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Details on Nanyangosaurus



Nanyangosaurus Xu, Zhao, Lu, Huang, Li and Dong 2000
N. zhugeii Xu, Zhao, Lu, Huang, Li and Dong 2000
etymology- "Zhuge's Nanyang lizard", Zhuge Liang being an ancient strategist
and philosopher and Nanyang being a place name.
Sangping Formation, Henan, China
Albian?, Early Cretaceous
holotype- (IVPP V 11821) eight dorsal vertebrae, sacrum (six true sacrals),
thirty-six caudal vertebrae, three proximal chevrons, humerus, radius, ulna,
incomplete manus, partial ischium, femur, tibia, fibula, astragalocalcaneum,
pes
diagnosis- partially fused metacarpals II-IV; metacarpal II more than 90%
the length of subequal metacarpals III and IV; metacarpal IV more robust
than other metacarpals and with a thick distal end; manual phalanx IV-1
wider transversely than proximodistally; metatarsal II dorsoventrally
thicker than metatarsal III.
main measurements-
    humerus        265 mm
    radius            230 mm
    ulna                243 mm
    mcII                28 mm
    mcIII               92 mm
    mcIV             102 mm
    mcV              102 mm
    femur             517 mm
    tibia               548 mm
    fibula             503 mm
    mtII                155 mm
    mtIII               193 mm
    mtIV              165 mm
description-
This dinosaur was found in 1994, Mike Keesey had the name "Nanyoungosaurus"
reported to him as a museum label, then it was announced in a 1999 SVP
abstract.  The specimen was 4.5 meters long.  It is an adult because of the
well fused vertebral centra and fused ischia.  As I am not an iguanodont
expert and the authors did a good job describing this taxon, the following
description is based purely on the text.
The first preserved dorsal is slightly opisthocoelous, the others are
platycoelous.  They have heart-shaped articular ends, the third through
seventh preserved dorsals are fused together and only the fifth and sixth
have a well-developed ventral keel.
There are eight sacral vertebrae, including a sacrodorsal and a sacrocaudal.
The anterior articular end is nearly round and the posterior articular end
is flattened and circular.  The sacral centra are low and wide, not very
constricted and there is a ventral groove on sacrals 4-8.
The caudals are platycoelous and get lower and narrower transversely faster
than they get shorter, so that the last caudals are elongate.  The centra
are subcircular (1-3), subrectangular (4-14), trapezoidal (15-17), irregular
hexagonal (18-22), regular hexagonal (23-35) and rounded (36) in anterior
and posterior view.  The last transverse process is on caudal 20 and the
neural spines are taller than corressponding chevrons.
The forelimb is comparatively slender and the humerus has an angular
deltopectoral crest and dorsoventrally thick distal end (1.3 times as thick
as transversely wide).  The radial condyle is smaller than the ulnar condyle
and extends further distally.  Metacarpal I is absent, II-IV are fused and
III and IV are ronust, with IV being more so with an expended distal end.
The phalanges are robust and the unguals are hoof-shaped.
The distal ischium is moderately curved with a well-developed foot.
The femur is straight laterally and the medial distal condyle is more than
twice as wide as the lateral.  The anterior intercondylar groove is
tunnel-like, but the condyles are unfused.  The tibia has a transversely
wide proximal end and the fibula is semilunate proximally.  The
astragalocalcaneum is fused and rectangular anteriorly with a weak ascending
process.  Metatarsal I is absent, metatarsal II is deeper proximally than
metatarsal III and the pedal unguals are hoof-shaped.
Relationships-
The authors perform a cladistic analysis, with Hypsilophodon, Camptosaurus,
Iguanodon, Ouranosaurus, Probactrosaurus, Nanyangosaurus and Hadrosauridae
based on forty-five postcranial characters (in Chinese) and show a cladogram
with the above taxa, in order, being progressively closer outgroups to the
Hadrosauridae.  Nanyangosaurus is more basal than hadrosaurs based on:
- six true sacrals
- proximal caudal centra rectangular or rounded
It is their sister group based on:
- caudal neural spines longer than corrsponding chevrons
- angular ventral margin of deltopectoral crest
- ulnar condyle larger than radial condyle
- reduced carpus
- slender metacarpals
- metacarpal I absent
- straight femur
- tunnel-like anterior intercondylar groove of femur
- transverse widening of proximal tibial head extending onto shaft
- distal tarsals absent
- metatarsal I absent

Those of you who want scans of the axial and appendicular elements (1 1/2
pages) can contact me offline.

Mickey Mortimer