Dinosaur eggshell assemblage from Japan reveals unknown diversity of small theropods

The Lower Cretaceous (Albian) Sasayama Group in the Hyogo Prefecture of southwestern Japan has yielded various vertebrate fossils, including skeletal remains of dinosaurs, anurans, lizards, and mammals, and recently eggshell fragments. Here we report on numerous fossil eggshells from the bone-bearing Kamitaki locality in Tamba City, which represents a diverse dinosaur eggshell assemblage. Of the more than 90 eggshell fragments recovered, five different types were identified, including eggshells that likely belong to a variety of theropods (Nipponoolithus ramosus oogen. et oosp. nov., Elongatoolithus sp., Prismatoolithus sp., and Prismatoolithidae indet.) and at least one ornithopod (Spheroolithus sp.). All eggshells are relatively thin, and a new derived estimation method correlating egg mass with eggshell thickness indicates that they are among the smallest (28–135 g) theropod eggs known, likely laid by small bodied forms. The eggshell assemblage from this locality suggests that a diverse small dinosaur fauna, consisting primarily of theropods, nested in the region, a diversity yet to be evidenced from skeletal remains in Japan.     

Dinosaur eggshells from the Santonian Milk River Formation of Alberta,Canada

The North American fossil record of dinosaur eggshells for the Cretaceous is primarily restricted to formations of the middle (Albian–Cenomanian) and uppermost (Campanian–Maastrichtian) stages, with a large gap in the record for intermediate stages. Here we describe a dinosaur eggshell assemblage from a formation that represents an intermediate and poorly fossiliferous stage of the Upper Cretaceous, the Santonian Milk River Formation of southern Alberta, Canada. The Milk River eggshell assemblage contains five eggshell taxa: Continuoolithus, Porituberoolithus, Prismatoolithus, Spheroolithus, and Triprismatoolithus. These ootaxa are most similar to those reported from younger Campanian–Maastrichtian formations of the northern Western Interior than they are to ootaxa reported from older middle Cretaceous formations (i.e., predominantly Macroelongatoolithus). Characteristics of the Milk River ootaxa indicate that they are ascribable to at least one ornithopod and four small theropod species. The taxonomic affinity of the eggshell assemblage is consistent with the dinosaur fauna known based on isolated teeth and fragmentary skeletal remains from the formation, although most ornithischians and large theropods are not represented by eggshell. Relative to the Milk River Formation eggshell, similar oospecies occurring in younger Cretaceous deposits tend to be somewhat thicker, which may reflect an increase in body size of various dinosaur lineages during the Late Cretaceous.     

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

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 × 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.     

Dinosaur eggs in the Upper Cretaceous of the Coll de Nargó area,Lleida Province,south-central Pyrenees,Spain: Oodiversity,biostratigraphy and their implications

The Coll de Nargó area (Lleida Province, south-central Pyrenees) has yielded thousands of dinosaur eggs distributed in more than 30 levels across 370 m of Upper Cretaceous Tremp Formation deposits. Two stratigraphic units yielding dinosaur eggshells, eggs and clutches, can be distinguished. Multiple eggshells were collected from up to 75 different in situ clutches, located in consecutive stratigraphical levels throughout the Mas de Pinyes section. Four different oospecies have been recognized: Megaloolithus aureliensis, Megaloolithus siruguei, Megaloolithus cf. baghensis and Cairanoolithus cf. roussetensis. In absence of typical biochronological markers, fossil eggshells may have potential as a tool for dating. Based on these ootaxa, three oozones can be established along the stratigraphic section. The lower assemblage is composed by M. aureliensis, M. siruguei and Cairanoolithus cf. roussetensis; the middle one consists only of M. siruguei, while the upper oozone is characterized by M. cf. baghensis. Results suggest that the age of Coll de Nargó rocks ranges from the latest Campanian to the beginning of the Late Maastrichtian. Also reported is the first evidence of the oogenus Cairanoolithus outside of France, where it was regarded as an endemic ootaxon. The Coll de Nargó area is considered to be one of the most important dinosaur nesting areas in Europe recurrently used by several dinosaurs during a long time span. Finally, the presence of fossilized eggshell membrane in several specimens from Coll de Nargó contributes to understanding the taphonomic process of megaloolithid eggs in this area.     

河南淅川盆地上白垩统恐龙蛋一新蛋种

河南淅川盆地的恐龙蛋发现与研究始于1974年,淅川盆地恐龙蛋具有非常高的多样性,共计发现4个蛋科、6个蛋属、6个蛋种,尤其以树枝蛋类最为丰富。近年来,河南地质博物馆对全省地质遗迹调查过程中,在淅川盆地再次有新的恐龙蛋类型的发现,本文对其中的部分标本进行记述,根据壳单元呈多分叉的不规则树枝状,蛋壳厚度为1. 62~1. 74 mm,锥体间隙明显,壳单元自锥体上部开始出现分枝,蛋壳中部大多具有3~4个分枝,近蛋壳外表面形成融合层,蛋壳具有复杂的气孔系统等特征区别于其他类型的树枝蛋类,建立一新蛋种:大石桥树枝蛋（Dendroolithus dashiqiaoensis oosp. nov. )。通过对淅川盆地恐龙蛋分类与对比、不同类型恐龙蛋在地层中的分布研究,将有助于盆地内白垩纪红层的划分,也将为秦岭东段各盆地中同一时期红层的划分与对比、古地理、古环境和古气候等研究提供更加翔实的古生物学证据。     

吉林省公主岭早白垩世泉头缍网形蛋（Dictyoolithus）一新科

报道了吉林省公主岭早白垩世泉头组发现的一窝恐龙蛋化石。蛋化石近圆形，蛋壳厚度1．4～1．7mm，蛋壳外表面均匀分布椭圆形或圆形大小不一的凹坑；蛋壳层由2、3个呈分树枝状的基本结构单元叠加而成，蛋壳基本单元之间气孔道阔大而不规则，靠近蛋壳外表面的基本结构单元相互连姑、融合形成一层相对致密的薄层。据以上特征将其归为网形蛋科（Dictyoolithidae），网形蛋属（Dictyoolithus），定为一新种：公主岭网形蛋（Dictyoolithus gongzhulingensis oosp.nov）。公主岭网形蛋是网形蛋类化石在中国东北地区的首次发现，同时也是早白垩世地层中网形蛋化石新的发现。     

吉林省公主岭早白垩世泉头组网形蛋(Dictyoolithus)一新种

报道了吉林省公主岭早白垩世泉头组发现的一窝恐龙蛋化石。蛋化石近圆形,蛋壳厚度1.4~1.7 mm,蛋壳外表面均匀分布椭圆形或圆形大小不一的凹坑;蛋壳层由2、3个呈分树枝状的基本结构单元叠加而成,蛋壳基本单元之间气孔道阔大而不规则,靠近蛋壳外表面的基本结构单元相互连结、融合形成一层相对致密的薄层。据以上特征将其归为网形蛋科(Dictyoolithidae),网形蛋属(Dictyoolithus),定为一新种:公主岭网形蛋(Dictyoolithus gongzhulingensisoosp.nov.)。公主岭网形蛋是网形蛋类化石在中国东北地区的首次发现,同时也是早白垩世地层中网形蛋化石新的发现。     

A new sauropod dinosaur (Dinosauria,Sauropoda) from the late Early Cretaceous of the Ruyang Basin (central China)

A new long-necked sauropod dinosaur, Yunmenglong ruyangensis gen. et sp. nov., is erected on the basis of an incomplete skeleton from the late Early Cretaceous Haoling Formation of the Ruyang Basin, Henan Province. The characters of the anterior cervical vertebrae, the shape of the neural canal of the dorsal vertebra and the ball-shaped distal end of the neural spine of caudal vertebrae with coarse surfaces differ from other long-necked sauropod dinosaurs. The new genus has characters in common with both Euhelopus and Erketu; it represents the first long-necked sauropod dinosaur recorded from central China to date. The rod-like, well-developed epipophyses and the pleurocoels on the cervical vertebrae indicate that it may be close to Euhelopus, an observation also confirmed by a phylogenetic analysis, which shows that Erketu, Yunmenglong and Qiaowanlong form a clade, and are more derived than Euhelopus.     

河南西峡晚白垩世恐龙蛋化石壳超高异常Sr的发现及其意义

利用电感耦合等离子体发射光谱仪(ICP-AES),对采自河南西峡晚白垩世的十三枚恐龙蛋化石壳及蛋内充填物和部分围岩进行了测试。发现Sr元素具有明显的超高异常。恐龙蛋化石壳中的Sr的含量分布在1962×10-6～11010×10-6之间,平均5532×10-6,比古代和现代富Sr的腕足类外壳高一到数倍,比地壳丰度值高一个数量级还多。这种超高异常可能与恐龙蛋壳中含有一定数量的文石有关。而由于文石稳定性较差,在石化过程中会逐渐向低镁方解石转化,所以现在已无法再见到蛋壳中的文石,但Sr却保留了下来。反映了中生代时陆生爬行动物的蛋壳与海相生物硬壳一样具有文石和方解石共存的局面。     

First Valanginian Polacanthus foxii (Dinosauria,Ankylosauria) from England,from the Lower Cretaceous of Bexhill,Sussex

A new partial skeleton of the armoured ornithischian dinosaur Polacanthus found in the Wadhurst Clay Formation (Valanginian stage) of Bexhill, Sussex is the oldest recorded occurrence of this taxon. Previous discoveries suggested that at least two armoured ornithischians occur in the Wealden succession: Polacanthus, which was mostly restricted to the Barremian, and Hylaeosaurus, which was recorded as present only in the Valanginian. The new discovery extends the stratigraphic range of Polacanthus into the Valanginian. Although these two taxa appear to be closely similar anatomically, their osteology now suggests they are not synonymous. The new specimen includes the first known jugal as well as a comparatively rare polacanthid plate/spine (splate) which probably comes from the shoulder (pectoral) area of these animals.     

The carbon isotopic characteristics of dinosaur eggshell fossils in Late Cretaceous from Xixia Basin and their significance

This paper studies the Late Cretaceous dinosaur eggshell fossils from the Xixia Basin,Henan Province,by icroscopy and carbon isotope method.Careful observation under microscope revealed that all dinosaur eggshell fossils consist of primary calcite and secondary calcite.The content of the former is about 60.5% and the latter 39.5% according to image analysis.The δ13C values of secondary carbonate mineral filling within the dinosaur eggs in the strata range from-5.63‰ to -5.68‰,with an average value of -5.64‰,the δ^13 C values of sixteen dinosaur eggshell fossils are in the range from-5.88‰ to -7.79‰,Then we calculated the δ^13 C values of primary carbonate minerals,ranging from-6.03‰ to-9.19‰.Bsed on the δ^13C values of the primary carbonate ,the ancient food type and food proportion of dinosaurs were deduced.The dinosaru‘s food proportions of C3 plant and C4 plant are 61% and 39%,respectively.Finally,it is inferred that the palaeoclimate in the Xixia Basin should be a warm-sub-humid-sub-arid climate in the subtropical zone of the Xixia Basin.     

河南西峡晚白垩世恐龙蛋化石壳微量元素组成及其对恐龙灭绝的指示意义

恐龙蛋化石是探索恐龙生存和灭绝的重要研究材料,目前对恐龙蛋化石的研究集中在生物学和埋藏特征方面。本文利用电感耦合等离子体发射光谱法(ICP-OES)对采自河南西峡晚白垩世的12枚恐龙蛋化石壳及部分围岩进行分析测试,研究其生命微量元素组成及其与恐龙灭绝的关系。结果表明,恐龙蛋壳中缺乏碳氮磷硫等有机质元素,而主要由钙铝镁铁钾等生命必需元素和锶锰钡镧锌硼钒钴铱等微量元素组成,其中锶和铱均具有明显的超高异常,这可能与地外撞击事件引起生态环境的急剧变化有关。元素的组合规律表明西峡盆地晚白垩世应为干旱、半干旱的气候环境,来自于环境中异常含量的锶和铱共同作用使这一时期该地区大量的恐龙蛋在恐龙体内遭受污染,发育孵化机能受到影响,成为导致盆地内恐龙灭亡的主要原因之一。这一发现为探讨恐龙生活环境变化、灭绝原因以及揭示晚白垩纪古气候提供了重要依据。     

汝阳盆地早白垩世恐龙蛋壳的发现及其意义

汝阳盆地是豫西地区的一个中—新生代断陷盆地,自2006年以来发现了一个以巨型蜥脚类恐龙为代表的恐龙动物群。本文描述了近期发现于汝阳盆地下白垩统郝岭组中的若干恐龙蛋蛋壳碎片。基于以下对蛋壳宏观形态和显微特征的分析,这些蛋壳碎片可以归入长形蛋科(Elongatoolithidae)的长形蛋属(Elongatoolithus):蛋壳外表面具分散瘤点状或线性脊状的纹饰;蛋壳自内而外分为锥体层和柱状层,二层之间的界线不清晰;锥体层中锥体排列紧密;柱状层中具波浪状的平行生长纹。这一发现代表了长形蛋属在早白垩世地层中的首次记录,进一步拓展了该蛋属的地史和古地理分布。由以往已知的化石关联推测,这些蛋壳可能与该层位中的窃蛋龙类如刘店洛阳龙(Luoyanggia liudianensis)等具有相关性,表明汝阳盆地在早白垩世晚期具有适宜该类恐龙生存与繁殖的环境。     

湖北郧县青龙山一带晚白垩世地层及恐龙蛋化石初步研究

郧县青龙山一带的上白垩统是一套以冲积扇相为主体的红色陆源碎屑沉积，依据岩性变化，可分为上、中、下３个组合．下部组合含多个产恐龙蛋化石的层位．上部组合与毗邻的李官桥盆地胡岗组（Ｋ３２ｈｇ）可以对比．红寨子、青龙山一带的恐龙蛋化石分布集中，藏量丰富，类型较多，埋藏甚浅，保存好，实属举世罕见．据初步研究，蛋壳的显微结构有５种类型，分属于５个恐龙蛋科，即Ｄｅｎｄｒｏｏｌｉｔｈｉｄａｅ，Ｄｉｃｔｙｏｏｌｉｔｈｉｄａｅ，Ｆａｖｅｏｌｏｏｌｉｔｈｉｄａｅ，Ｐｒｉｓｍａｔｏｏｌｉｔｈｉｄａｅ和Ｓｐｈｅｒｏｏｌｉｔｈｉｄａｅ，其中以Ｄｅｎｄｒｏｏｌｉｔｈｉｄａｅ分布最广、数量最多．     

元谋姜驿中侏罗世一蜥脚龙新种

记述产自元谋县姜驿乡半箐村中侏罗统中的恐龙新种。根据骨骼特征鉴定，认为：有别于云南省已发现的早侏罗世原蜥脚类恐龙，而与四川会理及自贡大山铺出土的蜀龙有相似处，但也存在一些较明显的差别，据此，建蜀龙新种。     

A Late Cretaceous madtsoiid snake from Romania associated with a megaloolithid egg nest – Paleoecological inferences

Here we report on the taphonomy and paleoecological implications of the first record of a small madtsoiid snake (Nidophis insularis) closely associated with a megaloolithid dinosaur egg nest. Taphonomic and sedimentologic evidence suggest that the snake was buried autochthonously within or nearby the egg nest, with at least partially articulated skeleton. Count of growth rings on the vertebral zygapophyses indicates that the holotype of Nidophis belonged to an adult individual approaching the limit of its maximum body size of about 1 m length. The presence of layers of arrested growth on the zygapophyses, together with other independent data (e.g., paleomagnetic data, sedimentology, paleosol development stage, stable isotope geochemistry) indicates that Nidophis lived under a semi-arid, seasonally variable subtropical climate, having alternative periods of active feeding. The trunk vertebrae with relatively low neural spines and without prezygapophyseal accessory processes indicate a relatively heavy-bodied, slowly-moving animal, one that probably had a semifossorial habit and was an active forager, but definitively not a dinosaur nest raider as suggested for certain large madtsoiid snakes (the Indian Sanajeh). Potential prey items, available around the dinosaur nesting area, probably ranged from small squamate eggs to various small vertebrates. Finally, one anterior trunk vertebra of the holotype displays distinct bite marks left by a small-sized and pointed-toothed predator, most probably a crocodyliform or a theropod, thus documenting that madtsoiids were also preyed upon.     

A New Ootype of Dinosaur Egg (Faveoloolithidae: Duovallumoolithus shangdanensis oogen. et oosp. nov.) from the Late Cretaceous in the Shangdan Basin,Shaanxi Province,China

A new ootype collected from the Upper Cretaceous Lijiacun Formation in the Shangdan Basin, Shaanxi Province is described in this paper. Based on general external shape, size, eggshell thickness and honeycomb‐like eggshell microstructure, eggs are referable to the oofamily Faveoloolithidae. Compared with other members of Faveoloolithidae, specimens described in this paper show special characteristics: adjacent pores are usually separated by two eggshell units between which often develop interspaces; columnar eggshell units are relatively closely arranged in radial view. According to these characteristics, we erect a new oogenus and a new oospecies: Duovallumoolithus shangdanensis oogen. et oosp. nov. The new discovery expands the diversity of Faveoloolithidae.     

An accumulation of turtle eggs with embryos from the Campanian (Upper Cretaceous) Judith River Formation of Montana

A weathered accumulation of turtle eggs, interpreted as remnants of a single clutch composed of at least 16 turtle eggs (MOR 710) from the Campanian (Upper Cretaceous) Judith River Formation of north-central Montana, USA, represents a new oospecies Testudoolithus zelenitskyae. This ootaxon is diagnosed by the following unique combination of characters: spherical eggs 34–39 mm in diameter, 660–760 μm thick eggshell, shell unit height-to-width ratio of 3.15:1–5.5:1, and domed shell units. Estimated egg mass indicates that the egg-laying adult likely possessed a carapace 35.0–54.4 cm in length. Similarities between T. zelenitskyae oosp. nov. and Adocus sp. eggs, along with comparable body size, suggest that this taxon might have produced MOR 710. One egg exhibits abnormal multilayered eggshell, likely resulting from prolonged egg retention by the female turtle. At least five of these eggs, including the multilayered specimen, preserve embryonic remains that demonstrate a late stage of embryonic development. This suggests that death occurred just prior to hatching.     

A new ornithomimid dinosaur with North American affinities from the Late Cretaceous Qiupa Formation in Henan Province of China

A partial skeleton of the ornithomimid dinosaur, discovered from the Late Cretaceous Qiupa Formation of Luanchuan County, Tantou Basin, Henan Province, China, is described here and assigned to a new genus and species, Qiupalong henanensis, with unique features (a notch on the lateral surface of the lateral posterior process of the proximal end of tibia and a small pit at the contact between astragalus and calcaneum). A phylogenetic analysis in this study suggests that it is a derived ornithomimid and form a monophyly with North American ornithomimids (Struthiomimus altus and Ornithomimus edmontonicus), sharing two characters (straight pubic shaft and large acute angle between pubic shaft and boot). Some characters (small anterior process of the pubic boot and curved pedal unguals) are seen in basal ornithomimosaurs as well, but these features in Q. henanensis are reversal. Qiupalong is the first definitive ornithomimid from outside of the Gobi Desert and is the southern-most occurrence of Late Cretaceous ornithomimid from eastern Asia, demonstrating southern extension of ornithomimid distribution in Asia.