Show simple item record

dc.contributor.authorVarricchio, David J.
dc.contributor.authorBalanoff, Amy M.
dc.contributor.authorNorell, Mark A.
dc.date.accessioned2015-11-18T18:04:04Z
dc.date.available2015-11-18T18:04:04Z
dc.date.issued2015-06
dc.identifier.citationVarricchio, David J., Amy M. Balanoff, and Mark A. Norell. "Reidentification of Avian Embryonic Remains from the Cretaceous of Mongolia." PLoS One 10, no. 6 (June 2015): e0128458. DOI:https://dx.doi.org/10.1371/journal.pone.0128458 .en_US
dc.identifier.issn1932-6203
dc.identifier.urihttps://scholarworks.montana.edu/xmlui/handle/1/9379
dc.descriptionNSF grant #0847777 (EAR)en_US
dc.description.abstractEmbryonic remains within a small (4.75 by 2.23 cm) egg from the Late Cretaceous, Mongolia are here re-described. High-resolution X-ray computed tomography (HRCT) was used to digitally prepare and describe the enclosed embryonic bones. The egg, IGM (Mongolian Institute for Geology, Ulaanbaatar) 100/2010, with a three-part shell microstructure, was originally assigned to Neoceratopsia implying extensive homoplasy among eggshell characters across Dinosauria. Re-examination finds the forelimb significantly longer than the hindlimbs, proportions suggesting an avian identification. Additional, postcranial apomorphies (strut-like coracoid, cranially located humeral condyles, olecranon fossa, slender radius relative to the ulna, trochanteric crest on the femur, and ulna longer than the humerus) identify the embryo as avian. Presence of a dorsal coracoid fossa and a craniocaudally compressed distal humerus with a strongly angled distal margin support a diagnosis of IGM 100/2010 as an enantiornithine. Re-identification eliminates the implied homoplasy of this tri-laminate eggshell structure, and instead associates enantiornithine birds with eggshell microstructure composed of a mammillary, squamatic, and external zones. Posture of the embryo follows that of other theropods with fore- and hindlimbs folded parallel to the vertebral column and the elbow pointing caudally just dorsal to the knees. The size of the egg and embryo of IGM 100/2010 is similar to the two other Mongolian enantiornithine eggs. Well-ossified skeletons, as in this specimen, characterize all known enantiornithine embryos suggesting precocial hatchlings, comparing closely to late stage embryos of modern precocial birds that are both flight- and run-capable upon hatching. Extensive ossification in enantiornithine embryos may contribute to their relatively abundant representation in the fossil record. Neoceratopsian eggs remain unrecognized in the fossil record.en_US
dc.rightsCC BY 4.0en_US
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/legalcodeen_US
dc.titleReidentification of Avian Embryonic Remains from the Cretaceous of Mongoliaen_US
dc.typeArticleen_US
mus.citation.extentfirstpagee0128458en_US
mus.citation.issue6en_US
mus.citation.journaltitlePLoS ONEen_US
mus.citation.volume10en_US
mus.identifier.categoryLife Sciences & Earth Sciencesen_US
mus.identifier.doi10.1371/journal.pone.0128458en_US
mus.relation.collegeCollege of Letters & Scienceen_US
mus.relation.departmentEarth Sciences.en_US
mus.relation.universityMontana State University - Bozemanen_US
mus.contributor.orcidVarricchio, David J.|0000-0002-0594-0929en_US


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record

CC BY 4.0
Except where otherwise noted, this item's license is described as CC BY 4.0

MSU uses DSpace software, copyright © 2002-2017  Duraspace. For library collections that are not accessible, we are committed to providing reasonable accommodations and timely access to users with disabilities. For assistance, please submit an accessibility request for library material.