New papers in Science:
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Michael Hanson, Eva A. Hoffman, Mark A. Norell & Bhart-Anjan S. Bhullar (2021)
The early origin of a birdlike inner ear and the evolution of dinosaurian movement and vocalization.
Science 372(6542): 601-609
DOI: 10.1126/science.abb4305
https://science.sciencemag.org/content/372/6542/601
Revealing behavioral secrets in extinct species
Extinct species had complex behaviors, just like modern species, but fossils generally reveal little of these details. New approaches that allow for the study of structures that relate directly to behavior are greatly improving our understanding of the lifestyles of extinct animals (see the Perspective by Witmer). Hanson et al. looked at three-dimensional scans of archosauromorph inner ears and found clear patterns relating these bones to complex movement, including flight. Choiniere et al. looked at inner ears and scleral eye rings and found a clear emergence of patterns relating to nocturnality in early theropod evolution. Together, these papers reveal behavioral complexity and evolutionary patterns in these groups.
Abstract
Reptiles, including birds, exhibit a range of behaviorally relevant adaptations that are reflected in changes to the structure of the inner ear. These adaptations include the capacity for flight and sensitivity to high-frequency sound. We used three-dimensional morphometric analyses of a large sample of extant and extinct reptiles to investigate inner ear correlates of locomotor ability and hearing acuity. Statistical analyses revealed three vestibular morphotypes, best explained by three locomotor categoriesâquadrupeds, bipeds and simple fliers (including bipedal nonavialan dinosaurs), and high-maneuverability fliers. Troodontids fall with Archaeopteryx among the extant low-maneuverability fliers. Analyses of cochlear shape revealed a single instance of elongation, on the stem of Archosauria. We suggest that this transformation coincided with the origin of both high-pitched juvenile location, alarm, and hatching-synchronization calls and adult responses to them.
News:
Hesperornis inner ear
What can a dinosaur's inner ear tell us? Just listen
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Jonah N. Choiniere, James M. Neenan, Lars Schmitz, David P. Ford, Kimberley E. J. Chapelle, Amy M. Balanoff, Justin S. Sipla, Justin A. Georgi, Stig A. Walsh, Mark A. Norell, Xing Xu, James M. Clark & Roger B. J. Benson (2021),
Evolution of vision and hearing modalities in theropod dinosaurs.
Science 372(6542): 610-613
DOI: 10.1126/science.abe7941
https://science.sciencemag.org/content/372/6542/610
Revealing behavioral secrets in extinct species
Extinct species had complex behaviors, just like modern species, but fossils generally reveal little of these details. New approaches that allow for the study of structures that relate directly to behavior are greatly improving our understanding of the lifestyles of extinct animals (see the Perspective by Witmer). Hanson et al. looked at three-dimensional scans of archosauromorph inner ears and found clear patterns relating these bones to complex movement, including flight. Choiniere et al. looked at inner ears and scleral eye rings and found a clear emergence of patterns relating to nocturnality in early theropod evolution. Together, these papers reveal behavioral complexity and evolutionary patterns in these groups.
Abstract
Owls and nightbirds are nocturnal hunters of active prey that combine visual and hearing adaptations to overcome limits on sensory performance in low light. Such sensory innovations are unknown in nonavialan theropod dinosaurs and are poorly characterized on the line that leads to birds. We investigate morphofunctional proxies of vision and hearing in living and extinct theropods and demonstrate deep evolutionary divergences of sensory modalities. Nocturnal predation evolved early in the nonavialan lineage Alvarezsauroidea, signaled by extreme low-light vision and increases in hearing sensitivity. The Late Cretaceous alvarezsauroid Shuvuuia deserti had even further specialized hearing acuity, rivaling that of todayâs barn owl. This combination of sensory adaptations evolved independently in dinosaurs long before the modern bird radiation and provides a notable example of convergence between dinosaurs and mammals.
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News:
Nocturnal dinosaurs: Night vision and superb hearing in a small theropod suggest it was a moonlight predator
Shuvuuia: A dinosaur that hunted in the dark (with videos)
Video
Dinosaurs that hunted in the dark
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Summary
Birds are dinosaurs. A couple of decades of revealing finds and careful phylogenetic work have shown that birds are nested within the group of small, mostly predatory, and running dinosaurs that includes dromaeosaurs and troodontids, among others (1). Now, scientists are using that phylogenetic tapestry to trace the evolution of traits such as sensory biology and behavior. Two studies in this issue pair cutting-edge imaging with sophisticated statistical analyses to explore the evolution of the hearing apparatus and other sensory systems. On page 601, Hanson et al. (2) show that the inner ear of dinosaurs, as well as that of other archosaurs (the group that includes crocodilians, dinosaurs, and birds), provides clues to locomotion, hearing, and the evolution of vocalization. On page 610, Choiniere et al. (3) examine the inner ear and also aspects of the visual system to demonstrate the notably owl-like nocturnal adaptations of one group of birdlike dinosaurs.
News:
Dinosaur skull scans reveal clues about flightâand communication