Nocturnality in Dinosaurs Inferred from Scleral Ring and Orbit Morphology

Variation in daily activity patterns facilitates temporal partitioning of habitat and resources among species. Knowledge of temporal niche partitioning in paleobiological systems has been limited by the difficulty of obtaining reliable information about activity patterns from fossils. On the basis o...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2011-05, Vol.332 (6030), p.705-708
Main Authors: Schmitz, Lars, Motani, Ryosuke
Format: Article
Language:English
Subjects:
Activity Cycles
Amniota
Animals
Behavior, Animal
Biological rhythms
Biological taxonomies
Birds - anatomy & histology
Birds - physiology
Circadian Rhythm
Dinosaurs
Dinosaurs - anatomy & histology
Dinosaurs - classification
Dinosaurs - physiology
Earth sciences
Earth, ocean, space
Ecology
Ecosystem
Evolution
Exact sciences and technology
Foraging
Fossils
Herbivores
Light
Mammals
Morphology
Niche differentiation
Night Vision
Orbit - anatomy & histology
Paleontology
Phylogenetics
Phylogeny
Predators
Sclera
Vertebrate paleontology
Vision, Ocular
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Summary:Variation in daily activity patterns facilitates temporal partitioning of habitat and resources among species. Knowledge of temporal niche partitioning in paleobiological systems has been limited by the difficulty of obtaining reliable information about activity patterns from fossils. On the basis of an analysis of scleral ring and orbit morphology in 33 archosaurs, including dinosaurs and pterosaurs, we show that the eyes of Mesozoic archosaurs were adapted to all major types of diel activity (that is, nocturnal, diurnal, and cathemeral) and provide concrete evidence of temporal niche partitioning in the Mesozoic. Similar to extant amniotes, flyers were predominantly diurnal; terrestrial predators, at least partially, nocturnal; and large herbivores, cathemeral. These similarities suggest that ecology drives the evolution of diel activity patterns.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1200043