Dataset Information

Microscopic and immunohistochemical analyses of the claw of the nesting dinosaur, Citipati osmolskae.

ABSTRACT: One of the most well-recognized Cretaceous fossils is Citipati osmolskae (MPC-D 100/979), an oviraptorid dinosaur discovered in brooding position on a nest of unhatched eggs. The original description refers to a thin lens of white material extending from a manus ungual, which was proposed to represent original keratinous claw sheath that, in life, would have covered it. Here, we test the hypothesis that this exceptional morphological preservation extends to the molecular level. The fossil sheath was compared with that of extant birds, revealing similar morphology and microstructural organization. In living birds, the claw sheath consists primarily of two structural proteins; alpha-keratin, expressed in all vertebrates, and beta-keratin, found only in reptiles and birds (sauropsids). We employed antibodies raised against avian feathers, which comprise almost entirely of beta-keratin, to demonstrate that fossil tissues respond with the same specificity, though less intensity, as those from living birds. Furthermore, we show that calcium chelation greatly increased antibody reactivity, suggesting a role for calcium in the preservation of this fossil material.

SUBMITTER: Moyer AE

PROVIDER: S-EPMC5124102 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature

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Microscopic and immunohistochemical analyses of the claw of the nesting dinosaur, Citipati osmolskae.

Moyer Alison E AE Zheng Wenxia W Schweitzer Mary H MH

Proceedings. Biological sciences 20161101 1842

One of the most well-recognized Cretaceous fossils is Citipati osmolskae (MPC-D 100/979), an oviraptorid dinosaur discovered in brooding position on a nest of unhatched eggs. The original description refers to a thin lens of white material extending from a manus ungual, which was proposed to represent original keratinous claw sheath that, in life, would have covered it. Here, we test the hypothesis that this exceptional morphological preservation extends to the molecular level. The fossil sheath ...[more]

PMID: 28120795

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Project description:The cuticle layer consisting mainly of lipids and hydroxyapatite (HAp) atop the mineralized avian eggshell is a protective structure that prevents the egg from dehydration and microbial invasions. Previous ornithological studies have revealed that the cuticle layer is also involved in modulating the reflectance of eggshells in addition to pigments (protoporphyrin and biliverdin). Thus, the cuticle layer represents a crucial trait that delivers ecological signals. While present in most modern birds, direct evidence for cuticle preservation in stem birds and non-avian dinosaurs is yet missing. Here we present the first direct and chemical evidence for the preservation of the cuticle layer on dinosaur eggshells. We analyze several theropod eggshells from various localities, including oviraptorid Macroolithus yaotunensis eggshells from the Late Cretaceous deposits of Henan, Jiangxi, and Guangdong in China and alvarezsaurid Triprismatoolithus eggshell from the Two Medicine Formation of Montana, United States, with the scanning electron microscope (SEM), electron probe micro-analysis (EPMA), and Raman spectroscopy (RS). The elemental analysis with EPMA shows high concentration of phosphorus at the boundary between the eggshell and sediment, representing the hydroxyapatitic cuticle layer (HAp). Depletion of phosphorus in sediment excludes the allochthonous origin of the phosphorus in these eggshells. The chemometric analysis of Raman spectra collected from fossil and extant eggs provides further supportive evidence for the cuticle preservation in oviraptorid and probable alvarezsaurid eggshells. In accordance with our previous discovery of pigments preserved in Cretaceous oviraptorid dinosaur eggshells, we validate the cuticle preservation on dinosaur eggshells through deep time and offer a yet unexplored resource for chemical studies targeting the evolution of dinosaur nesting ecology. Our study also suggests that the cuticle structure can be traced far back to maniraptoran dinosaurs and enhance their reproductive success in a warm and mesic habitat such as Montana and southern China during the Late Cretaceous.

Dataset Information

Microscopic and immunohistochemical analyses of the claw of the nesting dinosaur, Citipati osmolskae.

Publications

Microscopic and immunohistochemical analyses of the claw of the nesting dinosaur, Citipati osmolskae.

Similar Datasets

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