Fossil egg and eggshells from the Upper Cretaceous Hell Creek Formation, Montana

Jackson, Frankie D.; Varricchio, David J.

doi:10.1080/02724634.2016.1185432

Cited by 21 publications

(12 citation statements)

References 56 publications

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“…Electron backscatter diffraction imaging shows that the calcite grains with horizontal c-axis are present in the inner part of eggshell whereas c-axis align vertically toward the outer surface ( Figure 7A). As seen from the extinction pattern (see PLM observation above), the shell units are usually wedge-like ( Figures 7A-C), a feature also known in modern and fossil crocodyliform eggshells (see Hirsch and Quinn, 1990;Tanaka et al, 2011;Moreno-Azanza et al, 2014aMarzola et al, 2015, Table 3;Srivastava et al, 2015;Jackson and Varricchio, 2016;Russo et al, 2017). One may think that the calcite grains with horizontal c-axis are diagenetic calcites, but the extant crocodyliform eggshells also show calcite with horizontal c-axis to the middle part of the eggshell (see "Comparative Study" below).…”

Section: Electron Backscatter Diffractionmentioning

confidence: 65%

Raman Spectroscopy Detects Amorphous Carbon in an Enigmatic Egg From the Upper Cretaceous Wido Volcanics of South Korea

et al. 2020

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Raman spectroscopy has been widely used in micropaleontology and organic geochemistry to identify carbonaceous materials and evaluate their thermal maturity in fossils or metasedimentary rocks. Meanwhile, fossil egg researches have mostly focused on biomineralized calcite, but preserved carbonaceous (or possibly organic) materials inside the eggshells have been usually neglected until recently. Here we report an enigmatic egg from the Wido Volcanics (Upper Cretaceous) of South Korea that was analyzed using diverse methods including polarized light microscope, scanning electron microscope, electron probe microanalyzer, electron backscatter diffraction, and Raman spectroscopy. The eggshell not only shows the crystallography of archosaurian eggshells but also contains peculiar dark bands, which were previously known as the trait of fossil and modern Crocodyliformes eggshells. Raman spectroscopic analysis showed that the dark bands are mainly due to amorphous carbon, as evidenced by the clear graphite (G) and disordered (D) bands. The deconvolution of amorphous carbon peaks and resultant parameters made it possible to infer the paleotemperature inscribed in the eggshell. The result suggests that preserved amorphous carbon in the fossil eggshells can be identified using Raman spectroscopy and Raman parameters may make it possible to compare the thermal maturity of spatiotemporally diverse fossil eggshells. The biogenicity of the dark band is not clear because Raman spectroscopic analysis is not sufficient to confirm biogenicity. However, overall distribution of the dark band may imply the biogenic origin. It is apparent that the material of this study is not a dinosaur egg but might belong to a crocodyliform or choristoderan egg, and even other non-dinosaur archosaur can be a candidate as well.

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Section: Electron Backscatter Diffractionmentioning

confidence: 65%

Raman Spectroscopy Detects Amorphous Carbon in an Enigmatic Egg From the Upper Cretaceous Wido Volcanics of South Korea

et al. 2020

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“…Dromiceiomimus) and the basicranium of an intermediate maniraptora from the Glacier County;Martineau (2014) also mentions four undescribed dinosaur bonebeds in Lewis and Clark County near Augusta, Montana, and Hunter et al (2010) describe mammal remains from Shell Hell (MOR Locality 703), which lies along the Two Medicine River in Glacier County south of Browning, Montana. The Buffalo Lake site and Shell Hell localities References: 1, Horner (1982); 2, Hirsch and Quinn (1990);3, Varricchio et al (2002);4, Grellet-Tinner et al (2006);5, Jackson et al (2010);6, Bray (1999); 7, Horner and Makela (1979); 8, Horner and Currie (1994); 9, Clouse (2001); 10, ; 11, ; 12, Jackson and Varricchio (2016);13, Zelenitsky et al (1996); 14, Zelenitsky and Therrien (2008); 15, Jackson and Schmitt (2008); 16, Lawver and Jackson (2014); Lawver and Jackson (2017).…”

Section: St Mary River Formation Vertebrate Faunamentioning

confidence: 99%

Paleoecological implications of two closely associated egg types from the Upper Cretaceous St. Mary River Formation, Montana

Jackson

Varricchio

2017

Cretaceous Research

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Two 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 Â 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.

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“…Two Medicine(Jackson and Varricchio 2010), and Willow Creek formations(Zelenitsky et al 2017a), whereas theropod ootaxa dominate eggshell assemblages in other formations, including the Dinosaur Park(Zelenitsky and Sloboda 2005), Fruitland(Tanaka et al 2011), and Hell Creek formations(Jackson and Varricchio 2016). The ootaxonomic composition of the St. Mary River Formation is most similar to those of the Willow Creek(Zelenitsky et al …”

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confidence: 99%

“…North America, the vast majority of which are known from Campanian deposits (Horner and Makela 1979;Hirsch and Quinn 1990;Zelenitsky andHills 1996, 1997;Varricchio et al 2002;Zelenitsky and Sloboda 2005;Welsh and Sankey 2007;Zelenitsky and Therrien 2008a;Jackson and Varricchio 2010;Tanaka et al 2011). Comparatively limited egg material is known from the Maastrichtian, with most specimens described from upper Maastrichtian formations, including the Hell Creek Formation of Montana (Jackson and Varricchio 2016), North Horn Formation of Utah (Bray 1999;Cifelli et al 1999;Difley 2007), and Willow Creek Formation of Alberta (Zelenitsky et al 2017a). The recent report of two egg types from the St. Mary River Formation of northern Montana represents the first record of lower Maastrichtian-aged eggshell in North America (Jackson and Varricchio 2017).…”

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Dinosaur eggshells from the lower Maastrichtian St. Mary River Formation of southern Alberta, Canada

et al. 2018

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North America is known for its rich uppermost Cretaceous record of dinosaur egg remains, although a notable fossil gap exists during the lower Maastrichtian. Here we describe a diverse dinosaur eggshell assemblage from the St. Mary River Formation of southern Alberta that, in conjunction with recently described eggs from the same formation in Montana, helps fill this gap and sheds light on the dinosaur diversity in this poorly fossiliferous formation. Three theropod eggshell types (Continuoolithus cf. C. canadensis, Montanoolithus cf. M. strongorum, and Prismatoolithus cf. P. levis) and one ornithopod (Spheroolithus cf. S. albertensis), are reported from Albertan exposures of the St. Mary River Formation, increasing the ootaxonomic diversity of the formation from two to five ootaxa. The taxonomic composition of the eggshell assemblage is consistent with the dinosaurian fauna known from the St. Mary River Formation based on skeletal remains. Spheroolithus eggshells constitute the majority of identifiable eggshells in our assemblage, a trend also observed in several other Upper Cretaceous formations from North America. Continuoolithus is shown to be synonymous with Spongioolithus, thus expanding the Maastrichtian geographic range of the ootaxon to include Utah. The St. Mary River eggshell assemblage supports a general trend of increase in eggshell thickness among theropod ootaxa from the uppermost Santonian through the Maastrichtian, which is inferred to reflect an increase in body size among some clades of small theropods through the Upper Cretaceous. Eggshell preservation in the St. Mary River Formation may be related to the semiarid climatic and environmental conditions that prevailed.

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Fossil egg and eggshells from the Upper Cretaceous Hell Creek Formation, Montana

Cited by 21 publications

References 56 publications

Raman Spectroscopy Detects Amorphous Carbon in an Enigmatic Egg From the Upper Cretaceous Wido Volcanics of South Korea

Raman Spectroscopy Detects Amorphous Carbon in an Enigmatic Egg From the Upper Cretaceous Wido Volcanics of South Korea

Paleoecological implications of two closely associated egg types from the Upper Cretaceous St. Mary River Formation, Montana

Dinosaur eggshells from the lower Maastrichtian St. Mary River Formation of southern Alberta, Canada

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