Animatronic Dinosaur Factory From China

Dinosaur ontogeny of walking posture changes

Since the 1990s, western Liaoning Province in China a lot of output psittacosaur (Psittacosaurus) fossil, Psittacosaurus is a small herbivorous original angle dragon. Lot Psittacosaurus fossils of dinosaurs living habits in order to further understand the growth pattern and provides a rich research base.
 Institute of Vertebrate Paleontology and Paleoanthropology of Dr. Zhao Qi, who published their latest research results in the June 28 "natural communication" Nature Communications, the first time combined with bone histology confirmed the parrot mouth of the dragon the existence of the process of individual development process from quadruped to biped transition, walking posture for the study provides a new way.

 As we all know, most of the reptiles creeping quadruped walking posture is forward, and there are many groups of dinosaurs are bipedal. Some scholars believe that there is a shift in the individual walking posture during the development of some dinosaurs. The traditional method is by measuring and related statistical analysis appendage bones to prove the existence of this transformation. Usually we think, when the approximate length of the hind legs in front, the possibility of four-legged relatively large, if hind limb length was significantly longer than the forelimbs, are more inclined to think that it is bipedal. But for this method, there are some doubts, some scholars believe that even the hind limb length was significantly longer than the forelimbs, can not explain it is bipedal, such as Stegosaurus and Ankylosaurus, etc., while having long hind legs, but its still quadruped walking.
 Bone histology was paleontology research stage in a more popular research method, mainly used in judging vertebrate fossils age at death and growth stages. Its application in motor function learning area is still in its initial stage of development, a lot of research in this area is still in the trial stage. And this study Kee Zhao et al in this area is the first attempt.
 This study first bone age through detailed analysis, the precise age of 16 Psittacosaurus specimens, since the sample covers the complete sequence of juvenile individuals, it is possible to get an accurate age of adult individuals through the projection method, the work for Subsequent research has provided a solid foundation.
 Followed by detailed appendages skeleton length statistical analysis, the researchers found that with age forelimbs, hind legs relative to its length, the approximate length of the development from the early to late significantly shorter than the hind legs. And forelimbs of the humerus, radius, ulna humerus relative to the hind legs, also has a significant negative allometric (negative allometry) trend.
 And traditional research methods is different is that the study also 16 Psittacosaurus individuals 41 appendicular skeleton for a detailed analysis of bone tissue sections. The study found that in young Psittacosaurus specimens, representative of its forelimb bone rapidly growing radial vascular channels (vascular canals), while the hind legs was relatively slow growth of longitudinal development of vascular channels. In the late stages of development, that is, sub-adult and adult stages hindlimb vascular channel structure showed the growth rate faster than the forelimbs. The results of bone tissue areas with the previous results of the analysis of bone length is consistent, for the transformation of Psittacosaurus walking posture provides strong evidence.
 Similar Psittacosaurus this walking posture shift in dinosaurs are not isolated cases, in another big group of sauropod dinosaurs also found, such as Ojo Long (Massospondylus). Among the theropod dinosaurs, fossils also retains some embryonic approximately equally long forelimbs and hind legs, indicating its infancy prefer four-legged. These ontogeny in the reserved quadruped to biped change information, and tetrapod system evolution trend is consistent. Early Triassic archosaurs by the four-legged before the trip (archosaurs) to the Late Triassic evolution of bipedal primitive dinosaur that up to thousands of years of evolutionary history of a long and perhaps it was this just a dozen concentrate In ontogeny being. (BioValley