimen is described as Caviramus
schesaplanensis gen. et sp. nov.
E. E. MAXWELL and M. W. CALDWELL (2006). A NEW GENUS OF ICHTHYOSAUR FROM THE
LOWER CRETACEOUS OF WESTERN CANADA. 1043-1052
Abstract: A new fauna of Lower Cretaceous (Albian) ichthyosaurs, which
includes at least one new genus and species, was recovered from deposits of
the Loon River Formation at Hay River, Northwest Territories, Canada. All
Cretaceous ichthyosaurs have been referred to a single genus,
Platypterygius. The Loon River Formation material, however, does not satisfy
the diagnosis for Platypterygius, and it is distinctive enough to warrant
the erection of a new genus and species of ichthyosaur. Maiaspondylus
lindoei gen. et sp. nov. is distinguished from other ichthyosaurs by an
extensive overlapping contact of the jugal and the maxilla; marginal teeth
with smooth crowns, fluted cementum, lingual curvature and implantation in a
dental groove; and humerus with isomorphic proximal and distal ends,
featuring three distal articular facets in which the medial articular facet
is smaller than the lateral facets. The holotype and referred material is
described here, and the relationship of Maiaspondylus to other
ophthalmosaurs is discussed.