Lastly, our results emphasize the importance of performing complete adductor muscle reconstructions when running FEAs, and analyses that simplify muscle vectors to single points will possibly miss key data on functional performance. [11/11]

Size mediated resource partitioning is common in modern systems, suggesting that although hadrosaurids, ceratopsids, and ankylosaurians were specialized for different plants, within-group partitioning was subtle and ecological signals cannot be found, apart from size. [10/11]

Our results have important implications:
Resource partitioning between hadrosaurids was size mediated, where similarly sized animals had similar potential for food processing. Larger hadrosaurines had stronger bites than lambeosaurines, and likely had a wider diet breadth. [9/11]

This difference in stress distribution is likely a product of extreme cranial anatomy in Corythosaurus, where the lambeosaurine cranial crest resulted in a change to cranial biomechanics. Further testing of other lambeosaurines is underway to explore this possibility. [8/11]

Curiously, our analysis also reveals that Gryposaurus and Corythosaurus skulls dissipated stress very differently from each other. Gryposaurus had the typical tetrapod stress distribution, but Corythosaurus differed in experiencing very little stress in the snout. [7/11]

These differences in muscle size and efficiency mean similarly sized Gryposaurus and Corythosaurus had similar bite forces. However, Gryposaurus could attain much larger skull sizes than Corythosaurus, meaning adults had higher bite forces and could eat tougher plants. [6/11]

Our analyses reveal biologically relevant differences in the arrangement of the jaw muscles in these animals, where Gryposaurus had proportionately larger jaw muscles than Corythosaurus, but those of Corythosaurus had better leverage and could impart a greater force. [5/11]

Here, we sought out to test whether there are differences in feeding mechanics between the hadrosaurine Gryposaurus, and the coexisting lambeosaurine Corythosaurus from the DPF using Finite Element Analysis. [4/11]

Hadrosaurids are particularly interesting when discussing adaptations for feeding because of their high diversity, complex feeding system, and the frequent co-occurrence of multiple hadrosaurid species within an ecosystem. [3/11]

The DPF is unusual in the large number of herbivores that coexisted, and is commonly explained by resource partitioning. Evidence for resource partitioning between major groups has frequently been found, but evidence within groups, like hadrosaurids, has been subtle. [2/11]

Thanks Ali!

Clarification: Hadrosaurus must be in Hadrosaurinae by strict clade definition, but here we mean in the traditionally conceived clade composition

We also hope that our dataset and multivariate comparisons may help identify isolated jaws and teeth, providing a new potential avenue for identifying microsite material to a finer resolution. [14/14]

With these analyses, we hope future studies will amend character states following our recommendations, and individual and ontogenetic variation will be better incorporated into character coding to construct more accurate phylogenies. [13/14]

Among these 5 problematic taxa, perhaps the most phylogenetically significant was Hadrosaurus, which was found to most likely to pertain to Hadrosaurinae with very high probability (0.996). [12/14]

Lastly, we were curious what impact these results would have on historically problematic iguanodontians, so we used our multivariate analyses to predict the phylogenetic placement of Hadrosaurus, Eotrachodon, ‘Trachodon’ cantabergiensis, Claosaurus, and Yamatosaurus. [11/14]

Our analysis came with some unexpected observations, most notably the presence of secondary ridges and rounded mammillations on the teeth of early diverging hadrosaurines like Brachylophosaurus and Maiasaura, features classically thought of as lambeosaurine. [10/14]

Secondary ridges and rounded denticles often co-occurred together in the same taxa, and are often present in lambeosaurines and absent in hadrosaurines. These characters may therefore be most useful when applied together. [9/14]