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Eotyrannus details



No, it's not a Details on...., yet.  This is just to inform you all of a few things about the newly discovered coelurosaur- Eotyrannus lengi.  This is the inaccurately described "cat-like" theropod first announced July 7, 1998.  A good portion of the skeleton (MIWG 1997.550) is known (premaxilla, partial maxilla, nasals, lacrimal, quadrate, axial arch, cervicals, dorsals, last sacral centrum, caudals?, scapula, coracoid, humerus, partial ulna, radius fragment, carpal, metacarpals, manual phalanges, manual unguals, ilial fragment, proximal tibia, proximal fibula, metatarsals, phalanges, pedal ungual), although much is incomplete.  Hutt et al. place this in the Tyrannosauroidea based on- D-shaped premaxillary teeth, premaxillary arcade aligned close to mediolaterally, premaxilla taller than long, fused nasals, premaxillary teeth smaller than maxillary teeth, acromion more than twice shaft width.  The premaxilla isn't nearly as tall as that of tyrannosaurids, it's more similar to the plesiomorphic condition in Allosaurus for instance.  Similar things could be said for the acromial expansion.  It is also more primitive than tyrannosaurids because of the coracoid tubercle and unreduced forelimbs, among other features.  Actually, entering it into my data matrix makes it come out as a dromaeosaurid (fused interdental plates, posterior serrations much larger than anterior serrations).  However, I have not added a couple potential tyrannosauroid synapomorphies yet and there are some characters I will hopefully know the states of soon which will help place it securely.  Some odd characters of this taxon are the apically complete denticulation, pleurocoelous last sacral vertebra, last sacral with ventral keel and extremely elongate manus (95% humeral length).  Makes me wonder if the sacral is actually a cervicodorsal ;-) .  Finally, the true identity of Thecocoelurus is revealed-
"BMNH R181, the incomplete holotype cervical vertebra of Thecocoelurus daviesi, has a distinctive hourglass-shaped ventral sulcus and ventrolateral raised edges. In these features and others (absent from the vertebrae of Eotyrannus) T. daviesi is reminiscent of the cervical vertebrae of Chirostenotes pergracilis (Sues, 1997) and probably represents an oviraptorosaur
(Naish, 1999a; Naish & Martill, submitted)."
Look forward to Details on Eotyrannus, after I get the new characters entered, and after I finish Details on Liaoxiornis (is it small because it's a juvenile?........).
 
Mickey Mortimer