Vertebrate Tracksites in the Middle Jurassic-Upper Cretaceous of South Tunisia

Four vertebrate tracksites from the Middle Jurassic and Upper Cretaceous in the Tataouine basin of southern Tunisia are described. Approximately 130 tridactyl footprints distributed over an area of 200 square meters, preserved on Callovian beds exposed at the Beni Ghedir site, represent the oldest evidence of a dinosaur fauna in Tunisia. In addition, three tracksites—Chenini, Ksar Ayaat, and Jebel Boulouha—have been discovered in the Cretaceous beds of the upper Continental Intercalaire, previously considered as a strictly marine depositional sequence. In addition to dinosaur tracks, the Chenini tracksite (late Albian) includes poorly preserved crocodilian tracks, and footprints assigned to a pleurodiran turtle have been recovered at the Ksar Ayaat locality (early Cenomanian). The Jebel Boulouha tracksite is dominated by well-preserved tridactyl tracks referred to small-sized theropods. Depositional settings of each tracksite have been defined on stratigraphic and sedimentologic data, and tracks were ascribed to different ichnocoenoses in relation to their paleoenvironments. This new and differentiated track record gives important information on how the fossil vertebrate fauna changed in southern Tunisia during mid-Jurassic to mid-Cretaceous times. These data provide a unique and useful census of tetrapod associations along the southern margin of the peri-Mediterranean area.     

Dinosaur Tracks as Paleogeographic Constraints: New Scenarios for the Cretaceous Geography of the Periadriatic Region

A really unexpected finding of sauropod and theropod footprints in southern Latium raises to four the number of the trampled levels recognized in central and southern Italy. After the recent findings in Latest Jurassic and Early, mid and Late Cretaceous carbonate platform deposits of the Periadriatic region, dinosaur footprints seem to provide very important paleogeographic constraints for reconstructing the geodynamic history of the Mediterranean area. The presence of a varied ichnoassociation makes acceptance of the current paleogeographic models concerning the relative and absolute position of the Laziale-Abruzzese-Campano and of Apulian-Dinaric domains during the Late Cretaceous more and more problematic. Dinosaur footprints, combined with other paleontological data, demonstrate that these areas were never completely pulled apart by deep seaways, while frequent or continuous links between them, and to southern and northern mainlands, probably persisted. These data also allowed us to improve our understanding of the timing of the Mesozoic plate motion in this segment of the Western Tethys.     

内蒙古查布地区下白垩统巨齿龙足印化石

内蒙古鄂尔多斯市鄂托克旗查布地区下白垩统中产有大量的蜥脚类和兽脚类恐龙足迹及鸟类足迹化石,作者对这个地区的足迹化石进行全面普查,发现许多新暴露出来的恐龙足迹化石,包括兽脚类恐龙足迹一新属新种Chapuslockleyiichnogen.etichnosp.nov.属于巨齿龙类(megalosaurid)所留。与兽脚类足迹保存在一起的蜥脚类足迹Brontopodusbirdi分布凌乱,反映了造迹恐龙搏斗的场面。通过测量连续的兽脚类足迹计算,Chapuslockleyi的造迹恐龙的行走速度为4.33km/h。通过足迹化石还识别出造迹恐龙的病态特征。     

安徽省黄山地区恐龙(足迹)脚印化石的初步研究

简要报道了安徽省黄山地区所发现的恐龙足迹化石。从脚印的形态和足迹上看,至少有三种不同的恐龙（蜥脚类、兽脚类、鸟脚类）共同生存过,其中多数恐龙为两足行走性的。记述了两个典型的小型兽脚类和小型鸟脚类恐龙所留下的脚印化石。黄山地区恐龙足迹、骨骼化石及其蛋化石的发现,对于研究晚白垩世恐龙生活习性以及古气候环境均有着一定的意义。     

Dinosaur footprints from the Sao Khua Formation (Early Cretaceous) of Phu Kao National Park,Northeast Thailand

The first documented dinosaur footprints from Southeast Asia were theropod footprints found in Thailand at Phu Luang Wildlife Sanctuary. Since then, Mesozoic vertebrate footprints have been discovered in twelve different localities in Thailand. In 2000, dinosaur footprints were found in Phu Kao National Park in Northeastern Thailand, however, they have never been studied in detail. The following study presents the first map, the complete measurements, the geology, and stratigraphy of the site and surrounding area. The study discusses the nature of the trackmaker and the digitigrade character of the footprints. This discovery represents the first documented occurrence of dinosaur footprints inside the Early Cretaceous Sao Khua Formation from Thailand.     

Valdosaurus, a hypsilophodontid dinosaur from the Lower Cretaceous of Europe and Africa

Material of the hypsilophodontid dinosaur Valdosauruscanaliculatus (Ornithischia: Ornithopoda) is described from the Lower Cretaceous (Barremian) of southern England and a new species is recognized from the Lower Cretaceous (Aptian) of Niger, West Africa. This occurrence of Valdosaurus in Europe and Africa provides evidence of a land connection between these continents across Tethys sometime in the early Cretaceous.     

First evidence of stegosaurian Deltapodus footprints in North Africa (Iouaridène Formation, Upper Jurassic, Morocco)

Abstract:  New findings of dinosaur footprints are described from the Upper Jurassic Iouaridène ichnosite of Morocco. On the top of two surfaces, stratigraphically close to that bearing the famous Breviparopus taghbaloutensis trackways, two footprints were excavated and assigned to the ichnogenus Deltapodus . This ichnogenus is well known from the Middle Jurassic of Yorkshire and also occurs in Upper Jurassic deposits from Iberia and the United States. This finding represents the first record of Deltapodus from Africa. These footprints, probably produced by stegosaurian dinosaurs, add new data on the distribution of this type of dinosaur and on the connection between the northern and southern margin of Tethys. 3D models have been generated to allow more detailed studies and to record these unique footprints.     

Los Cayos Dinosaur Tracksite: An Overview on the Lower Cretaceous Ichno-Diversity of the Cameros Basin (Cornago,La Rioja Province,Spain)

The Los Cayos dinosaur tracksite is located at the eastern sector of the Cameros Basin (Cornago Township, La Rioja province), NE Spain. The sediments consist of interbedded terrigenous siliciclastics and carbonates belonging to the Enciso Group (Early Cretaceous, Aptian in age). The sedimentological and faunal evidence suggests that these sediments were deposited in a low gradient lacustrine environment. Los Cayos constitutes a relatively wide area with at least 6 localities that have yielded dinosaur tracks. More than 2,000 dinosaur tracks have been discovered to date. Medium to large theropod dinosaurs constitute about 95% of the ichnofauna. Ornithopod dinosaur tracks have been reported from only one of the outcrops (Los Cayos D). Los Cayos S has yielded theropod and sauropod tracks. One sauropod trackway shows a narrow-gauge locomotion pattern and a manus print morphology suggesting that the trackmaker was a titanosaurid, or at least a titanosauriform sauropod. Some pterosaur manus impressions, avian-like footprints of small size and possible turtle tracks complete the assemblage of one of the most impressive and best-preserved dinosaur tracksites of the European Lower Cretaceous.     

Deux nouveaux sites à traces de pas dinosauroïdes dans la Formation Dolomitique de l’Hettangien de Lozère,Languedoc-Roussillon,France

Recent ichnological studies revealed two new localities showing dinosaur footprints in the Hettangian Dolomitic Formation from the Causses Basin, southern France. The traces are reported from the northern part of the basin, in Lozère, an area where Lower Jurassic dinosaur ichnites were poorly documented. The surfaces bearing footprints are characterized by a large number of traces. The ichnites are ascribed to Grallator (Hitchcock, 1858), Dilophosauripus (Welles, 1971) and Eubrontes (Hitchcock, 1845) whose trackmakers were theropods. Although numerous tracksites were previously described in the southern part of the Causses Basin, these three ichnotaxa are for the first time observed in association into the Dolomitic Formation.     

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.     

Were some dinosaurs gregarious?

A careful survey of the dinosaur footprints and trackways (identified as Eubrontes, Anchisauripus and Grallator) at the Mt. Tom site north of Holyoke, Massachusetts, and plots of their orientations reveal that an improbable percentage (70%) of the tracks are oriented in a nearparallel course. All but one of these coincident ancient traverses were probably made by the same kind of Triassic dinosaur (the footprints of which are referred to as Eubrontes). Comparable trackway orientation patterns have been reported by Albritton (1942) near Comanche, Texas for an Early Cretaceous dinosaur (iguanodobntid?) and Bird (1941, 1944) cited paralled sauporod trackways of Early Cretaceous age near the Paluxy River in Texas. Probability dictates that these sub-parallel traverses were not independent events and the presence of other deviating trackways at all three sites indicates that the trackmakers probably were not confined in their passage by physical barriers. Furthermore, the coincidental occurrence of such natural barriers at all of the sites mentioned here seems highly improbable. the combinedevidence of the Massachusetts site and the two Texas localities, together with the apparently widespread occurrence of dinosaur trackway lineation, strongly indicates gregarious habits for several different kinds of dinosaurs.     

Las cerradicas tracksite (Berriasian,Galve, Spain): Growing evidence for quadrupedal ornithopods

Dinosaur footprints occur in shallow marine sedimentary units of the Berriasian Villar del Arzobispo Formation in the Aliaga basin, NE Spain. Las Cerradicas is a small outcrop (25 m²), near Galve, with four dinosaur trackways. Three tridactyl trackways indicate bipedal animals, and have parallel orientation. A fourth or‐nithopod trackway indicates a quadrupedal animal and is the smallest among any reported in the literature (L = 23 cm, W = 23 cm of pes tracks). It has manus prints that are oval‐shaped impressions. These and other recent discoveries shed much light on the abundance of quadrupedal ornithopods during the early Cretaceous.     

Biometric and morphometric approaches on Lower Hettangian dinosaur footprints from the Rodez Strait (Aveyron,France)

Along the southern crystalline border of the Rouergue, the detrital Sandstones-variegated Mudstones Formation and the Dolomitic Formation yields numerous dinosaur footprints from the Earliest Hettangian. Among the 25 sites distributed along the 40 km-long transect between Marcillac-Vallon and Saint-Geniez-d’Olt, two of them, Puech de Castres and Le Bouyssou, have yielded abundant ichnites in various well-defined stratigraphic units. The combined analysis of these footprints with biometric and morphometric methods (Fourier analysis) warrants their identification to Grallator, Eubrontes and Dilophosauripus. The dual methodological approach also reveals two new morphotypes previously unknown in the Causses Basin. Moreover, the footprints assigned to Grallator and Eubrontes tend to be morphologically similar, suggesting that they might correspond to a same taxon of Coelophysoidea theropod at different growth stages. This dinosaur fauna was living in a vast floodplain, in which fluvial channels carried southward the detrital material coming from the Rouergue substratum. The Dolomitic Formation was deposited in the context of a northward marine transgression during which shallow and aerial environments prevailed in the area.     

Review of Japanese Dinosaur Track Localities: Implications for Ichnotaxonomy,Paleogeography and Stratigraphic Correlation

Nine dinosaur ichnospecies from the Lower Jurassic to Upper Cretaceous of Japan, including two that are new, are described herein. The new ichnotaxa are Asianopodus pulvinicalx ichnogen. et ichnosp. nov. and Schizograllator otariensis ichnosp. nov. The Japanese ichnotaxa are allied to Lower Jurassic ichnospecies in South China, North America, Western Europe and South Africa, and Upper Jurassic to Lower Cretaceous ichnospecies from Southeast and East Asia. This suggests they were part of a global ichnofauna before continental drift began in the Middle Jurassic, leading to the development of a more endemic dinosaur fauna in the Cretaceous. At least two assemblages, an ornithopod-gracile-toed theropod-dominated community, in northeastern Asia, and a robust theropod- and sauropod-dominated community in the southern part of the continent, existed in the Cretaceous. This parallels North American dinosaur distribution patterns in the Cretaceous and seems to be a reflection of paleolatitudinal controls.     

An enigmatic early mesozoic dinosaur trackway from Zimbabwe

A trackway from Zimbabwe of probably the smallest dinosaur footprints recorded in Africa, is described and tentatively assigned to the Early Jurassic. The footprints are possibly those of a theropod and show strong negative (outward) rotation of the pes and are associated with manus prints. The shape of the footprints, unusual negative rotation, posterior curvature of digit IV and curious positioning of the manus prints in relation to the pes are enigmatic but somewhat reminiscent of Atreipus. Although a number of propositions are considered the most likely is that the animal was an immature dinosaur using a quadrupedal gait. A second trackway of slightly larger footprints of a bipedal theropod dinosaur is also recorded along with other diminutive tracks that suggest an early dinosaur assemblage, possibly dating from near the Trias‐sic‐Jurassic boundary.     

Shape variability in tridactyl dinosaur footprints: the significance of size and function

The functional anatomy of the hindlimb of bipedal dinosaurs has been intensively studied. Yet, surprisingly little work has been done concerning functional adaptation of digits for terrestrial locomotion. While complete and articulated pes skeletons are scarce, pes shape is abundantly recorded by fossil footprints. We elucidate the significance of footprint shape and size for locomotion using a large sample (n = 303) of tridactyl dinosaur footprints from a broad range of geographical localities and time slots. Size and shape variation are characterized separately for theropods and ornithischians, the two principal trackmaker taxa. At smaller sizes, theropod footprints are best discriminated from ornithischian footprints by their smaller interdigital angle and larger projection of digit III; at larger sizes digital widths are effective discriminants. Ornithischian footprints increase in size from the Early Jurassic to the Late Cretaceous, a trend not observed in theropod footprints. Size and function are argued to be important determinants of footprint shape, and an attempt made to infer function from shape. Digit III projection and length-to-width ratio of the footprints are negatively correlated with size in both groups; digit impression width is positively correlated with size only in ornithischians. Digit III projection appears to be positively correlated with cursorial ability. Increased interdigital angles are associated with a decrease in digital width, possibly an adaptation for stability. Weak digit III projection and increased digital width are interpreted as adaptations for graviportality. Footprints yield great potential for the understanding of the functional morphology of dinosaur feet.     

Considerations on the age of the Tiouaren Formation (Iullemmeden Basin,Niger, Africa): Implications for Gondwanan Mesozoic terrestrial vertebrate faunas

Pre-Aptian mid-Mesozoic terrestrial vertebrates from the African continent are still very poorly known. In Niger, the Tiouaren Formation in the Iullemmeden Basin has yielded dinosaur and other vertebrate remains, and this unit has been dated as Early Cretaceous, most probably pre-Aptian, on the basis of its fish fauna and geological relations to other units in the basin. A review of the fish fauna and invertebrates from this formation does not provide any evidence for such an age, and the geological relations only help to constrain the upper limit for the age of the formation (Aptian). In contrast, the described dinosaur taxa are phylogenetically nested with late Middle Jurassic to Early Late Jurassic taxa from other localities, and thus indicate a pre-Kimmeridgian, probably late Middle Jurassic age for the Tiouaren Formation. Under the assumption of such an age, the dinosaur fauna of this formation provides new insights into dinosaur faunal provincialism during the latest Middle Jurassic. Northern Gondwanan faunas of that time seem to have been different from southern Gondwanan faunas, and show closer affinities to Eurasian faunas than to the latter. A possible explanation for this might be a climatically controlled geographic barrier due to pronounced arid conditions and thus desert environments in central Gondwana during this time.     

The extinction of the dinosaurs

Non‐avian dinosaurs went extinct 66 million years ago, geologically coincident with the impact of a large bolide (comet or asteroid) during an interval of massive volcanic eruptions and changes in temperature and sea level. There has long been fervent debate about how these events affected dinosaurs. We review a wealth of new data accumulated over the past two decades, provide updated and novel analyses of long‐term dinosaur diversity trends during the latest Cretaceous, and discuss an emerging consensus on the extinction's tempo and causes. Little support exists for a global, long‐term decline across non‐avian dinosaur diversity prior to their extinction at the end of the Cretaceous. However, restructuring of latest Cretaceous dinosaur faunas in North America led to reduced diversity of large‐bodied herbivores, perhaps making communities more susceptible to cascading extinctions. The abruptness of the dinosaur extinction suggests a key role for the bolide impact, although the coarseness of the fossil record makes testing the effects of Deccan volcanism difficult.     

Hoof-Like Unguals,Skin, and Foot Movements Deduced from Deltapodus Casts of the Galve Basin (Upper Jurassic-Lower Cretaceous,Teruel, Spain)

Galve (Teruel, Spain) is a town in the interior of a synclinal fold with Upper Jurassic marine limestones along its flanks, and, in its core, Upper Jurassic–Lower Cretaceous continental and shoreline sediments crop out. The core sediments cover an area about 8 km², and contain a concentration of sites with footprints, bones, and eggshells of dinosaurs. The footprints are both shafts and natural casts. Some casts are attributed to stegosaurs (Deltapodus). The Deltapodus casts are characterized by features that allow us to make direct observations on the skin formed by polygonal scales, and ellipsoidal “hooves,” as well as deductions on the movement of the limbs during walking. According to the opinion of some authors, dinosaur footprints are indicators of the motion of their limbs and sometimes of the whole body. So far, results have been deduced from theropod, ornithopod, and sauropod footprints. This article shows the results obtained from analis of the aforementioned Deltapodus casts, i.e., forelimb movement similar to that of the forelimbs of sauropods, and the rigid structure of the autopodial part of the hind limb.     

Dinosaurs and the Cretaceous Terrestrial Revolution

The observed diversity of dinosaurs reached its highest peak during the mid- and Late Cretaceous, the 50 Myr that preceded their extinction, and yet this explosion of dinosaur diversity may be explained largely by sampling bias. It has long been debated whether dinosaurs were part of the Cretaceous Terrestrial Revolution (KTR), from 125-80 Myr ago, when flowering plants, herbivorous and social insects, squamates, birds and mammals all underwent a rapid expansion. Although an apparent explosion of dinosaur diversity occurred in the mid-Cretaceous, coinciding with the emergence of new groups (e.g. neoceratopsians, ankylosaurid ankylosaurs, hadrosaurids and pachycephalosaurs), results from the first quantitative study of diversification applied to a new supertree of dinosaurs show that this apparent burst in dinosaurian diversity in the last 18 Myr of the Cretaceous is a sampling artefact. Indeed, major diversification shifts occurred largely in the first one-third of the group's history. Despite the appearance of new clades of medium to large herbivores and carnivores later in dinosaur history, these new originations do not correspond to significant diversification shifts. Instead, the overall geometry of the Cretaceous part of the dinosaur tree does not depart from the null hypothesis of an equal rates model of lineage branching. Furthermore, we conclude that dinosaurs did not experience a progressive decline at the end of the Cretaceous, nor was their evolution driven directly by the KTR.