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Some Miocene ratite eggshell fragments from Gashunyinadege (about 17.5 Ma) and Baogedawula (7.11 ± 0.48 Ma), Inner Mongolia, China, are described. The outer surfaces of eggshell frag-ments from Gashunyinadege are smooth with a sting pore pattern, while their entire thickness is around 2.12 mm. In a cross-sectional view, the surface crystal layer is...
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... Secondly, in the Cenozoic deposits, palaeognath eggshells have been frequently reported in diverse regions of the world (Sauer, 1972;Harrison and Msuya, 2005;Bibi et al., 2006;Worthy et al., 2007;Patnaik et al., 2009;Donaire and López-Martínez, 2009;Wang et al., 2011;Pickford, 2014;Blinkhorn et al., 2015;Mikhailov and Zelenkov, 2020). However, most previous investigations focused on the thickness and pore canal structures on the outer surface of eggshells. ...
... They are useful information, but a few published images show peculiar microstructure (e.g. Donaire and López-Martínez, 2009;Patnaik et al., 2009;Wang et al., 2011), which are not observed in modern palaeognath eggshells (see below). It means that there may be diverse eggshell microstructures in the fossil record and to understand the difference correctly, a more comprehensive, baseline understanding of the microstructure and crystallography of modern palaeognath eggshells is necessary. ...
... The eggshells have been conventionally differentiated into 'struthionid' and 'aepyornithid' types based on the shape of pore openings (Sauer, 1972). This simple criterion has been widely adopted in subsequent studies (Sauer and Rothe, 1972;Stern et al., 1994;Harrison and Msuya, 2005;Donaire and López-Martínez, 2009;Patnaik et al., 2009;Wang et al., 2011;Pickford, 2014;Blinkhorn et al., 2015;Field, 2020;Mikhailov and Zelenkov, 2020). However, (Hirsch et al., 1997, p. 363) stated that "The 'struthionid' and 'aepyornithid' pore system … should not be used solely in the identification and classification of eggshell". ...
The avian palaeognath phylogeny has been recently revised significantly due to the advancement of genome-wide comparative analyses and provides the opportunity to trace the evolution of the microstructure and crystallography of modern dinosaur eggshells. Here, eggshells of all major clades of Palaeognathae (including extinct taxa) and selected eggshells of Neognathae and non-avian dinosaurs are analysed with electron backscatter diffraction. Our results show the detailed microstructures and crystallographies of (previously) loosely categorized ostrich-, rhea-, and tinamou-style morphotypes of palaeognath eggshells. All rhea-style eggshell appears homologous, while respective ostrich-style and tinamou-style morphotypes are best interpreted as homoplastic morphologies (independently acquired). Ancestral state reconstruction and parsimony analysis additionally show that rhea-style eggshell represents the ancestral state of palaeognath eggshells both in microstructure and crystallography. The ornithological and palaeontological implications of the current study are not only helpful for the understanding of evolution of modern and extinct dinosaur eggshells, but also aid other disciplines where palaeognath eggshells provide useful archive for comparative contrasts (e.g. palaeoenvironmental reconstructions, geochronology, and zooarchaeology).
... Their extreme cursoriality is evinced by their unique foot morphology: ostriches are the only extant didactyl birds, an anatomical configuration that may be the result of similar selective pressures as those that drove digit reduction in horses [77]. The fossil record of ostrich eggshell is rich, and although the present review focuses only on skeletal remains, we note that the occurrence of palaeognath eggshells in the early Miocene of China 17 million years ago [77,141] supports the theory that struthionids either originated outside of Africa or else underwent rapid range expansion after their emergence. For a thorough review of the ostrich eggshell record, see Mikhailov and Zelenkov [78]. ...
The extant diversity of the avian clade Palaeognathae is composed of the iconic flightless ratites (ostriches, rheas, kiwi, emus, and cassowaries), and the volant tinamous of Central and South America. Palaeognaths were once considered a classic illustration of diversification driven by Gondwanan vicariance, but this paradigm has been rejected in light of molecular phylogenetic and divergence time results from the last two decades that indicate that palaeognaths underwent multiple relatively recent transitions to flightlessness and large body size, reinvigorating research into their evolutionary origins and historical biogeography. This revised perspective on palaeognath macroevolution has highlighted lingering gaps in our understanding of how, when, and where extant palaeognath diversity arose. Towards resolving those questions, we aim to comprehensively review the known fossil record of palaeognath skeletal remains, and to summarize the current state of knowledge of their evolutionary history. Total clade palaeognaths appear to be one of a small handful of crown bird lineages that crossed the Cretaceous-Paleogene (K-Pg) boundary, but gaps in their Paleogene fossil record and a lack of Cretaceous fossils preclude a detailed understanding of their multiple transitions to flightlessness and large body size, and recognizable members of extant subclades generally do not appear until the Neogene. Despite these knowledge gaps, we combine what is known from the fossil record of palaeognaths with plausible divergence time estimates, suggesting a relatively rapid pace of diversification and phenotypic evolution in the early Cenozoic. In line with some recent authors, we surmise that the most recent common ancestor of palaeognaths was likely a relatively small-bodied, ground-feeding bird, features that may have facilitated total-clade palaeognath survivorship through the K-Pg mass extinction, and which may bear on the ecological habits of the ancestral crown bird.
... The giant ostrich from the Nihewan Formation adds an Early Pleistocene link to a succession of large to very large ostriches known from Neogene and Quaternary formations in China. The earliest record of ostriches or ostrich-like birds from China seems to be eggshell fragments from two Lower Miocene localities in Inner Mongolia [27]. However, Mikhailov and Zelenkov [28] have suggested that the eggshell fragments may have been derived from more recent sediments. ...
A large incomplete ostrich femur from the Lower Pleistocene of North China, kept at the Muséum National d'Histoire Naturelle (Paris), is described. It was found by Father Emile Licent in 1925 in the Nihewan Formation (dated at about 1.8 Ma) of Hebei Province. On the basis of the minimum circumference of the shaft, a mass of 300 kg, twice that of a modern ostrich, was obtained. The bone is remarkably robust, more so than the femur of the more recent, Late Pleistocene, Struthio anderssoni from China, and resembles in that regard Pachystruthio Kretzoi, 1954, a genus known from the Lower Pleistocene of Hungary, Georgia and the Crimea, to which the Nihewan specimen is referred, as Pachystruthio indet. This find testifies to the wide geographical distribution of very massive ostriches in the Early Pleistocene of Eurasia. The giant ostrich from Nihewan was contempora-neous with the early hominins who inhabited that region in the Early Pleistocene.
... The eggshells have been conventionally differentiated into "struthionid" and "aepyornithid" types based on shape of pore openings (Sauer 1972). Because it is a simple criterion, it has been widely used in subsequent studies (Sauer and Rothe 1972;Sauer 1972;Stern et al. 1994;Harrison and Msuya 2005;Patnaik et al. 2009;Wang et al. 2011;Pickford 2014;Blinkhorn et al. 2015;Field 2017). However, Hirsch et al. (1997) stated that "The "struthionid" and "aeyornithid" pore system … should not be used solely in the identification and classification of eggshell". ...
... al. 2009;Wang et al. 2011; Pickford 2014;Blinkhorn et al. 2015). These investigations would not only be helpful for understanding the evolutionary history of paleognath eggshells, an unexplored avenue of ornithology and paleontology, but also be useful for archaeologists and anthropologists who need biostratigraphic tools for their localities(Harrison and Msuya 2005; see alsoSharp et al. 2019 for the potential of absolute age dating for fossil paleognath eggshells).Finally, paleoenvironmental information can be acquired from eggshells(Montanari 2018;Niespolo et al. 2020). ...
Eggshells are biominerals that provide reproductive information of vertebrates. In paleontology, fossil eggshells offer a unique chance to investigate the reproductive
paleobiology of extinct taxa because diverse information inscribed in fossil eggshells are
unavailable from other types of fossils such as fossil bone and trace fossi ls. In addition,
geologic information has been added to once-purely-biogenic-biomineral because fossil
eggshells have experienced fossilization process . Being a discipline with biogenic calcite,
compared to other fields of vertebrate paleontology, fossil eggshell research can share
diverse methodologies with other fields of geology and biology, which are based on
analytical approaches (e.g. mineralogy) . Hence, it can have broad implications to diverse
fields including, but not limited to, paleontology per se, neontology, and sedimentology. In
this dissertation, firstly, I focused on the microstructure and crystallography of fossil and
modern eggshells using a device called Electron Backscatter Diffraction (EBSD), which has been a powerful tool in materials science and structural geology. The results can be
summarized in the four points. First, the crystallographies of gekkotan and archosaur
eggshells were completely different from each other, meaning that calcified eggshells of
those clades are independent and homoplastic in their origin. Secondly, the presence of the external zone and squamatic zone in maniraptoran eggshells can be identified by comparing the linearity of grain boundaries of the two zones. In addition, the two different
misorientation distribution pattern could be found between them. Thirdly, the crystallography of "geckoid‟ eggshells from Upper Cretaceous deposits in Europe confirmed that they are, in fact, maniraptoran dinosaur eggshells. Fourthly, the microstructural and crystallographic evolution of modern paleognath eggshells were investigated, which can be helpful to understand the evolution of eggshells in modern maniraptoran clades. Moreover, the dark color of fossil eggshells from the Korean Peninsula is mainly attributable to the presence of amorphous carbon, which can be detected by Raman spectroscopy. The amorphous carbon signal of Raman spectrum records the maximum paleotemperature that the fossil material experienced. The deconvolution approach of amorphous carbon in Raman spectrum developed by organic geochemist was adopted in this study, which allows estimating the maximum paleotemperature of fossil locality. These studies clearly show that EBSD can provide more objective results on the microstructure and crystallography of diverse amniotic
eggshells than conventional techniques do. They are not only useful for correct identification and classification for fossil eggshells but also helpful to read latent paleobiological information. Notably, crystallographic data might be related to the ethological feature of Maniraptora because the strength of eggshells might be related to the microstructure and crystallography of eggshells. Raman spectroscopic results imply that fossil eggshells might be a useful material to infer the maximum paleotemperature of terrestrial basins. It is because the spectroscopic analysis has been usually focused on marine microfossils and kerogen organic materials rather than terrestrial macrofossils. If the same logic works in the biocarbonate of amniotic eggshells, fossil eggshells can be used as invaluable materials to infer the sedimentological and taphonomic setting of the terrestrial fossil-bearing deposits. In short, EBSD and Raman spectroscopy are essential tools to get novel information from eggshells that we had never acquired before. Along with this new technology, future research should be focused on combining statistical and analytical methods to correctly interpret hidden information from fossil and modern eggshells.
... A very similar Type A-S eggshell (originally reported as "aepyornithids"; Wang et al., 2011), judging from the illustrations, but obviously thinner (1.7-2.1 mm) have been reported from the late Miocene (MN 12; 7.11 ± 0.48 Ма) Boagedawula site in the Chinese Inner Mongolia (Wang et al., 2011). These authors further report a very similar eggshell (also Type A-S; ETR=1.7-2.2 mm) from a closely located but much older (early Miocene;~17.5 Ma) locality Gashunyinadege. ...
... A very similar Type A-S eggshell (originally reported as "aepyornithids"; Wang et al., 2011), judging from the illustrations, but obviously thinner (1.7-2.1 mm) have been reported from the late Miocene (MN 12; 7.11 ± 0.48 Ма) Boagedawula site in the Chinese Inner Mongolia (Wang et al., 2011). These authors further report a very similar eggshell (also Type A-S; ETR=1.7-2.2 mm) from a closely located but much older (early Miocene;~17.5 Ma) locality Gashunyinadege. ...
Ostriches (Struthionidae) are iconic Old-World giant flightless birds. The two living African species represent only a small part of ancient struthionid diversity, which comprises a number of fossil taxa, including the largest known birds of Northern Hemisphere – Pleistocene giants Pachystruthio. In comparison with most other birds, ostriches have an extensive fossil record, mostly represented by eggshell fossils, which are rather common in many Neogene to Quaternary localities of Africa and Eurasia. The global Old-World diversity of the fossil ostrich eggshell is here for the first time analyzed and put together with bone fossil record as well as current palaeoenvironmental and stratigraphic/biochronological data. The available fossil record indicates a complicated geographical pattern of ostrich evolutionary history during the Miocene, Pliocene and Pleistocene of Africa and Eurasia, with a number of evolutionary transformations and proposed dispersal events (both out-of-Africa and out-of-Eurasia). The evolution of ostriches is further put into a context of the overall environmental and faunal evolution, and paleontology-based hypotheses of the origin of modern taxa are developed. 17 Figures: Fig.1 - Classification of pore structures in 3 PPMs; Fig.2 - The model of mechanism of pore canal development, Fig.3-12 - the pore patterns of Eurasian ostrish oospecies (photographs), Fig.13 - Chronological table, showing temporal and geographic (by region) distribution of fossil eggshell with various PPM and their possible reference to particular oospecies. Fig. 16-17 - Chronological maps, showing distribution of ostrich oospecies and proposed dispersal events in the history of ostriches. 50 days' free access to the article - https://authors.elsevier.com/c/1bPwn2weQiqau
The avian palaeognath phylogeny has been recently revised significantly due to the advancement of genome-wide comparative analyses and provides the opportunity to trace the evolution of the microstructure and crystallography of modern dinosaur eggshells. Here, eggshells of all major clades of Palaeognathae (including extinct taxa) and selected eggshells of Neognathae and non-avian dinosaurs are analysed with electron backscatter diffraction. Our results show the detailed microstructures and crystallographies of (previously) loosely categorized ostrich-, rhea-, and tinamou-style morphotypes of palaeognath eggshells. All rhea-style eggshell appears homologous, while respective ostrich-style and tinamou-style morphotypes are best interpreted as homoplastic morphologies (independently acquired). Ancestral state reconstruction and parsimony analysis additionally show that rhea-style eggshell represents the ancestral state of palaeognath eggshells both in microstructure and crystallography. The ornithological and palaeontological implications of the current study are not only helpful for the understanding of evolution of modern and extinct dinosaur eggshells, but also aid other disciplines where palaeognath eggshells provide useful archive for comparative contrasts (e.g. palaeoenvironmental reconstructions, geochronology, and zooarchaeology).
We describe new fossils from the late Eocene of Mongolia, which show that the crane-like Eogruidae and Ergilornithidae are stem group representatives of the Struthioniformes (ostriches). Currently, both taxa are unanimously assigned to the neognathous Gruiformes (cranes and allies). However, ergilornithids show a progressive reduction of the second toe, and a few earlier authors likened these birds to ostriches, which are the only extant birds with just 2 toes. So far, eogruids and ergilornithids were mainly known from hindlimb bones from the Cenozoic of Asia, and here we provide important new data on the skeletal anatomy of these birds. A partial skull exhibits characteristic features of palaeognathous birds, and ostriches in particular. In its distinctive shape, it furthermore closely resembles the skull of the Eocene palaeognathous Palaeotididae, which are here also considered to be stem group representatives of the Struthioniformes. A femur from the late Eocene of Mongolia likewise corresponds to that of ostriches in derived traits, whereas cervical vertebrae exhibit features of neognathous birds. The fossils suggest that true ostriches (crown group Struthionidae) originated in Asia, and the Neognathae-like morphology of some bones opens a new perspective on the evolution of skeletal characteristics of palaeognathous birds.
Detailed understanding to the evolution of Neogene land mammals in East Asia and its intercontinental correlation has been impeded by the absence of an integrated biochronological system of this region. The numerous and diverse records of Neogene vertebrate fossils preserved in Inner Mongolia of northern China play a key role in the establishment of an independent biochronological framework in East Asia. However, most of these faunas are poorly constrained by independent chronological controls due to the scattered distribution of fossil localities and insufficient exposure of the fossiliferous strata. Additionally, age estimates by mammalian evolution and correlation often have uncertainties greater than ~1–2 million years. Here we present new magnetostratigraphic results of the Baogeda Ula Fauna, which was generally assigned an early Baodean Age (Late Miocene), or equivalent to the European MN12 zone (middle Turolian). Hipparion remains and associated vertebrate fossils were excavated from the upper part of the fluvio-lacustrine Baogeda Ula Formation near Abaga Banner, central Inner Mongolia of northern China. At least two layers of basalt sheet flows can be observed on top of the Baogeda Ula Formation. Our magnetostratigraphy, aided by published biochronology data and K–Ar ages of the lower basalt layer suggests that the Baogeda Ula Fauna consisting of three fossiliferous horizons can be placed within chron C4n.1n with an age range of 7.642–7.528 Ma. Thus, the Baogeda Ula Fauna becomes the first and only Baodean assemblage that is constrained by both magnetostratigraphy and radiometric ages, offering an anchoring point for future biochronological correlations.
