A diverse Upper Jurassic dinosaur ichnofauna from central‐west Portugal

Mateus, O. & Milàn, J. 2009: A diverse Upper Jurassic dinosaur ichnofauna from central‐west Portugal. Lethaia, Vol. 43, pp. 245–257. A newly discovered dinosaur track‐assemblage from the Upper Jurassic Lourinhã Formation (Lusitanian Basin, central‐west Portugal), comprises medium‐ to large‐sized sauropod tracks with well‐preserved impressions of soft tissue anatomy, stegosaur tracks and tracks from medium‐ to large‐sized theropods. The 400‐m‐thick Lourinhã Formation consists of mostly aluvial sediments, deposited during the early rifting of the Atlantic Ocean in the Kimmeridgian and Tithonian. The stratigraphic succession shows several shifts between flood‐plain mud and fluvial sands that favour preservation and fossilization of tracks. The studied track‐assemblage is found preserved as natural casts on the underside of a thin bivalve‐rich carbonate bed near the Tithonian–Kimmeridgian boundary. The diversity of the tracks from the new track assemblage is compared with similar faunas from the Upper Jurassic of Asturias, Spain and the Middle Jurassic Yorkshire Coast of England. The Portuguese record of Upper Jurassic dinosaur body fossils show close similarity to the track fauna from the Lourinhã Formation. □Dinosaur tracks, Lusitanian Basin, Portugal, skin impressions, Upper Jurassic.     

New evidence of Ceratosaurus (Dinosauria: Theropoda) from the Late Jurassic of the Lusitanian Basin,Portugal

A theropod assigned to Ceratosaurus was previously reported from the Portuguese Lusitanian Basin based on a limited number of elements of a single individual. Here, we describe newly discovered elements that likely pertain to same, earlier described, specimen. The new elements provide additional evidence that the range of Ceratosaurus spanned from what is now North America into Europe. Previously, some differences were noted between the Portuguese specimens and the North American Ceratosaurus. We consider these differences to be trivial and attribute them to individual variation and/or ontogeny. The following set of features (lesser trochanter positioned low on the femur; crista tibiofibularis obliquely oriented with respect to the axis of the femoral shaft; infrapopliteal ridge present posteriorly on the femur; large cnemial crest; and medial condyle of the tibia continuous with proximal end) indicate that the Portuguese specimen is assignable to Ceratosaurus. This record constitutes one of the scarce evidence of basal ceratosaurian theropods in the Late Jurassic of Europe. Despite the abundance, diversity and wide geographical distribution of ceratosaurs during the Late Cretaceous, its early evolutionary history remains poorly understood. The Portuguese specimens constitute an important evidence for the knowledge of the paleobiogeographic evolution of the clade during the Late Jurassic.     

The oldest turtle from Portugal corresponding to the only pre-Kimmeridgian plesiochelyid (basal Eucryptodira) recognized at the generic level

A shell coming from an upper Oxfordian section of the Lusitanian Basin located in Alqueidão da Serra (Municipality of Porto de Mós, West Central Portugal) is here presented. It corresponds to the oldest remain of a turtle identified in Portugal. In fact, the record of Jurassic turtles identified in pre-Kimmeridgian levels of Europe is very scarce. The new specimen represents the second worldwide identification of a Plesiochelyid turtle (basal Eucryptodira) performed in pre-Kimmeridgian levels, being the only one recognized at generic level. Therefore, this specimen corresponds to the oldest identification of Craspedochelys, a genus well-represented in Kimmeridgian and Tithonian levels of several European countries. This finding contributes the first evidence on the synchronous coexistence of more than a member of Plesiochelyidae in pre-Kimmeridgian levels, which provides arguments to justify the relatively wide diversity known for this exclusively Jurassic clade during the Kimmeridgian and the Tithonian.     

Theropod fauna from southern Australia indicates high polar diversity and climate-driven dinosaur provinciality

The Early Cretaceous fauna of Victoria, Australia, provides unique data on the composition of high latitude southern hemisphere dinosaurs. We describe and review theropod dinosaur postcranial remains from the Aptian-Albian Otway and Strzelecki groups, based on at least 37 isolated bones, and more than 90 teeth from the Flat Rocks locality. Several specimens of medium- and large-bodied individuals (estimated up to ~8.5 metres long) represent allosauroids. Tyrannosauroids are represented by elements indicating medium body sizes (~3 metres long), likely including the holotype femur of Timimus hermani, and a single cervical vertebra represents a juvenile spinosaurid. Single specimens representing medium- and small-bodied theropods may be referrable to Ceratosauria, Ornithomimosauria, a basal coelurosaur, and at least three taxa within Maniraptora. Thus, nine theropod taxa may have been present. Alternatively, four distinct dorsal vertebrae indicate a minimum of four taxa. However, because most taxa are known from single bones, it is likely that small-bodied theropod diversity remains underestimated. The high abundance of allosauroids and basal coelurosaurs (including tyrannosauroids and possibly ornithomimosaurs), and the relative rarity of ceratosaurs, is strikingly dissimilar to penecontemporaneous dinosaur faunas of Africa and South America, which represent an arid, lower-latitude biome. Similarities between dinosaur faunas of Victoria and the northern continents concern the proportional representatation of higher clades, and may result from the prevailing temperate-polar climate of Australia, especially at high latitudes in Victoria, which is similar to the predominant warm-temperate climate of Laurasia, but distinct from the arid climate zone that covered extensive areas of Gondwana. Most dinosaur groups probably attained a near-cosmopolitan distribution in the Jurassic, prior to fragmentation of the Pangaean supercontinent, and some aspects of the hallmark 'Gondwanan' fauna of South America and Africa may therefore reflect climate-driven provinciality, not vicariant evolution driven by continental fragmentation. However, vicariance may still be detected at lower phylogenetic levels.     

A theropod tooth from the Late Triassic of southern Africa

An isolated, large recurved and finely serrated tooth found associated with the prosauropodEuskelosaurus from the Late Triassic part of the Elliot Formation is described here. It is compared to the Triassic thecodonts and carnivorous dinosaurs and its possible affinity is discussed. The tooth possibly belongs to a basal theropod and shows some features similar to the allosauroids. This tooth is of significance, as dinosaur remains except for some footprints and trackways, are poorly known in the Late Triassic horizons of southern Africa.     

First occurrences of non-neosauropod eusauropod procoelous caudal vertebrae in the Portuguese Upper Jurassic record

The Upper Jurassic of the Lusitanian Basin (Portugal) is particularly rich in sauropod fossil remains, with four established taxa: Dinheirosaurus, Lusotitan, Lourinhasaurus and Zby. The presence of sauropod caudal procoelous vertebrae is reported for the first time in the Upper Jurassic of Portugal, with specimens described from the localities of Baleal, Paimogo, Praia da Areia Branca, Porto das Barcas, and Praia da Corva. The presence of slightly procoelous centra and fan-shaped caudal ribs with smooth prezygapophyseal centrodiapophyseal fossa in the more anterior caudal vertebrae allows for the assignment of these specimens to an indeterminate eusauropod, probably belonging to a non-neosauropod eusauropod form. The absence of several features in the Portuguese specimens that are common in diplodocids, mamenchisaurids and titanosaurs, prevents the establishment of sound relationships with these clades. The described specimens are almost identical to the anterior caudal vertebrae of the Iberian turiasaur Losillasaurus. During the Iberian Late Jurassic, Turiasauria is the only Iberian group of sauropods, which shares this type of morphology with the Baleal, Paimogo, Praia da Areia Branca, Porto das Barcas and Praia da Corva specimens. These specimens represent one of the four anterior caudal vertebral morphotypes recorded in the Upper Jurassic of the Lusitanian Basin and briefly described herein.     

A description of Megalosaurus bucklandii (Dinosauria: Theropoda) from the Bathonian of the UK and the relationships of Middle Jurassic theropods

Megalosaurus bucklandii (Dinosauria: Theropoda), the oldest named dinosaur taxon, from the Bathonian (Middle Jurassic) of England, is a valid taxon diagnosed by a unique character combination of the lectotype dentary. Abundant referred material is described and several autapomorphies are identified: ventral surfaces of first and third to fifth sacral centra evenly rounded, ventral surface of second sacral centrum bearing longitudinal, angular ridge; dorsally directed flange around midheight on the scapular blade; an array of posterodorsally inclined grooves on the lateral surface of the median iliac ridge; anteroposteriorly thick ischial apron with an almost flat medial surface; and complementary groove and ridge structures on the articular surfaces between metatarsals II and III. A new phylogenetic analysis focuses on basal tetanurans and includes 41 taxa, six of which have never been included in a cladistic analysis, and 213 characters, 29 of which are new. This is the first phylogenetic analysis to focus on basal tetanuran relationships, and it reveals several new results. Megalosauroidea (= Spinosauroidea) includes two clades, basal to the traditional content of Megalosauridae + Spinosauridae. These comprise Xuanhanosaurus, Marshosaurus, Condorraptor + Piatnitzkysaurus and Chuandongocoelurus + Monolophosaurus. Almost all large‐bodied Middle Jurassic theropods are megalosauroids, but Poekilopleuron is an allosauroid. Megalosauroids show geographical differentiation among clades, indicating the development of endemic theropod faunas across Pangaea during the Middle Jurassic. Notably, megalosaurids are not known from outside of Europe during this epoch. Megalosauroids are less diverse and abundant during the Late Jurassic, when most theropods are neotetanurans and allosauroids dominate the large‐bodied predator niche. This indicates faunal turnover between the Middle and Late Jurassic. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 882–935.     

Palynofacies and TOC analysis of marine and non-marine sediments across the Middle–Upper Jurassic boundary in the central-northern Lusitanian Basin (Portugal)

The Middle–Upper Jurassic transition is a geodynamic benchmark in the evolutionary history of several peri-Atlantic basins. Contrary to the vast Tethyan and peri-Tethyan areas, in the Lusitanian Basin (Portugal), this interval corresponds to a major basin-wide disconformity preceded by a complex forced regression that induced sharp facies variations across the depositional systems. The Middle Jurassic units below are fully marine, whereas the Upper Jurassic sediments (Lower?-Middle Oxfordian), correspond to freshwater/brackish lacustrine, grading into punctuated brackish-restricted lagoonal and shallow-marine paleoenvironments. This study presents total organic carbon and palynofacies data of 34 samples (total analyzed thickness about 85 m) collected from three key sections encompassing the Middle–Upper Jurassic transition in the central-northern sector of the Lusitanian Basin. The palynofacies of the analyzed part of Middle Jurassic units (Cabo Mondego Formation) are characteristic of marine environments at their base, evidencing upwards a regressive trend of the depositional systems. Total organic carbon content is generally low, reaching up to 1.94 wt%. The Upper Jurassic Cabaços Formation presents kerogen assemblages mostly of continental origin, although punctuated by minor intervals of marine influence. Total organic carbon content is more variable, reaching up to 30.56 wt%. Intraclasts of re-deposited fragments of microbial mats were found incorporated in the kerogen assemblages, which point to highly dynamic erosional and depositional processes. Diversity of Botryococcus sp. occurrences was confirmed as an indicator of the degree of paleoenvironmental stability. The vertical distribution and comparison of the kerogen assemblages of the different sections indicate major changes of these parameters among relatively close settings and along narrow vertical intervals, attesting to the high sedimentary dynamics observed in the Lusitanian Basin.     

Small theropod teeth from the Upper Jurassic coal mine of Guimarota (Portugal)

Isolated teeth of small theropod dinosaurs from the Upper Jurassic lignite coal mine of Guimarota (near Leiria, Portugal) are described and illustrated. The well known Upper Jurassic theropods from Europe,Archaeopteryx andCompsognathus, are the most common taxa in the Guimarota assemblage. One morphotype is closely related to an allosaurid theropod. Six further morphotypes of theropod teeth are also described, which are closely related to Cretaceous theropods such as dromaeosaurids, troodontids, tyrannosaurids,Richardoestesia andParonychodon. A Late Jurassic origin of these groups of theropods, which is very often postulated, is discussed.     

Sauropod and Small Theropod Tracks from the Lower Jurassic Ziliujing Formation of Zigong City,Sichuan, China,with an Overview of Triassic–Jurassic Dinosaur Fossils and Footprints of the Sichuan Basin

A dinosaur footprint assemblage from the Lower Jurassic Ziliujing Formation of Zigong City, Sichuan, China, comprises about 300 tracks of small tridactyl theropods and large sauropods preserved as concave epireliefs (natural molds). The theropod footprints show similarities with both the ichnogenera Grallator and Jialingpus. Three different morphotypes are present, probably related to different substrate conditions and extramorphological variation. A peculiar preservational feature in a morphotype that reflects a gracile trackmaker with extremely slender digits, is the presence of a convex epirelief that occurs at the bottom of the concave digit impressions. It is possibly the result of sediment compaction underweight load when the pes penetrated the substrate, being a resistant residue during exhumation and weathering. The sauropod tracks belong to a trackway with eight imprints consisting of poorly preserved pes and manus tracks and a better preserved set, probably all undertracks. The narrow-gauge trackway pattern resembles the ichnogenus Parabrontopodus well known from the Jurassic but other features such as the minor heteropody are different. The assemblage enriches the dinosaur record from the famous Zigong locality and the evidence from the Lower Jurassic in this area that was restricted to a few skeletal remains and footprints. Furthermore it proves the presence of small theropods, whereas skeletons of the group, well- known from the Middle-Upper Jurassic of Zigong, are of medium to large size only. Remarkable is the dominance of saurischians in these assemblages, which is characteristic of Jurassic dinosaur communities whereas the Cretaceous record shows an increase of ornithopod groups. An overview of the dinosaur trace and body fossil record of the Sichuan Basin supports this view. The paleoenvironment can be designated as a low-latitude tropical freshwater lake as it is indicated by bivalve shells.     

A modern-type Kimmeridgian reef (Ota Limestone,Portugal): Implications for Jurassic reef models

Upper Jurassic reefs rich in microbial crusts generally appear in deeper (sponge—‘algal’ crust reefs) or in very shallow but protected settings (coral or coral-coralline sponge meadows with ‘algal’ crusts). Upper Jurassic high-energy reefs (coral reefs and coral-stromatoporoid reefs) normally lack major participation of microbial crusts but rather represent huge bioclastic piles with only minor framestone patches preserved. An exception to this rule is represented by the high-energy, coral-‘algal’ Ota Reef from the Kimmeridgian of the Lusitanian Basin (Portugal). The narrow Ota Reef tract rims a small intra-basinal carbonate platform exhibiting perfect facies zonation (from W to E: Reef tract, back reef sands, peritidal belt, low-energy shallow lagoon). The reef is dominated by massive corals (Thamnasteria, Microsolena, Stylina). Complete preservation of coral framework is rare: like other Upper Jurassic high-energy reefs, the Ota Reef is very rich in debris; however, this debris is largely stabilized by algal and microbial crusts, what contrasts the other examples and gives the Ota Reef the appearance of a typical modern high-energy coral-melobesioid algal reef. Further similarities to modern reefs are the likely existence of a spur-and-groove system, the perfect sheltering of inner platform areas and the occurrence of small islands, as indicated by local blackenings and early vadose and karstic features.     

Theropod and possible ornithopod track assemblages from the Jurassic–Cretaceous boundary Houcheng Formation,Shangyi, northern Hebei,China

Dinosaur track assemblages from the Houcheng Formation in the small continental Shangyi Basin of northern Hebei Province, China bridge a gap in the record of vertebrates from this unit and enrich our knowledge of ichnofaunas from the Jurassic–Cretaceous boundary. Their stratigraphic position between the Middle Jurassic Yan-Liao Biota and the Lower Cretaceous Jehol Biota gives them a special importance. New discoveries allow a re-assessment of theropod and possible ornithopod tracks that are present with several trackways. Seventy-three footprints were examined and documented. Despite their smaller size, the tridactyl mesaxonic theropod tracks show morphological similarities with the ichnogenus Therangospodus known from the Upper Jurassic deposits of North America, Europe, and Central Asia. The possible ornithopod tracks lack an associated manus imprint, suggesting a bipedal trackmaker. These possible ornithopod tracks from the Houcheng Formation provide evidence for the presence of small basal ornithopods or basal Cerapoda in the Upper Jurassic–Lower Cretaceous in this region. The depositional environment was the margin of an extensive shallow lake with fluctuating water levels under seasonally dry climate.     

新疆准噶尔盆地侏罗纪石树沟组上部一大型兽脚类跖骨

准噶尔盆地中侏罗世晚期到晚侏罗世早期沉积的石树沟组产出过包括多种兽脚类恐龙在内的大量脊椎动物化石。描述了一件新的采自准噶尔盆地东北缘五彩湾地区石树沟组上部的兽脚类恐龙左第四跖骨标本(IVPPV18060)。通过与其他兽脚类恐龙第四跖骨对比,该标本可归入异特龙超科(Allosauroidea)。它与其他异特龙超科第四跖骨的相似性包括:近端关节面三角形并有一向后方延伸的舌状突出,向外侧轻微弯曲的骨干,位于骨干后方靠近外侧边的半月形肌肉凹陷,三角形骨干横截面。在异特龙超科当中,V18060与准噶尔盆地将军庙地区石树沟组中发现的董氏中华盗龙(Sinraptordongi)最为相似(除了以上相似性,V18060和董氏中华盗龙的相似性还包括远端关节轮廓呈近梯形,骨干后部肌肉凹陷与周围边界呈半开放状态)。但是,V18060和董氏中华盗龙也存在着一些明显的区别:V18060明显比董氏中华盗龙的第四跖骨粗壮,远端内外两髁大小差异相反。这些形态差异可能是由于个体发育或者性双形造成的,也可能代表分类学差异。对比研究和基于第四跖骨形态信息进行的分支系统学分析结果更偏向后一种解释:V18060代表一个不同于董氏中华盗龙但与后者亲缘关系很近的新的兽脚类恐龙。新材料的发现增加了中晚侏罗世石树沟动物群兽脚类恐龙的分异度。在五彩湾和将军庙地区发现不同的中华盗龙类恐龙指示了晚侏罗世早期准噶尔盆地中相邻地区可能存在着一定的生态分异性或者地理隔离。     

A tyrannosauroid dinosaur from the Upper Jurassic of Portugal

Fragmentary theropod remains from the Upper Jurassic (Kimmeridgian) of Guimarota, Portugal, represent a new taxon of theropod dinosaurs, Aviatyrannis jurassica gen. et sp. nov. Together with Stokesosaurus from the Morrison Formation of North America, Aviatyrannis represents the oldest known tyrannosauroid, indicating that tyrannosauroid origins may be found in the Middle–Late Jurassic of Europe/North America. Furthermore, current evidence suggests that early tyrannosaurs were rather small animals, which is in general accordance with their origin amongst the generally rather small coelurosaurs.     

Osteology and relationships of a new theropod dinosaur from the Middle Jurassic of Patagonia

Abstract:  A new taxon of theropod dinosaur is described as Condorraptor currumili gen. et sp. nov., from the Middle Jurassic (Callovian) Cañadón Asfalto Formation of Chubut Province, Argentinean Patagonia. The taxon is represented by a single fragmentary postcranial skeleton. Although incompletely known, Condorraptor is the second most complete theropod from the Middle Jurassic of Gondwana. The new taxon is characterized by the absence of a posterior incision between the fibular condyle and the medial side of the proximal articular end of the tibia, the pleurocoels in the anterior cervicals being situated posteroventral to the parapophyses, and the presence of a pronounced 'step' between the distal articular facet and shaft of Mt IV. Pneumatic features of the vertebral column show strong variation between the left and right side. Condorraptor gen. nov. can be referred to the Tetanurae and is a representative of a global radiation of basal tetanurans in the Early to Mid Jurassic.     

重庆晚侏罗世两处兽脚类足迹组合与四川盆地侏罗纪地层(英文)

重庆市已报道了4处侏罗纪的恐龙足迹点,包括下侏罗统珍珠冲组的大足化石点,该地点发现了中国迄今最古老的蜥脚类行迹;另外两处化石点(南岸和金鸡)的层位曾被视为中或上侏罗统,这里首次将其确认为上侏罗统上沙溪庙组;第4处化石点(成渝), 本文全部作者目前都未曾观察,这里不做描述。南岸化石点是南岸重庆足迹(Chongqingpus nananensis)模式标本的所在地,位于重庆市中心,曾发现过大量兽脚类足迹,如今已消逝在城市化进程中。幸运的是,这批标本被保存于重庆自然博物馆,本文作者曾前后两次对其进行研究,并得出文中的结论。南岸重庆足迹为中型足迹(平均长约29 cm), 最可能被卡岩塔足迹(Kayentapus)所囊括,这批标本中有一些保存着边界不清的拇趾迹。该化石点的其他足迹被归于似异样龙足迹(cf. Anomoepus)。其他较小的、来自重庆市周边中侏罗统中部的足迹此前已被归于跷脚龙足迹(Grallator)。金鸡化石点保存了一条孤立的兽脚类行迹,因其粗壮的特征而被暂时归于似窄足龙足迹(cf. Therangospodus)。金鸡点的行迹也保存了非连续出现的拇趾迹。虽然重庆市和四川盆地及其周边更广泛地区之侏罗纪地层发现的兽脚类足迹日渐增多,但要明确其确切地质年龄及有效的足迹分类依然需要进一步工作。这是因为侏罗纪的恐龙足迹尽管丰富,但显示出连续变化的形态学特征,而保存状况的变化更使其难以在时间与空间上做出定义与鉴别。