New information on multispherulitic dinosaur eggs: Faveoloolithidae and Dendroolithidae

Kundrát, Martin; Cruickshank, A. R. I.

doi:10.1080/08912963.2021.1961764

Cited by 4 publications

(2 citation statements)

References 45 publications

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“…Embryos of therizinosaurid theropods (Kundrát et al 2008) and Troodon (Varricchio et al 2002) have been interpreted as being precocial based on their degree of ossification of the skull and postcranial skeleton. Whether the fossil record of oviraptorosaur embryos illustrates the same pattern is also questionable because of variable eggshell microstructure, substrate moisture, and nesting strategy in these groups (Varricchio et al 1997(Varricchio et al , 2018Deeming 2002Deeming , 2006Weishampel et al 2008;Hogan and Varricchio 2021;Kundrát and Cruickshank 2021). Resolution of these issues will depend on more specimens of oviraptorosaur embryos in eggs being uncovered.…”

Section: Resultsmentioning

confidence: 99%

Interpretation of fossil embryos requires reasonable assessment of developmental age

Deeming¹,

Kundrát²

2022

Paleobiology

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Dinosaur embryos cause a lot of excitement in the scientific literature and are often widely reported because of the general public's interest in dinosaur biology. Well-preserved, articulated oviraptorosaur embryos in eggs are usually interpreted as representing a stage of development close to hatching because of their large size and good level of skeletal ossification. Based on this evidence, a recent report suggested that the position of the one embryo's head was reminiscent of an avian-like hatching position. Here we explore how the developmental stage of well-preserved oviraptorosaur embryos can be estimated, rather than assumed. This will help in our understanding of their developmental biology and its evolutionary consequences. Using quantitative methods and comparison with modern crocodilian embryos, we show that all articulated oviraptorosaur embryos are small relative to the egg and most likely at a stage of development equivalent to around 50%–60% of the developmental period, that is, not even close to hatching. This conclusion is supported by the fact that many elements of the crocodilian skeleton are well ossified many weeks before hatching and the position of oviraptorosaur embryos’ heads was also comparable to a crocodilian embryo many days before hatching. Misunderstandings about the stage of the developmental biology of these well-preserved oviraptorosaur embryos hampers our understanding of the true nature of their reproductive biology. We urge a more conservative approach to their interpretation. This is important, because misunderstandings in the minds of the public about dinosaur biology are hard to counter once poorly evidenced ideas have been reported around the world.

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Section: Resultsmentioning

confidence: 99%

Interpretation of fossil embryos requires reasonable assessment of developmental age

Deeming¹,

Kundrát²

2022

Paleobiology

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“…In theropod eggs the two‐layer structure can be identified in all known maniraptoran eggshells (Mikhailov 1997 a , b ) except for therizinosaur eggshells, which are remarkably similar to either Dendroolithidae or Spheroolithidae (Mikhailov 1997 a ; Zelenitsky 2004; Barta et al . 2014; Kundrát & Cruickshank 2021).…”

Section: Discussionmentioning

confidence: 99%

Microstructural description of the maniraptoran egg Protoceratopsidovum

Choi

Barta

Moreno‐Azanza

et al. 2022

Papers in Palaeontology

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Since their discovery in the 1920s, some asymmetric, elongated dinosaur eggs from the Upper Cretaceous of Mongolia have been interpreted as ceratopsian eggs. However, recent views support a maniraptoran affinity mainly based on macroscopic features. Technical advancements in palaeontology provide a novel approach to diagnose maniraptoran eggs, and the discovery of soft ceratopsian eggs makes the debate a timely issue worth revisiting. Here, we analysed Protoceratopsidovum eggshell from southern Mongolia with electron backscatter diffraction and the results were compared with East Asian and North American maniraptoran and ornithischian eggs. The microstructure and crystallography of Protoceratopsidovum confirms the maniraptoran hypothesis, given that it shows diagnostic features of the clade absent from ornithischian (e.g. hadrosaur) eggs. Additional characters, such as egg shape, ornamentation, egg pairing and clutch structure also support a maniraptoran affinity. Protoceratopsidovum has both elongatoolithid (oviraptorosaur egg) and prismatoolithid (troodontid egg) features, and it may bridge the morphological gap between the two established oofamilies. Considering the similarity between Protoceratopsidovum and potential dromaeosaur eggs, at least some Protoceratopsidovum may be deinonychosaur eggs. Fossil localities that yield both deinonychosaurs and Protoceratopsidovum may yield conclusive evidence for the true affinity of this ootaxon. Future discovery of the egg‐laying taxon of Protoceratopsidovum will not only improve our understanding of maniraptoran reproductive biology but also make Protoceratopsidovum a reliable indicator of the palaeobiogeography of that maniraptoran clade.

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Protocol for electron backscatter diffraction (EBSD) analysis of fossil eggshells

Choi,

Park,

Moreno-Azanza

2023

Journal of Vertebrate Paleontology

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New information on multispherulitic dinosaur eggs: Faveoloolithidae and Dendroolithidae

Cited by 4 publications

References 45 publications

Interpretation of fossil embryos requires reasonable assessment of developmental age

Interpretation of fossil embryos requires reasonable assessment of developmental age

Microstructural description of the maniraptoran egg Protoceratopsidovum

Protocol for electron backscatter diffraction (EBSD) analysis of fossil eggshells

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