Na artykuł o czaszce Nanotyrannus
czekam już półtora roku i wreszcie jest, ale nowy, pierzasty krewny limuzaura - Archaeocursor
z nową wersją filogenezy teropodów jest dużo lepszy!
[ADDED 08.04.2011: THIS IS AN APRIL FOOL'S DAY JOKE] "Basalmost theropod with filamentous integumentary structures and new clade of basal 'carnivorous' dinosaurs" Sereno, P., Rauhut, O., Xing, X., Wang, Y., Zhu, T., Gao, X. & Gong, D. Kirtlandia 37: 82-113
We describe a new, unusual basal theropod dinosaur from the Middle-Late Jurassic Tiaojishan Formation of northeasten China, known from single articulated skeleton, missing only tail, pelvic girdle and femora. Archaeocursor inexpectatus gen. et sp. nov. is the basalmost theropod with filamentous integumentary structures, which morphology is transitional between ornithischian and coelurosaurian dinosaurs, hence providing new evidence to hypothesis of dinosaurs ancestrally covered with proto-feathers. Archaeocursor is remarkably similar to near-contemporary Limusaurus, but has more cursorial proportions. Manus morphology of new taxon suggest that reduced manual digit I of Limusaurus is apomorphic and tetanuran digit formula is I-II-III. Pes shows extremely antarctometatarsalian condition: metatarsal and digit III are very robust, while II and IV are reduced in way unobserved in other theropods.
New, comprehensive cladistic analysis shows that Archaeocursor and other theropods, recently recognized as basal ceratosaurs, form a clade, here termed Bahariasauroidea. This taxon, sister to Averostra (Ceratosauria+Tetanurae), includes Berberosaurus, Ozraptor, Spinostropheus and the derived Bahariasauridae: Archaeocursor, Bahariasaurus (which we consider senior synonym of Deltadromeus), their sister taxon Limusaurus and also Elaphrosaurus along with material once referred to this taxon from Kimmeridgian of USA. Bahariasaurids are rare, cursorial, cosmopolitan, at least in Jurassic period, and possibly herbivorous theropods. A number of small theropods generally recognized as basal abelisauroids may be in fact bahariasauroids. Archaeocursor shares some mandibular similarities with putative Early Jurassic therizinosaur Eshanosaurus, but more material is needed to confirm it's relationship with Bahariasauroidea.
The Cleveland tyrannosaur skull (Nanotyrannus or Tyrannosaurus): new findings based on ct scanning, with special reference to the braincase. Witmer. L.M. & Ridgely, R.C. Kirtlandia 37: 61-81.
The Cleveland Museum of Natural History’s skull of a small tyrannosaurid theropod dinosaur (CMNH 7541) collected from the Hell Creek Formation has sparked controversy, with competing hypotheses suggesting that it represents a separate taxon of dwarf tyrannosaurid (Nanotyrannus lancensis), a juvenile specimen of Tyrannosaurus rex (the only other acknowledged Hell Creek tyrannosaurid), or a compromise position (a juvenile Nanotyrannus). Beyond this controversy, CMNH 7541 holds importance because of the anatomical information that such a well preserved skull can provide, and it is in this context that we have sought to probe the structure of the braincase region (e.g., pneumatic sinuses, cranial nerve foramina), as well as other regions of the skull.
We subjected the skull to computed x-ray tomography (CT scanning), followed by computer analysis and 3D visualization. The braincase and a number of other bones (e.g., vomer, quadrate, quadratojugal, palatine, mandible) were digitally "extracted" from the CT datasets. Although the new findings strongly confirm the long-held view that CMNH 7541 pertains to a tyrannosaurid, the mosaic of characters it presents makes finer taxonomic assignment difficult. For example, some characters support affinities with T. rex, yet other characters argue for a much more basal position.
The key question that awaits resolution is whether the differences observed can be attributed to juvenility, and such resolution will require information from new, as yet unpublished specimens. Nevertheless, some of the differences seen in CMNH 7541 (e.g., the pattern of pneumatic foramina in the basicranium) are highly divergent and are harder to attribute to ontogeny. Among other findings, we report here thin, laminar structures within the main nasal airway that are interpretable as being respiratory turbinates, which have potential implications for metabolic physiology.