Biology subjects

Benson, R. B.

Publications and source records attributed to Benson, R. B..

3 recordsLinked to original sources

bioRxiv2022

The mammalian forelimb diversity as a morphological gradient of increasing evolutionary versatility

Vertebrate limb morphology often reflects the environment, due to variation in locomotor requirements and other ecological traits. However, proximal and distal limb segments may evolve differently to each other, reflecting an anatomical gradient of functional specialization that has been suggested to be impacted by the timing of bone condensation during ontogeny. Here we explore whether the temporal sequence of bone condensation predicts variation in the capacity of evolution to generate morphological diversity between proximal and distal forelimb segments across more than 600 species of mammals. Our findings are consistent with the hypothesis that late developing distal limb elements should display greater morphological variation than more proximal limb elements, which condense earlier during morphogenesis. Distal limb elements, belonging to the autopod, not only exhibit higher diversity of form, but are also more integrated and, on average, show greater evolutionary versatility than intermediate and upper limb segments. Our findings indicate that the macroevolutionary patterns of proximal and distal limb segments are not the same, suggesting that strong functional selection, combined with the higher potential of development to generate variation in more distal limb structures, facilitate the evolution of high autopodial disparity in mammals.

evolutionary biology↗

bioRxiv2022

Sinking a giant: quantitative macroevolutionary comparative methods debunk qualitative assumptions

Myhrvold et al.1 suggest that our inference of subaqueous foraging among spinosaurids2 is undermined by selective bone sampling, inadequate statistical procedures, and use of inaccurate ecological categorizations. Myhrvold et al.1 ignore major details of our analyses and results, and instead choose to portray our inferences as if they were based on qualitative interpretations of our plots, without providing additional analyses to support their claims. In this manuscript, we thoroughly discuss all the concerns exposed by Myhrvold et al.1. Additional analyses based on our original datasets2 and novel data presented by Myhrvold et al.1 do not change our original interpretations: while the spinosaurid dinosaurs Spinosaurus and Baryonyx are recovered as subaqueous foragers, Suchomimus is inferred as a non-diving animal.

paleontology↗

bioRxiv2022

Earliest evidence for frugivory and seed dispersal by birds

The Early Cretaceous diversification of birds was a major event in the history of terrestrial ecosystems, occurring during the earliest phase of the Cretaceous Terrestrial Revolution. Frugivorous birds play an important role in seed dispersal today, and may have done so since their origins. However, evidence of this has been lacking. Jeholornis is one of the earliest-diverging birds, only slightly more derived than Archaeopteryx, but its cranial anatomy has been poorly understood, obscuring diet-related functional interpretations. Originally hypothesised to be granivorous based on seeds preserved as gut contents, this interpretation has become controversial. We conducted high-resolution synchrotron tomography on an exquisitely preserved new skull of Jeholornis, revealing remarkable cranial plesiomorphies combined with a specialised rostrum. We use this to provide a near-complete cranial reconstruction of Jeholornis, and exclude the possibility that Jeholornis was granivorous, based on morphometric analyses of the mandible (3D) and cranium (2D), and comparisons with the 3D alimentary contents of extant birds. We show that Jeholornis was at least seasonally frugivorous, providing the earliest evidence for fruit consumption in birds, and indicating that seed dispersal was present from early in the avian radiation. As highly-mobile seed dispersers, early frugivorous birds could expand the scope for biotic dispersal in plants, and may explain, in part, the subsequent evolutionary expansion of fruits, indicating a potential role of bird-plant interactions in the Cretaceous Terrestrial Revolution.

paleontology↗