Mandibular symphyseal fusion in fossil primates: Insights from correlated patterns of jaw shape and masticatory function in living primates.

Title

Mandibular symphyseal fusion in fossil primates: Insights from correlated patterns of jaw shape and masticatory function in living primates.

Creator

Knigge RP;Vinyard CJ;McNulty KP

Publisher

American Journal Of Physical Anthropology

Date

2020
2020-10

Description

Objectives: Variation in primate masticatory form and function has been extensively researched through both morphological and experimental studies. As a result, symphyseal fusion in different primate clades has been linked to either the recruitment of vertically directed balancing‐side muscle force, the timing and recruitment of transversely directed forces, or both. This study investigates the relationship between jaw muscle activity patterns and morphology in extant primates to make inferences about masticatory function in extinct primates, with implications for understanding the evolution of symphyseal fusion. Materials and methods: Three‐dimensional mandibular landmark data were collected for 31 extant primates and nine fossil anthropoids and subfossil lemur species. Published electromyography (EMG) data were available for nine of the extant primate species. Partial least squares analysis and phylogenetic partial least squares analysis were used to identify relationships between EMG and jaw shape data and evaluate variation in jaw morphology. Results: Primates with partial and complete symphyseal fusion exhibit shape‐function patterns associated with the wishboning motor pattern and loading regime, in contrast to shape‐function patterns of primates with unfused jaws. All fossil primates examined (except Apidium) exhibit jaw morphologies suggestive of the wishboning motor pattern demonstrated in living anthropoids and indriids. Discussion Partial fusion in Catopithecus, similar to indriids and some subfossil lemurs, may be sufficient to resist, or transfer, some amounts of transversely directed balancing‐side muscle force at the symphysis, representing a transition to greater reliance on transverse jaw movement during mastication. Furthermore, possible functional convergences in physiological patterns during chewing (i.e., Archaeolemur) are identified. [ABSTRACT FROM AUTHOR]

Subject

fusion; mandible; PRIMATES; geometric morphometrics; symphysis; ELECTROMYOGRAPHY; LEMURS; MANDIBLE; MORPHOMETRICS

Identifier

Rights

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

Format

journalArticle

Search for Full-text

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Pages

322-336

Issue

2

Volume

173

ISSN

29483

NEOMED College

NEOMED College of Medicine

NEOMED Department

Department of Anatomy & Neurobiology

Update Year & Number

September 2020 List

Citation

Knigge RP;Vinyard CJ;McNulty KP, “Mandibular symphyseal fusion in fossil primates: Insights from correlated patterns of jaw shape and masticatory function in living primates.,” NEOMED Bibliography Database, accessed June 19, 2021, https://neomed.omeka.net/items/show/11272.

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