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Cursorial ecomorphology and temporal patterns in theropod dinosaur evolution during the mid-Cretaceous
Kohta Kubo1,2, Yoshitsugu Kobayashi3
1Department of Natural History Sciences, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan.
Royal Society Open Science
|January 16, 2025
Summary
The evolution of cursorial traits, like the arctometatarsus foot specialization, in theropod dinosaurs (Coelurosauria) occurred independently across lineages during the mid-Cretaceous. These adaptations for running show varying evolutionary patterns and phylogenetic constraints.
Area of Science:
- Paleontology
- Evolutionary Biology
- Biomechanics
Background:
- Coelurosauria, a diverse group of theropod dinosaurs including birds, exhibit significant morphological adaptations.
- The arctometatarsus, a specialized foot morphology, evolved independently in several coelurosaurian lineages and is linked to cursoriality (running ability).
- The precise timing, evolutionary origins, and drivers of this parallel evolution remain poorly understood.
Purpose of the Study:
- To investigate the temporal patterns of cursorial trait evolution, specifically the arctometatarsus and hind limb proportions, within Coelurosauria.
- To determine the evolutionary sequence of hind limb segment elongation relative to arctometatarsus development in different theropod groups.
- To identify potential phylogenetic constraints influencing the distribution of the arctometatarsus.
Main Methods:
- Analysis of temporal evolution of cursorial traits, including hind limb proportions and arctometatarsus.
- Comparative analysis of evolutionary patterns across different coelurosaurian subgroups (ornithomimosaurs, oviraptorosaurs, tyrannosauroids, alvarezsaurs, troodontids).
- Estimation of divergence times for cursorial trait emergence based on compiled evolutionary data.
Main Results:
- Proportional elongation of distal hind limb segments preceded arctometatarsus evolution in ornithomimosaurs and oviraptorosaurs.
- In tyrannosauroids, alvarezsaurs, and troodontids, hind limb elongation and arctometatarsus acquisition occurred in parallel.
- The arctometatarsus is phylogenetically constrained, appearing exclusively within Coelurosauria.
- Emergence of these cursorial traits is dated to the mid-Cretaceous (93-120 Ma).
Conclusions:
- The evolution of cursoriality in theropod dinosaurs involved diverse temporal pathways for hind limb and foot specialization.
- Phylogenetic history played a role in the distribution of the arctometatarsus within Coelurosauria.
- Mid-Cretaceous theropods experienced selective pressures favoring enhanced locomotor performance, driving the evolution of cursorial adaptations.
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