Journal
HISTORICAL BIOLOGY
Volume 26, Issue 3, Pages 279-414Publisher
TAYLOR & FRANCIS LTD
DOI: 10.1080/08912963.2013.777533
Keywords
jaw adductors; dental wear; Crocodyliformes; dental occlusion; heterodont dentition; complex jaw mechanism
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Funding
- Bolyai Fellowship, OTKA [PD 73021, NF 84193]
- MTA-ELTE Lendulet Dinosaur Research Group
- Hantken Foundation
- Jurassic Foundation
- National Geographic Society
- Hungarian Natural History Museum
- European Union Synthesys' Grant
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Heterodont dentition sometimes including multicuspid crowns appeared in numerous fossil forms through all main lineages of the Crocodyliformes. Teeth in these complex dentitions frequently bear wear facets that are exclusive indicators of tooth-tooth occlusion. Besides, dental features, specialisations of the jaw apparatus, jaw adductors and mandibular movement can be recognised, all reflecting a high variability of jaw mechanism and of intraoral food processing. Comparative study of these features revealed four main types of jaw mechanism, some of which evolved independently in several lineages of Crocodyliformes. Isognathous orthal jaw closure (precise jaw joint, rough wear facets) is characteristic for heterodont protosuchians and all forms possessing crushing posterior teeth. Proal movement (protractive powerstroke) occurred independently in Malawisuchus and Chimaerasuchus is supported by the antagonistic, vertically oriented carinae. Developed external adductors are the main indicators of palinal movement (retractive powerstroke) that evolved at least two times in various South American taxa. The fourth type (in Iharkutosuchus) is characterised by lateromedial mandibular rotation supported by extensive horizontal wear facets. This evolutionary scenario resembles that of the masticatory system of mammals and suggests that the ecological roles of some mammalian groups in North America and Asia were occupied in Western Gondwana by highly specialised crocodyliforms. http://www.zoobank.org/urn:lsid:zoobank.org:pub:D6CE962F-2B38-47F8-BD4B-B9E035917F20
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