Claremont, CA, United States
Claremont, CA, United States

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Farke A.A.,Raymond M. Alf Museum of Paleontology | Patel P.P.,The Webb Schools
Cretaceous Research | Year: 2012

An isolated coracoid represents the first described occurrence of an enantiornithine bird from the Kaiparowits Formation (Upper Cretaceous) of southern Utah, USA. The specimen is identified as enantiornithine by the convex scapular facet, approximate alignment of this facet with the humeral articular facet and acrocoracoid process, and the presence of an acrocoracoidal tubercle. This coracoid came from a comparatively large individual, consistent with previous reports of other large enantiornithines from strata of Campanian strata in North America, South America, and Europe. The occurrence of enantiornithines in the Kaiparowits Formation and their apparent absence in the well-sampled Dinosaur Park Formation of similar age in Alberta represents yet another faunal difference between the two areas, although this may be a result of environmental differences rather than the endemism proposed for non-avian dinosaurs. © 2012 Andrew A. Farke and Priyanka P. Patel.

Herrero L.,The Webb Schools | Farke A.A.,Raymond M. Alf Museum of Paleontology
PalArch's Journal of Vertebrate Palaeontology | Year: 2010

Skin impressions from hadrosaurid dinosaurs are relatively common finds throughout the Cretaceous Western Interior of North America. A recently discovered specimen from the late Campanian-aged Kaiparowits Formation of southern Utah is typical for hadrosaurs, with randomly arranged polygonal tubercles averaging around 4 mm in length and 3 mm in width. Based on the associated bones, these impressions likely originated on the thorax of the animal. In contrast with most previously published finds, the skin is not preserved in perfect articulation with the skeleton. This suggests a taphonomic mode in which the skeleton and soft tissues were partially disarticulated prior to burial. © PalArch Foundation.

Farke A.A.,Raymond M. Alf Museum of Paleontology | Wilridge C.A.,The Webb Schools
PalArch's Journal of Vertebrate Palaeontology | Year: 2013

An isolated bone from the late Campanian-aged Kaiparowits Formation of southern Utah is tentatively identified as the terminal wing phalanx (manual phalanx IV-4) from a pterosaur, representing the first report of this clade from the formation. The specimen is 60 mm long and hollow, with thin and delicate walls and expanded ?proximal and ?distal ends. This is consistent with anatomy reported for equivalent elements in pterodactyloid pterosaurs. Although the specimen cannot be more precisely identified, it is consistent with occurrences of pterosaurs in penecontemporaneous terrestrial depositional environments throughout western North America. © PalArch Foundation.

Farke A.A.,Raymond M. Alf Museum of Paleontology | Chok D.J.,The Webb Schools | Herrero A.,The Webb Schools | Scolieri B.,The Webb Schools | Werning S.,University of California at Berkeley
PeerJ | Year: 2013

The tube-crested hadrosaurid dinosaur Parasaurolophus is remarkable for its unusual cranial ornamentation, but little is known about its growth and development, particularly relative to well-documented ontogenetic series for lambeosaurin hadrosaurids (such as Corythosaurus, Lambeosaurus, and Hypacrosaurus). The skull and skeleton of a juvenile Parasaurolophus from the late Campanian-aged (~75.5 Ma) Kaiparowits Formation of southern Utah, USA, represents the smallest and most complete specimen yet described for this taxon. The individual was approximately 2.5 m in body length (~25% maximum adult body length) at death, with a skull measuring 246 mm long and a femur 329 mm long. A histological section of the tibia shows well-vascularized, woven and parallel-fibered primary cortical bone typical of juvenile ornithopods. The histological section revealed no lines of arrested growth or annuli, suggesting the animal may have still been in its first year at the time of death. Impressions of the upper rhamphotheca are preserved in association with the skull, showing that the soft tissue component for the beak extended for some distance beyond the limits of the oral margin of the premaxilla. In marked contrast with the lengthy tube-like crest in adult Parasaurolophus, the crest of the juvenile specimen is low and hemicircular in profile, with an open premaxilla-nasal fontanelle. Unlike juvenile lambeosaurins, the nasal passages occupy nearly the entirety of the crest in juvenile Parasaurolophus. Furthermore, Parasaurolophus initiated development of the crest at less than 25% maximum skull size, contrasting with 50% of maximum skull size in hadrosaurs such as Corythosaurus. This early development may correspond with the larger and more derived form of the crest in Parasaurolophus, as well as the close relationship between the crest and the respiratory system. In general, ornithischian dinosaurs formed bony cranial ornamentation at a relatively younger age and smaller size than seen in extant birds. This may reflect, at least in part, that ornithischians probably reached sexual maturity prior to somatic maturity, whereas birds become reproductively mature after reaching adult size. © 2013 Farke et al.

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