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Archaeorhynchus (basal ornithuromorph bird) anatomy



From: Ben Creisler
bcreisler@gmail.com

A paper in the new JVP:

Shuang Zhou, Zhonghe Zhou & Jingmai K. O’Connor (2013)
Anatomy of the basal ornithuromorph bird Archaeorhynchus spathula from
the Early Cretaceous of Liaoning, China.
Journal of Vertebrate Paleontology 33(1):141-152
DOI:10.1080/02724634.2012.714431
http://www.tandfonline.com/doi/full/10.1080/02724634.2012.714431


As one of the earliest-known beaked ornithuromorph birds,
Archaeorhynchus spathula is important for understanding the early
evolution of this derived avian clade. Recently, two new complete and
articulated specimens of Archaeohyrnchus spathula were collected from
Lower Cretaceous deposits of Jianchang, Liaoning, northeastern China.
These specimens preserve new anatomical information, particularly in
regards to the morphology of the skull (including the inner structure
of the occiput), forelimbs, hind limbs, and sternum. The sternum is
similar to that of an unnamed ornithuromorph from the Xiagou
Formation, Gansu Province. These new specimens are subadult: together
with the holotype of Archaeorhynchus, they constitute the entire Early
Cretaceous record of subadult ornithuromorphs and reveal important
information regarding the ontogeny of this group. The caudal vertebrae
are complete in the two referred specimens and provide information
about the development of the pygostyle in basal ornithuromorphs. At
least four vertebrae form the pygostyle of Archaeorhynchus and fusion
progresses distoproximally. The preservation of gastroliths in all
known specimens of Archaeorhynchus signifies that it was likely
herbivorous