This can also be seen in the size comparison between ornithocheirids and istiodactylids, with the wingspan of "Tropeognathus" for example, measuring almost double that of "Istiodactylus". Ornithocheirids like "Tropeognathus" and "Coloborhynchus" are considered to be fish-eaters, and had longer and sharper teeth compared to the more rounded teeth of "Istiodactylus", though this is still sometimes disputed. Another difference that can be seen in more primitive ornithocheiromorphs their eyes being proportionally smaller compared to the assumed predatory and more advanced ornithocheirids, this again adds to the fact that the more primitive groups (istiodactylids) were most likely scavengers, and later got more successful within the food chain, leading the later, more advanced groups (ornithocheirids and lonchodectids) to be the dominant fish hunters during the early Late Cretaceous. A 2017 study confirmed that most ornithocheirids were fish-eaters, though in a deeper analysis, paleontologists found carbon isotopes within several teeth, and later compared the enamel values of the ornithocheirid teeth between the aquatic and terrestrial consumers near the fossil site. Pterosaur enamels from the Twin Mountains Formation were shown with lower enamel values in comparison to the aquatic consumers that lived near, suggesting a more terrestrial diet, this is mostly due to the similarly low enamel values found in carnivorous theropods such as "Acrocanthosaurus", which mainly had a terrestrial diet. The enamels found in the Paw Paw Formation however, were described with higher values, in comparison to the nearby terrestrial consumers. Analyzing these enamel remains, paleontologists found out that the values seen were more comparable to the aquatic consumer values rather the terrestrial ones. These analyses are considered a very useful reference to the evolutionary changes between the earlier and later species of ornithocheirids, as well as other ornithocheiromorphs. The diet changes were also taken into account, with earlier genera such as "Coloborhynchus" having a varied diet, preying partially on fish, while also hunting on land. The later genera such as "Uktenadactylus" however, fed almost entirely on fish, and rarely hunted on land. This can be demonstrated with the age difference between the Twin Mountains Formation and the Paw Paw Formation.