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Mirischia asymmetrica



The Santana compsognathid with an obturator foramen on one pubis and an
obturator notch on the other, and an obturator foramen with no
post-obturator notch on one ischium and an obturator process with
post-obturator notch on the other, has been named.  It's also notable for
the preservation of intestines and a possible air sac.  The paper has a
suggested phylogeny of compsognathids (Sinosauropteryx (Mirischia
(Aristosuchus, Compsognathus))).  I can send a pdf to those who request one.

Mirischia Naish, Martill and Frey, 2004
M. asymmetrica Naish, Martill and Frey, 2004
Albian, Early Cretaceous
Romualdo Member of Santana Formation, Brazil
Holotype- (SMNK 2349 PAL) (~2.1 m; subadult) posterior twelfth dorsal
vertebra, thirteenth dorsal vertebra (26 mm), thefth dorsal rib, gastralia,
first sacral vertebra, second sacral vertebra, anterior third sacral
vertebra, partial ilia, pubes, ischia, incomplete femora (165 mm), proximal
tibia, proximal fibula, intestine, postpubic airsac(?)
Diagnosis- (after Naish et al., 2004) pubic peduncle of ilium with concave
cranial surface; pubic boot with no cranial expansion and 32% total length
of pubis; pedicular fossae located craniodorsal to neural canal on caudal
dorsal vertebra; distal tips of the neural spines between 63% and 67% longer
than their bases; ventral surface of sacral centra bearing shallow median
depressions at either end; extremely thin bone walls to all known elements.
References- Martill, Frey, Sues and Cruickshank, 2000. Skeletal remains of a
small theropod dinosaur with associated soft structures from the Lower
Cretaceous Santana Formation of northeastern Brazil. Canadian Journal of
Earth Sciences. 37, 891-900.
Naish, Martill and Frey, 2004. Ecology, Systematics and Biogeographical
Relationships of Dinosaurs, Including a New Theropod, from the Santana
Formation (?Albian, Early Cretaceous) of Brazil. Historical Biology. 2004,
1-14.

Mickey Mortimer
Undergraduate, Earth and Space Sciences
University of Washington
The Theropod Database - http://students.washington.edu/eoraptor/Home.html