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dc.contributor.authorJackson, Frankie D.
dc.contributor.authorVarricchio, David J.
dc.date.accessioned2018-04-05T13:54:57Z
dc.date.available2018-04-05T13:54:57Z
dc.date.issued2017-11
dc.identifier.citationJackson, Frankie D. , and David J. Varricchio. "Paleoecological implications of two closely associated egg types from the Upper Cretaceous St. Mary River Formation, Montana." Cretaceous Research 79 (November 2017): 182-190. DOI: 10.1016/j.cretres.2017.08.003.en_US
dc.identifier.issn0195-6671
dc.identifier.urihttps://scholarworks.montana.edu/xmlui/handle/1/14469
dc.description.abstractTwo closely associated egg types occur at the same locality in the Upper Cretaceous (Maastrichtian) St. Mary River Formation in north central Montana. These specimens represent the first fossil eggs described from this formation. At least fifteen small ovoid eggs or egg portions are scattered through a 25 cm interval of rock. Five significantly larger, round eggs overlie these smaller eggs and are in close proximity to one another on a single bedding plane. The best preserved egg of the smaller size measures 36 mm × 62 mm and exhibits the prismatic, two-layered eggshell structure of a theropod egg. The dispersed distribution and inconsistent angles of these small eggs likely resulted from disturbance by subsequent nesting activity and/or possibly nest predation. At least twelve additional small prismatic eggs also occur at this site. We assign the small eggs as a new oogenus and oospecies, Tetonoolithus nelsoni, within the Prismatoolithidae. The large round eggs measure 130 mm in diameter and the eggshell displays substantial diagenetic alteration. These eggs likely belonged to a hadrosaur due to their similarity in egg size, shape, and eggshell thickness to Maiasaura eggs from the stratigraphically lower Two Medicine Formation. Eggs at different stratigraphic levels at this site indicate that conditions favorable to both dinosaur species persisted for an extended period of time. However, determining whether these dinosaurs occupied the nesting site at the same or different years remains beyond the resolution of the rock record.en_US
dc.description.sponsorshipNational Science Foundation (EAR-9219035)en_US
dc.titlePaleoecological implications of two closely associated egg types from the Upper Cretaceous St. Mary River Formation, Montanaen_US
mus.citation.extentfirstpage182en_US
mus.citation.extentlastpage190en_US
mus.citation.journaltitleCretaceous Researchen_US
mus.citation.volume79en_US
mus.identifier.categoryLife Sciences & Earth Sciencesen_US
mus.identifier.doi10.1016/j.cretres.2017.08.003en_US
mus.relation.collegeCollege of Letters & Scienceen_US
mus.relation.departmentEarth Sciences.en_US
mus.relation.universityMontana State University - Bozemanen_US
mus.data.thumbpage5en_US


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