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Ceratopsians were herbivorous dinosaurs that dominated many of the terrestrial ecosystems in Asia and North America during the Cretaceous. The bizarre variety of skulls and lower jaw morphologies as well as the inferred ecological abundance of many species in this clade indicate that Ceratopsia was a successful group. Here we analyzed 126 lower jaws from 50 ceratopsian species, using two-dimensional geometric morphometrics and finite element analysis to investigate differences in shape and structural performance of this part of the feeding apparatus across Ceratopsia. Morphological differences in lower jaws across ceratopsian clades are said to originate from feeding adaptation. Our results show that the stress (physical loadings modeled in response to biting) in lower jaws was quite similar between “basal” and “derived” taxa, whereas major differences among clades occur for stress values associated with the coronoid process. The basal ceratopsians Hualianceratops and Yinlong had a highly stressed and primitive lower jaw, indicating that those animals may have fed on relatively soft foliage and fruits. A similar condition was found for basal neoceratopsians and protoceratopsids. Psittacosaurids possessed a well-integrated and compact lower jaw able to withstand high stress, at the cost of having a highly stressed coronoid process. Leptoceratopsids were characterized by the opposite condition. Taxa such as Leptoceratops , Prenoceratops , Zhuchengceratops and Cerasinops appear to have had a comparatively efficient feeding apparatus. Ceratopsidae represents the clade with the most efficient masticatory apparatus within Ceratopsia, even if the horizontal ramus of the lower jaw appears less able to withstand high levels of stress as compared with other ceratopsians. Additionally, we found the dentary and surangular–angular complex co-evolved to generate a masticatory apparatus able to withstand high stress, particularly in Protoceratopsidae and Triceratopsini. The major phenotypic evolutionary rate and morphological changes occurred during the mid- to Late Cretaceous, when intense climate change and angiosperm diversification could have affected the evolution of ecological diversity and feeding biomechanics in Ceratopsia. [ABSTRACT FROM AUTHOR]

The evolutionary trends of tooth size in quaternary carnivores support an almost direct association with climate. However, phenotypic trait may follow distinct tempo and mode of evolution such as Brownian, Ornstein–Uhlenbeck or random walk. Here, we investigated the morphometric variations and evolutionary trends in the carnassial teeth size of the European wolf ( Canis lupus ) by means of modern statistical tools. Recent contributions highlighted linear increase trend in tooth size through the Pleistocene, but those differences in time have not been tested using modern statistical strategies. Examining a wide sample of linear measurements of carnassials of extinct and extant wolves (486 M 1 and 491 P 4 ), we tested which evolutionary model (random walk, stasis, Ornstein–Uhlenbeck) better explains the dimensional pattern of teeth through time at the continental scale and at the regional scale (France and Italy). Our results clearly show different models for the carnassials of C . lupus . Lower and upper carnassials for the entire sample of C . lupus are characterized by a directional trend, whereas Italian and French subsets show a random fluctuation of carnassials size through time. The carnassials dimensions are not directly correlated with the climate changes during the Middle–Late Pleistocene and Holocene, but they are possibly correlated with spread of the cold mega-fauna in Europe, and thus with the changes in the dietary regime. [ABSTRACT FROM AUTHOR]