Parataxonomy and palaeobiogeographic significance of dinosaur eggshell fragments from the Upper Cretaceous strata of the Cauvery Basin,South India

Abstract

In the past, fossilised dinosaur eggshells have been extensively documented from the Upper Cretaceous Lameta Formation of Central India and as many as nine oospecies are known at present from this formation. Compared to this, only one dinosaur oospecies has been described from the Cretaceous succession of the Cauvery Basin. However, the first fossil egg from India, identified as a chelonian egg, was documented from the Aptian – Albian Karai Formation of the Cauvery Basin in 1957. Following this, a solitary titanosaurid dinosaur egg was described from the Upper Cretaceous (Lower Maastrichtian) Kallankuruchhi Formation, Cauvery Basin in 1996. More recently, we have recovered isolated eggshell fragments from the marine part of the Upper Cretaceous (Late Maastrichtian) Kallamedu Formation. Based on eggshell morphology, microstructure and ultrastructure, these eggshell fragments are assigned to the oospecies Fusioolithus baghensis. The new find from the Cauvery Basin is important from palaeobiogeographic point of view as the oofamily Fusioolithidae is found in the Upper Cretaceous strata of India, France, Argentina and Morocco. Based on the common occurrence of similar oospecies in South America, Africa, Europe and India, a Late Cretaceous palaeobiogeographic connection between India and South America as well as Europe via Africa is suggested.     

Extramorphological Features of Sauropod Dinosaur Tracks in the Uhangri Formation (Cretaceous), Korea

Sauropod footprints in the Uhangri Formation (Cretaceous) of Korea exhibit an unusual pattern of morphology, with the interior of each print partitioned into a series of pockets by conspicuous radial crests. The crests are evidently extramorphological features and have been interpreted as upwellings of sediment extruded through the floor of the footprint following its fracture by impact of the trackmaker's foot. That explanation entails some inconsistencies, and an alternative explanation is proposed here. The alternative explanation envisages delamination of a superficial sheet of sediment that was lifted into a canopy, which subsequently collapsed in radiating folds. The superficial sheet of sediment might have been lifted by either or both of two mechanisms—by adhering to the underside of the trackmaker's foot or by being forced upward into a blister-like dome by the backflow of water previously displaced by impact of the trackmaker's foot. These alternative explanations draw attention to minor morphological features that were previously unexplained.     

Cretaceous plant taxonomy and angiosperm ancestors: sources of difficulty

HUGHES, N. F., 1984. Cretaceous plant taxonomy and angiosperm ancestors: sources of difficulty. It is suggested that one of the primary reasons for slow progress in identifying angiosperm ancestors is restriction of investigation resulting from inappropriate and unimaginative taxonomic handling of the now much-extended available data. Because of the incomplete nature of any palynologic evidence, identification of ancestors from it can only come from a very large number of observations of fossils and from strict application of stratigraphic sequence information; quick solutions are most unlikely. The removal of any Mesozoic gymnosperm group from the list of ancestor candidates should only arise from prolonged investigation.     

山西天镇晚白垩世一新鸭嘴龙超科恐龙（英文）

记述了山西天镇晚白垩世灰泉堡组发现的一鸭嘴龙超科恐龙新属种:天镇大同龙Datonglong tianzhenensis gen.et sp.nov.。标本为一保存较完好的右侧齿骨并带牙齿。与其他鸭嘴龙超科恐龙不同,大同龙每个齿槽有两个功能齿,而且舌面齿冠上嵴的发育也具有独特的特征组合(主嵴向远中方向偏移;次嵴发育;无其他附嵴;主嵴上半段略后弯)。对比研究发现,在较进步的非鸭嘴龙科鸭嘴龙超科类群中齿骨和牙齿的演化过程复杂,许多鸭嘴龙科的特征在这些类群中时而出现,如:巴克龙Bactrosaurus齿冠具有较大的高/宽比;吉尔摩龙Gilmoreosaurus齿冠上只有一个主嵴和纤弱的附嵴;张衡龙Zhanghenglong齿冠上主嵴中置;南宁龙Nanningosaurus下颌冠状突前倾;大同龙Datonglong每个齿槽有两个功能齿。这表明为了获得更有效的牙齿咀嚼方式,在鸭嘴龙科起源前它的姐妹群们曾进行过多种尝试;这也告诫我们,受大量趋同演化的影响,要厘清这些类群间的关系并非易事。     

Dinosaurs and other tetrapods in an Early Cretaceous bauxite-filled fissure, northwestern Romania

The bauxite mine at Cornet near Oradea in northwestern Romania produced thousands of bones in an excavation in 1978, mainly from ornithopod dinosaurs and rarer pterosaurs. Bird specimens reported previously from this fauna are equivocal. The fossils are disarticulated bones in good condition which occur highly concentrated in lenses within bauxite clays, which are dated as Berriasian (earliest Cretaceous). The bauxite represents detrital material washed into deep fissures and caves formed within a karst of uplifted Tithonian (latest Jurassic) marine limestones. The bones are generally uniform in size and shape, and they are abraded, evidence for considerable transport and for winnowing of the deposit. The area was one of several islands on the northern shore of Tethys, and it was inundated by the sea later in the Early Cretaceous. There is evidence for insular adaptations in the dinosaur faunas. The ornithopod dinosaurs may include several taxa, but they are smaller on average than an assemblage of typical Wealden ornithopods, perhaps because of dwarfing on the island. In addition, sauropods are absent and theropods are barely represented in the fauna. The fauna is geographically significant since it shows relationships with western Europe and with Asia.     

Eggs and clutches of the Spheroolithidae from the Cretaceous Tiantai basin,Zhejiang Province,China

Numerous discoveries in the Tiantai basin of Zhejiang Province, China, enrich our understanding of the parataxonomy, paleobiology and taphonomic histories of fossil eggs from a diverse array of Cretaceous oofamilies. We describe the most abundant of these egg types catalogued in the Zhejiang Museum of Natural History, Spheroolithus cf. zhangtoucaoensis (oofamily Spheroolithidae). Scanning electron microscopy, here utilised for the first time on Spheroolithus eggs from Tiantai, and petrographic microscopy reveal 0.81–1.37-mm thick eggshell composed of a single structural layer of calcite with slightly flaring shell units, irregular pores, horizontal accretion lines and a sweeping extinction pattern under crossed polars. This contradicts previous reports of the presence of two structural layers in Tiantai Spheroolithus. Clutches consist of 2–13 eggs arranged in an irregular, single-layered pattern. As these eggs are among the oldest Asian examples of Spheroolithus currently known, they may shed light on the early evolution of this oogenus. This study establishes the definitive presence of the Spheroolithidae in the Tiantai basin, contra recent reports, and provides the framework for ongoing examination of egg diversity and taphonomy in the Tiantai basin.     

Diverse Dinosaur-Dominated Ichnofaunas from the Potomac Group (Lower Cretaceous) Maryland

Until recently fossil footprints were virtually unknown from the Cretaceous of the eastern United States. The discovery of about 300 footprints in iron-rich siliciclastic facies of the Patuxent Formation (Potomac Group) of Aptian age is undoubtedly one of the most significant Early Cretaceous track discoveries since the Paluxy track discoveries in Texas in the 1930s. The Patuxent tracks include theropod, sauropod, ankylosaur and ornithopod dinosaur footprints, pterosaur tracks, and miscellaneous mammal and other vertebrate ichnites that collectively suggest a diversity of about 14 morphotypes. This is about twice the previous maximum estimate for any known Early Cretaceous vertebrate ichnofauna. Among the more distinctive forms are excellent examples of hypsilophodontid tracks and a surprisingly large mammal footprint. A remarkable feature of the Patuxent track assemblage is the high proportion of small tracks indicative of hatchlings, independently verified by the discovery of a hatchling-sized dinosaur. Such evidence suggests the proximity of nest sites. The preservation of such small tracks is very rare in the Cretaceous track record, and indeed throughout most of the Mesozoic.

This unusual preservation not only provides us with a window into a diverse Early Cretaceous ecosystem, but it also suggests the potential of such facies to provide ichnological bonanzas. A remarkable feature of the assemblage is that it consists largely of reworked nodules and clasts that may have previously been reworked within the Patuxent Formation. Such unusual contexts of preservation should provide intriguing research opportunities for sedimentologists interested in the diagenesis and taphonomy of a unique track-bearing facies.     

An Early Late Cretaceous Dinosaur Tracksite in Central Yukon Territory,Canada

Dinosaur tracks were first reported from the coal-bearing clastic sequences of the Ross River Block in 1999 by members of a University of Alaska Museum field party, and track sites were confirmed by a joint Alaska-Yukon team in 2000. This fault-bounded sedimentary block is 3 kilometers west of Ross River, in the Yukon Territory. The discovery was followed by two years of field mapping and collection. This research has resulted in the documentation of 251 individual tracks at two separate but stratigraphically related sites, as well as a short (four-footprint) trackway at one of the sites. Six ichnogenera were identified. Ornithomimipus, Amblydactylus, and Gypsichnites were recognized at one site. At a stratigraphically higher site, four ichnogenera were documented including Tetrapodosaurus, Irenesauripus, Amblydactylus, and Columbosauripus. This ichno-assemblage is compared with those of Aptian to Cenomanian age from Alberta, British Columbia, and Alaska.

The discovery of unequivocal dinosaur evidence in a small structural inlier in the Tintina Trench that was previously assumed to be Eocene in age resulted in a restudy of the palynology and biostratigraphy of this coal-bearing sequence and the recent assignment of a middle Albian to early Cenomanian age to the upper part of the dinosaur-bearing interval.     

Fossil evidence for a herbaceous diversification of early eudicot angiosperms during the Early Cretaceous

Eudicot flowering plants comprise roughly 70% of land plant species diversity today, but their early evolution is not well understood. Fossil evidence has been largely restricted to their distinctive tricolpate pollen grains and this has limited our understanding of the ecological strategies that characterized their primary radiation. I describe megafossils of an Early Cretaceous eudicot from the Potomac Group in Maryland and Virginia, USA that are complete enough to allow reconstruction of important life-history traits. I draw on quantitative and qualitative analysis of functional traits, phylogenetic analysis and sedimentological evidence to reconstruct the biology of this extinct species. These plants were small and locally rare but widespread, fast-growing herbs. They had complex leaves and they were colonizers of bright, wet, disturbance-prone habitats. Other early eudicot megafossils appear to be herbaceous rather than woody, suggesting that this habit was characteristic of their primary radiation. A mostly herbaceous initial diversification of eudicots could simultaneously explain the heretofore sparse megafossil record as well as their rapid diversification during the Early Cretaceous because the angiosperm capacity for fast reproduction and fast evolution is best expressed in herbs.     

Cretaceous diversification of angiosperms in the western part of the Iberian Peninsula

The classic leaf fossil floras from the Cretaceous of the Lusitanian Basin, Portugal, which were first described more than one hundred years ago, have played an important role in the development of ideas on the early evolution of angiosperms. Insights into the nature of vegetational change in the Lusitanian Basin through the Cretaceous have also come from studies of fossil pollen and spores, but the discovery of a series of mesofossil floras containing well-preserved angiosperm reproductive structures has provided a new basis for understanding the systematic relationships and biology of angiosperms at several stratigraphic levels through the Cretaceous. In the earliest mesofossil floras from the Torres Vedras locality, which are of probable Late Barremian-Early Aptian age, angiosperms are surprisingly diverse with about 50 different taxa. In slightly later mesofossil floras, which are of probable Late Aptian-Early Albian age, the diversity of angiosperms is still more substantial with more than hundred different kinds of angiosperm reproductive structures recognized from the Famalicão locality alone. However, this early diversity is largely among angiosperm lineages that produced monoaperturate pollen (e.g., Chloranthaceae, Nymphaeales) and early diverging monocots (Alismatales). Eudicots are rare in these Early Cretaceous mesofossil floras, but already by the Late Cenomanian the vegetation of the western Iberian Peninsula is dominated by angiosperms belonging to various groups of core eudicots. The Normapolles complex is a particularly conspicuous element in both mesofossil floras and in palynological assemblages. In the Late Cretaceous mesofossil floras from Esgueira and Mira, which are of Campanian-Maastrichtian age, core eudicots are also floristically dominant and flowers show great organisational similarity to fossil flowers from other Late Cretaceous floras described from other localities in Asia, Europe and North America.     

Fossil Woods From Williams Point Beds, Livingston Island, Antarctica: A Late Cretaceous Southern High Latitude Flora

The wood flora from Williams Point, Livingston Island, contains 12 wood types of gymnosperm and angiosperm origin. Recent collections of material have increased the biodiversity of a postulated species-rich vegetation. The gymnosperm wood can be readily assigned to four form-genera: Araucarioxylon Kraus, Araucariopitys Jeffrey, Podocarpoxylon Gothan and Sahnioxylon Bose and Sah. This indicates a diversity of coniferous araucarian and podocarp trees alongside woods of uncertain affinity ( Sahnioxylon ; Bennettitales). Two angiosperm morphotypes are assigned to the organ genera Hedycaryoxylon Su¨ss (Monimiaceae) and Weinmannioxylon Petriella (Cunoniaceae). The remaining four taxa of angiosperm wood cannot be confidently placed in extant families as they exhibit features that suggest relationships with the Magnoliidae, Hamamelidae and Rosidae. This paper presents the first comprehensive taxonomic revision of the wood flora from Livingston Island and discusses the palaeoecology that prevailed at a latitude of about 60 degrees south during the Late Cretaceous. Newly described taxa are Araucarioxylon chapmanae sp. nov., Araucariopitys antarcticus sp. nov., Podocarpoxylon chapmanae sp. nov., P. verticalis sp. nov., P. communis sp. nov., Weinmannioxylon ackamoides sp. nov., Antarctoxylon livingstonensis gen. et sp. nov., A. multiseriatum gen. et sp. nov., A. heteroporosum gen. et sp. nov. and A. uniperforatum gen et sp. nov.     

The oldest known avian eggshell,Plagioolithus fukuiensis,from the Lower Cretaceous (upper Barremian) Kitadani Formation,Fukui, Japan

Fossil record of Early Cretaceous birds may be geographically biased, and eggs and eggshells predating the Late Cretaceous were unknown. Here, we report the oldest known bird eggshell (FPDM-V-0009175) collected from the upper Barremian Kitadani Formation in Katsuyama City, Fukui, Japan. The Kitadani Formation likely represents fluvial environments. Thin-section and scanning electron microscope analyses revealed diagnostic characters of FPDM-V-0009175, including thin (0.44 mm) shell, smooth external surface, non-branching and narrow pore canals with relatively constant width, three structural layers, oblique crystal orientation from vertical in the external layer, and mammillary to continuous to external layer thickness ratio of 1:1:0.44. These characters allow assignment of FPDM-V-0009175 to a new oogenus and oospecies, Plagioolithus fukuiensis, and suggest it belonging to a bird. The three-layered eggshell structure is seen in extant and extinct birds, Plagioolithus fukuiensis, and non-avian theropods. Therefore, such structure may be plesiomorphic among theropods, appearing in the late Barremian or earlier. As the first bird body fossil from the Mesozoic of Japan, Plagioohlithus fukuiensis suggests extensive distribution and abundance of birds in the Barremian East Asia. Plagioolithus fukuiensis indicates that the late-Barremian birds inhabited and reproduced in the fluvial environments within a basin located along the eastern margin of the Asian continent.http://www.zoobank.org/urn:lsid:zoobank.org:pub:90A8CCE8-57F7-473C-855C-B2CCE2BBD1A2     

The first well-preserved Early Cretaceous brachiosaurid dinosaur in Asia

A new genus and species of brachiosaurid sauropods, Qiaowanlong kangxii gen. et sp. nov., is reported, representing the first well-preserved Early Cretaceous brachiosaurid in Asia and expanding the distribution of brachiosaurids undoubtedly into the Asian continent. The new taxon was recovered from the late Early Cretaceous Xinminpu Group of Yujingzi Basin in northwestern Gansu Province, China, and is represented by a series of eight mid-cervical vertebrae, a right pelvic girdle and some unidentified bones. The existence of deeply excavated cervical neural spines and a rising transition in the neural spine height among mid-cervical vertebrae clearly show the affinity of Qiaowanlong as a member of brachiosaurids. Among brachiosaurids, Qiaowanlong shares a derived feature with the North American Early Cretaceous brachiosaurid Sauroposeidon: the lack of cranial centrodiapophyseal lamina. However, Qiaowanlong is unique in possessing a suite of features, such as a low central length/cotyle height ratio, bifurcated cervical neural spines and a much reduced ischium. The discovery of Qiaowanlong and other new material indicates a diverse and abundant sauropod assemblage in China during the Early Cretaceous.     

甘肃早白垩世恐龙蛋化石新类型（英文）

甘肃省早白垩世地层中,出土了大量恐龙骨骼以及恐龙足迹化石,但是至今未有蛋化石的报道。根据发现于兰州-民和盆地下白垩统河口组的蛋壳化石,建立一恐龙蛋新蛋属、蛋种,并将其归于一新蛋科:Polyclonoolithidae(多小枝蛋科)。新发现的蛋化石标本不同于所有已知的恐龙蛋类型,具有独特的显微特征组合:分叉的蛋壳单元向外延伸至蛋壳外表面,并未在靠近蛋壳外表面处融合成层;弦切面上具相互链接或独立的多角形的蛋壳单元;以及不规则的气孔道。中国的恐龙蛋化石大多出自晚白垩世地层,仅在辽宁有早白垩世恐龙蛋的报道。新发现扩展了中国恐龙蛋化石的地质和地理分布,也有可能为圆形蛋科蛋壳结构的起源提供新的认识。     

山东莱阳晚白垩世恐龙与恐龙蛋研究历史和新进展

简要回顾了莱阳恐龙和恐龙蛋化石群的研究历史和以杨钟健为代表的老一代地质古生物学者对莱阳恐龙和恐龙蛋研究发现的杰出贡献,并介绍了莱阳恐龙和恐龙蛋的最新发现和若干研究进展.在近年来对莱阳周边地层进行的大规模考察中,发现了一系列发育在平原上的恐龙峡谷群,以及其中蕴含的十几个恐龙和恐龙蛋新地点和新层位.2010年开始,在对莱阳金岗口村附近的2个化石地点的发掘中,发现了以鸭嘴龙科为主的大量脊椎动物化石和蛋化石,包括一类新的栉龙亚科成员,一些大型兽脚类恐龙化石,以及一新的龟鳖类蛋化石等.2号地点化石富集层具有典型的泥石流沉积特征和骨骼埋藏特征.对棘鼻青岛龙的特殊头饰进行了CT扫描和三维重建,发现其头饰是实心结构,但其他骨骼特征证明棘鼻青岛龙属于具有头饰的赖氏龙亚科是确定无疑的,所以目前发现的头饰应不是其真实状态或根本不属于其头部骨骼.此外,对谭氏龙1属3种的重新观察研究得出以下结论:中国谭氏龙和金刚口谭氏龙应是有效属种,但部分骨骼还有疑问,还需要进一步研究,而莱阳谭氏龙为无效属种.     

Formation binning: a new method for increased temporal resolution in regional studies,applied to the Late Cretaceous dinosaur fossil record of North America

The advent of palaeontological occurrence databases has allowed for detailed reconstruction and analyses of species richness through deep time. While a substantial literature has evolved ensuring that taxa are fairly counted within and between different time periods, how time itself is divided has received less attention. Stage-level or equal-interval age bins have frequently been used for regional and global studies in vertebrate palaeontology. However, when assessing diversity at a regional scale, these resolutions can prove inappropriate with the available data. Herein, we propose a new method of binning geological time for regional studies that intrinsically incorporates the chronostratigraphic heterogeneity of different rock formations to generate unique stratigraphic bins. We use this method to investigate the diversity dynamics of dinosaurs from the Late Cretaceous of the Western Interior of North America prior to the Cretaceous–Palaeogene mass extinction. Increased resolution through formation binning pinpoints the Maastrichtian diversity decline to between 68 and 66 Ma, coinciding with the retreat of the Western Interior Seaway. Diversity curves are shown to exhibit volatile patterns using different binning methods, supporting claims that heterogeneous biases in this time-frame affect the pre-extinction palaeobiological record. We also show that the apparent high endemicity of dinosaurs in the Campanian is a result of non-contemporaneous geological units within large time bins. This study helps to illustrate the utility of high-resolution, regional studies to supplement our understanding of factors governing global diversity in deep time and ultimately how geology is inherently tied to our understanding of past changes in species richness.     

A new peculiar dinosaur egg,Sankofa pyrenaica oogen. nov. oosp. nov. from the Upper Cretaceous coastal deposits of the Aren Formation,south‐central Pyrenees,Lleida, Catalonia,Spain

Abstract: A new type of small, ovoid dinosaur egg, Sankofa pyrenaica oogen. nov. oosp. nov., with a prismatic type eggshell is described from upper Cretaceous (upper Campanian–Maastrichtian) deposits of the Montsec area, South Pyrenean Central Unit, Lleida, Catalonia, Spain. This egg type was sub‐vertically laid in only two rich monospecific sites of a single stratigraphic layer from coastal deposits of the Aren Formation, interpreted as an emerged beach ridge of a barrier island – lagoon depositional system. The size and shape of these eggs with their asymmetric poles are roughly similar to modern hen eggs, which is unusual in the Cretaceous fossil egg record. Its phylogenetic position clusters with bird and Troodontid eggs. A morphospace analysis of egg shapes shows the similarity of the new egg to a Campanian fossil bird egg from Argentina, both being intermediate between modern‐bird eggs and extinct nonavian theropod eggs. However, the eggshell microstructure of Sankofa pyrenaica differs from that of bird eggs in its incipient squamatic texture. It has a peculiar pattern of interlocking small crystals in the middle of the palisade layer, instead of the thick squamatic structure commonly present in modern avian eggshells. This new egg type is attributed to a small theropod, probably with a single oviduct like birds and whose mosaic distribution of features is a combination between that of birds and nonavian theropods. This enhances the arguments supporting the close phylogenetic relationships between both groups.     

Entobia exogyrarum (Frič, 1883) from the Upper Cretaceous of the Bohemian Cretaceous Basin

The validity of the little-known ichnospecies Entobia exogyrarum (Fri?) is verified. Shells of an oyster, Rhynchostreon suborbiculatum (Lam.), represent the substrate for the sponge borings. The borings occur in many Upper Cenomanian to Middle Turonian localities of the Bohemian Cretaceous Basin. This study revealed that the sponges attacked shells of living oysters. Entobia exogyrarum (Fri?) also represents one of the shallowest occurrences of Entobia borings in the Upper Cretaceous rocks.     

Hadrosauroid Dinosaurs from the Late Cretaceous of the Sultanate of Oman

Fragmentary post-cranial remains (femora, tibia, vertebrae) of ornithischian dinosaurs from the Late Cretaceous of the Sultanate of Oman are described and referred to hadrosauroids. The specimens come from the Al-Khod Conglomerate, of latest Campanian to Maastrichtian age, in the north-eastern part of the country. Although the fragmentary condition of the fossils precludes a precise identification, various characters, including the shape of the fourth trochanter of the femur and the morphology of its distal end, support an attribution to hadrosauroids. With the possible exception of a possible phalanx from Angola, this group of ornithopod dinosaurs, which apparently originated in Laurasia, was hitherto unreported from the Afro-Arabian plate. From a paleobiogeographical point of view, the presence of hadrosauroids in Oman in all likelihood is a result of trans-Tethys dispersal from Asia or Europe, probably by way of islands in the Tethys shown on all recent paleogeographical maps of that area. Whether hadrosauroids were widespread on the Afro-Arabian landmass in the latest Cretaceous, or where restricted to the « Oman island » shown on some paleogeographical maps, remains to be determined.