In addition to these morphological differences, in 2019 Button and Zanno note that herbivorous dinosaurs followed two main distinct modes of feeding. One of these was processing food in the gut which is characterized by gracile skulls and relatively low bite forces. The second was oral food processing, characterized by features associated with extensive processing such as the lower jaws or dentition. Segnosaurus was found to be in the former mode, whereas Erlikosaurus was more likely to fall in the second group, indicating these two therizinosaurids were functionally separated and occupied different niches. During the same year, Ali Nabavizadeh concluded that most therizinosaurs were mainly orthal feeders (moving their jaws up and down and not to the sides) and raised their jaws isognathously whereby the upper and lower teeth of each side contacted each other at once. However, advanced Late Cretaceous therizinosaurids had relatively weak bite forces compared to primitive therizinosaurs. In 2013 the paleontologist Stephan Lautenschlager performed digital reconstructions for the cranial musculature in Erlikosaurus and found the bite force of Edmontosaurus being greater than that for the former. The lesser bite force for Erlikosaurus better served in stripping and cropping leaves, rather than active mastication. On a newer study with more therizinosaur taxa, Lautenschlager found similar conclusions. The evolutionary trends in jaw mechanics of therizinosaurs noticed a change in bite force through time, from higher bite forces in early members to lesser ones in the advanced therizinosaurids. Therizinosaurids were aided by the down-turned tip and symphyseal regions (union between bones) of the dentaries, and probably also by beaks. By contrast, the straighter and more elongated dentaries of primitive therizinosaurs had the highest magnitudes of stress and strain. A downwards-pulling motion of the head while gripping vegetation was more likely than a sideways or upwards movement, though such behavior would be more likely in therizinosaurids with their stress-mitigating jaws. Foraging Among therizinosaurids, the forelimbs were increased in robustness and the flexibility of the wrist was increased as well, with this, the presumed reach for foraging is likely to have lengthened. Moreover, the pectoral girdle has been modified to further augment upright reach, however the grasping ability of the animals is thought to have decreased. These adaptations are more linked to assist with their herbivorous lifestyle, as they have specialized the ability to harvest and collect vegetation. Moreover. in the therizinosaurids Neimongosaurus, the range of motion in the arms was