The tenth skeletal specimen of Archaeopteryx

Abstract

We describe the tenth skeletal specimen of the Upper Jurassic Archaeopterygidae. The almost complete and wellpreserved skeleton is assigned to Archaeopteryx siemensii Dames, 1897 and provides significant new information on the osteology of the Archaeopterygidae. As is evident from the new specimen, the palatine of Archaeopteryx was tetraradiate as in non-avian theropods, and not triradiate as in other avians. Also with respect to the position of the ectopterygoid, the data obtained from the new specimen lead to a revision of a previous reconstruction of the palate of Archaeopteryx . The morphology of the coracoid and that of the proximal tarsals is, for the first time, clearly visible in the new specimen. The new specimen demonstrates the presence of a hyperextendible second toe in Archaeopteryx . This feature is otherwise known only from the basal avian Rahonavis and deinonychosaurs (Dromaeosauridae and Troodontidae), and its presence in Archaeopteryx provides additional evidence for a close relationship between deinonychosaurs and avians. The new specimen also shows that the first toe of Archaeopteryx was not fully reversed but spread medially, supporting previous assumptions that Archaeopteryx was only facultatively arboreal. Finally, we comment on the taxonomic composition of the Archaeopterygidae and conclude that Archaeopteryx bavarica Wellnhofer, 1993 is likely to be a junior synonym of A. siemensii , and Wellnhoferia grandis El { anowski, 2001 a junior synonym of A. lithographica von Meyer, 1861.

New Specimens ofAnchiornis huxleyi(Theropoda: Paraves) from the Late Jurassic of Northeastern China

“…The nasal process tapers posterodorsally and is almost three times the length of the premaxillary main body. The nasal process of PKUP V1068 is very similar to that of Archaeopteryx (Mayr et al, 2005(Mayr et al, , 2007, in having an anteroposteriorly expanded base and a premaxillary foramen positioned laterally on the base of the nasal process (fig. 5).…”

“…Dotted lines encircle the areas that were reconstructed before acquisition of the specimen. similar to the condition in basal troodontids and basal dromaeosaurids, such as Sinovenator and Microraptor, as well as Archaeopteryx Mayr et al, 2005Mayr et al, , 2007Pei et al, 2014). In derived troodontids and dromaeosaurids, the lateral lamina of the ascending process is broad (Osborn et al, 1924;Norell et al, 2006;Xu et al, 2010;Tsuihiji et al, 2014).…”

“…5), less than one-third the length of the antorbital fossa, which is the also the case in other Jianchang paravians, troodontids, and some dromaeosaurids such as Microraptor and Bambiraptor (Burnham et al, 2000;Xu et al, 2011;Godefroit et al, 2013aGodefroit et al, , 2013bPei et al, 2014). In avialans, derived dromaeosaurids, and some more-basal coelurosaurians, the rostral process of the maxilla is much longer, at more than two-thirds the length of the antorbital fenestra (e.g., Chiappe et al, 1999;Mayr et al, 2005Mayr et al, , 2007Turner et al, 2012).…”

“…The main body of the premaxilla (the laterally exposed portion except the nasal process and the subnarial process) lies mostly anterior to the external naris. Only a small posterior portion of the premaxillary body extends ventral to the external naris, as in Archaeopteryx (Mayr et al, 2005(Mayr et al, , 2007, which differs from the condition in troodontids and dromaeosaurids . The nasal process tapers posterodorsally and is almost three times the length of the premaxillary main body.…”

Archaeopteryx feathers and bone chemistry fully revealed via synchrotron imaging

“…This Archaeopteryx is preserved within a matrix of limestone from the Solnhofen region of Bavaria, Germany (3,4) and was selected because of its remarkable preservation. Housed at the Wyoming Dinosaur Center in Thermopolis (Wyoming, USA), it is hence referred to as the Thermopolis specimen (WDC-CSG-100).…”