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Classification
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Pterosauria,
Pterodactyloidea,
Istiodactylidae Howse et al, 2001
Istiodactylus
latidens (Seeley, 19
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Description
of Material
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(Don't
understand all the terminology? visit the Glossary)
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Istiodactylus
was not always known as this, as the holotype is actually material
belonging to the dinosaur Ornithodesmus,
which was originally mistaken for bird and then pterosaur material,
but once the specimen was designated dinosaur, the later "Ornithodesmus"
material had to be renamed.
The skull
is elongate, but with a short snout region in front of the nostrils.
There is an unusually extensive naso-antorbital fenestra occupying
most of the snout. The orbit is anterodorsally capped by a hemispherical
tuberosity, and is continuous with a long, narrow suborbital vacuity.
The mandible has an abbreviated symphysis, with the mandible deepest
at the divergence point of the jaw rami. There are 24 teeth in the
upper jaw, which are limited to the prenarial region, and 25, including
an anterior median tooth, in the lower jaw.
The teeth
are labio-lingually compressed, with pointed crowns and truncated
triangular roots, shorter than the crowns. The upper and lower teeth
interlock, with the front teeth closely spaced compared to those
to the posterior.
The neural
arches have tall, steeply sloping laminae, the six shoulder vertebrae,
which are fused into a notarium, are completely fused with the neural
spines fused as a supraneural plate. The main body of the sternum
is deep, with an obtusely bowed leading edge and a transversely
triangular keel.
The humerus
has an acutely curved deltopectoral crest, with a free margin that
terminates beneath the infra-axial surface.
The sternum
has a saddle-shaped coracoid facet situated dorsally, and is arranged
asymmetrically, which is a primitive feature unique in pterodactyloids.
Material
is rare, so please report it if you find some...
How
do I know if I've found a bone?
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