Recent discoveries of basal dromaeosaurids from the Early Cretaceous Jiufotang and Yixian formations of Liaoning, China, add significant new information about the transition from non-avian dinosaurs to avians. Here we report on a new dromaeosaurid, Tianyuraptor ostromi gen. et sp. nov., from the Early Cretaceous Yixian Formation of western Liaoning, China, based on a nearly complete skeleton. T...

Feathers are appendages of skin in avians and provide a model for analyzing skin appendage morphogenesis. The feathers of Chinese Silky (CS) and White Leghorn (WL) chickens have distinct phenotypes. Based on preliminary genetic results, we cloned the chicken gene sobp (encoding sine oculis binding protein homolog, which is expressed at a higher level in the dorsal skin and in the feather follic...

We have cloned and sequenced a chicken cDNA encoding an l-DOPAchrome tautomerase (DCT) from an embryonic melanocyte cDNA library. The chicken DCT gene encodes a deduced protein of 516 amino acids (aas) and shares 69.2% and 69.9% aa sequence identity with the deduced mouse and human DCT proteins, respectively. Northern blot hybridisation analysis reveals a DCT transcript of 3.5kb in RNA from the...

Five groups of 10-day-old chicks were continuously exposed to either 500 or 1500 Hz pure tone at 125 dB for 4 or 12 h and killed 10 days later. The basilar papillae were fixed, embedded in plastic, sectioned, and hair cells were counted according to type: tall or short. Short hair cells were found to be more susceptible to acoustic overstimulation than tall hair cells. Further, the position of ...

In birds, it is thought that head movements play a major role in the reflexive stabilization of gaze and vision. In this study, we investigated the contributions of the eye and head to gaze stabilization during rotations under both head-fixed [vestibuloocular (VOR)] and head-free conditions in two avian species: pigeons and quails. These two species differ both in ocular anatomy (the pigeon has...

Moving target detection in cluttered backgrounds is always considered a challenging problem for artificial visual systems, but it an innate instinct of many animal species, especially the avian. It has been reported that spatio-temporal information accumulation computation may contribute to high efficiency and sensitivity avian tectal neurons detecting moving targets. However, its functional ro...

Background: Avian tongue has a significant role in the feeding process. The current investigation was planned to study histological and ultrastructural features of two avians. Java sparrow (Lonchura oryzivora) Hoopoe (Upupa epops). Methods: Fourteen birds were used including seven sparrows Hoopoes during investigation. Careful procedures dissection process avian species. Their heads separated f...

The gross size and shape of the brain is often preserved in extinct vertebrates with well-ossified braincases, such as dinosaurs. The volume within the braincase, termed the endocast, is the space occupied by the brain, cerebrospinal fluid, and surrounding tissues. Endocasts of most nonavian dinosaurs differ little in size and shape from those of living reptiles (Jerison, 1969, 1973; Hopson, 19...