JOURNAL ARTICLE
RESEARCH SUPPORT, NON-U.S. GOV'T
REVIEW
Add like
Add dislike
Add to saved papers

The Evolution of the Zygomatic Bone From Agnatha to Tetrapoda.

Establishing the homology of the zygomatic or jugal bone and tracing its origin and early evolution represents a complex issue because of large morphological gaps between various groups of vertebrates. Using recent paleontological findings, we discuss the deep homology of the zygomatic or jugal bone in stem gnathostomes (placoderms) and examine its homology and modifications in crown gnathostomes (acanthodians, chondrichthyans and osteichthyans). The discovery of the placoderm Entelognathus from the Silurian of China (∼423 million years ago) established that the large dermal plates in placoderms and osteichthyans are homologous. In Entelognathus, the jugal was joined by a new set of bones (premaxilla, maxilla, and lachrymal), marking the first appearance of the typical vertebrate face found in tetrapods including humans. In non-Entelognathus placoderms, the jugal (homologized with the suborbital plate) occupied most of the cheek region and covered the palatoquadrate laterally. In antiarch placoderms (the most basal jawed vertebrates), the jugal (represented by the ventrally positioned mental plate) functioned as part of the upper jaw. In osteichthyans, the preopercular arose as a novel bone and separated the jugal from the opercular in piscine osteichthyans. A single bone in basal osteichthyans, the preopercular may have divided into two or three elements (the preopercular, the squamosal and/or the quadratojugal) in several later osteichthyan groups. Subsequent modifications of the jugal in the fish-tetrapod transition (its enlargement leading to its contact with the quadratojugal and the separation of the squamosal from the maxilla) brought the vertebrate face to the typical model we see in living tetrapods. Anat Rec, 300:16-29, 2017. © 2016 Wiley Periodicals, Inc.

Full text links

We have located links that may give you full text access.
Can't access the paper?
Try logging in through your university/institutional subscription. For a smoother one-click institutional access experience, please use our mobile app.

For the best experience, use the Read mobile app

Mobile app image

Get seemless 1-tap access through your institution/university

For the best experience, use the Read mobile app

All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.

By using this service, you agree to our terms of use and privacy policy.

Your Privacy Choices Toggle icon

You can now claim free CME credits for this literature searchClaim now

Get seemless 1-tap access through your institution/university

For the best experience, use the Read mobile app